JPS62100632A - Load detector - Google Patents

Abstract

PURPOSE:To enable a load detector to be prevented from deteriorating performance and a breakage even when an excessive load is applied to the detector by bringing a pin fixed to a pin fixing portion into contact with the inner wall of a hole when a load in an overload above a given value exceeding a rated load. CONSTITUTION:When an excessive downward force Fz is applied to an upper annular body 16a for some cause, the quantity of displacement of the annular body 16a is extremely increased and the clearance (g) between a pin 33a and the upper inner wall of a through-hole 32a is reduced to zero, both abutting against each other. On the other hand, since a projected portion 22a wherein a pin fixing portion 31a is formed in connected to a lower annular body 16b, a force to tend to further displace the upper annular body 16a, that is, a force to tend to further deform the thin wall portions of a cylindrical body is transmitted to the lower annular body 16b via the pin 33a, pin fixing portion 31a and the projected portion 22a. Since similar operations are conducted in other stoppers, even when the excessive force Fz is applied to the upper annular body 16a, the thin wall portions of the projected portion 22a do not have a deformation above a predetermined quantity and a plastic deformation or a breakage does not occur, being perfectly protected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a load detection device for detecting loads applied to various objects.

[Background of the invention]

Detecting loads (forces and moments) applied to an object or a specific part of an object is essential in many fields. As a load detection device for detecting such a load, an excellent load detection device having a parallel flexure beam structure, a radial flexure beam structure, or both has been proposed in Japanese Patent Laid-Open No. 60-62497. This publication does not disclose various types of load detection devices using the parallel flexure beam structure and the radial flexure beam structure. One type of load detection device will be explained with reference to FIG.

FIG. 4 is a partially cutaway perspective view of a conventional load detection device.

In the figure, X, Y-Z indicate coordinate axes. 22 is a columnar body, and this columnar body 22 has projecting portions 22a, 22b, 22c,
22d is formed, a through hole 23 is bored in the center, and a through hole reaching the through hole 23 is formed between each adjacent overhang, thereby forming thin parts 24a, 24a'.
......24d and 24d' are formed.

Strain gauges 25a to 25h' are provided at the base center portions of the upper and lower surfaces of each thin portion. 26a.

26b, 26c, and 26d are the respective projecting portions 22a.
This is a through hole drilled in the Z-axis direction at H22b + 22c + 22d.

These through holes 26a to 26d allow the thin wall portions 15a, 1
5a°...15d, 15d' are formed. A strain gauge 17c is provided at the center of the root of each of these thin parts.
The upper parts of b and 22d are connected to the upper annular body 1('; aK, and the lower parts of the other opposing projecting parts 22a and 22c are connected to the lower annular body 16b.
There are considerable gaps between the upper surface of the coiled body 16a and the overhangs 22a and 22c, and between the lower annular body 1fib and the lower surfaces of the overhangs 22b and 22d.

In this configuration, the upper annular body 16a and the lower annular body 16
When a force Fz in the Z-axis direction, a moment (moment about the X-axis, and Yiill) acts between 24a, 24a'...
...Deformation occurs in the corresponding thin wall portions of 24d and 24d'. or.

The X axis is between the upper annular body 1fia and the lower annular body 16b.

Force Fx in the Y-axis direction, Fy - moment MZ around the Z-axis
When this occurs, each overhang is formed into a thin wall portion 15a, 15a' of the parallel flexible beam structure.
Deformation occurs in the corresponding thin wall portions of 5d and 15d'. These deformations are detected by the strain gauges of the relevant parts, and each of the above forces and moments are detected by configuring an appropriate bridge circuit with each strain gauge. The deformation of each thin portion, the bridge circuit, etc. are not described in detail in the above-mentioned publication. in the end.

This load detection device can detect six load components: forces acting in the X-axis, Y4111 and Z-axis directions, and moments acting around the X-axis, Y-axis and Z@.

By the way, in the above-mentioned load detection device using a parallel deflection beam structure or a radial deflection beam structure.

Naturally, greater output sensitivity is required. and,
In order to increase the output sensitivity, it is necessary to increase the stress of the parallel flexure beam structure and radial flexure beam structure as much as possible when the rated load is applied. However.

If the stress is increased in this way, if an overload exceeding a certain limit is applied, for example a large load several times the rated load, the stress value in the flexible beam will become excessive and plastic deformation will occur in that part. or become damaged, and
The effects of such an excessive load may be caused not only by the actual load to be detected being excessive but also by incorrect operation of the machine or device to which the load detection device is installed, or by handling errors such as dropping the load detection device itself. also occurs.

[Purpose of the invention]

The present invention has been made in view of these circumstances, and its purpose is to provide a load detection device that can prevent performance deterioration and damage even when an excessive load is applied.

