JPS6375633A - Load detector - Google Patents

Abstract

PURPOSE:To miniaturize the title detector and to set moment rating to a large value, by connecting two parts opposed to each other of a load detection mechanism part constituted in an annular shape to the first rigid part in one direction and further connecting two parts opposed to each other to the second rigid part in the direction crossing said direction at a right angle. CONSTITUTION:A load detection mechanism part is constituted in an annular shape such as a circular or square shape and two parts opposed to each other in an X-axis direction are connected by a rod-shaped rigid part 11 and two parts opposed to each other in a Y-axis direction are connected by a rod-shaped rigid part 12. Then, a force component detection element 13Ax mainly detecting the force in the X-axis direction, a force component detection element 12Ay mainly detecting the force in the Y-axis direction and a force component detection element 13Az mainly detecting the force in a Z-axis direction are provided, for example, to a beam-shaped member 13A. As mentioned above, since a load detection element is present at an annular part separated from the center, the stress generated in the load detection element by the moment acting between two rigid parts 11, 12 is reduced and the space necessary for one having the same outer dimension can be sufficiently secured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a load detector that detects force components in the direction of each coordinate axis and moment components around each coordinate axis in loads applied to various objects.

[Prior art]

Detecting loads (forces and moments) applied to an object or a specific part of an object is essential in many fields. For example, when performing assembly work, polishing, and deburring work using a high-performance robot, it is necessary to accurately detect the force acting on the robot's hand, and it is also necessary to perform model tests on aircraft, ships, vehicles, etc. Detection of the load applied to each part is also a key item when implementing this.

A) As a sensor for detecting such loads, a parallel plate structure that detects only force elements in the direction of a certain reference axis, and a radial plate structure that detects only moment elements around a certain reference axis are used. The detector was published in 1986-62.
This method has been proposed in Publication No. 497. An example of the load detector disclosed in the publication will be described below with reference to FIG. 13.

FIG. 13 is a partially cutaway perspective view of a load detector using a parallel plate structure and a radial plate structure. In the figure, 1 is an annular rigid body part, 2 is an annular rigid body part facing Oka 1 body part 1, and 3 is an annular rigid body part.
is a cross-column-shaped load detection mechanism section connected between the rigid body sections 1 and 2. The load detection mechanism section 3 is
Parallel plate structure 3FX, 3FY that detects force components in the axial direction
, 3FZ, and the X-axis, Yilil, radial plate structure 3~iX, which detects moment components around X@,
It is composed of 3MY and 3MZ. In the symbols indicating these parallel plate structures and radial plate structures, F is force, M is moment, X, Y, and Z are coordinate types, llX, Y
.

Let it represent Z. For example, the symbol r3FXJ means a parallel plate structure that detects a force component in the X-axis direction. Each parallel plate structure is a thin plate 3a, 3b parallel to each other, as shown in the parallel plate structure 3FX, for example.
and has a through hole 3c for forming these, and
Each radiating plate structure is, for example, radiating plate +1! As shown in Structure 3 MZ, it has thin flat plates 3d and 3e that extend radially from each other with respect to a predetermined point, and a through hole 3f for forming these.

This load detector can detect all the loads acting between the rigid body parts 1 and 2, and has extremely little interference from load components on other axes (good load separation characteristics), allowing for highly accurate detection. It has excellent sensitivity and hardness.

Note that the radiation plate structure described above is detailed in the above-mentioned publication, so a description thereof will be omitted. Further, the parallel plate structure is also detailed in the above-mentioned publication, but since the parallel plate structure is used in the embodiments of the present invention to be described later, this will be mentioned in the description of the embodiments.

[Problem that the invention seeks to solve]

Although the load detector shown in FIG. 13 has excellent characteristics as described above, it also has the following problems. That is, (1) The load detection mechanism section 3 has a large number of parallel plate structures and radial plate structures within a limited cross-column-shaped space (in the configuration shown in the figure, 16 structures are used to maintain the overall balance). is provided from the periphery toward the center, so it is not possible to secure sufficient dimensions to configure each parallel plate structure and each radiation plate structure, and there are restrictions on the size of the Ti detector. However, it is difficult to configure it so that it has ideal characteristics.

(2) Since the parallel plate structure 3FZ and the radial plate structure 3MZ exist near the center of the load detector inside the rigid body parts 1 and 2, when a large moment acts between the rigid body parts 1 and 2, these parallel plate structures 3FZ and radial plate structure 3
A large isometric force will act on the MZ, and unreasonable stress will be generated there. Therefore, the rated value for the moment of the load detector must be kept to a small value.

This poses a major restriction when applying this sensor to robots and machine tools where large moments may act.

(3) When a processing tool such as hand grinding is attached to a tool holder of a machine tool or a robot hand to perform work, the center point of the load detector and the point of application of the force acting on the processing tool are The distance between them is often large.

However, as mentioned in (2) above, the moment rating of the load detector is limited, so the machining reaction force acting on the machining tool must be kept small.
This will significantly reduce the efficiency of machining work.

The present invention has been made in view of the above circumstances, and its purpose is to solve the problems of the prior art described above, and to improve the load detection mechanism in the load detection mechanism compared to the conventional one having the same external dimensions. It is an object of the present invention to provide a load detector that can secure a sufficient space for each load detection element and can set a moment rating to a larger value.

