JPS63193024A - Load detector - Google Patents

Abstract

PURPOSE:To easily alter detection sensitivity and rigidity, by providing a fixing member having rigidity not deformed by the load applied to a rigidity part at the predetermined place between parallel elastic members so that the arrangement place is movable. CONSTITUTION:Slits 12, 13 are provided to thin flat plates 8, 9 on the center lines thereof and a fixing block 14 generating no deformation by load F is inserted between the flat plates 15, 16, and fixed by the clamp screw 17, 18 passing through the slits 12, 13 via block pressers 15, 16. This block 14 can move to an arbitrary position by the slits 12, 13. When the load F acts on a rigidity part 31, a parallel flat plate structure 3a' deforms and the same deformation is generated in the flat plates 8, 9 on both sides of the block 14. At this time, the strain quantity generated in the strain gauge 10 adhered to flat plates 8, 9 and the strain quantities delta1, delta2 of the flat plate structures on the left and right sides of the block 14 change by changing the distance l1 between the left end of the block 14 an the ends of the flat plates 8, 9. That is, by moving the block 14, detection sensitivity or rigidity can be altered.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a load detector that detects a load acting on an object.

[Conventional technology]

Detecting loads (forces, moments) applied to objects is essential in many fields.

For example, when a high-performance robot performs assembly work, polishing, or deburring work, it is necessary to accurately detect the force acting on the robot's hand.
When conducting model tests on ships, vehicles, etc., the main item is to detect the loads applied to each part. A load detector with excellent performance for detecting such loads is
QZ is disclosed in Japanese Patent Application Laid-Open No. 60-62497.

The schematic configuration will be explained below with reference to the drawings.

Fig. 3 is a perspective view of a conventional load detector;
y, z indicate the assumed coordinate axes, 1 indicates a load detector, and the load detection 231 detects the center portion 2 of the rigid body and the rigid blocks 3, 4 . It has a rigid block 5.6 extending in the Y-axis direction. The block 3 has parallel plate structures 3a and 3b formed on its end side and on the center part 2 side, respectively. Parallel plate structure 3a
is constructed by forming a through hole 7 in the Y-axis direction in the block 3. By forming this through hole 7, thin flat plates 8 and 9 are formed parallel to each other so as to connect the rigid bodies on both sides thereof. 10 is a strain gauge attached to each of these thin flat plates 8.9. Note that the strain gauge 10 attached to the thin flat plate 9 is not shown in the figure, and this parallel plate structure 3a constitutes a single load detector.

On the other hand, the parallel plate structure 3b has +1! by forming a through hole in the Z-axis direction in the block 3! It is equipped with mutually parallel thin flat plates and strain gauges attached to each of these thin flat plates. Similarly for each block 4.5.6,
Two parallel plate structures are each constructed.

In such a load detector 1, when a load is applied between the end portion and the center portion 2 of the block, the corresponding thin plate is deflected, and the strain gauge is distorted in accordance with this deflection. The resistance value of the strain gauge changes. The load can be detected by extracting this change in resistance value as an electrical signal using a Wheatstone bridge circuit, an amplifier, etc. (not shown). , force components in the Z-axis direction, and moment components around the X-, Y-, and Z-axes can be detected.

Next, when the load is applied as described above, parallel plane +Ii
Regarding the relationship between load and strain in ++% construction, Part 4
This will be explained with reference to the figures. FIG. 4 is a perspective view showing only the parallel plate structure 3a shown in FIG. 3, and the same parts as shown in FIG. 3 are given the same reference numerals. 3
1 is a rigid body part on the end side of the block 3, and 32 is a rigid body part on the parallel plate structure 3b side of the block 3. Here, figure [1]
Each dimension shown in is determined as follows.

h: Thickness of the thin flat plate 8.9 b: Width of the thin flat plate 8, 9 Lo: 't' Length j2 of the V-thick flat plate 8.9 G: Length δ between the end of the rigid body part 32 and the strain gauge 10
: Amount of deflection in the Z-axis direction The thin plate 8.9 is deformed as indicated by the dash-dotted line in the figure. In this case, load ff1F
The moment 1-M generated by 1-M is expressed by the following equation, assuming that the moment resisting the load F is M and C, with the clockwise direction being positive.

