JP2656599B2 - Rotary load sensor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load sensor for a rotating mechanism that detects a thrust or a thrust and a torque generated in a rotating mechanism of a machine mechanism or other various machines.

[Conventional technology]

In a machine having a rotating mechanism, detecting a load (thrust, torque) generated in the rotating mechanism is indispensable when controlling driving of the machine. Conventionally, as a load sensor for detecting such a load, for example, a torque using a so-called parallel plate structure as described in Journal of the Japan Society of Mechanical Engineers, Vol. 86, No. 774, pp. 480-481, has been proposed. Sensors have been proposed. However, in this torque sensor, since the strain gauge that converts the amount of torsional deformation of the rotating shaft into an electric signal rotates integrally with the rotating body, the electric signal must be extracted to the outside via a slip ring or an FM oscillator. For this reason, it has been impossible to avoid a decrease in detection accuracy due to the generation of noise due to the use of the slip ring, or an increase in the cost of the torque sensor due to the use of the FM oscillator.

A torque sensor that solves such a problem is disclosed in
61-76927. The outline of this torque sensor will be described with reference to FIG. FIG. 3 is a sectional view of a conventional torque sensor. In the figure, reference numeral 4 denotes a main body, on which a first rotating shaft 7 and a second rotating shaft 8 are rotatably supported via bearings 5 and 6, respectively. The axes of the rotating shafts 7, 8 are on the same line, and both the rotating shafts 7, 8 are regulated so as not to be displaced in the thrust direction.

FIG. 4 is a side view showing the details of the first rotary shaft 7, and FIG. 5 is a cross-sectional view taken along the line BB of FIG. At the left end, a first rectangular plate-shaped transmitting portion 9a and a thin flat plate-shaped first slanted flat plate portion 9b are used.
Are connected in series. The three transmitting portions 9a extend radially from the outer peripheral surface of the first rotary shaft 7, and the first swash plate portions 9b are relatively opposed to each other so as to communicate the distal end portion of each transmitting portion 9a and the first ring 9. The first swash plate portion 9b is inclined at a predetermined angle θ with respect to the axis of the first rotary shaft 7.

The first rotating shaft 7 having the first ring 9 having such a structure.
Can be integrally formed from a metal material without using a joining means such as welding or a bolt. Hereinafter, an example of the processing method will be described.

First, a solid metal material is cut by a lathe into a shape having a first rotating shaft 7 having a predetermined dimension and a first ring 9 having a thickness B as shown in FIG. Cut out. Next, at the connecting portion between the first rotating shaft 7 and the first ring 9,
Drill three eyebrow holes 10 (see Fig. 5) by electric discharge machining, wire cutting, laser machining, drilling, etc.
Processing is performed so that the first rotating shaft 7 and the first ring 9 are connected to each other in a portion left between the holes 10. Finally,
New through-holes 11 are drilled at three places on the peripheral wall of the first ring 9 from outside toward the holes 10 by electric discharge machining, drilling, or the like. These through-holes 11 are formed two by two, leaving a predetermined thickness T at one place, so that a total of six holes are formed, and a rectangular columnar transmission part 9a and length, width, and thickness dimensions are L, B,
A first inclined flat plate portion 9b of T is formed (see FIGS. 5 and 6).

Returning to FIG. 3, at the right end of the second rotating shaft 8,
A quadrangular prism-shaped transmission portion 12a and a thin flat plate-shaped second inclined plate portion 12b
A second ring 12 is provided continuously through the first and second rings. Transmission unit 12
a extends three radially from the outer peripheral surface of the second rotating shaft 8, and the second inclined plate portions 12 b are opposed to each other so as to communicate the tip portion of each transmission portion 12 a and the second ring 12. And two at a time,
A total of six sheets are provided, but all of them are the first oblique flat plate part 9b.
And the absolute value of the tilt angle is equal and the tilt direction is opposite, that is, the tilt angle is −θ with respect to the axis. The second rotating shaft 8, the transmitting portion 12a, the second swash plate portion 12b, and the second ring 12 are also integrally formed from a metal material by the same processing method as the first rotating shaft 7 described above. The first ring 9 and the second ring 12 are fixed by welding 13 or the like in a state where the first ring 9 and the second ring 12 are accurately fitted to each other by utilizing the unevenness of the facing surface.

Numeral 14 denotes a non-contact type displacement meter such as a magnetic type or an optical type. The displacement meter 14 is mounted inside the main body 4 so that the detecting portion 14a faces the end face of the first ring 9. The minute displacement of the integrated rings 9 and 12 in the thrust direction is detected by a displacement meter 14, and input / output operations to the displacement meter 14 are performed from outside the main body 4 via a cord 15. The first rotary shaft 7 is connected to a rotary drive source, for example, a motor, and the second rotary shaft 8 is connected to a rotary body, for example, a tool such as a drill.