[Means for solving problems]

In order to achieve the above object, the present invention includes a first rigid body part, a second rigid body part, and a load detection mechanism part, and the load detection mechanism part includes a first rigid body part and a second rigid body part. The load detection mechanism is configured in an annular shape such as a circle or a square in the load detection cannula, which is provided with at least one load detection element for detecting the load acting between the rigid body part of the The first rigid body part is connected to two parts on the load detection mechanism part that face each other on an axis in a predetermined direction defined in the section, and also on an axis in a direction substantially orthogonal to the axis in the predetermined direction. It is characterized in that two parts on the load detection mechanism part facing each other and the second rigid body part are connected.

[For production]

When a load acts between the first rigid body part and the second rigid body part, this load is transmitted to the load detection mechanism part and detected by a load detection element provided therein. In this case, the load detection element is located in the annular load detection mechanism part that is away from the center and corresponds to its peripheral part, so compared to the case where the load detection element is located in the center, the load detection element is located in the first rigid body part and Second
The stress generated in the load sensing element is reduced due to the moment acting between the rigid body parts.

〔Example〕

Hereinafter, the present invention will be explained based on the illustrated embodiments.

FIG. 1 is a perspective view of a load detector according to a first embodiment of the present invention. In the figure, X, Y, and Z indicate coordinate axes. 11 is X
Rod-shaped rigid body parts 11a and llb extending in the axial direction are connecting parts of the rigid body part 11. 12 is a rod-shaped rigid body portion extending in the Y-axis direction, and 12a and 12b are connecting portions of the rigid body portion 12. 1
3A is a beam-like member that connects the connecting portions 11a and 12a, 1
3B is a beam-like member that connects the connecting portions 12a and 12b, 1
3C is a beam-like member that connects the connecting portions 11b and 12b, 1
3D is a beam-like member that connects the connecting portions 12b and 11a. The beam member 13A includes a force component detection element 13AX that mainly detects force in the X-axis direction, a force component detection element 13AY that mainly detects force in the Y-axis direction, and a force component detection element 13AY that mainly detects force in the X-axis direction. Element 13A2 is provided. Similarly, other beam-like members 13B, 13C, 13D
Also, force component detection elements 13BX regarding the Z-axis.

13Cx, 13Dx, force component detection element 13 regarding the Y axis
By, 13Cy, 13Dv, force component detection elements 13Bz, )3Cz, 13Dz regarding the Z axis are provided. Each beam-like member 13A to 13D2 and each connecting portion 11a to 12
b constitutes an annular load detection mechanism section 14.

When a force in any direction acts between the rigid body parts 11 and 12, the X-axis direction component, Y-axis direction component, and Z-axis direction component of the force are detected as force components related to the Y-axis of each beam member 13A to 13D. element, a force component detection element related to the Y axis, and a force component detection element related to the Z axis.

Here, each of these force component detection elements is required to have the basic function of detecting force components in a predetermined direction, as well as to have high rigidity against all load components, and to prevent deformation of itself from other force components. It is also desired that the sensor has the property of not affecting the magnitude or direction of the load acting on the detection element. A second force component detection element that satisfies these demands is a force component detection element using a parallel plate structure. Therefore, the configuration and operating principle of the parallel plate structure will be explained below.

FIGS. 2(a) to 2(f) are side views of force component detection elements each using a parallel plate structure. In the figure, 21 is the support part 2
0 is a fixed part made of a rigid body supported by 22, a support part 20
It is a movable part made of a rigid body located on the opposite side. 23.23
' is a thin part connecting between the fixed part 21 and the movable part 22, and these thin parts 23 and 23' are arranged parallel to each other. Reference numeral 24 indicates a parallel plate structure constituted by these, and 25, 26, 27, and 28 are thin wall portions 23, respectively.
．． This is a strain gauge provided at the root portion of 23'. Note that 29 indicates a rectangular through hole for forming the thin wall portion 23, 23'.

In such a parallel plate structure 24, the movable part 22 has a Z
When a force F2 is applied in the axial direction (direction perpendicular to the flat plates arranged in parallel, hereinafter referred to as the reference axial direction),
The parallel plate structure 24 has a thin wall portion 2 as shown in FIG. 2(b).
3.23' causes bending deformation of the same shape. Therefore, the force component detection element for detecting the force in the F2 direction is constructed by forming a Wheatstone bridge with each of the strain gauges 25 to 28 so as to obtain an output proportional to the deformation mode. In this case, as shown in Figure 2(c), the second
In order to cause the same degree of deformation as shown in Figure (d), a very large moment My must be applied.In other words, since the parallel plate structure 24 originally has a high rigidity relative to the moment Mv, the strain gauge Although the output is small7, if the Wheatstone bridge is configured to compensate for the minute output due to the moment M,/, it can be made into a force component detection element with higher accuracy. In addition, this force component detection element is arranged in parallel with thin wall portions 23 and 23'.
Even if a force is applied in the axial direction of the parallel plate structure 24 which is parallel to , a small shadow 1S is applied. Higher precision force meter;・
It is desirable to build a Wheatstone bridge in such a way as to compensate for this. The fixed part 21 and the movable part 22 of the parallel plate structure 24 are relatively connected (the rigidity of the parallel plate structure 24 alone is not necessarily high against the kneading moment, but the strain gauge is placed on the axis of the moment). The deformation of the parallel plate (δ structure 24) against other loads other than these is very small, and its effects can be ignored.