M--M, -F・, x--・--・・・・・・・・・・
−−・−・・・・・・(1) Also, if the deflection factor of the thin flat plates 8 and 9 is generally 2 (in the case shown, 2−δ), the Young's modulus is E, and the moment of inertia of area is ■. , If we sequentially integrate equation (3) from equations (1) and (2), we get...---------(4) +C, x+C! −・・−・・−・・
−・・−m=−−−・・・・−(5) Here, due to the characteristics of the parallel thin plate 8.9, at x=0, dz/dH
= O, z = δ, so by substituting this, c, −0・−・−・−・−・−・・−・−・・・−・・・
−・−・−・・−・−・−・−・・−・(6) C1
=E・■・δ −−−−−・−・−・・−・・−・−・
−・−・・−・−・・− (7) Furthermore, in xxL, di/d×−0, 2= 0, so by substituting this, we get M, −−F−L6 /2 ・−・・・・・・－・・・・
・・・・・・−・・−・・−・−・・(81B-1・δ−
-F -L, >'/12 ...
(9) Also, since the parallel thin flat plates 8.9 can be regarded as one beam made up of two thin flat plates, the moment of inertia I of area is expressed by the following equation.

1-2b-h3/12 −・・−・−・−・・−・−−
---------・-・-Q(0(5)2~01I From the formula, the deflection lz is expressed by the following formula.

However, δ−−F−L@' /2 bh' ・−・−
・--------- θ Next, ) The amount of strain ε'' of

s = −”−・−′−・−−−−−−−−−=−=
-tJ2E・! 2 CIM-ε −・・・・・・−−−１−・・・−・・・
−・−・−・−・・−・・・The distance of the strain gauge 10 is x z L @ −16, and using this value, equations (1), (8), From the al formula, each strain amount ε
, ε° are as follows.

3F-L, -6F・(Lo-j!c)”=
2Ebh"・・・・・・－・Qツ・'x
3F'' Uniryo Dogami [J Wataru・-・・・・Q1Ubht (1!9 formula and 0 formula will express the strain in the strain gauge lO when a load 'mF is applied.

[Problem that the invention seeks to solve]

By the way, there are cases where it is desired to change the detection sensitivity of the load detector depending on the state, change, change, etc. of the object to be detected. Tokoroke, the above 09 type.

As is clear from the α0 formula, in order to change the detection sensitivity, that is, the strains it and al for a certain load, it is necessary to change each characteristic value L@, b, h, 1@ in the parallel plate structure, and therefore In this case, the r=li detector had to be replaced with one having the desired detection sensitivity or modified by processing.

Furthermore, there are cases where a load detector is applied to a certain system and the system is controlled based on the detected value, but in such cases, if the load detector is highly rigid, the control may become unstable. Therefore, there is a desire to reduce the rigidity. However, in order to reduce the rigidity of the load detector (that is, increase the deflection δ), the above (b)
As is clear from the equation, the characteristic values of the parallel plate structure are: , b,
h must be changed, and for that purpose, as in the case of the detection sensitivity, the attached load ffi detector must be replaced with one having the desired rigidity or modified by processing, and, In order to avoid this replacement and processing, it was necessary to prepare a separate appropriate spring system and install this spring system in series with the load detector to reduce the overall rigidity.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the prior art described above and to provide a load detector whose detection sensitivity and rigidity can be easily changed.

[Means for solving problems]

In order to achieve the above object, the present invention provides a load detector consisting of mutually parallel elastic members connected to two rigid body parts, in which a load applied to the rigid body parts is applied to a predetermined location between the parallel elastic members. is characterized by providing a fixing member having rigidity that does not deform.

(Function) By providing a fixed member between the elastic members, the characteristic value of the load detector changes substantially when it is deformed. Therefore, by selecting the installation location of the fixed member, any detection sensitivity, stiffness, etc. It becomes possible to obtain.

〔Example〕

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

FIG. 1 is a perspective view of a parallel plate structure constituting a load detector according to an embodiment of the present invention, and the same parts as those shown in FIG. 4 are given the same reference numerals and explanations are omitted. . 12 is a slit provided in the thin flat plate 8, 13 is a slit provided in the thin flat plate 9, and the center line of each slit 12.13 coincides with the center line of the thin flat plate 8, 9, respectively.
A fixed block 14 is inserted between the thin flat plates 8.9 and has a rigidity that does not cause deformation under the load F.

15 and 16 are block pressers that press the fixed block 14, respectively, and 17 is a block presser that presses the fixed block 1 through the slit 12.
4, the blower, and the presser foot 15. The set screw that fastens the fixed block 14 and the block presser 1G is not shown in the figure.The fixed block 14 is attached to the slit 12.
．． 13, it can be moved to any position.

The thickness and length of the thin flat plates 8 and 9 are the same as those shown in FIG.
．． The widths on both sides of 13 are each b/2, and the combined width of both is b. The thickness of the fixed block 14 is m10%, and its left end position is a distance f from the left end of the thin flat plate 8.9.
It's on ll 11. Furthermore, the position of the strain gauge 10 is a distance i! from the left end of the thin flat plate 8.9, as shown in FIG. ill 1c.

