JPH0669756U - Weighing device - Google Patents

Abstract

(57) [Abstract] [Purpose] When measuring the weight of an article, each side of the frame is prevented from bending toward the center, and the weighing error due to this bending is eliminated, and the weighing accuracy is improved. To improve. A load applying portion 23 to which a load is applied, a frame 43 formed in an annular shape so as to surround the outer periphery of the load applying portion 23 and having a substantially square planar shape, and provided at each corner portion 45 of the frame 43. Strain elements 24, 25, 26, 27 that connect the frame body 43 and the load applying portion 23, and strain gauges 28 to 35 provided on the strain elements 24 to 27 are provided.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a weighing device provided with a strain gauge, such as a platform scale.

[0002]

[Prior art]

 FIG. 4 is a plan view showing an example of the conventional weighing device, and FIG. 5 is a cross-sectional view of the weighing device shown in FIG. As shown in FIG. 4, this weighing device has a load applying section 5 having a substantially square planar shape, and a frame body having an outer contour shape of a substantially square shape, which is formed in an annular shape so as to surround the outer circumference of the load applying section 5. 40 and 40. Then, the right side edge of the load applying section 5 appearing in FIG. 4 and the inner edge of the right side section 2 of the frame body 40 appearing in FIG. 1 are connected via the flexure element 6. Two strain gauges 10 and 11 are provided on the upper surface of the flexure element 6. Then, similarly to the above, the lower edge, the left edge and the upper edge of the load applying section 5 and the inner edges of the lower section 3, the left side section 4 and the upper section 1 of the frame body 40 are the same as above. The strain elements 7, 8 and 9 (each strain element is provided with a strain gauge) are connected to each other. The four small circles appearing at the four corners of the frame body 40 shown in FIG. 1 are attachment holes 41 for attaching the legs 42 for supporting the weighing device, and the legs 42 shown in FIG. Installed.

Although not shown in the figure, this weighing device has a loading table attached to the load applying section 5, and when an article is placed on this loading table, as shown in FIG. The strain bodies 6 to 9 generate strain, and the strain gauges 10 to 17 detect the strain amount, whereby the weight of the article can be measured.

[0004]

[Problems to be solved by the device]

However, in the above-described weighing device, when a load in the direction of gravity is applied to the load application unit 5 shown in FIG. 4, a force based on the load is applied to the right side portion 2 of the frame body 40, the lower side through the respective flexure elements 6 to 9. Various stresses such as torsional stress, bending stress and tensile stress are applied to the side part 3, the left side part 4 and the upper part 1 and the right side part 2, the lower part 3 and the like are applied. Then, among these various stresses, particularly considering tensile stress, the central portions of the right side portion 2, the lower side portion 3, the left side portion 4 and the upper side portion 1 (bonded to the flexure elements 6 to 9). 4), a tensile stress F _A toward the inside of the frame 40 acts on the portion), and the tensile stress F _A causes the right side portion 2, the lower side portion 3 and the like A, A shown in FIG. , A, A, and so on. When such bending occurs, an error occurs in the amount of strain generated in each of the flexure elements 6 to 9 with respect to the load applied to the load applying section 5, as compared with the case where the bending does not occur. There is a problem that the measurement accuracy is reduced.

According to the present invention, it is possible to prevent each side of the frame body from being bent toward the center at the time of weighing and eliminate a weighing error due to the bending, thereby improving the weighing accuracy. With the goal.

[0006]

[Means for Solving the Problems]

 According to the present invention, a load applying part to which a load is applied, a frame body formed in an annular shape so as to surround the outer periphery of the load applying part and having a polygonal planar shape, and provided at each corner of the frame body. The present invention is characterized by comprising a strain-generating body that connects the frame body and the load applying section, and a strain gauge provided on the strain-generating body.

[0007]

[Action]

 According to this invention, when a load is applied to the load applying section, a force based on the load is applied to each corner of the frame through each strain element, and a torsional stress, a bending stress, and a pulling stress are applied to these corners. Various stresses such as tensile stress are applied. Of these various stresses, the tensile stress that acts on each corner in the direction toward the inside of the frame is decomposed into the component force in the direction along each side that connects the corners of the frame. It Therefore, these components acting on each corner of the frame work in the direction of compressing each side forming the frame, but do not work to bend each side toward the inside of the frame.

[0008]

[Embodiment] An embodiment of the present invention will be described with reference to FIGS. In the drawings, 23 is a load applying part, 43 is a frame, 24-27 are flexure elements, and 28-35 are strain gauges.

As shown in FIGS. 1 and 2, the load applying section 23 is a flat plate having a substantially square planar shape, and has four mounting holes 44 formed in the center thereof. The mounting hole 44 is for mounting a mounting table (not shown).

As shown in FIGS. 1 and 2, the frame body 43 is formed in an annular shape so as to surround the load applying portion 23 with a predetermined gap, and has a rectangular cross-sectional shape and an outer edge. The contour shape is almost square. That is, as shown in FIG. 1, the frame body 43 includes an upper part 19 parallel to the upper edge of the load applying part 23, a right side part 20 parallel to the right edge, and a lower part 21 parallel to the lower edge. , A left side portion 22 parallel to the left edge. It should be noted that mounting holes 41 are formed at four corners of the frame body 43, and legs 42 for raising the measuring device are screwed into the mounting holes 41, as shown in FIG. Then, as shown in FIG. 1, notches are provided inside the four corners 45 of the frame body 43, and the flexures 24, 25, 26, and 27 are connected.