This parallel below! The characteristics of the force component detection element using N structure 24 are as follows! It is possible to manufacture the device at low cost using a one-piece wound support, and to obtain a signal proportional only to the force component perpendicular to the thin-walled portions 23 and 23' arranged in parallel. It also has characteristics that meet the requirements mentioned earlier, such as high rigidity against all load components and its own deformation having no effect on the magnitude or direction of the load acting on other load component generating elements.

As mentioned above, the rigidity is low relative to the force in the reference axis direction that deflects the parallel plate as shown in Figure 2 (b), but the In terms of whether or not it affects the sheath direction, it can be said that this parallel plate structure 24 has sufficiently high rigidity, including the rigidity against forces in the subaxial direction.

The parallel plate structure 24 shown in FIG. 2(a) has a rectangular through hole 29 formed in one side of a prismatic body. However, the parallel plate structure 24 is not limited to this shape.

Other configuration examples are shown in FIGS. 2(d) to 2(f).

The parallel plate structure shown in FIG. 2(d) has a rectangular through hole 30 with rounded corners instead of the rectangular through hole 29. Further, the parallel plate structure shown in FIG. 2(e) has a configuration in which the parallel plate structure is replaced with a circular through hole 31. Both of these two examples are force component detection elements having almost the same characteristics as the parallel plate structure 24 shown in glF(a). The parallel plate structure 24 shown in FIG. 2(a) and the second
Figure (d).

The difference from the parallel plate structure shown in (e) is that the maximum value of strain that occurs when a force component acts on the latter becomes lower and the sensitivity becomes duller, but the strain distribution becomes gentler and strain gauges 25 to 28 The tolerance width for the positional accuracy is increased, making it easier to manufacture, and furthermore, [
This also makes processing easier. Furthermore, a parallel plate structure in which two circular through holes 32 are connected by a slit 33 as shown in FIG. 2(f) is also conceivable. This configuration is convenient for constructing a parallel plate structure within a limited space.

Next, a description will be given of the configuration and load detection principle when the parallel plate structure described above is used for each force component detection element of the embodiment shown in FIG.

FIG. 3 is a plan view of the configuration of a specific example of the first embodiment.

In this specific example, force component detection elements 13AX, 13BX, and 13CX in the X-axis direction shown in FIG.

13Dx, force component detection element 13AY in the Y-axis direction.

13By, 13Cv, 13Dy, and force component detection elements in the Z-axis direction 13Az, 13B2.13Cz
.

13Dz is composed of force component detection elements each using a parallel plate structure, and elements corresponding to each force component detection element shown in FIG. 1 are given the same reference numerals. In addition, S and ~s4 indicate the bonding positions of the strain gauges in each parallel plate structure, and which of these bonding positions the strain gauges are bonded to will be shown in the Wheatstone Bridge Theory (described later). That's it. It is believed that the configuration of the above specific example is clear from the description of the force component detection element shown in FIG. 2(a), even if no special explanation is given.

Here, the load detection principle of this specific example is explained in Fig. 4(a) to (
This will be explained with reference to g). First, FIG. 4(a) shows the deformation when the rigid body part 12 is fixed and a force FX in the positive direction of the X axis is applied to the rigid body part 11. As shown in this figure, in this case, force component detection elements 13Ax, 13Bx, which mainly detect force in the direction of the °rx axis are used.
Only l 3CX and 13DX are deformed. of course,
The deformations in this figure are exaggerated. The reason why such deformation occurs is that each force component detection element has a characteristic that it deforms only with respect to force in the direction of its reference axis. Therefore, each force component detection element 13AX to 13D
A strain gauge (not shown) affixed to a predetermined position of X
The force FX can be supplied by constructing a Wheatstone bridge such that a signal corresponding to the force FX is obtained. Note that the Wheatstone bridge constituted by the strain gauge will be described later.

Similarly, when the rigid body part 12 is fixed and a force FY in the positive direction of the Y axis is applied to the rigid body part 11, the force mainly in the Y axis direction is detected in the same manner as shown in FIG. 4(a). force component detection elements 13Ay, 13Bv.

Only 13CY and 13DY are deformed. Therefore, if the strain gauges (not shown) attached to the predetermined positions of the force component detection elements 13AY to 13D7 are configured as a Wheatstone bridge (described later) from which a signal corresponding to the force F9 is obtained, the force FV can be detected. can be detected.

Next, FIG. 4(b) shows deformation when the rigid body part 12 is fixed and a moment M2 about the Z axis is applied to the rigid body part 11. In this case, the connecting portion 11a.

There is a gap between the connecting parts 11b, 12a and the connecting parts 12b, and conversely, the connecting parts 11b, 12a and the connecting parts 1
Since the mutual distance between 18 and 12b increases, the beam-like members 13A and 13C protrude outward, and the beam-like members 13B and 13D retract inward, as shown in the figure. The reason why such deformation occurs is also due to the characteristic that the force component detection element using the parallel plate structure 24 is easily deformed only in the reference direction. Therefore, force component detection elements 13AX to 13D
The moment M2 can be detected by configuring the strain gauges attached to predetermined positions of x, 13Av to 13DY into a Wheatstone bridge (described later) from which a signal corresponding to the moment M2 is obtained. However, in this case, the force component detection elements 13AX to 13Dx and 13AY to 13Dy used for detecting force FX+Fv are commonly used, so even if forces FX and FV act, their effects are canceled. , it is necessary to configure the pointstone bridge of the strain gauge to detect only the moment t-M z.

