JPH0560624A - Load detector - Google Patents

Abstract

PURPOSE:To obtain stable detecting accuracy irrespective of the rigidity of an external coupling member by providing three projecting parts at least for one of coupling parts. CONSTITUTION:A strain generating part interposed between two coupling parts 25 and 29 which are coupled to external members is deformed corresponding to the size of the load acting thereto. The amount of the deformation of the strain generating part is detected by a strain gauge 20. At this time, three projecting parts 26a-26c, 30a-30c are provided for at least either of the coupling parts 25, 29. The load is transmitted from one external member to the other member via the projecting parts 26a-26c, 30a-30c. Accordingly, it becomes possible always to obtain stable load detecting accuracy irrespective of the rigidity of the external members coupled to the coupling parts provided with the projecting parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load detector for detecting a load (force, moment) applied to an object.

[0002]

2. Description of the Related Art Detecting a load (force, moment) applied to an object is essential in many fields. For example, when performing assembly work, polishing, and deburring work with a high-performance robot, it is necessary to accurately detect the force acting on the hand of the robot, and to conduct model tests of aircraft, ships, vehicles, etc. When doing so, the detection of the load applied to each part is a major item. Hereinafter, some conventional load detectors will be described with reference to FIGS. FIG. 7 is a perspective view of a load detector described in US Pat. No. 4,094,192. In the figure, 1 is a first connecting part configured in a ring shape to connect an external member, 2 is a ring-shaped structure similar to the first connecting part 1, and is connected to another external member. The second connecting portions 3, 4, 5 are flat plate-shaped strain generating portions interposed between the first connecting portion 1 and the second connecting portion 2. A strain gauge 6 is provided on the surface of the strain-flexing parts 3, 4, and 5.
Is attached. In such a load detector, when a load acts on one of the external members, the load is transmitted to the other external member via the connecting portions 1 and 2 and the strain-flexing portions 3, 4 and 5 of the load detector. To be done. As a result, the strain-flexing parts 3, 4, 5 are deformed according to the applied load, the amount of this deformation is detected by the strain gauge 6, and the applied load is calculated based on the detected amount of deformation.

FIG. 8 is a perspective view of a load detector disclosed in Japanese Patent Application Laid-Open No. 57-169643. In the figure, reference numeral 7 denotes a first connecting portion which is formed in a disc shape and which connects an external member,
Reference numeral 8 is a second connecting portion formed in a large-diameter ring shape on the outer periphery of the first connecting portion 7 and connected to another external member,
Reference numerals 9, 10, 11, and 12 are strain generating portions which are formed in a rectangular parallelepiped and are interposed between the first connecting portion 1 and the second connecting portion 2. Strain gauges 13 ... Are also attached to the strain-flexing parts 9, 10, 11, and 12. The operation of this load detector conforms to the operation of the load detector shown in FIG.

FIG. 9 is a perspective view of a load detector disclosed in Japanese Patent Laid-Open No. 64-32140. In the figure, 14 is a ring-shaped first connecting part for connecting an external member, and 15 is a disk-shaped member having a diameter larger than that of the first connecting part 14 and is connected with other external members. Second connecting part, 1
Reference numeral 6 denotes a flat plate strain element interposed between the first connecting portion 1 and the second connecting portion 2, and 17a denotes a through hole opened in the arrow X direction between the opposing surfaces of the strain element 16. Reference numeral 17b is a through hole formed above the through hole 17a in the arrow Y direction orthogonal to the arrow X direction. Reference numerals 18a and 18b are flexible portions formed of a thin plate formed by the through holes 17a,
Reference numerals 18c and 18d denote flexures made of a thin plate formed by the through holes 17b. Reference numerals 19a, 19b, and 19c denote rigid portions separated by forming the through holes 17a and 17b, respectively, and the rigid portions 19a and 19b are flexible portions 18a and 1b.
8b, the rigid portions 19b and 19c are connected to the flexible portion 18b.
It is configured to be connected by c and 18d. On the other hand, 20
A strain gauge that detects the amount of deformation of the flexible portion 18d, and although not shown, a predetermined number of sheets are attached to predetermined portions of the other flexible portions 18a to 18c. Such a load detector has a force acting in the X-axis, Y-axis, and Z-axis directions, and an X-axis, by attaching a strain gauge at an appropriate position.
It is possible to detect an arbitrary load among the six loads of the moment acting around the Y axis and the Z axis. The operation of the load detector thus configured also conforms to the operation of each load detector described above.