[Summary of the invention]

In order to achieve the above object, the present invention comprises a rigid block having a flexible part and two rigid bodies connected to different predetermined parts of the rigid block, and a bending mechanism that acts between the two rigid parts. In the load detection device for discharging a load, a protruding portion is fixed to at least one of the two rigid body parts and to one of the rigid body blocks at a location other than the predetermined location.

A hole is formed in the other side, a protruding member is inserted into the hole, a predetermined gap is created between the protruding member and the inner wall of the hole, and when the load is an overload of a certain value or more exceeding the rated load, the protruding member Embodiment of the present invention The present invention will be described below based on the illustrated embodiment.

FIG. 1 is a perspective view of a load detection device according to an embodiment of the present invention. In the figure, parts that are the same as those shown in FIG. 4 are given the same reference numerals, and description thereof will be omitted. 30 a.

30c are the overhanging parts 22a, 22c and the upper annular body 1, respectively.
6a, a stopper configured between 30b, 30
d (not shown) are the overhanging portions 22b, 2.
2d and the lower annular body 16b. Since the configurations of each of the stoppers 30a, 30b-30c, and 30d are the same, only the configuration of the stopper 30a will be described below.

31a is a pin fixing part formed in the delivery part 22a.

This pin fixing part 31a has thin parts 15a, 15a
' and a portion facing the upper annular body 16a, and is formed at approximately the same height as the upper annular body 16a. 32a is attached to the upper annular body 16a and fixed with a pin fa 31
a Ic This is a through hole formed in the opposing portions. 3
3a is a pin fixed to the pin fixing part 31a, and the pin 3a is inserted through the first through hole 32a.
The construction of a is shown in more detail in FIG.

FIG. 2 is a cross-sectional view of a portion σ) of the stopper 30a shown in FIG. In the figures, the same partial pressures as those shown in FIG. A predetermined clearance g exists between the pin 33a and the inner wall of the through hole 32a.

Now, when a thin downward force Fz in the Z-axis direction is applied to the upper annular body 16a at the 1.2-th point 1, this force Fz is applied to the overhang portion 22b.

It acts on the columnar body 22 via 22d. For this reason, each thin portion 24a, 24aξ...mountain...24d, 24
d' is deformed in accordance with this b]. This deformation (σ) is detected by strain gauges (not shown) in each thin-walled portion, and is determined by obtaining a signal proportional to the force FZ by a bridge circuit consisting of strain gauges. During this operation, the upper annular body 163 is displaced downward at 1 due to the deformation of each thin wall portion of the columnar body 22.

Therefore, the clearance g between the pin 33a and the upper inner wall of the 5 (1116 hole 32a) becomes smaller, and the clearance g with the lower inner wall becomes larger.

By the way, if an excessive downward force Fz acts on the upper annular body 16a for some reason, the amount of displacement of the upper annular body 16a becomes extremely large, and the clearance g between the pin 33a and the upper inner wall of the through hole 32a becomes O. 1 Both are in contact. On the other hand, the overhanging portion 22 in which the pin fixing portion 3]a is formed
Since a is connected to the lower annular body 16b, the force that tries to displace the upper annular body 16a by more than the warp, that is, the force that tries to deform each thin part of the columnar body 22 by more than the warp, is caused by the pin. 33a, the pin fixing part 31a, and the overhanging part 22a to the lower annular body 16b. Others σ) Stopper 30b
, 30c, 30d A similar operation occurs with K. As a result, even if no excessive force Fz is applied to the upper annular body 16a, each thin portion of the columnar body 22a does not deform by a predetermined amount on the plate.
It will not undergo plastic deformation or damage and will be completely preserved. in this case.

In the figure, the upper and lower clearance g is the amount of displacement of the upper annular body 16a that occurs when the rated force Fz is applied in a state where no load is applied (the values of the upper and lower clearances g are equal in this state). A predetermined number of times is selected. This multiple value cannot be determined mainly based on the characteristics of the thin wall portion.

In the above explanation, the case where force Fz acts was described, but force Fx, FY - moment Mx, My +
Even when Mz acts, each thin portion is protected by an operation similar to the above. The stoppers that have a protective function against each load are summarized as follows. ,J-'flchi,
Stoppers 30a, 30c for force FX; bust collars 30b, 30d for force FY; stoppers 30a, 30b, 30c for force Fz;
, 30 d, stoppers 30a and 30c for moment MX, stoppers 30b and 30d for moment ~IY, and stopper 3 for moment Mz.
0 a , 30 b , 30 c , and 30 d exhibit a magical protective shell ability.