Next, FIG. 4(c) shows the deformation when the rigid body part 12 is fixed and force F2 is applied to the rigid body part 11. In this case, the force component detection element 13A is ~13D! , 13AY~1
The deformation of 3D7 can be ignored, and the force component detection element 13Az,
13Bz, I3Cz.

Since only 13DZ is deformed, the deformation is as shown in the figure. Note that S and ~S indicate positions where the strain gauge can be attached. Therefore, the force component detection elements 13A2 to 13D2
The force F2 can be detected by configuring a strain gauge attached to a predetermined position as a Wheatstone bridge (described later) such that No. 43 corresponding to the force F2 is obtained.

Next, FIG. 4(d) shows deformation when the rigid body part 12 is fixed and a moment M8 about the X axis is applied to the rigid body part 11. In this case as well, force component detection elements 13Ax to 13Dx
, 13Ay to 13Dv can be ignored, and only the force component detection elements 13A2.13B2°13Cz and 13Dz are deformed, resulting in the deformation as shown. Furthermore, when the moment Mv around the Y-axis is applied, the movement around the Y-axis is shown in Fig. 4 (
Deformation as shown in e) occurs. By the way, in all the explanations so far, we have considered 881 in which the rigid body part 12 is fixed and a load is applied to the rigid body part 11, so the moment 1" M
In contrast to the deformation shown in Figure 4(d) where x is applied, both ends are fixed and the center rotates.
When the moment My is applied, as shown in FIG. 4(e), the center part is fixed and both ends rotate as one body. However, in either case, since the relative relationship between both ends and the center is the same, the deformation in the parallel plate structure is exactly the same. Note that the positions of the strain gauges appear different in Figure 4(d) and Figure 4(f3) due to the difference in viewing direction; in the former, the positions S+, S
4 is inside position i? 23z, S3 is visible on the outside, while 2, the latter is the opposite. That’s all, Moment MX,
For M, deformation similar to B described above occurs, so the strain gauges attached to the predetermined positions of the force component detection elements 13A2 to 13D2 are connected to a Wheatstone bridge ( (described later), the moment M X I M y can be detected.

Also in this case, the moment MX.

M, and force F,! Force component detection element 13 for detection of
Since A2 to 13D7 are used in common, it is necessary to configure the Wheatstone bridge of the strain gauge so that their mutual features are canceled and only the force or moment to be determined can be detected.

Here, the attachment position of the strain gauge to obtain the desired load detection signal (the attachment position of each force component detection element 5l-84)
(where to attach the strain gauges) and the Wheatstone bridge formed by the attached strain gauges (how to combine each strain gauge to form a Wheatstone bridge). will be explained with reference to the circuit diagrams shown in FIGS. 5(a) to 5(f).

A specific example of a Wheatstone bridge configuration using strain gauges so that an output is generated for a load in a certain direction, and for loads other than that, the output is canceled between the signals of each strain gauge and becomes O. The procedure may seem complicated at first glance to people other than the engineer concerned, but to the engineer concerned, it is self-evident that it is simply determined by following simple rules. Therefore, only one example of the Wheatstone bridge configuration will be shown here regarding the specific example shown in FIG.

As mentioned above, S and -S4 shown in FIG. 3 indicate the strain gauge attachable position π in each force component detection element. As is clear from the Wheatstone bridge configuration described below, the strain gauge is actually
~ S4 will be pasted at some positions, and will not be pasted at other positions.

By the way, from the explanation so far, the force component detection element 13A
2~13D2 is the force in the X and Y axis directions FX+F7 and Z
It has high rigidity against the moment M2 around the axis, and the force component detection elements 13A2 to 13
The output (change in resistance value, the same applies hereinafter) of each strain gauge D2 is approximately O. In addition, the force component detection element 13
Ax ~ 13Dx, 13Ay ~ 13D7 are the force F2 in the Z-axis direction and the moments around the X and Y axes M
Its rigidity is high for v, and force component detection elements 13AX to 13DX and 13Av to 1 are used for these load components.
The output of each strain gauge of 3D9 is approximately O. Then, each force component detection element detects a fourth force component for each load component.
Considering the deformation as shown in Figures (a) to (d), if a Wheatstone bridge is constructed by combining strain gauges as shown in Figures 5(a) to (f), the desired load detection signal can be obtained. fX""m can be obtained.

In FIGS. 5(a) to (f), the symbols of the strain gauges constituting each Wheatstone bridge are the symbols of the force component detection elements to which they are installed (for example, 13AX, 13BX).
) followed by a code indicating the position of the strain gauge (Sl
, 32, etc.). For example, in Figure 5 (
In a), 13AXS is the position i'l? of the force component detection element 13AX shown in FIG. The strain gauge attached to F S , + is shown.

In addition, fX”m indicates the output signal of each Wheatstone bridge.Furthermore, in order to verify that such a bridge configuration is appropriate, Tables 1 and 2 below show the respective output signals for each load input. The direction and magnitude of the signal generated in the strain gauge are indicated by "+", r-J, rOJ, and at the same time, the output produced by the Wheatstone bridge is also indicated. In these tables, the symbols r+J and r-J indicate the output directions for positive direction inputs of each load component, and as a matter of course, they are all reversed for negative inputs.

I'll add a note just in case, but is it 'L' shown here? The configuration example of the C Wheatstone bridge is one of many possible examples.