When a load F is applied to the rigid body part 31, this parallel plate structure 3
a' is deformed as shown by the dashed line in the figure.

Note that the illustration of the slits 12.13 in the deformed state is omitted. In this embodiment, each thin plate 8.9 is restrained by the fixed block 14 during deformation, and the fixed block 1
The thin flat plates 8.9 on both sides of 4 are deformed in the same manner as shown in FIG.

The above deformation can be considered to be the same as the deformation that occurs when the load F acts on the fixed block 14 when looking at the strain gauge IO.

Therefore, the strain deflections ε and ε° generated in the strain gauge 10 in this case are expressed by the following formula according to the above-mentioned formula 09 (the old formula).

・・・・・・−・−・・・−・・−・−・・・−・・・
aη・・・・−・−・・・−・−・・・・−・・−Q
lAs is clear from the above αη equation and side equation, strain shop ε.

ε°, that is, the detection sensitivity is the distance! , by changing the value of . Therefore, according to this embodiment, the detection sensitivity of the load detector can be freely changed by moving the fixed block 14, and there is no need to replace or process the load detector.

Next, the spring rigidity in this example will be considered. As shown in FIG. 1 and evident from the above-mentioned deformation, the presence of the fixed block 14 allows this parallel plate structure 3
al has a single parallel plate structure on the left and right sides of the fixed block 14, and has a structure in which two parallel plate structures are connected in series. Therefore, the rigid body part 3
When a load F is applied to the fixed block 14, the deflection star δ1 of the parallel plate structure on the left side of the fixed block 14 and the deflection amount 62 of the parallel plate structure on the right side can be expressed as follows according to the above formula 02.

δ,=r"j','/2bh' -----------
−−−・−・−・(1 smell δ2±F (t, 0−z, −!
! . )' / 2 b b ”−・−・・・−・−・・
-(2's deflection ζ, the deflection δ of the parallel plate structure 3a'' is the sum of these deflections ■δ4.δ2, so δ−δ1+
δz=F (La lo”) ((Lo Noν3
(Lo l1o) 11+ 3 j! 1”) / 2
b h3・−・・−・・−・・・・・・・(21>
becomes.

Figure 2 is a graph of this equation (21), where the horizontal axis shows the distance E''
1tl l, and the deflection ■δ is taken on the vertical axis.

That is, 1+-10/2.11=L6- (j!6/2)
At '+=(Lo j!o)/2, there is a maximum amount of deflection, and the rigidity can be made the lowest, and at '+=(Lo j!o)/2, there is a minimum amount of deflection, and the stiffness can be made the most. In other words, the rigidity of the load detector can be freely changed by moving the fixed block 14, and the rigidity can be adjusted to the optimum rigidity for controlling the applied system without replacing or modifying the load detector. can be obtained.

In the above description of the embodiment, one parallel plate (14 structures) was explained, but it is of course applicable to a parallel plate structure in a combination structure as shown in FIG. When applied, the optimum detection sensitivity and rigidity can be selected for the load components in each direction.

Furthermore, it is also applicable to those using a rod-shaped elastic member instead of a thin flat plate. Also, fixed blocks.

Fixation is not necessarily limited to block holders and screws,
Other suitable fixing means can be used.

Also, it is clear that the slit is not necessarily required.

〔Effect of the invention〕

As described above, in the present invention, since the fixing member is provided at a predetermined position between the parallel elastic members, it is possible to easily improve the detection sensitivity of the load detector without requiring replacement or processing of the load detector. You can change the controlling gender.

, Simple explanation of the drawings FIG. 1 shows a parallel plate (
A perspective view of 1-1 structure, Figure 2 shows the parallel plate shown in Figure 1) 1
・! FIG. 3 is a perspective view of a conventional load detector, and FIG. 4 is a perspective view of the parallel plate structure of the load detector shown in FIG. 3.

3 a+−・−・−・Parallel plate structure, 8.9・・・・−
・-・Thin flat plate, 10...-Strain gauge, 14
...Fixed block, 15゜16---
Block holder, 31.32-- Rigid body part.

Figure 2 δ

Claims (2)

[Claims] (1) A load detector comprising two rigid body parts, mutually parallel elastic members connected to these two rigid body parts, and displacement detection means for detecting displacement of one of the two rigid body parts, A load detector characterized in that a fixing member is provided at a predetermined location between each elastic member and is not deformed by a load acting on each of the rigid body parts. (2) The load detector according to claim (1), wherein the fixed member is movable between the elastic members.