JP2003149038A - Load cell and electronic weighing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a weighing machine which is thin and light, and facilitates fitting of load cells between a stage and legs. SOLUTION: A rectangular stage 12, load cells 20 arranged at the four corners of the rear side of the stage 12 and have planar strain producing portions 24, and a computing means 30 for totalizing the load signals of the load cells 20, and a display means 40 for digital-displaying a measured value of the computing means 30, legs 14 fitted to the strain portions 24 of the load cells 20, and hard balls 18 which are arranged between the strain portions 24 and the legs 14 and transmit loads. Hard ball supporting recessions 16a are formed in the upper surfaces of the legs 14, and the hard balls 18 touch the undersides of the strain portions 24. Since the legs 14 also function as fitting members for fitting the hard balls 18, hard ball fitting members for exclusive use which are required conventionally can be dispensed with. Accordingly, the number of components required for a weighing machine becomes smaller to that extent, and its structure also becomes concise. The machine becomes thin and light, and load cell fitting work becomes simpler too.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat plate type load cell arranged on the back side of a mounting table and a weight scale equipped with the flat plate type load cell.

[0002]

2. Description of the Related Art FIG. 13 shows a conventional weight scale (actual flat panel 4-) having load cells 2 arranged at four corners on the back side of a mounting table 1.
No. 106731). The load cell 2 has a structure in which a spectacle-shaped lateral hole 3 is provided in a thick rectangular block-shaped metal material to form a thin strain element 2a, and a strain gauge 8 is attached to the strain element 2a. The weighted portion of the load cell 2 is connected to the mounting table 1 via the hard ball 7, and the fixed portion of the load cell 2 is fixed on the base 4 having the legs 5. Reference numerals 6a and 6b are hard ball mounting members that are interposed between the mounting table 1 and the load cell 2 and configured to support the hard balls 7.

[0003]

In the conventional scale described above, a thick rectangular block material is used as the load cell 2, and the load cell 2 and the mounting table 1 are provided with a pair of upper and lower hard ball mounting members 6a and 6b. Connected, and further,
Since the fixed part of the load cell 2 is fixed on the base 4 having the legs 5 at the four corners, the load cell 2 is arranged between the mounting table 1 and the base 4 because of the large number of parts constituting the weight scale and the complicated structure. In addition to the complicated mounting work, it was difficult to make the weight scale thin and lightweight.

Further, even if a flat plate load cell known in the related art is used to reduce the thickness, the weight scale has a simple structure due to the presence of the hard-ball mounting members 6a and 6b and the base 4. There was a limit to improving the performance and reducing the thickness and weight.

The present invention has been made to solve the above-mentioned problems of the prior art. A first object of the present invention is to provide a load cell which can be easily attached and fixed to a mounting table and which allows a weight scale to be made thin. The second purpose is to provide a load cell in which the legs can be easily attached and fixed, and the weight scale can be made thin. The third purpose is to simplify the structure so that the weight between the mounting table and the legs can be reduced. An object of the present invention is to provide a thin and lightweight scale that allows easy attachment of a load cell.

[0006]

[Means and Actions for Solving the Problems]
In order to achieve the above object, in the load cell according to claim 1, it is a flat plate type load cell arranged on the back side of the mounting table, and a corner arrangement in which a part of the outer shape is formed in the same shape as the corner portion of the mounting table. Part, a slit provided in the center,
Formed by the slit, comprising a strain-generating part which is a cantilever supported in a cantilever manner, and a strain gauge arranged on the base side of the strain-generating part, and the outside of the slit is attached to the mounting table. Configured to do so. (Operation) Since the corner placement portion of the load cell and the corner portion of the mounting table have the same shape,
By arranging the corner arranging portion of the load cell at the corner portion of the mounting table, the load cell can be easily aligned, and the arranging work of the load cell on the back side of the mounting table becomes quick and accurate.

Further, since the outside of the slit of the load cell composed of one plate serves as a mounting portion to the mounting table, a dedicated mounting member conventionally required is not necessary, and the number of parts constituting the scale is reduced accordingly. Less. Further, since the load cell is fixed to the mounting table, the mounting work is easier than before and the scale can be flattened.

In order to achieve the above-mentioned second object, the load cell according to a second aspect is a flat plate type load cell arranged on the back side of the mounting table, wherein a slit provided at the center and the A strain gauge formed by a slit and having a shape that substantially follows the outer shape of the leg that is attached to the lower side by cantilever support, and a strain gauge that is arranged on the base side of the strain strain section are provided. The distal end side is configured to be the attachment portion of the leg. (Operation) Since the distal end side of the strain-flexing portion of the load cell serves as the leg mounting portion, a dedicated mounting member that has been conventionally required is not necessary, and the number of parts constituting the weight scale is reduced accordingly. Also,
Since the legs can be attached to the strain-flexing part, the attaching work is easy and the scale can be made flat.

In order to achieve the above-mentioned third object, in an electronic scale according to a third aspect of the present invention, a rectangular mounting table and four flat corners arranged on the back four corners of the mounting table are provided. A load cell having a strained portion, a calculation means for totalizing load signals of the load cell, a display means for digitally displaying a weight value of the calculation means, a leg attached to the strained portion of the load cell, and the strain generating portion. And a hard ball for transmitting a load disposed between the leg and the leg, a recess for supporting the hard ball is provided on the upper surface of the leg, and the hard ball is configured to contact the lower surface of the strain-flexing portion. (Function) A dedicated mounting member conventionally required for mounting a hard ball is not required, and the number of parts constituting the scale is reduced accordingly. Also, since the leg also serves as a mounting member for mounting the hard ball, it is sufficient to mount the leg accommodating the hard ball in the concave portion for supporting the hard ball on the strain-flexing portion, and the mounting work is easy.
The scale can be flattened.

According to a fourth aspect of the present invention, the leg according to the third aspect uses a metal plate provided with a recess for supporting a hard ball and a screw hole for fastening a strain-flexing portion, and the leg is formed by a resin or rubber molded body. I configured it. (Operation) The metal plate provided with the concave portion for supporting the hard ball is made of a metal material having high hardness, the concave portion for supporting the hard ball is hard to wear, and the rotating function of the hard ball is not impaired for a long time. Further, the resin layer or the rubber layer covering the lower surface of the leg does not damage the floor surface and absorbs some unevenness of the floor surface.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Next, preferred embodiments of the present invention will be described in detail based on examples.

1 to 8 show a weight scale according to a first embodiment of the present invention. FIG. 1 is a plan view of the weight scale, FIG. 2 is a bottom perspective view of the weight scale, and FIG. Vertical cross-sectional view of the scale (cross-sectional view taken along line III-III shown in FIG. 1), FIG. 4 is a vertical cross-sectional view of the same scale (cross-sectional view taken along line IV-IV shown in FIG. 1), and FIG. 6 is a plan view of the leg, and FIG. 7 is a longitudinal sectional view of the leg (a line VII-V shown in FIG. 6).
FIG. 8 is a perspective view of a metal disk insert-molded on the leg.

In these figures, a scale 10 includes a mounting base 12 having a square shape in plan view, which is formed so that a person can ride on it, and legs 14 provided below the four corners of the mounting base 12, respectively. The load cell 20 interposed between the lower surface of the mounting table 12 and each leg 14, and an operation control unit (CP) that is an operation unit that adds up load signals detected by the load cell 20.
U) 30 and a display unit 40 which is exposed on the surface side of the mounting table 12 and which is a display unit for digitally displaying the calculation result (measured value) of the calculation control unit (CPU) 30.

The load cell 20 is constructed by attaching a strain gauge 28 to a strain-generating portion 24 of a flat-plate strain-generating body 21. More specifically, as shown in FIG. 5, a slit 2 extending in a substantially U-shape is formed substantially in the center of a pentagonal metal plate body.
By forming 2, the strain element 21 having the cantilever type strain element 24 is configured, and the strain gauge 28 is attached to the narrow base portion of the strain element 24 of the strain element 21. Then, it becomes the load cell 20. That is, as shown by symbol P in FIG. 4, when a load is applied to the mounting table, the U-shaped slit 22
The tongue-shaped strain-generating portion 24 surrounded by oscillates upward with respect to the strain-generating-member peripheral region 23 outside the slit 22, and the strain generated in the strain-generating portion 24 at this time passes through the strain gauge 28. Detected.