Table 1 Table 2 As described above, in this embodiment, in each connecting portion of orthogonal rigid body parts, adjacent connecting portions are connected by beam-like members to form an annular load detection mechanism as a whole, and this load is By providing a force component detection element on each beam-like member of the detection mechanism section, each force component detection element is arranged along the periphery of the load detector, so that the force component detection element is arranged along the periphery of the load detector. Compared to arranging the force component detection elements from the periphery toward the center, each force component detection element can be arranged with more space, which allows for the necessary The detection accuracy can be improved. In addition, since each force component detection element is arranged along the periphery, excessive stress does not occur in the load component detection element in the center, unlike conventional load detection, and therefore the rated value of the moment can be selected to a larger value. In addition, this makes it possible to increase the processing reaction force when applied to force control such as grinding processing, thereby increasing work efficiency.

Furthermore, if the parallel plate structure shown in the specific example of this embodiment is used for the force component load element, the surrounding beam members can be simply i'tii!
! Since it can be configured by simply drilling a hole, its structure is much simpler than the conventional load detector shown in Figure 13, and it can be easily processed, making the load detector inexpensive. can be manufactured. Furthermore, if the Wheatstone bridge is appropriately constructed using a strain gauge as illustrated in FIG. 5, all loads can be detected with extremely high accuracy.

The first embodiment of the present invention has been described above, but among the detection structures that have been proposed to date, the parallel plate structure is the most suitable as a detection structure that satisfies the above-mentioned characteristics required for a force component detection element. It is thought that Therefore, in the following embodiments, a parallel plate structure will be exemplified as a force component detection element.

FIG. 6 is a plan view of a load detector according to a second embodiment of the present invention. In the figure, parts that are the same as those shown in FIG. 3 are given the same reference numerals, and explanations thereof will be omitted. The difference between this embodiment and the configuration shown in FIG. 3 is Zl shown in FIG. ! While the parallel plate structure of the force component detection element in the force direction is composed of a through hole along the intermediate direction between the X-axis and the Y-axis, the parallel plate structure of the force component detection element in the X-axis direction of this embodiment is In other respects, both are the same. In FIG. 6, the force component load elements in the X-axis direction are 13Az', 13Bz', and 13Cz', respectively.

13D2', and the beam-like members including them are denoted by 13A', 13B', and 13C', respectively.

13D'.

In the operation of this embodiment, the deformation with respect to forces FX, FY, F7 and moment M2, and the method of load detection using them are exactly the same as in the specific example shown in FIG. This second embodiment differs from the specific example shown in FIG. 3 in the detection operations of moments) Mx and Mv. moment) When M x acts, the force component detection elements 13Az', 13Bz', 13C2',
13DZ' each produces only pure bending deformation,
While the same type of deformation as shown in FIG. 4(d) occurs, when moment MV acts, each of the force component detection elements 13Az' to 13D2' causes bending deformation including some torsional deformation. arise. As mentioned above, the parallel plate structure does not have very high rigidity against torsion, but in the configuration of this embodiment, each of the force component detection elements 13A2' to 13D
, ' are arranged symmetrically away from the axis on which the torsional torque acts, so the main part of the deformation is bending deformation, and the torsional deformation is only a small part of it. in fact,
In the specific example shown in FIG. 3, the moment I-M×1 M
The deformation with respect to y was explained using FIG. 4(d) as if only pure bending deformation occurred, but strictly speaking, the deformation in that case is the deformation due to the moment M in the second embodiment. The deformation is exactly between the deformation caused by the moment M7 and the deformation caused by the moment M7.

The effect of this example is that although there is a slight difference in sensitivity to moment) MxlMy, other than this, the
It is the same as the cited example (including the effect of the specific example).

FIG. 7 is a plan view of a load detector according to a third embodiment of the present invention. In the figure, 11.12 is a rigid body part, 11a, 11b
12a is a connecting portion of the rigid body portion 11;

Reference numeral 12b represents a connecting portion of the rigid body portion 12, and these are the same as those in the previous embodiment. In this embodiment, each connecting portion 11
The beam-like members between a, llb, 12a, and 12b are formed in an arc shape, and the parallel plate structure of the force component detection element constructed in these beam-like members has a circular through hole shown in FIG. 2(e). Since a device is used, the beam-like member and the force component detection element will be described with reference numerals different from those in each of the above embodiments. 4
3A is a beam-like member connecting between the connecting portions 11a and 12a; 4;
3B is a beam-shaped member connecting between the connecting portions 12a and llb;
3G is a beam-like member that connects the connecting portions 11b and 12b; 4;
3D is a beam-like member that connects the connecting portions 12b and lla. These connecting portions and beam-like members constitute an annular load detection structure 44. Each of the beam-like members 43A to 43D has a force component detection element 43A using a parallel plate structure.
The reference axes of x~43DX, 43A, ~43D are arranged in directions that differ from the X and Y axes by an angle θ, respectively.

Next, FIG. 8(a) shows the load detection principle of this embodiment.

This will be explained with reference to (b). The load detection principle of this embodiment is basically the same as that of the specific example shown in FIG. In particular, the deformation and load detection principles regarding force F2 and moments Mx, M't are exactly the same. However, the detection principle for other load components is the force component detection element 43.
The direction of the reference axes of AX to 43DK and 43Av to 43Dv is tilted by an angle θ with respect to each of the X and Y axes, so this is somewhat different from the specific example shown in FIG. This will be explained with reference to partial plan views of the load detector of this embodiment shown in FIGS. 8(a) and 8(b). In addition, Fig. 8(a)
, (b), the same parts as those shown in FIG. 7 are given the same reference numerals.

