JPH0672824B2 - Load detector - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load detecting device for detecting loads applied to various objects, and particularly to a load having means for preventing an excessive load from being applied. Regarding a detection device. [0002] A load detecting device for detecting a load (force and moment) applied to a certain object is used in many fields. As this load detecting device, an excellent device having a parallel flexural beam structure, a radial flexural beam structure, or both of them has been proposed in JP-A-60-62497. This load detection device is composed of two rigid body parts, a plurality of flexible beams connecting these rigid body parts, and a strain gauge provided at a predetermined position of these flexible beam parts. When a load acts between both rigid body parts. The strain gauge detects the strain of the flexible beam that occurs in the. A load detecting device using such a flexible beam is required to have a larger output sensitivity, and in order to increase the output sensitivity, a parallel flexible beam structure and a radial flexible beam structure when a rated load is applied are used. It is necessary to maximize the stress. However, if the stress is increased in this way, the stress value in the flexible beam becomes excessive when an excessive load exceeding a certain limit is applied, and the flexible beam is plastically deformed or the flexible beam is damaged. And, such an excessive load is caused by a mistake in handling such as a machine to which the load detecting device is attached, an erroneous operation of the device, or dropping the load detecting device itself, etc., except when the load to be detected is actually excessive. Also occurs. For this reason, there has been proposed means for preventing plastic deformation and damage of the flexible beam due to an excessive load acting on the load detecting device. This means will be described with reference to the drawings. FIG. 3 is a side view of the parallel flexible beam structure. In this figure, 1 is one rigid body portion, 2 is the other rigid body portion, 3a,
Reference numeral 3b is a parallel plate-shaped flexible beam that connects the rigid bodies 1 and 2 to each other. Reference numerals 4a and 4b are through holes formed when the rigid bodies 1 and 2 and the flexible beams 3a and 3b are formed of one rigid block. Reference numeral 5 denotes a strain gauge provided near the connecting portion between the flexible beams 3a and 3b and the rigid body portions 1 and 2. Reference numeral 6 denotes a convex portion protruding from the rigid body portion 1 toward the rigid body portion 2, and reference numeral 7 denotes a concave portion formed on the rigid body portion 2 and facing the convex portion 6. Reference numerals 8a, 8b and 8c are slits formed by the wall surface of the convex portion 6 and the wall surface of the concave portion 7, the slit 8a communicates with the through hole 4a, the slit 8b communicates with the through hole 4b, and the slit 8c includes both slits. It communicates with 8a and 8b. The slits 8a and 8b are parallel to the flexible beams 3a and 3b, and the gap size between them is indicated by ε. The operation of the parallel flexible beam structure will be described with reference to FIG. 4 is a side view of the parallel flexural beam structure similar to FIG. 3, and the same parts as those shown in FIG. 3 are designated by the same reference numerals. Now, it is assumed that the rigid body portion 2 is fixed to the fixed portion, and the force F acts on the rigid body portion 1 as indicated by the arrow in that state. At this time, the rigid portion 1 is displaced with respect to the rigid portion 2 while bending the flexible beams 3a and 3b as illustrated. The same displacement also occurs in the convex portion 6, and the slit 8a
Becomes wider by the displacement, and conversely, the slit 8b becomes narrower by the displacement. In FIG. 4, the flexible beam 3
The deformations of a and 3b and the displacement of the rigid body 1 are drawn extremely exaggerated. Here, if the force F is an excessive force, the displacement becomes large, and when the displacement reaches the value ε in the process of this displacement, as shown in FIG. Recess 7
The dimension of the slit 8b becomes 0 and the dimension of the slit 8a becomes 2ε by contacting the wall surface of the slit. As a result, further displacement of the rigid body portion 1 is prevented, and further deformation of the flexible beams 3a, 3b is also prevented, so that the flexible beams 3a, 3b are prevented.
Plastic deformation and damage of b are prevented. Even if the direction of the force F is the opposite direction, the upper surface of the convex portion 6 contacts the wall surface of the concave portion 7, and plastic deformation and damage of the flexible beams 3a and 3b are prevented in the same manner. [0008] By the way, in the load detecting device using the flexible beam, it is desired to detect a load as large as possible within a range in which the flexible beam is not plastically deformed or damaged. . That is, it is advantageous to keep the capacity of the load detecting device to the maximum limit. Further, it has been proposed to detect loads on a plurality of axes by using one parallel flexural beam structure or radial flexural beam structure. In this case, the deformation mode of the flexural beam differs depending on the load acting on each axis. As described above, in order to pursue the above-mentioned advantage, and also to pursue the above-mentioned advantage even when the deformation mode of the flexible beam is different, it is necessary to control the gap size ε of the slit with high accuracy. However, the gap size ε of the slits 8a and 8b shown in FIG. 3 is extremely small, and the gap size ε corresponding to the maximum load within the range where the flexible beam does not undergo plastic deformation or damage is processed with high precision. Difficult to mold. [0010] To solve this problem, for example
As disclosed in Japanese Patent Laid-Open No. 6-137045, a means has been proposed in which a screw is screwed into the slits 8a and 8b from the outside of the recess 7 and the gap size of the slit is adjusted by the tip position of the screw. However, as described above, the gap size ε is extremely small, and further adjustment with screws is impossible to adjust. An object of the present invention is to solve the above problems in the prior art and to provide a load detecting apparatus capable of finely adjusting the wall clearance between the convex portion and the concave portion for protecting the flexible beam. In order to achieve the above-mentioned object, the present invention provides a first rigid body portion, a second rigid body portion, and a plurality of flat plate-like portions connecting these rigid body portions. A flexible beam, a convex portion formed on the first rigid body portion, and a concave portion having a wall surface that is formed on the second rigid body portion and faces the wall surface of the convex portion on the flexible beam side, 1 rigid body and the second
In the load detecting device for detecting the load acting between the rigid body parts, at least one of the convex portion and the concave portion is provided with gap adjusting means for forcibly deforming itself, and the deformation causes the wall surface of the convex portion and the It is characterized in that at least one of the wall surfaces of the recess is brought close to the facing wall surface. When the gap adjusting means is formed in the convex portion, the convex portion itself is forcibly deformed by operating this adjusting means, and the deformation causes the wall surface of the convex portion to become the wall surface of the facing concave portion. approach. Since the above-mentioned deformation is a rigid body in which the convex portion is continuous with the rigid body portion, the deformation is extremely minute, and therefore minute adjustment of the gap size can be easily performed. When the gap adjusting means is formed in the recess, the recess is deformed to adjust the gap size. The gap adjusting means may be provided in both the concave portion and the convex portion, and in this case, the gap size is adjusted by the deformation of both. The present invention will be described below with reference to the illustrated embodiments. 1 is a side view of a load detecting device according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line II-II of the load detecting device shown in FIG. In FIGS. 1 and 2, the same or equivalent parts as those shown in FIG. 3 are designated by the same reference numerals and the description thereof will be omitted.
A slit 10 is formed in the center of the convex portion 6, is parallel to the slits 8a and 8b, and has one end communicating with the slit 8c. By this slit 10, the convex portion 6 is divided into upper and lower parts in the figure. Reference numeral 11 is a through hole formed in the middle of the slit 10, and 12 is a rod-shaped member inserted into the through hole 11. FIG. 2 shows the shapes and structures of the through hole 11 and the rod-shaped member 12. 11a and 11b are through holes 11
Is a taper portion formed at the end of the. Reference numeral 13 denotes a tapered end portion formed at one end portion of the rod-shaped member 12 and fitted with the tapered portion 11a of the through hole 11. 14 is a threaded portion provided at the other end of the rod-shaped member 12, and 15 is a threaded portion 1.