In the torque sensor configured as described above, it is assumed that the first rotating shaft 7 is driven to rotate, and the torque M _{0 is} transmitted between the first rotating shaft 7 and the second rotating shaft 8. ,
The torque M ₀ is applied to the first rotating shaft 7 → the transmitting portion 9a → the first swash plate 9b → the first ring 9 → the second ring 12 → the second swash plate.
12b → the transmission section 12a → the transmission to the second rotating shaft 8.

In such a structure, the torque M between the rotating shafts 7 and 8 is
_{When 0} is transmitted, both rings 9, 12 are displaced in the thrust direction by a displacement amount δ. This displacement is expressed by the following equation.

Here, r: distance from the axis to the radial center of the inclined plate portions 9b, 12b l: length of the inclined plate portions 9b, 12b b: width of the inclined plate portions 9b, 12b t: inclined plate portion 9b, Thickness of 12b n: Number of each of swash plate portions 9b, 12b E: Elastic coefficient of swash plate portions 9b, 12b θ: Angle formed between swash plate portions 9b, 12b and axes of rotating shafts 7, 8 . It can detect the torque M ₀ by measuring such displacement δ in displacement meter 14. Since the displacement gauge 14 is provided on the main body 4 as a fixed portion, there is no need to provide a slip ring for taking out a detection signal to the outside or use an FM oscillator, and the above-mentioned problem is completely solved. .

[Problems to be solved by the invention]

By the way, among the machines to which the above-mentioned torque sensor is applied, the magnitude of the thrust acting on the rotating body attached to the second rotating shaft 8 is also used as a control factor of the machine to perform more preferable control. Some are requested.
For example, when the machine is a machine tool such as a drill or a grinder, it is important to detect the magnitude of the thrust in order to reliably detect the abnormality of the tool (the rotating body) and control the processing force. However, the above-described torque sensor cannot naturally detect thrust, and
No other load sensors have been proposed which can also detect thrust.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in the prior art, and to detect a thrust and a torque acting on a rotating body or only a thrust by a low-cost configuration without fear of noise generation and a load sensor for a rotating mechanism. Is to provide.

[Means for solving the problem]

In order to achieve the above object, a first aspect of the present invention provides a first rotary shaft supported by a main body and connected to a rotary drive source, a rotary body driven by the rotary drive source, In a rotating mechanism including a second rotating shaft that connects a rotating body, and a load sensor interposed between the first rotating shaft end and the second rotating shaft end, the load sensor includes the second rotating shaft and the second rotating shaft. A plurality of first swash plates fixed to an arm extending in a radial direction from one rotation axis at a predetermined angle with respect to the axis thereof; and an arm extending in a radial direction from the second rotation axis. A plurality of second swash plates fixed at an angle different from the predetermined angle with respect to the axis, a ring connecting each of the first swash plates and each of the second swash plates, A first non-contacting device which is disposed on the main body so as to face a ring end face and detects displacement of the ring in a thrust direction; A displacement meter, a plate connected to the second rotating shaft, and a second non-contact displacement meter configured to detect a displacement in a thrust direction of the plate installed on the main body facing the plate. And detecting the torque and the thrust acting on the rotating body.

According to a second aspect, in the first aspect, the first non-contact type displacement meter is removed, and the thrust acting on the rotating body is determined by the effect value of the second non-contact type displacement meter. It is characterized by detecting.

(Operation)

In the first aspect, when the torque and the thrust act on the rotating body simultaneously, the first swash plate and the second swash plate are bent by the torque and bent by the thrust, whereby the ring and the second rotating plate are rotated. The shaft and the plate are displaced in the thrust direction. The magnitude of the displacement is detected by the first non-contact displacement meter and the second non-contact displacement meter, and the magnitude of the torque and the magnitude of the thrust are calculated separately based on the detected values.

In the second aspect, when a thrust acts on the rotating body, the first and second swash plates bend, and the deflection displaces the plate in the thrust direction.
This displacement is detected by a non-contact displacement meter facing the plate, and the magnitude of thrust is calculated based on the detected value.

〔Example〕

 Hereinafter, the present invention will be described with reference to the illustrated embodiments.

FIG. 1 is a sectional view of a torque / thrust sensor according to an embodiment of the present invention. In the figure, the same parts as those shown in FIG. Reference numeral 16 denotes a disk fixed to the second rotation shaft 8, and reference numeral 17 denotes a non-contact type displacement meter fixed to the main body 4. This displacement meter 17 has a detection unit 17a whose disk 1
It is installed to face 6. 15 'is a cord connected to the displacement meter 17 and drawn out of the main body.