In FIG. 8(a), the rigid body part 12 is fixed, and the rigid body part 1
When force FX is applied to 1, each beam-like member 43A to 43D
A force of FX/4 acts on each of them. At this time, force component detection elements 43AX to 43Dx.

The force acting in the reference axis direction of 43A7 to 43DV is F r
! l F'ry, and if the force acting in the tangential direction perpendicular to the reference axis is F tX+ F Ly, then F rx
= (F x / 4) cosθ...
・・・・・・・・・(1) Fry=(Fx /4)sinθ
・・・・・・・・・・・・(2) Ftx= (F
X /4) sin θ ・・・・・・・・・・・・(
3) FLy= (Fx /4)cosθ...
......(4). Note that the force component detection element using a parallel plate structure has an angle 11 in the tangential direction.
The stress caused by the tangential force is very small and its influence can be ignored.

By the way, the force component detection elements 43AX to 43DX.

Since strain gauge output signals proportional to the force acting in the reference axis direction are obtained from 43A7 to 43DY, in this example, the force component detection required T: 43A x to 43DX, which mainly detects the force in the X-axis direction, is The output when a Wheatstone bridge using a strain gauge attached to the strain gauge is configured to obtain a signal corresponding to the force Fx is as shown in the specific example shown in Figure 3. It is cosθ times smaller than the output of . Similarly, force component detection element 43A mainly detects force in the Y direction.
FX/4 sin for each strain gauge from y to 43DY
A signal equivalent to θ times is output. Since these force component detection elements 43Av to 43D are used to detect the force Fv in the Y-axis direction, a Wheatstone bridge configuration may be used so that the force FX signal is canceled.

When the force Fy in the Y-axis direction is applied, the opposite is true, and the force component detection elements 43AY~ mainly detect the force in the Y111 direction.
A signal corresponding to F Y-cos θ is obtained from the output of 43Dv, and at this time, a Wheatstone bridge is used so that the outputs of force component detection elements 438X to 43D, which mainly detect force in the X-axis direction, cancel each other out. Configure.

Next, in FIG. 8(b), when the rigid body part 12 is fixed and a moment M2 is applied to the mouth body part 11, the force transmitted through each of the beam-like members 43A to 43D causes the force component detection element to be detected. 43AX~43DK.

The equivalent force acting on 43Av to 43Dv is represented by the force F balanced on a straight line passing through points P and Q located at a distance I- from the center O of the load detector, as shown in the figure. Elements 43AX to 43DX.

The force F in the direction of the reference axis of 43A7 to 43DY and the force F in the tangential direction perpendicular thereto are expressed by the following equation. However, the angle 1/2 of the angle formed by the line OP and the line OQ is assumed to be φ.

F,=F,sinφ・・・・・・・・・・・・
...(5) F t ” F @cosφ
(6) As mentioned above, for force Ft in the tangential direction, force component detection elements 43A to 4 are used.
3Dx, 43Ay to 43Dv do not output significant signals. Therefore, each force component detection element 43AX to 43Dx,
The strain gauges provided at 43Av to 43Dy may be configured as a Wheatstone bridge that detects only the force F in the direction of the reference axis. Of course, in this case, the force component detection elements 43AX to 43D and 43Av to 43Dv are X,
Since it is also used to detect the forces FX and FY in the Y-axis direction, the Wheatstone bridge is constructed so that these cases can be distinguished from the case where the moment M2 is acting. The specific method is obvious to those skilled in the art, so it will be omitted.

When the force F is determined, from equation (5), Fs ” Fr /sinφ ・・・・・・・・・
......(7). On the other hand, the moment M2 is M2-4F according to the relationship shown in the figure, ・Lcosφ ・・
・・・・・・・・・・・・(8). In the end, the moment M2 is calculated from equations (7) and (8) as follows: MZ = 4 F −・Lcotφ ・・・・・・・・・
Since it is expressed by (9), moment M2 can be found by finding force F. Here the value Lcotφ
is a constant specific to this force sensor.

This embodiment also has the same effect as the first embodiment and its specific examples, but in addition to this, the beam-like member and the end of each rigid body form a ring, and each force component detection element is parallel to each other. Since the flat plate structure is constituted by circular through holes, it also has the effect of further facilitating processing.

FIG. 9 is a perspective view of a load detector according to a fourth embodiment of the present invention. In the figure, 45 is a rigid body part, 45a and 45b are connection parts of the rigid body part 45, 46 is a rigid body part, 46a (hidden and cannot be seen in the figure), and 46b are connection parts of the rigid body part 46. These rigid body parts and connecting parts are the rigid body parts 11.12 and the connecting parts 11a, llb, 12a, 12 of each of the preceding embodiments.
Corresponds to b.

Reference numeral 47 designates a load detection mechanism section including force component detection elements 43AX and subsequent force component detection elements disposed on the beam-like members 43A to 43D1 shown in FIG. 7 and connecting portions 45a to 46b. In addition, illustration of each force component detection element of the load detection mechanism section 47 is omitted in the figure.

In the third embodiment, each rigid body part 11.12 was located within the thickness plane of the load detection mechanism part 47. However, each rigid body part 11.12 does not necessarily have to lie within the plane in question. In this embodiment, these rigid body parts are
5.46, which is placed outside the plane. The load detection principle is the same as that of the third embodiment. In addition, in this embodiment, each rigid body part 45, 46 is connected to the load detection mechanism part 47.
Although an example has been described in which this embodiment is applied to the structure shown in the third embodiment, it is natural that this arrangement of each rigid body part can also be applied to the first embodiment and the second embodiment. .

This embodiment has the same effect as the third embodiment, and also has the effect of being easier to process, although the thickness is larger.

FIG. 10 is a perspective view of a load detector according to a fifth embodiment of the present invention. In the figure, 47 is the same load 1i detection mechanism as shown in the fourth embodiment. 48.degree. 49 is a rigid body portion, which corresponds to the rigid body portion 45.degree. 46 of the fourth embodiment. The rigid body portion 48 has both connecting portions 48a.

48b, and a central annular portion 48C. Similarly,
The rigid portion 49 has both connecting portions 49a, 49b and a central annular portion 49c. Since the annular portions 48C and 149C are located substantially opposite to each other and located inside the annular body of the load detection mechanism portion 47, a hollow portion passing through the crown is formed. The illustrated reference numeral 50 indicates this cavity. This example is the third
The only difference from the embodiment is that annular parts 48c and 49c are provided at the center of each rigid body part 48, 49. The load detection principle is the same as that of the third embodiment. It is clear that the rigid body portion of this embodiment is applicable to the first embodiment and the second embodiment.

This embodiment not only has the same effect as the fourth embodiment, but also has a cavity 50, so when this load detector is installed at a predetermined location on a robot or machine tool, etc. It is extremely easy to attach using the section. It is also convenient for inserting cables for various signal lines. Furthermore, tools such as a hand grinder can be stored in the cavity, making it possible to downsize the entire device. Furthermore, by housing the processing tool in the cavity, the point of application of processing can be brought significantly closer to the load detector, and the moment acting on the load detector can be suppressed. That is, if the point of application of machining is far from the load detector, the moment acting on the load detector will increase and may exceed the rated value of the moment, which can be kept low as described above. This drawback can be avoided by adopting a method of storing the processing tool in the cavity.

FIG. 11 is a perspective view of a load detector according to a sixth embodiment of the present invention. In the figure, 47 is the fourth. This is the same load detection mechanism as in the fifth embodiment. In the figure, a parallel plate structure in the load detection mechanism section 47 is illustrated. Reference numeral 51 denotes an annular rigid body portion, the inner diameter and outer diameter of which are equal to the inner diameter and outer diameter of the annular load detection mechanism portion 47 . 51a and 51b are connection parts of the rigid body part 51, and 51C is a through hole drilled at a predetermined location of the rigid body part 51. The reason for installing this ji11 hole will be described later. 52 is an annular rigid body part, and its inner diameter and outer diameter are equal to the inner diameter and outer diameter of the load detection mechanism part 47, similar to the rigid body part 51. 52a and 52b are connection parts of the rigid body part 52. 53 passes through the rigid body portions 51° 52 and the load detection mechanism portion 47 i1! ! This shows the cavity.

This load detector has a cavity 53 in one cylindrical block.
, the rigid body parts 51 and 52, the notches for configuring the load detection mechanism section 47, and the through holes for configuring the parallel plate structure of each force component detection element in the load detection mechanism section 47. It consists of: In this process, the process for configuring the parallel plate structure of the force component detection element that detects force components in the X-axis and Y-axis directions is troublesome because of the presence of the rigid body parts 51 and 52. The through hole 51c drilled in the rigid body portion 51 is a hole created when performing the processing. The load detection principle is the same as that of the third embodiment.

In addition to the effects of the fifth embodiment, the effects of this embodiment are that each rigid body part and the load detection step part have the same annular cross section, so that machining is further facilitated, and the hollow part is reduced. Since it is larger, it has the effect of being able to accommodate more processing tools and signal line cables.

FIG. 12(a) is a perspective view of the load 1 moxibustion device according to the seventh embodiment of the present invention, with a part cut and removed, and FIG. 12(b) is the part cut and removed in FIG. 12(a). Perspective view of Figure 12 (
c) is a plan view of the load detector shown in Fig. 12(a);
Figure 2(d) is the line χn c-x n c in Figure 12(c).
FIG.

In each figure, 47 is a stress detection mechanism section, and the same reference numerals are given to the same parts in each of the parallel plate structures constructed there as shown in FIG. 7. 55 is circular rt
It is an annular rigid body section provided on the side of the single-double ratio detection mechanism section 47, and the connection sections 55a and 55b connect the load detection mechanism section.! 7
is connected to. 56 is load detection 8! It is an annular rigid body part provided inside the structure part 47, and the connecting parts 56a, 5
It is connected to the load detection mechanism section 47 at 6b and h. Rigid body part 5
5.56 are located at opposing positions, and their inner peripheral surfaces are on the same plane. 57 is a groove that separates the rigid body part 55 and the rigid body part 56, and 58 is a slit 1 that separates the ejection mechanism part 47 (triple with the rigid body part 55) except for the connecting part with the connecting parts 55a and 55b. -159 is a slit that separates the rigid body part 56 and the first part 47, except for the connecting parts with the connecting parts 56a and 56b. 60 is a hollow part that penetrates the rigid body part 55 and 56. The load detection principle of this embodiment is the same as that of the third embodiment.

” The processing method for manufacturing the load detector will be briefly described. First, the outside dimensions are machined using a lathe. At this time, the grooves 57 that separate the rigid body parts 55 and 56 are also processed. Next, both slits 58 and 59 are machined by electric discharge machining using electrodes having the same shape as the semicircular slits 58 and 59. The through holes for each parallel plate structure of each force component detection element may be formed using a drilling machine or the like. In this way, it can be easily manufactured with extremely simple processing.

Note that the rigid body parts 55 and 56 can also be provided outside the load detection eight-layer structure part 47. In this case, the load detection mechanism section 47
Since each force component detection section will be located inside the connection point with the external mechanism, the value of the moment rating must be selected to be a slightly lower value than in the configuration shown above.

Furthermore, one of the rigid parts 55, 56 could be provided on the inside and the other on the outside. With such a configuration, the thickness of each rigid body part can be adjusted to the load detection mechanism section 4 without increasing the overall thickness.
7, and the rigidity of the rigid body portion can be increased. Therefore, when the load detector is attached to a robot or the like, deformation of the rigid body portion can be prevented and detection accuracy can be further improved.

In addition to the effects of the sixth embodiment, the effect of this embodiment is that since both open body parts are within the thickness of the load detection mechanism part, the overall thickness is reduced, making it extremely easy to attach to an external mechanism such as a robot hand. It also has the effect of being suitable.

Although the present invention has been described in detail above, it is obvious that the present invention is not limited thereto and that other structures can be used.

〔Effect of the invention〕

As described above, in the present invention, the load detection mechanism section is configured in an annular shape, and the load detection elements are arranged in this load detection mechanism section, so that the load detection elements are arranged from the periphery toward the center. Compared to conventional devices with the same structure and external dimensions, it is possible to secure sufficient space for configuring the load detection element, making it possible to configure a highly accurate load detector, as well as achieving a higher moment rating. can be selected to a larger value. Conversely, when constructing a load detector with the same performance, it can be constructed smaller and lighter than the conventional one.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a load detector according to a first embodiment of the present invention, and FIGS. 2(a), (b), and (c). (d), (e), (f) are side views of the parallel plate structure, Figure 3 is a plan view showing a specific example of the load detector shown in Figure 1, Figures 4 (a), (b), (c), (
d). (, 3) is an explanatory diagram of the detection principle of the load detector shown in FIG. 3, and FIG. 5 is (a), (b), (c), and (d). (e), '(f) are circuit diagrams of the Wheatstone bridge used in the load detector shown in Fig. 3, and Figs. 6 and 7 are the second and third embodiments of the present invention, respectively. Plan view of the load detector according to Fig. 8 (a>, (b)
) is an explanatory diagram of the detection principle of the load detector shown in Fig. 7, and Fig. 9
1org+ and FIG. 11 are perspective views of cart detectors according to the fourth embodiment, fifth embodiment, and sixth embodiment of the present invention, respectively, and FIGS. 12(a), (b), (c),
(d) is a partially cutaway perspective view, plan view, and sectional view of a load detector according to a seventh embodiment of the present invention, and FIG. 13 is a perspective view of a conventional load detector. 11.12,45,46.48,49,51゜52.5
5.56...Rigid body part, 13AX. 13AY, 13Az, 13Az', 138K. 13By, 13Bz, 13Bz', 13Cx. 13Cy, 13C2, 13c2', 13DX. L3Dv, 13Dz, 13Dz', 43Az. 43A,, 438Zl 4381+, 43By, 43
Bz+ 43Cx, 43Cv, 43Cz, 43Dx. 43Dv, 43Dy...Force component detection element, 14°14', 44.47...Load detection mechanism part Fig. 3m Fig. 4(a) Fig. 4(b) Fig. 4, Fig. 5 rσ of
(b)(c)
(d)(e)
(
f) Fig. 6 13C'130' Fig. 7 Fig. 8 (O) Fig. 8 Fig. 9 Fig. ii Fig. 12 (C)

Claims (10)

[Claims] (1) A load detection mechanism including a first rigid body part, a second rigid body part, and at least one load detection element that detects a load acting between the first rigid body part and the second rigid body part. In the load detector, the load detection mechanism has an annular configuration, and two parts of the load detection mechanism and the first part are opposed on an axis in a predetermined direction set in the load detection mechanism. and the second rigid body part is connected to two parts of the load detection mechanism part facing each other on an axis substantially perpendicular to the predetermined direction. vessel. (2) In claim (1), the load detection element is a force component detection element that mainly detects force in the predetermined direction, and a force component detection element that mainly detects force in a direction perpendicular to the predetermined direction. and at least one of a force component detection element that mainly detects force in a direction substantially perpendicular to either of the two directions. (3) A load detector according to claim (2), characterized in that the force component detection element has a parallel plate structure. (4) In claim (1), the load detection element is provided between adjacent connection parts of the first rigid body part and the second rigid body part in the load detection mechanism part. A load detector characterized by: (5) The load detector according to claim (4), wherein the load detection element is disposed in the load detection mechanism portion symmetrically with respect to an axis in the predetermined direction. (6) The load detector according to claim (1), wherein each of the first rigid body part and the second rigid body part has an annular structure at its center. (7) The load detector according to claim (1), wherein the first rigid body part and the second rigid body part are formed in an annular shape. (8) Claim (7) is characterized in that the first rigid body part and the second rigid body part are formed in an annular shape having substantially the same shape as the load detection mechanism part. Load detector. (9) The load detector according to claim (7), wherein the first rigid body part and the second rigid body part are arranged inside the load detection mechanism part. (10) In claim (7), the first
A load detector, wherein one of the rigid body part and the second rigid body part is disposed inside the load detection mechanism part, and the other one is disposed outside the load detection mechanism part.