On the back side of the four corners of the mounting table 12, a strain-flexing part 24 is provided.
Member 26 for securing the upper swinging space of the
Are fixed by welding, bonding, or other fixing means, and screw holes 23a are provided at equal intervals in the flexure element peripheral region 23. The screw holes are also formed in the horseshoe-shaped spacer member 26 integrated with the mounting table 12. A screw hole 26a corresponding to 23a is provided. The load cell 20 (strain element peripheral region 23) is screwed to the spacer member 26 by aligning the screw holes 23a and 26a with each other. That is, the outside of the slit 22 of the load cell 20 is fixed to the mounting table 12 by the fastening screw 26b.

Further, the corner placement portion 20a of the load cell 20 (strain element 21) corresponding to the right-angled corner portion of the mounting table 12 is provided.
Is formed with a vertical angle of 90 degrees, and as shown in FIG.
When the corner placement portion 20a of the load cell 20 is engaged with the right angled corner portion of the mounting table 12 turned upside down, the screw hole 23a of the load cell 20 and the screw hole 26b of the spacer member 26 are aligned, so that the load cell 20 can be easily mounted on the mounting table 12. Can be attached to.

Further, the distal end side 24a of the strain-flexing portion 24 is connected to the leg 1
4 is formed in an arc shape almost the same as the outer shape (circular shape) of FIG.
Screw insertion holes 24b, 24b for inserting 7 are provided. Then, the legs 14 are attached and fixed to the lower surface of the strain-flexing portion 24 via the hard balls 18 by the screws 27,
The eccentric load acting on the load cell 20 is absorbed by the hard balls 18.

That is, in the center of the upper surface of the leg 14, a concave hole (recess) 16a which is a hard ball bearing portion is provided, and a pair of screw holes 16b and 16b are provided so as to sandwich the concave hole 16a. On the other hand, the screw insertion hole 24b on the strain-flexing portion 24 side is
The strain-flexing portions 24 are provided so as to be separated from each other in the direction orthogonal to the extending direction of the strain-flexing portions 24 (the width direction of the tongue-shaped strain-generating portions 24).
The screw 27 inserted through the screw insertion hole 24b of the
By being screwed into 6b, the hard ball 18 housed in the recessed hole 16a is held in a state of contacting the lower surface of the strain-flexing portion 24. Reference numeral 19 in FIGS. 3 and 5 is a metal collar that is inserted into the screw insertion hole 24b and is interposed between the lower surface of the head of the screw 27 and the peripheral portion of the screw hole 16b.
It is designed not to apply excessive load (pressure contact force) to the.

Further, as shown in FIGS.
Is formed of a resin molded body into which a disc 16 made of a high-hardness metal (for example, SK material) as a core material is inserted. The upper surface of the disk 16 has a recessed hole 1 which is a hard ball bearing.
6a and a screw hole 16b for screwing the screw 27 are formed, and the concave hole 16a and the screw hole 16b are exposed above the leg 14 through the opening of the surface resin layer. Further, the disk 16 may have a structure covered with rubber instead of resin.

Considering that the strain element 24 of the load cell 20 also holds the strain element 24 in contact with the hard ball 18, the disk 16 provided with the concave hole 16a serving as the hard ball bearing portion. Like SK, it is desirable that the SK material is hard to wear.

Then, as shown in FIG. 5, the hard ball 18 is housed in the recessed hole 16a of the leg 14, and the insertion hole 24b of the strain-flexing portion 24 is inserted.
By inserting the collar 19 and the screw 27 into the screw, and screwing the screw 27 into the screw hole 16 b of the leg 14,
Can be easily attached and fixed to the strain-flexing portion 24, and the hard ball 18 can be held in a form supported by the recessed hole 16.

Further, although the strain-flexing portion 24 and the leg 14 are fastened together by a pair of screws 27, 27, since there is a minute gap between the insertion hole 24b, the collar 19 and the screw 27,
When a load is applied to the mounting table 12, the strain-flexing portion 24 and the leg 14
Is the horizontal axis L that mainly passes through the pair of screws 27, 27 and the hard ball 18.
Relative tilting around x (the hard ball 18 rotates at this time) absorbs an eccentric load, and a load signal corresponding to an appropriate strain that is not affected by the eccentric load is detected. That is, as shown in FIG. 1, in each load cell 20, the extending longitudinal directions Ly of the respective strain-flexing portions 24 are coincident with and orthogonal to each other at the center O of the mounting table 12, and the load acting on the mounting table 12 is increased. Acts on each strain-generating portion 24 as a force around the horizontal axis (tilt central axis) Lx of the strain-generating portion 24 orthogonal to the Ly direction, and the strain gauge 28
In, the load signal which is not affected by the unbalanced load is detected.