Next, the operation of this embodiment will be described with reference to FIG. The operation when the torque is transmitted between the first rotating shaft 7 and the second rotating shaft 8 is described in detail in the above-mentioned publication, so that the description is omitted. On the other hand, the operation when the thrust force F ₀ is transmitted between the first rotating shaft 7 and the second rotating shaft 8 will be discussed below with reference to the vector diagram shown in FIG. When the force F ₀ is transmitted, the swash plate portion 9b, 12b
As shown in FIG. 2, a force of F ₀ / n is applied to each of the rotating shafts 7,
Acting in the axial direction of 8, the slanted plate portions 9b and 12b bend in the thin direction of the slanted plate portions. In this case, the oblique flat plate part 9
Component force W in the direction perpendicular to b and 12b is, as shown in FIG. Becomes Meanwhile, the oblique flat portion 9b, the deflection amount v ₁ and 12b is the second moment of the oblique flat plate as shown in the above publication is I And the second moment of area I is In the end, the deflection amount v ₂ of the oblique plate portions 9b and 12b when the force F ₀ is applied is Becomes The displacement amount δ of the ring 10 in the thrust direction at this time
_F is Becomes The deflection amount v ₂ and the displacement amount [delta] _F is shown in Figure 2. In the above (6), the values b, t, l, E, n, since θ is known either by measuring the thrust direction of the displacement of [delta] _F of the ring 9, 12 by the displacement gauge 14, the force F ₀
Can be calculated.

The above is a consideration of the detection operation using only the displacement meter 14 when the force F ₀ is applied. On the other hand, the detection operation using only the displacement meter 14 when the torque M ₀ is applied is described in the above publication. Therefore, this time, the displacement meter when the torque M ₀ is applied
The detection operation of the displacement meter 14 and the displacement meter 17 and the detection operation of the displacement meter 14 and the displacement meter 17 when the force F ₀ acts will be described below.

If only torque M ₀ is applied between the first rotary shaft 7 and the second rotary shaft 8, although the ring 9, 12 is displaced in the thrust direction as described above, the first rotary shaft 7 first No displacement in the thrust direction occurs on the second rotating shaft 8. Was but connexion, _14M the detected amount of displacement of the displacement meter 14 at the time when the torque M ₀ acts [delta], when the detected amount of displacement of the displacement meter 17 and _{δ 17M, δ 14M = C 1} · M 0 ...... (7) provided that , δ _17M = 0 (9)

On the other hand, a force F ₀ is applied between the first rotating shaft 7 and the second rotating shaft 8.
When only the first rotating shaft 7 acts, the relative displacement of the first rotating shaft 7 and the rings 9 and 12 in the thrust direction and the second rotating shaft 8 and the ring
Becomes equal to the thrust direction of the relative displacement amount between 9,12, this value [delta] _F is the value shown in equation (6). Therefore, when the force F ₀ is applied, the detected displacement of the displacement meter 14 is δ
_14F , and the detected displacement of the displacement meter 17 is δ _17F , However, Becomes

From the above considerations, when an arbitrary torque M ₀ and an arbitrary thrust F ₀ simultaneously act between the first rotation shaft 7 and the second rotation shaft 8, the detected displacement amount δ ₁₄ of the displacement meter ₁₄ and the detected amount of displacement [delta] ₁₇ of displacement gauge 17, it can be seen that it is possible to detect and separate the torque M ₀ and the thrust F _0.

 Hereinafter, the method will be described.

The value [delta] _14, the [delta] ₁₇ is assumed by the torque M ₀ and the thrust F _0, respectively, the values [delta] _14, [delta] ₁₇ can be expressed by the following equation.

δ ₁₄ = δ _14M + δ _14F (12) δ ₁₇ = δ _17M + δ _17F (13) Substituting equations (7), (9), and (10) into equations (12) and (13) , Δ ₁₄ = C ₁ · M ₀ + C ₂ · F ₀ (14) δ ₁₇ = 2 · C ₂ · F ₀ (15) Then, by solving the equations (14) and (15), Becomes That is, according to the configuration of the present embodiment shown in FIG. 1, the torque M ₀ and the thrust F ₀ simultaneously acting between the two rotating shafts 7 and 8 are separated based on the detected values of the displacement meters 14 and 17. You can ask.

Here, in reality, since there is a processing error in the wall thickness and plate width of each of the inclined plate portions 9b and 12b, a variation in the inclination angle θ, and the like,
Equations (7), (8), and (9) are not always true. Therefore, if the torque / thrust sensor is calibrated as follows, the torque and the thrust can be accurately detected. That is, first, only the torque M ₀ having a known magnitude is applied, and the actual measured values δ _14M and δ _17M of the displacement meters 14 and 17 at that time are obtained, and these are calculated by the above equations (7) and (9). Into the following equations (18) and (19) instead of

_{δ 14M = C 3 · M 0} ...... (18) δ 17M = C 4 · M 0 ...... (19) In addition, C _3, C ₄ is some constant. Then, the constant C ₄ is equal to 0 theoretically, as shown in (9), not always 0 when the processing error or the like is present.

