JPH032824Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Field of Application) The present invention relates to a mounting structure for a load cell in a measuring instrument using a load cell.

(Prior art) As shown in FIG. 8, a pair of beam parts 4 and 5 are provided vertically in parallel between the rigid body parts 2 and 3 at both ends, and low rigidity parts are provided in two places each in the beam parts 4 and 5. 4
A load cell 1 in which strain sensing elements 6...6 such as strain gauges are attached to the surfaces of the load cells a, 4a, 5a, and 5a, respectively, is used as a load sensing device for a measuring instrument. This load cell 1 includes one rigid body part 2 (hereinafter referred to as a fixed rigid body part) of the rigid body parts 2 and 3.
is fixed to the base frame 7 of the weighing instrument, and the other rigid body part 3 (hereinafter referred to as the movable rigid body part) is fixed to the weighing pan 8, so that the load of the object to be weighed placed on the weighing pan 8 can be moved. It is attached so that a load is applied to the rigid body part 3. Then, the movable rigid body part 3 is displaced downward in response to the above load, and accordingly, each of the low rigidity parts 4a, 4a, 5a, 5a of the beam parts 4, 5 is subjected to tensile strain or compressive strain corresponding to the above load. When this occurs, the strain detection elements 6...6 are configured to detect this and output the weight of the object to be weighed.

However, since this type of load cell 1 allows relative displacement in the vertical direction between the rigid body parts 2 and 3,
As shown in Fig. 8, a mounting base 9 that also serves as a spacer,
10 to the base frame 7 and weighing pan 8. In this case, as shown in the figure, the mounting bases 9 and 10 are attached to the lower surface 2a of the fixed rigid body part 2 and the upper surface 3a of the movable rigid body part 3. The following problems occur. In other words, in such an attached state, when a downward load is applied to the movable rigid body part 3, the lower surface 2a of the fixed rigid body part 2 contacts the inner corner parts 9a, 10a of the mounts 9, 10. A large stress is generated on the upper surface 3 of the movable rigid body part 3, and this stress is applied to the vicinity of the strain detection elements 6, 6 attached to the surfaces of the beam parts 4, 5, as shown by arrows x, x. As a result, an error occurs in the outputs of the strain detection elements 6, 6, and measurement accuracy decreases. To solve this problem, the distance from the rigid body parts 2, 3 at both ends to the attachment positions of the strain detection elements 6, 6 in the beam parts 4, 5 can be made sufficiently large, but if this is done, the load cell 1 becomes unnecessary. Another disadvantage was that it became larger.

(Problems to be solved by this invention) This invention deals with the above-mentioned actual situation regarding the mounting structure of a load cell in a measuring instrument.
When the lower surface of the fixed rigid body part and the upper surface of the movable rigid body part are attached to the base frame or weighing pan of a measuring instrument via a mounting base, the stress generated in the mounting part can be reduced without unnecessarily increasing the size of the load cell. The purpose is to reduce the influence of strain on the strain detection element, thereby realizing a highly accurate measuring instrument using a compact load cell.

(Means for solving the problem) A fixed rigid body part and a movable rigid body part located at both ends, and a pair of beam parts provided vertically in parallel between both rigid body parts, and a low beam part provided in both beam parts. A load cell mounting structure for a measuring instrument in which a load cell having a strain detection element affixed to the surface of a rigid part is attached to a base frame and a weighing pan at both of the rigid parts, the lower surface of the fixed rigid part and the upper surface of the movable rigid part. The gist of the invention is a mounting structure for a load cell in a measuring instrument, which is characterized in that the mounting base is mounted on a base frame or a weighing pan via a slotted part.

(Example) Examples of the present invention will be described below.

As shown in FIG. 1, the weighing device 21 has a base frame 22 with an open top, a weighing pan 23 located above the frame 22, and a load cell 31 interposed between the two. Above load cell 3
1 has a hollow shape with a fixed rigid body part 32 at one end, a movable rigid body part 33 at the other end, and a pair of beam parts 34 and 35 provided vertically in parallel between both the rigid body parts 32 and 33. , both beam portions 34,
35, two low-rigidity parts 34a, 35a with thinner walls are provided at positions near both the rigid body parts 32, 33, and these low-rigidity parts 34a,
Strain gauges 36, . . . , 36 are attached as strain detection elements to the surfaces of 34a, 35a, and 35a, respectively. Here, in this load cell 31, the upper and lower surfaces of both the rigid body parts 32 and 33 are connected to the beam part 34,
It protrudes upward and downward from surfaces 34b and 35b of 35, respectively.

In the load cell 31, the lower surface 32a of the fixed rigid body part 32 is fixed to the inner bottom surface of the base frame 22 via the mount 37, and the upper surface 33a of the movable rigid body part 33 is fixed to the inner bottom surface of the base frame 22 via the mount 38. It is fixed to the back surface of the plate 23. That is, the mounting base 37 is attached to the lower surface 32a of the fixed rigid body part 32 using bolts 39...39, and the mounting base 37 is fixed to the inner bottom surface of the base frame 22 by appropriate fixing means (not shown). Similarly, a mounting base 38 is attached to the upper surface 33a of the movable rigid body part 33 using bolts 40...40, and the mounting base 38 is fixed to the back surface of the weighing pan 23 by appropriate fixing means (not shown). ing.

However, as shown in FIGS. 1 to 3, the mounting bases 37 and 38 are attached to the mounting surfaces 32 of both rigid body parts 32 and 33.
a, 33a (the lower surface of the fixed rigid body part and the upper surface of the movable rigid body part), and are attached to the inner corner parts 37a, 3 of the mounting bases 37, 38.
A distance a is provided between the inner edge portions 32b and 33b of the mounting surfaces 32a and 33a, respectively. Also, surfaces 37b, 3 of the mounting bases 37, 38 that are in contact with the mounting surfaces 32a, 33a.
8b is provided with slotted portions 37c, 38c that reach the inner corner portions 37a, 38a, thereby attaching the mounting surfaces 32a, 33a of the rigid body portions 32, 33.
The vicinity of the edge portions 32b and 33b are spaced apart from the mounting bases 37 and 38, respectively, at the center in the width direction. Here, in this embodiment, the slotted portion 37 of the mounting bases 37 and 38 is
The openings in the corner portions 37a, 38a of the bolts 39...39, 40...40 are widened in the width direction within a range that does not interfere with the insertion holes 37d...37d, 38d...38d of the bolts 39...39, 40...40. The dimensions of contact points A and B in the width direction between the corner portions 37a and 38a of the stands 37 and 38 and the mounting surfaces 32a and 33a of the rigid body portions 32 and 33 are made as short as possible.

Next, the operation of the above embodiment will be explained.

As shown in FIG. 1, in a measuring instrument 21 in which a load cell 31 is interposed between a base frame 22 and a weighing pan 23, when an object to be weighed is placed on the weighing pan 23, the load is reduced. A load is applied to the movable rigid body part 33 of the load cell 31 through the mounting base 38, and the rigid body part 33 is displaced downward. At this time, in the beam parts 34, 35 of the load cell 31, the low rigid body parts 34a, 34a, 35a, 35a
is bent and tensile strain or compressive strain is generated on its surface, which is detected by each strain gauge 36...36, but since these strains correspond to the weight of the object to be weighed, each strain gauge 36 …3
By processing the output of No. 6 through a predetermined electric circuit, the weight of the object to be weighed is output.

However, when the movable rigid body portion 33 of the load cell 31 is displaced downward due to the load applied to the weighing pan 23 as described above, the load cell 31 is moved downward from the mounting surface 3.
Locations A and B that contact the inner corner portions 37a and 38a of the mounting bases 37 and 38 in 2a and 33a
will be deformed using the fulcrum as a fulcrum, and large stress will be generated at these locations A and B. However, the above mounting base 3
7 and 38 are provided with hollow parts 37c and 38c, and the corner parts 37a and 38a do not contact the mounting surfaces 32a and 33a of the load cell 31 at the center, so that the stress is applied to both sides of the mounting surfaces 32a and 33a. This will occur at the rear end edges of the hollow portions 37c and 38c. Therefore, even if this stress propagates to the beam parts 34, 35, especially at the rear end edges of the hollow parts 37c, 38c, the beam parts 34, 3
This means that the center portions of the surfaces 34b, 35b of 5, to which the strain gauges 36, 36 are attached, are hardly affected. As a result, the influence of stress acting on the attachment positions of the strain gauges 36, 36 is reduced by one layer, and errors in the outputs of the strain gauges 36, 36 due to this stress are prevented, and the measuring instrument 21 The measurement accuracy will be improved.

In addition, in the above embodiment, the load cell 31
The edge portion 32 on the mounting surfaces 32a, 33a of
Corner part 3 of mounting bases 37 and 38 from b and 33b
Although the configuration in which the mounts 7a and 38a are moved outward is also described, the mounting bases 37 and 38 are provided with a slotted portion 37c,
38c is provided to attach the load cell 31 to the mounting surface 32a,
33a may be adopted. That is, as shown in FIG.
The mounting base 4 using the mounting bases 47 and 48 having c.
The corresponding corner portions 47a, 48a of 7, 48 are connected to the edge portions 4 of the mounting surfaces 42a, 43a of the load cell 41.
2b and 43b. In addition, as shown in FIG. 6, the mounting surface 62 of the load cell 61
The same effect as the embodiment shown in FIGS. 1 to 3 or the embodiment shown in FIG. 4 can be obtained even if the slotted portions 62c and 63c are provided in the sections a and 63a.

Furthermore, in place of the configuration in which the mounting base is provided with a slotted portion, as shown in FIG. spacer 8
1 and 82 may be interposed. In that case, the spacers 81 and 82 have inner corner portions 8
Cut portions 81b and 82b are provided from 1a and 82a to form hollow portions. As a result, effects similar to those of the embodiment shown in FIGS. 1 to 3 or the embodiment shown in FIG. 4 can be obtained.

(Effects of the invention) As described above, according to the load cell mounting structure according to the present invention, the width is reduced at the contact point between the corner part of the mounting base, which becomes a fulcrum when the mounting surface of the load cell is deformed, and the rear edge of the slotted part. Since we decided to generate stress at the rear edge of the beam part at a location away from the strain detection element, the stress propagates to the strain detection element attached to the center of the beam part in the width direction, and Problems such as errors in the output of the element can be prevented, and the accuracy of the load cell and, ultimately, the measurement accuracy of the weighing device can be improved. In particular, according to the present invention, there is no need to increase the distance between the mounting surface of the load cell and the attachment position of the strain detection element, and therefore there is an advantage that the load cell does not become large.

[Brief explanation of the drawing]

1 to 3 show the first embodiment of the present invention, in which FIG. 1 is a schematic longitudinal sectional side view of the measuring instrument,
The figures are enlarged cross-sectional views of main parts taken along lines -- and -, respectively, in Fig. 1. Figures 4 and 5 are 2nd and 3rd, respectively.
FIG. 6 is an enlarged side view of the main part showing the embodiment, and FIG. 6 is an enlarged perspective view of the main part showing the fourth embodiment. FIG. 7 is a vertical sectional side view of a measuring instrument showing a conventional example. 21... Measuring instrument, 22... Base frame, 2
3...Weighing pan, 31, 41, 51, 61...Load cell, 32...Fixed rigid body part, 33...Movable rigid body part, 34, 35...Beam part, 36...Strain detection element (strain gauge), 32a, 33a, 42
a, 43a, 62a, 63a...Mounting surface, 32
b, 33b, 42b, 43b...edge part, 3
7, 38, 47, 48, 77, 78...Mounting base,
37a, 38a, 47a, 48a...corner part, 37c, 38c, 47c, 48c, 62c,
63c... Nusumi part, 81, 82... Spacer,
81b, 82b... cut portions.

Claims (1)

[Scope of utility model registration request] It has a fixed rigid body part and a movable rigid body part located at both ends, and a pair of beam parts provided vertically in parallel between both the rigid body parts, and a strain detection element is provided on the surface of the low rigidity part provided in both the beam parts. A load cell mounting structure for a measuring instrument in which a load cell is attached to a base frame and a weighing pan at both of the rigid body parts via a mounting base, the mounting structure including the mounting base, the lower surface of the fixed rigid body part, and the movable rigid body part. A mounting structure for a load cell in a measuring instrument, characterized in that a fitting part is provided on the top surface of the measuring instrument.