[0005]

In the above-mentioned conventional load detector, there are various materials and shapes for the external member connected to each connecting portion. The load may be adversely affected depending on the external member. Figure 1
0 to 13 will be described. 10 and 11 are schematic views showing a mounting state of the load detector and the external member. A in each figure
Is the first connecting portion 1, 7, 1 of the load detector shown in FIGS.
3, B corresponds to the strain-flexing parts 3 to 5, 9 to 12 and 16, and C corresponds to the second connecting parts 2, 8 and 15. Figure 10
The state shown in is when the rigid body D having high rigidity is connected to the second connecting portion C, and the force F indicated by the arrow acts on the first connecting portion A vertically downward. In this case, as shown in FIG. 11, the force F is transmitted to the second connecting portion C via the strain-flexing portion B, but since the rigidity of the external member D is high, the second connecting portion C is not deformed and is raised. The strained portion B deforms so as to shrink according to the magnitude of the force F, and the strain gauge takes out the deformation. On the other hand, in the state shown in FIG. 12, the external member D ′ having low rigidity is connected to the second connecting portion C, and the first connecting portion A is indicated by an arrow in FIG.
This is the case where a force F equal to the force indicated by 0 acts vertically downward. In this case, as shown in FIG.
However, since the external member D ′ has a low rigidity, the second connecting portion C is deformed, so that the strain-flexing portion B is deformed as shown in FIG. It is taken out by a strain gauge. The deformation of the strain-flexing part B shown in FIGS. 11 and 13 is drawn extremely exaggerated. As described above, when the rigidity of the external member connected to the second connecting portion C is high and when the rigidity is low, the deformed state of the strain-flexing portion B is different even when the same load is applied. The amount of deformation taken out by the strain gauge is also different, and eventually the obtained load detection value is also different for both. That is, the rigidity of the external member to be connected causes a difference in the load detection value, which has a drawback that the detection accuracy of the load detector is low.

An object of the present invention is to solve the above problems in the prior art and to provide a load detector capable of obtaining stable detection accuracy regardless of the rigidity of an external member to be connected.

[0007]

In order to achieve the above object, the present invention provides two connecting portions connected to an external member and a load acting between the connecting portions and interposed between the connecting portions. In a load detector including a strain-flexing portion that deforms according to the size and a detection unit that detects the amount of deformation of the strain-flexing portion, at least one of the connecting portions is provided with three projecting portions. It is characterized by

[0008]

Since the load is transmitted from one external member to the other external member through the protrusion, the rigidity of the external member connected to the connecting portion provided with the protrusion does not affect the detection result. Absent.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to illustrated embodiments. 1 is a perspective view of a load detector according to a first embodiment of the present invention. 9, those parts which are the same as those corresponding parts in FIG. 9 are designated by the same reference numerals, and a description thereof will be omitted. Reference numeral 25 denotes a first connecting portion formed in a ring shape, and three projecting portions 26a, 26b, 26c are integrally formed on the upper surface side in the drawing. Further, screw holes 28 are formed on each of the protrusions 26a, 26b, 26c for connection with an external member. 29 is the first
Is a second connecting portion formed in a disc shape having a diameter larger than that of the connecting portion 25 of FIG.
0a, 30b, 30c (the protruding portion 30c is in the invisible position) are integrally formed. Each protrusion 30a-30
A connecting means for connecting to an external member is also provided at c.

Next, the operation of the load detector of this embodiment will be described with reference to FIG.
This will be described with reference to FIGS. In each drawing, A'corresponds to the first connecting portion 25, B corresponds to the strain-flexing portion 15, and
C ′ corresponds to the second connecting portion 29, and C ″ is the protruding portion 26.
a, 26b ..., D and D ′ are protrusions 30a to 30
It corresponds to an external member connected to b. In addition, FIG.
The deformation of is extremely exaggerated as in FIGS. 11 and 13. First, when a highly rigid external member D is connected to the second connecting portion C ′ of the load detector as shown in FIG. 3, a force F acts vertically downward in the drawing on the first connecting portion A ′. At times, the force F is transmitted through the protrusion C ″, so that the second connecting portion C ′ is deformed as shown in FIG. 3, and the strain generating portion B is also deformed as shown in the figure. The amount of deformation is detected by a strain gauge, while the second connecting portion C ′ of the load detector is connected to the first connecting portion A when an external member D ′ having low rigidity is connected as shown in FIG. When the same force F as that shown in FIG. 3 acts on the ', the second connecting portion C'is deformed as shown in FIG. 6 together with the external member D'because the force F is transmitted through the protrusion C ". To do. As a result, the strain-flexing part B also deforms as shown in the figure,
The amount of this deformation is detected by the strain gauge.