Next, only the thrust F ₀ having a known size is actuated, and the actual measured values δ _14F and δ _17F of the displacement meters 14 and 17 at that time are applied.
, And these are replaced by the following equations (20),
Substitute in equation (21).

_{δ 14F = C 5 · F 0} ...... (20) δ 17F = C 6 · F 0 ...... (21) In addition, C _5, C ₆ is some constant. Although the constants C ₅ and C ₆ are theoretically equal as shown in the equation (10), they do not always become equal when the processing error or the like exists.

As described above, the constants C ₃ , C ₄ , C ₅ , and C ₆ can be obtained from the equations (19) to (21). On the other hand, equations (18) to (21) are
Substituting into equations (2) and (13) and finding the solution gives:

Since the constant C ₃ -C ₆ are known, as described above, after all,
According to equations (22) and (23), the torque M ₀ and the thrust F ₀ can be obtained separately.

As described above, in the present embodiment, a disk is newly fixed to the second rotating shaft and another displacement meter is provided to face the disk, and a predetermined value is determined based on the detection values of the two displacement meters. , The torque and thrust acting on both rotating shafts at the same time will not cause noise mixing, and
It can be obtained separately with an inexpensive configuration. Thereby, for example, it is possible to perform control of torque and thrust in drilling by a drill, instantaneous detection of penetration of a hole, instantaneous detection of breakage of a drill, and the like. Further, for example, when a grinder is connected to the tip of the second rotating shaft, the pressing force of the grinder and the grinding torque can be simultaneously detected, and the automatic control of the grinder can be performed extremely well.

In the description of the above embodiment, as is apparent from the equation (17), when a sensor that detects only thrust is configured, the displacement meter 17 and the disk 16 may be used. 14 becomes unnecessary.

Further, as apparent from the description of the calibration method in the description of the above embodiment, if only to ask for a constant C ₃ -C _6, the thickness of each swash plate and the plate width, the inclination angle, the number is different connexion nothing like bearing Torque and thrust can be detected.

〔The invention's effect〕

As described above, in the present invention, the plate body is fixed to the second rotating shaft, and the second non-contact type displacement meter is installed on the main body in opposition to the plate body. The torque or only the thrust can be detected with a low-cost configuration without fear of generating noise.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a torque and thrust sensor according to an embodiment of the present invention, FIG. 2 is a vector diagram for explaining the operation of the sensor shown in FIG. 1, and FIG. Sectional view of a torque sensor,
FIG. 4 is a side view of the rotating shaft with a ring shown in FIG. 3,
FIG. 5 is a cross-sectional view taken along the line BB of FIG. 4, and FIG. 6 is a cross-sectional view of the structure of the rotary shaft with a ring shown in FIG. 4... Body, 7... First rotation axis, 8... Second rotation axis, 9b, 12b.
Displacement gauge, 16 ... Disc.

Claims (3)

(57) [Claims] A first rotary shaft supported by a main body and connected to a rotary drive source; a rotary body driven by the rotary drive source; a second rotary shaft connecting the rotary body; A rotation mechanism including a first rotation shaft end and a load sensor interposed between the second rotation shaft end;
A plurality of first swash plates fixed to an arm extending radially from the first rotation axis at a predetermined angle with respect to the axis thereof; and an arm extending radially from the second rotation axis. A plurality of second swash plates fixed at an angle different from the predetermined angle with respect to the axis thereof, a ring connecting the first swash plate and the second swash plate, A first non-contact type displacement meter that is grounded to the main body and detects a displacement of the ring in a thrust direction in opposition to the end face of the ring, a plate connected to the second rotation shaft, A load sensor for a rotating mechanism, comprising: a second non-contact type displacement meter that is disposed on the main body to face and detects a displacement of the plate body in a thrust direction. A first rotary shaft supported by the main body and connected to a rotary drive source; a rotary body driven by the rotary drive source; a second rotary shaft connecting the rotary body; A rotation mechanism including a first rotation shaft end and a load sensor interposed between the second rotation shaft end;
A plurality of first swash plates fixed to an arm extending radially from the first rotation axis at a predetermined angle with respect to the axis thereof; and an arm extending radially from the second rotation axis. A plurality of second swash plates fixed at an angle different from the predetermined angle with respect to the axis thereof, a ring connecting the first swash plate and the second swash plate, A plate connected to the second rotating shaft, and a non-contact meter displacement type that is disposed on the main body so as to face the plate and detects displacement of the plate in a thrust direction. Load sensor for rotating mechanism. (3) In claim (1) or (2),
The inclination angle of the second swash plate is equal in absolute value to the inclination angle of the first swash plate, and the inclination direction is opposite to the inclination angle of the first swash plate.