4 is a taper-shaped member inserted into the rod-shaped member 12. The tapered member 15 fits into the tapered portion 11b of the through hole 11. Reference numeral 16 is a nut screwed into the screw portion 15. The through hole 11, the rod-shaped member 12, and the like constitute a flexible mechanism. Next, the operation of this embodiment will be described. In addition,
In this embodiment, the size of the gap between the slits 8a and 8b is slightly larger than the target size. here,
When the nut 16 shown in FIG. 2 is screwed into the threaded portion 14, the tapered end portion 13 and the tapered member 15 of the rod member 12 are respectively tapered portions 11 a, 1 of the through hole 11.
Migrate inward against 1b. Therefore, the convex portions 6a, 6
b is slightly deformed vertically, and slits 8a,
The gap size of 8b becomes narrower by the amount of the deformation. That is, by adjusting the nut 16, the slits 8a and 8b can be adjusted to a predetermined value with high accuracy. As described above, in this embodiment, the through hole 1 having the slit 10 and the tapered portions 11a and 11b in the convex portion 6 is used.
1, the rod-shaped member 12 having the tapered end portion 13, the tapered member 15 and the nut 16 constitute the flexible mechanism, so that the slits 8a and 8b can be finely adjusted with high precision, and the flexible beam can be also used. It is possible to maximize the detection capability of the load detection device while reliably preventing plastic deformation and damage of 3a and 3b. Further, since the slits 8a and 8b do not require high-precision dimension control,
Manufacturing is easy. In the description of the above embodiment, the parallel flexible beam structure is exemplified, but the flexible flexible beam structure and the multiple flexible beam structure having three or more flexible beams are also applicable. Further, in the description of the above embodiments, an example in which the flexible mechanism is configured to be a convex portion has been described, but the present invention is not limited to this, and it may be configured to be a concave portion, or it may be configured to both a concave portion and a convex portion. You can also As described above, in the present invention, the gap adjusting means for adjusting the dimension between the wall surfaces of either or both of the convex portion and the concave portion by the deformation of the convex portion and the concave portion is provided. Since it is provided, it is possible to perform fine adjustment of the dimension between the wall surfaces with high accuracy, and thus it is possible to maximize the detection capability of the load detection device while reliably preventing plastic deformation and damage of the flexible beam. can do.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of a load detection device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line II-II of the load detection device shown in FIG. FIG. 3 is a side view of a conventional load detection device. FIG. 4 is a side view of a conventional load detection device. [Explanation of reference numerals] 1, 2 Rigid body portions 3a, 3b Flexible beams 6a, 6b Convex portion 7 Recessed portion 10 Slit 11 Through hole 12 Rod-shaped members 11a, 11b Tapered portion 13 Tapered end portion 15 Tapered member 16 Nut

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takami Kusagi             Hitachi Construction Machinery Co., Ltd.             Ceremony Company Tsuchiura Factory              (56) Bibliographic references Sho 56-137045 (JP, U)               Actual development Sho 59-158451 (JP, U)

Claims (1)

[Claims] 1. A first rigid body portion, a second rigid body portion, a plurality of plate-shaped flexible beams connecting these rigid body portions, a convex portion formed on the first rigid body portion, and the second rigid body portion. And a concave portion having a wall surface facing each other on the side of the plate-shaped flexible beam, the load detecting device detecting a load acting between the first rigid body portion and the second rigid body portion. In, at least one of the convex portion and the concave portion is provided with gap adjusting means for forcibly deforming itself, and by the deformation, at least one of the wall surface of the convex portion and the wall surface of the concave portion is brought close to the opposing wall surface. A load detection device characterized by the above. 2. In Claim 1, the gap adjusting means is
A slit formed in at least one of the convex portion or the concave portion, a through hole provided in the middle of the slit and having an end taper, and a taper of the through hole inserted in the through hole and in contact with the taper of the through hole A load detecting device comprising: a rod-shaped member formed with a taper to be fitted; and a screw means for pushing the taper of the rod-shaped member into the through hole.