As described above, in this embodiment, the second connecting portion 2
By providing the three protrusions 30a to 30c in 5,
Since the external member D or D ′ is connected by three-point contact, the connecting portion 25 is deformed regardless of the rigidity of the external member when a load is applied, and the strain generating portion 15 is also deformed accordingly. Becomes After all, the load detector of the present embodiment can obtain stable detection accuracy without being affected by the rigidity of the external member.

FIG. 3 is a perspective view of a load detector according to a second embodiment of the present invention. In the figure, the same members as the members shown in FIG. Reference numeral 40 is a first connecting portion which is formed in a ring shape and is connected to an external member, and in the drawing, three screw holes for connecting an external member are formed on the upper surface. 41a, 41b and 41c are ring-shaped spacers each having a hole corresponding to a screw hole on the upper surface of the first connecting portion 40 and fixed at that position. Reference numeral 50 is a second connecting portion formed in a disk shape having a diameter larger than that of the first connecting portion 40. 51a, 51b, 5
1c is a spacer fixed to the bottom surface of the second connecting portion 50. The spacer 51c is not visible, and each of the spacers 51a to 51c has the same function as each of the protrusions 30a to 30c in the first embodiment. This second
It is clear that the operation and effect of the load detector according to the embodiment are the same as the operation and effect of the load detector according to the first embodiment.

In the description of each of the above embodiments, an example in which three protrusions are provided on both connecting portions has been described. However, the present invention is not limited to this, and an external member connected to one connecting portion may be used. If it is constant, the protruding portion may be provided only on the other connecting portion.

[0014]

According to the present invention, at least three projecting portions are provided on at least one of the connecting portions, so that the load detection is always stable regardless of the rigidity of the external member connected to the connecting portions. Accuracy can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view of a load detector according to a first embodiment of the present invention.

FIG. 2 is an explanatory view showing a state when a high-rigidity external member is connected to the connecting portion shown in FIG. 1 and a load is not applied.

FIG. 3 is an explanatory view showing a state when a high-rigidity external member is connected to the connecting portion shown in FIG. 1 and a load is applied.

FIG. 4 is an explanatory diagram showing a state in which an external member having low rigidity is connected to the connecting portion shown in FIG. 1 and a load is not applied.

5 is an explanatory diagram showing a state in which a low-rigidity external member is connected to the connecting portion shown in FIG. 1 and a load is applied.

FIG. 6 is a perspective view of a load detector according to a second embodiment of the present invention.

FIG. 7 is a perspective view showing a conventional load detector.

FIG. 8 is a perspective view showing another conventional load detector.

FIG. 9 is a perspective view showing still another conventional load detector.

FIG. 10 is an explanatory diagram showing a state when a high-rigidity external member is connected to the second connecting portion of the conventional load detector and no load is applied.

FIG. 11 is an explanatory diagram showing a state when a high-rigidity external member is connected to a second connecting portion of a conventional load detector and a load is applied.

FIG. 12 is an explanatory diagram showing a state when an external member having low rigidity is connected to the second connecting portion of the conventional load detector and no load is applied.

FIG. 13 is an explanatory diagram showing a state when an external member having low rigidity is connected to a second connecting portion of a conventional load detector and a load is applied.

[Explanation of symbols]

20 Strain gauge 25, 40 1st connection part 29, 50 2nd connection part 26a, 26b, 26c, 30a, 30b, 30c Protrusion part 31 Strain element part 41a, 41b, 41c, 51a, 51b, 51c Spacer

[Procedure amendment]

[Submission date] September 17, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Title of invention

[Correction method] Change

[Correction content]

Title of invention Load detector

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

[Figure 3]

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[Figure 5]

[Figure 7]

[Figure 8]

[Figure 6]

[Figure 9]

[Figure 10]

FIG. 11

[Fig. 12]

[Fig. 13]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kojiro Ogata 650 Kandamachi, Tsuchiura City, Ibaraki Prefecture Hitachi Construction Machinery Co., Ltd. Tsuchiura Factory

Claims (3)

[Claims] 1. Two connecting parts connected to an external member,
A load detector that is interposed between each of the connecting portions and that includes a strain-flexing portion that deforms according to the magnitude of the load that acts between the connecting portions, and a detection unit that detects the amount of deformation of the strain-generating portion. 3. The load detector according to claim 1, wherein three protrusions are provided on at least one of the connecting portions. 2. The load detector according to claim 1, wherein the protruding portion is formed integrally with the connecting portion. 3. The load detector according to claim 1, wherein the protruding portion is a spacer attached to the connecting portion.