The leg 14 is attached to the tip end side 24a of the strain-flexing portion 24 extending toward the corner portion of the mounting table 12, and is arranged at a position close to the corner portion of the mounting table 12. Therefore, even if a load is applied to a portion other than the center of the mounting table 12, the legs 14 are located in the vicinity of the corners of the mounting table 12, so that the weight scale can maintain a stable state without wobbling.

Further, in the present embodiment, as described above, since the load cell 20 is interposed between the mounting table 12 and the leg 14 without using a separate mounting member, the weight scale is constructed. Load cell 2 with a small number of parts
The installation work of 0 is easy, and it is thin and lightweight.

9 and 10 show a main part of a weight scale according to a second embodiment of the present invention. FIG. 9 is an exploded perspective view of a load cell mounting part which is a main part of the weight scale, and FIG. It is a longitudinal cross-sectional view of a scale (a view corresponding to FIG. 3 in the first embodiment).

In the above-described first embodiment, the peripheral area of the load cell 20 (the peripheral area 23 of the flexure element) is fixed to the lower surface of the horseshoe-shaped spacer member 26. Then, the peripheral region of the load cell 20 (the peripheral region 23 of the flexure element) is fixed to the upper surface of the horseshoe-shaped flange portion 26c of the L-shaped spacer member 26A.

A flange portion 26c of the spacer member 26A is provided with a screw insertion hole 26d corresponding to the screw hole 23a formed in the flexure element 21, and the load cell 20 is provided with a flange portion 26c as shown by an arrow in FIG. When pushed in to slide along the load cell 20, the load cell 20
The holes 23a and the holes 26d are aligned with each other by being positioned at the second corner portion. Therefore, as shown in FIG. 10, the peripheral area of the load cell 20 (the peripheral area 2
3) can be easily fixed to the spacer member 26A.

Others are the same as those of the first embodiment described above, and the same reference numerals are given to omit the duplicated description.

FIG. 11 is a perspective view showing an essential part of the third embodiment of the present invention and showing the mounting structure of the load cell and the leg.

In the load cells 20 of the two embodiments described above, the strain-flexing portion 24 is configured to extend toward the corner arranging portion 20a. However, in the load cell 20A of the third embodiment, The portion 24 is configured to extend toward the opposite side of the corner placement portion 20a.

Others are the same as those of the first and second embodiments described above, and the same reference numerals are given to omit the duplicated description.

Further, in the above-mentioned embodiment, the load cell 2
Although the width of the slit 22 formed in 0 (flexure body 21) is constant, the width of the slit 22A may not be constant as shown in FIG.

In the above-described embodiment, the mounting table 12 has a rectangular shape, and the corner placement portion 20a of the load cell 20 has a 90-degree width.
Although the corners of the mounting table 12 and the corners of the load cell 20 are not limited to 90 degrees, as long as they have the same angle, Good.

[0034]

As described above, according to claim 1,
Since the load cell can be smoothly arranged at a predetermined position on the back side of the mounting table and the outside of the slit of the load cell can be easily fixed to the mounting table, the work of mounting the load cell on the mounting table becomes easy. In addition, the structure of the weight scale is simple, thin, and lightweight because the dedicated mounting member conventionally required is unnecessary.

According to the second aspect, the legs can be fixed to the load cell smoothly, so that the work for attaching the legs can be simplified. In addition, since the dedicated mounting member that was required in the past is unnecessary,
The structure of the scale is simple, thin and lightweight.

According to the third aspect of the present invention, the following effects can be obtained because a dedicated mounting member for mounting the hard balls and a base for providing the legs are unnecessary. First, the structure of the scale is simple. Second
In addition, the work of mounting the load cell becomes easy. Third,
The scale is thin and lightweight.

According to the present invention, the durability of the hard ball bearing portion is ensured, and the unbalanced load absorbing action of the hard balls is not impaired for a long period of time. Therefore, highly accurate weight measurement that is not affected by the unbalanced load is guaranteed. It Further, since the lower surface of the leg is formed of the resin layer or the rubber layer, the floor surface is not damaged and the weight scale can be seated well.

[Brief description of drawings]

FIG. 1 is a plan view of a weight scale according to a first embodiment of the present invention.

FIG. 2 is a bottom perspective view of the weight scale.

FIG. 3 is a vertical cross-sectional view (cross-sectional view taken along line III-III shown in FIG. 1) of the weight scale.

FIG. 4 is a vertical cross-sectional view (cross-sectional view taken along line IV-IV shown in FIG. 1) of the weight scale.

FIG. 5 is an exploded perspective view of a load cell attachment portion of the weight scale.

FIG. 6 is a plan view of a leg.

FIG. 7 is a vertical sectional view of the same leg (a sectional view taken along line VII-VII shown in FIG. 6).

FIG. 8 is a perspective view of a metal disk insert-molded on a leg.

FIG. 9 is an exploded perspective view of a load cell attachment portion of a weight scale according to a second embodiment of the present invention.

FIG. 10 is a vertical cross-sectional view of the weight scale (a view corresponding to FIG. 3 in the first embodiment).

FIG. 11 is a perspective view of a main part of a weight scale according to a third embodiment of the present invention.

FIG. 12 is a perspective view of a main part of a weight scale according to a fourth embodiment of the present invention.

FIG. 13 is a vertical sectional view of a conventional scale.

[Explanation of symbols]

10 Electronic Scale 12 Placement Table 14 Leg 16 Metal Disk 16a Recessed Hole (Recess) for Bearing Hard Ball 18 Hard Ball Absorbing Unbalanced Load Acting on Load Cell 20, 20A Flat Load Cell 20a Corner Arrangement Part 21 of Load Cell 22, 22A U-shaped slit 23 Peripheral region of strain-flexing body that constitutes a mounting / fixing portion with a mounting table 24 Tongue-shaped strain-flexing portion 24a Strain-deflecting portion tip side 26, 26A that constitutes a mounting / fixing portion with a leg Spacer member 26b Screws that fasten the mounting table and the load cell 27 Screws that fasten the load cell and the leg 28 Strain gauge 30 Arithmetic control unit (CPU) 40 Display unit

Continued front page    (72) Inventor Takayasu Sasaki             1-243 Asahi, Kitamoto City, Saitama Stock Market             A & D Development and Technology Center             Within F term (reference) 2F049 AA16 BA15 CA01 CA05

Claims (4)

[Claims] 1. A flat plate type load cell arranged on the back side of a mounting table, wherein a part of the outer shape is formed into a corner portion of the mounting table in the same shape, a slit provided in the center, and A strain-generating part formed of a slit, which is a tongue piece supported in a cantilever manner, and a strain gauge arranged on the base side of the strain-generating part are provided, and the outside of the slit is used as a mounting part to the mounting table. A load cell characterized in that 2. A flat plate type load cell arranged on the back side of a mounting table, which substantially follows the outer shape of a slit provided in the center and a leg formed by the slit and attached to the lower side by cantilever support. A load cell comprising: a strain-generating portion having a shape; and a strain gauge arranged on a base side of the strain-generating portion, wherein a tip side of the strain-generating portion serves as a mounting portion of the leg. 3. A rectangular mounting table, and a load cell arranged at four corners on the back side of the mounting table and having a flat plate-shaped strain generating section,
Arranged between the calculation means for totalizing the load signals of the load cell, the display means for digitally displaying the measured value of the calculation means, the leg attached to the strain-flexing part of the load cell, and the strain-flexing part and the leg. An electronic weight scale, comprising: a hard ball that is configured to transmit a load, a recess for supporting a hard ball is provided on an upper surface of the leg, and the hard ball contacts a lower surface of the strain-flexing portion. 4. The metal plate provided with a recess for supporting a hard ball and a screw hole for fastening a strain-flexing part is used as the leg, and the leg is made of a molded body inserted into resin or rubber. The electronic weight scale according to claim 3.