The four flexure elements 24, 25, 26, 27 are equivalent to each other and are rectangular flat plates. As shown in FIG. 1, the four flexure elements 24 to 27 are arranged in the direction toward the center position 46 of the load applying section 23 and with respect to the upper surfaces of the load applying section 23 and the frame body 43. Are arranged in parallel with each other, their outer ends are connected to the corners 45 of the frame body 43 as described above, and their inner ends are respectively connected to the four corners of the load applying part 23. Are connected. Further, two strain gauges (28, 29), (30, 31), (32, 33), (34, 35) are provided on the upper surface of each of the flexure elements 24-27. Further, as shown in FIG. 2, two grooves 47 are provided on the lower surface of each flexure element 24-27. When the load is applied to the load applying section 23, the groove 47 increases the strain amount in the portion where the strain gauges (28, 29) of the flexure elements 24 ,. It is for doing.

FIG. 3 is an electric circuit diagram of the weighing device. As shown in the figure, a total of eight strain gauges 28 to 35 provided in each of the flexure elements 24 to 27 are electrically connected to each other and form a Wheatstone bridge circuit 48. An indicator 36 is connected to the Wheatstone bridge circuit 48 via a load signal transmission line 49 and an amplifier 50. Further, a paper battery 37 is connected as a DC power source. The indicator 36 and the amplifier 50 are provided in the upper portion 19 of the frame 43, and the paper battery 37 is provided in the lower portion 21.

Next, the operation of the weighing device configured as described above will be described. Although not shown in the figure, this weighing device has a loading table equivalent to that of the conventional example attached to the load applying section 23, and can weigh the articles placed on this loading table. That is, when an article is placed on this mounting table, as shown in FIG. 2, each of the flexure elements 24 to 27 is distorted, and the strain gauges 28 to 35 detect this distortion amount. Then, the load signal corresponding to the strain amount is amplified by the amplifier 50 and input to the indicator 36, and the weight value of the article is displayed.

Then, when the load of the article is applied to the load applying section 23, a force based on the load is applied to each of the four corner portions 45 of the frame body 43 via each of the strain generating bodies 24 to 27, and these corner portions 45 are formed. Various stresses such as torsional stress, bending stress, and tensile stress are applied to. Then, among these various stresses, as shown in FIG. 1, the tensile stress F _{A in the} direction of moving the corners 45 toward the central position 46 of the frame body 43 is Component forces F _x (component force in the horizontal direction in FIG. 1) and F _y (component force in the vertical direction in FIG. 1) along the upper part 19, the right part 20, the lower part 21, or the left part 22 to be connected. Is decomposed into and. Therefore, these component forces F _x and F _x acting on each corner portion 45 of the frame body 43 compress the upper part 19 and the lower side part 21 of the frame body 43, and the component forces F _y and F _y are the right side part 20. And the left side portion 22 and the like are compressed, but they do not work to bend the side portions 19 to 22 toward the central position 46 side of the frame body 43 as in the conventional example shown in FIG.

As a result, it is possible to eliminate a weighing error caused by the bending of each side portion 1 to 4 of the frame 40 of the conventional example, and to improve the weighing accuracy more than the weighing device of the conventional example. You can Incidentally, the weighing accuracy of the conventional weighing device is 1/1000 to 1/2000, whereas the weighing accuracy of the weighing device according to the present invention is 1/3000 to 1/4000.

However, as shown in FIG. 1, the frame body 43 of the above-described embodiment is a ring-shaped body having a square contour shape, but it may be a polygonal ring-shaped body having a contour shape other than a square shape. Also, when the frame body 43 is formed in a polygonal shape, similarly to the above-described embodiment, the flexures are provided at the respective corners of the frame so that the frame and the load applying section are connected via the flexures. Join.

In the above embodiment, two strain gauges are provided for each of the strain generating bodies 24-27, but other strain gauges are provided for each strain generating body 24-27. The gauge can be electrically connected to form a Wheatstone bridge circuit.

[0018]

[Effect of device]

 The weighing device of the present invention has a configuration in which a flexure element is provided at each corner of a polygonal frame element, and the frame element and the load applying section are connected via each flexion element. With this configuration, when a load is applied to the load applying section, a force is generated that causes each flexure element to pull each corner of the frame inward based on this load. It consists of component force in the direction along the side that connects the corners. Therefore, these component forces acting on the respective corner portions of the frame body work in the direction of compressing the respective side portions of the frame body, but do not work so as to bend the respective side portions toward the inside of the frame body. As a result, it is possible to eliminate a weighing error caused by bending the right side portion 2, the lower side portion 3 and the like of the frame body as shown in A as shown in FIG. There is an effect that it can be improved.

[Brief description of drawings]

FIG. 1 is a plan view of a weighing device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the weighing device of the embodiment as seen from the direction AA of FIG.

FIG. 3 is a diagram showing an electric circuit of the weighing device of the embodiment.

FIG. 4 is a plan view of a conventional weighing device.

FIG. 5 is a cross-sectional view of the conventional weighing device.

[Explanation of symbols]

 23 load application part 24-27 strain element 28-35 strain gauge 43 frame body

Claims (1)

[Scope of utility model registration request] 1. A load applying section to which a load is applied, a frame body formed in an annular shape so as to surround the outer periphery of the load applying section and having a polygonal planar shape, and provided at each corner of the frame body. A weighing apparatus, comprising: a strain-flexing body that connects the frame body and the load applying unit; and a strain gauge provided on the strain-flexing body.