In this way, in the fifth embodiment, a stopper is constructed between each overhang and the upper and lower annular bodies, so that even if a load 1 (more than a predetermined times the rated load) acts on each thin-walled part This prevents plastic deformation and damage to thin-walled parts due to excessive loads.

Further, since the fixing hole of the pin fixing part and the through hole are concentric holes, machining is easy.

FIG. 3 is a sectional view of a portion of a load detection device according to another embodiment of the present invention. In the figures, parts that are the same as those shown in FIGS. FIG. 3 is a sectional view of the same portion as shown in FIG. 2. This embodiment differs from the rabbit embodiment in the structure of the upper annular body 6a, the lower annular body 16b, and the stopper. The upper annular body] 6 is divided into a lower part 16a and an upper part 16a. 42a is a projecting portion 22a in the lower part 16a+
The grooved cylindrical hole 42a formed at the location facing the hole 42a is a hole communicating with the hole 42a. 43a is the overhanging portion 22
43 al is the flange portion of the head of the pin 43a fixed to the pin 43a. The pin 43a1 is inserted into the hole 42a2, and the flange portion 43a is positioned inside the hole 42a. A pin 43a having a flange portion 43a.
are fixed to the overhanging portion 22a in the illustrated state, and then the upper part 6a of the upper annular body 16a is fixed to the lower part 16a with bolts (4 not shown). In this state, a clearance g exists between the lower surface of the flange portion 43a and the bottom surface of the hole 42a, and between the upper surface of the flange portion 43a2 and the lower surface of the upper portion 16a. The lower annular body 1fib is similarly divided into an upper part 1fibl and a lower part 16b, and the pins with the flange parts of the stoppers 40b and 40d (19! not shown) are fixed.

The operation of this embodiment in which the lower part 16b is fixed to the upper part 16b by the bolt 44 is similar to that of the rabbit embodiment.

That is, 1, for example, when a force FZ acts on the upper annular body 16aK.

The clearance g between the upper surface of the flange portion 43a and the lower surface of the upper portion 16a2 is reduced. , : + - When a larger force FZ is applied -r, the clearance gap becomes 0 and the upper surface of the flange portion 43a and the lower surface of the upper part 16a come into contact, and a force F2 of 4 or more is applied to each thin wall. It is directly transmitted to the lower annular body 16b1C without going through the section. It operates in the same manner as kneading for other loads, and the stopper for 1 operation + 11IJ-J- also operates in the same manner as for the flow side of Sagi.

In this way, in this embodiment, a stopper is constructed between each overhang and the upper and lower annular bodies, so not only does it have the same effect as the previous embodiment, but also the clearance can be reduced by providing a flange on the pin. Can be easily adjusted.

In addition, in the explanation of the above embodiment, the load detection device that detects the force and moment about the -X@l-Y axis and the Z yuzu f is explained as an example, but it is not limited to kneading.
It is applicable to any rigid block that has a thin wall portion. Further, the number of stoppers can be determined depending on the load to be detected.

Simple explanation of the drawings Fig. 1 is a partially cutaway perspective view of a load detection device according to an embodiment of the present invention, and Fig. 2 is a sectional view of the stopper portion shown in Fig. 1.
FIG. 3 is a sectional view of a stopper portion of a load detection device according to another embodiment of the present invention, and FIG. 4 is a partially cutaway perspective view 1 of a conventional load detection device.

15 a to 15 d', 24 a to 24 d'
--Thin wall portion, 16a --Upper annular body, ]6b...
... lower annular body, 22 ... living body.

22a to 22d...Protrusion portion, 30a to 30d,
40a...Stopper, 31a...Pin fixing part, 32a...Through hole.

33 a, 43 a, ... pin, 42 a,
, 42a2...hole, 43a2...flange part.

Shiku・l diagram Mu Fang 2 30a 6b Figure 3 16bz 44

Claims (1)

[Claims] 1. Load detection that is composed of a rigid block having a flexible portion and two rigid bodies connected to this rigid block at different predetermined locations, and that detects the load acting between these two rigid bodies. In the apparatus, at least one of the two rigid body parts
and a protruding member fixed to one of the rigid blocks other than the predetermined location, and a hole formed in the other part into which the protruding member is inserted with a predetermined gap. Load detection device. 2. The load detection device according to claim 1, wherein the rigid block includes two sets of projecting portions forming a substantially cross shape. 3. The load detection device according to claim 2, wherein each set of overhang portions is connected to one and the other of the two rigid body portions, respectively. 4. In claim 1, the protruding member is
A load detection device characterized by being a pin. 5. In claim 1, the protruding member comprises:
A load detection device characterized by a pin with a flange. 6. In claim 1, the predetermined gap is set to a size such that the protruding member and the hole come into contact when the load is at least a predetermined value exceeding a rated value. A load detection device characterized by: