JP3086934B2 - Clearance sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a clearance sensor for measuring a clearance between two members.

[0002]

2. Description of the Related Art The measurement of a gap as described above is performed by, for example, a caliper. However, when measuring the clearance between the upper die 28 and the lower die 26 of the press at a deep place 29 as shown in FIG. 4, it is difficult to attain the purpose by using the caliper alone.
Therefore, for example, place the clay in the above place 29, crush the clay by matching the upper mold and the lower mold to a predetermined state, then take out the crushed clay by separating the upper mold and the lower mold, and reduce the thickness of the clay. The size of the gap is measured by measuring with a caliper.

[0003]

However, in the above-described method, the clay is easily deformed and deformed in the course of various operations such as separating the mold and removing the clay, and furthermore, the caliper is added to the clay. When applied, the clay is dented, so that the measurement size by the caliper tends to be out of order, and there is a problem that the measurement accuracy of the size of the clearance is extremely reduced.

In order to solve the above-mentioned problems, a spring plate bulged in an arc shape for contacting each one of two interval measurement objects on both surfaces of a tip of an elongated insertion plate. Further, when the tip of the elongated insertion plate is inserted into the gap between the two interval measurement objects and the spring plate expanded in an arc shape is compressed and contracted, the distortion is maximized. It is known that a strain gauge is provided at a corner portion (see Japanese Patent Application Laid-Open No. 4-42002). However, in the above-described strain gauge, for the time being each of the two interval measurement objects in the spring plate bulged in the arc shape,
Although it corresponds exactly to the movement of the inner surface of each of the two distance measurement objects, the location there is a place where distortion is least and a strain gauge cannot be provided. Therefore, in the above-described configuration, there is a problem that a strain gauge must be attached to a corner of a side edge of the spring plate, which is considered to have the largest distortion, by avoiding a great place corresponding to each of the two interval measurement objects. is there. With such a configuration, in the initial stage of the immediate change of each of the two distance measurement objects, the signal amount of the strain gauge is extremely small due to the small amount of distortion of the spring plate, and there is a problem that accurate measurement cannot be performed. . In addition, the above-mentioned technical idea utilizes the material properties (the amount of spring force) of the spring plate, so that the spring force in the spring plate is gradually reduced by repeated use .
You. Then , for a certain amount of movement of the spring plate ,
The pressing ability of the spring plate itself decreases. Addition of the spring plate itself
The decrease in pressure capacity is measured for a certain amount of change in the spring plate.
It means that there is a serious drawback that the value changes sequentially,
In addition to the above-described problem, there is a problem that a redundant error based on the properties of the spring plate occurs.

The present invention has been made to solve the above-mentioned problems (technical problems) of the prior art. The size of the clearance can be obtained as an electric signal corresponding to the clearance, and the clearance in the above-described location can be obtained. It is an object of the present invention to provide a clearance sensor capable of measuring a clearance dimension with high accuracy.

[0006]

A clearance sensor according to the present invention comprises a plate-shaped coil holder having an outer surface which is in contact with one of the distance measurement objects, and an outer surface which is provided with the distance measurement object. A plate-shaped conductive plate serving as an abutting surface for abutting the other is provided side by side so that the respective inner surfaces face each other, and the two abutting surfaces can be freely moved toward and away from each other via connecting means. Are connected in a state where they are urged in a direction away from the coil holding body,
A flat coil that generates an inductance having a value corresponding to a change in the distance from the conductive plate is provided on an inner surface facing the contact surface of the conductive plate so as to be parallel to the plate surface of the plate-shaped coil holder. It was done.

[0007]

The distance between the coil holder and the conductive plate is reduced according to the size of the gap of the distance measuring object. The coil attached to the coil holder has a value of inductance corresponding to the distance from the conductive plate. The size of the clearance can be known from the magnitude of the inductance.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. In FIG. 1A, reference numeral 1 denotes a clearance sensor,
It comprises a main body 2 and a signal extraction section 3. First, body 2
Will be described with reference to FIG. 1B, FIG. 2 and FIG. Reference numeral 4 denotes a coil holder, which is made of a material having good conductivity, for example, phosphor bronze. Its thickness is, for example, 0.1 mm. The coil holder 4 may be formed using a material such as copper, aluminum or iron. Reference numeral 5 denotes a contact surface of the holder 4, which is to be brought into contact with one of the distance measurement objects. Reference numeral 7 denotes a conductive plate arranged side by side with respect to the holder 4, which is formed of a metal plate having good conductivity, for example, a phosphor bronze plate. The thickness of the conductive plate 7 is, for example, 0.1 mm. The conductive plate 7 may also be formed using a material such as copper, aluminum or iron. Reference numeral 8 denotes a contact surface of the conductive plate for contacting the other of the distance measurement objects. Then 9
Denotes a connecting means for connecting the coil holder 4 and the conductive plate 7 so as to be freely movable in a distance. Reference numeral 10 denotes a connecting element in the connecting means 9 which is formed around the coil holder 4 and integrally therewith. Reference numeral 11 denotes another connecting element, which is formed around the conductive plate 7 and integrally therewith. The two connecting elements 10 and 11 are provided with space holding portions 10a and 11a formed in a conical spring shape, and space holding portions.
It is composed of joining flanges 10b and 11b provided around 10a and 11a, and is integrated by joining both joining flanges 10b and 11b. The joining of the flanges 10b and 11b is performed using, for example, an adhesive. In the integrated state, the two space holding portions 10a and 11a are
2, the conductive plate 7 is held at a predetermined distance as shown in FIG. 2, and the distance between the coil holder 4 and the conductive plate 7 is compressed as shown in FIGS. In this case, the conductive plate 7 is moved away from the holder 4 in FIG.
Function as urging means for urging to the position of.

Next, reference numeral 14 denotes a coil substrate, which is attached to the coil holder 4 via the connecting element 10.
The coil substrate 14 is made of, for example, a flexible plastic film and has a thickness of, for example, about 0.1 mm. The substrate 14 may be a rigid substrate having no flexibility. Reference numeral 15 denotes a planar coil attached to the coil substrate 14, which is composed of a coil element 15a provided on one surface side of the substrate 14 and a coil element 15b provided on the other surface side. Both coil elements 15a, 15b Each of the central portions is connected in series by a connection portion 16 by a through hole. The coil elements 15a and 15b are provided on both sides of the coil substrate 14 using a known printed wiring technique (for example, copper plating).
However, a copper wire wound in a flat spiral shape may be attached to the coil substrate 14. Reference numerals 17 and 18 denote insulating layers for protecting the coil elements 15a and 15b, respectively, and are formed, for example, as protective films made of polyimide. These insulating layers may be formed as protective films made of epoxy.

Next, the signal extracting section 3 will be described.
The lead portion 3 has lead wires 21 and 22 connected to the outer peripheral ends of the coil elements 15a and 15b, respectively, on one surface and the other surface of the lead portion substrate 20 integrally formed with the coil substrate 14,
The conductive wires 21 and 22 are protected by the same (integrally formed) insulating layers as the insulating layers 17 and 18. Then 23
Is a lead wire connected to the conducting wires 21 and 22 in the lead-out portion 3, for example, a coated copper wire having an outer diameter of 1 mm. The dimensions of the clearance sensor 1 having the above-described configuration are such that the diameter D of the main body 2 is, for example, 20 mm, the length L of the signal extraction section 3 is, for example, 70 mm, and the thickness T of the main body 2 is, for example, 1.8 mm.

Next, how to use the above clearance sensor 1 and how it is used will be described. The clearance sensor 1 is used for measuring the clearance between a pair of molding dies 26 and 28, for example, as shown in FIG. FIG. 4 shows a known press device, wherein 25 is a base, 26 is a lower die attached to the base 25, 27
Denotes a vertically movable elevating body, and 28 denotes an upper die attached to the elevating body 27, respectively.

When it is desired to measure the clearance between the lower mold upper surface 26a and the upper mold lower surface 28a at the location indicated by the reference numeral 29 in the above-described press apparatus, the lower mold 26 is separated from the lower mold 26 while the lower mold 26 is away from the lower mold 26. The main body 2 of the clearance sensor 1 is placed on the upper surface 26a of the mold 26 at the location 29 described above. Next, in this state, the upper mold 28 is lowered to a predetermined lowering position. When the upper mold 28 is lowered, the distance between the coil holder 4 and the conductive plate 7 in the main body 2 is reduced against the urging force of the urging means, as shown in FIG. 5 (gap size 1.6 mm) or FIG. 6 (gap size 0.5 mm). It is compressed as follows. In the compressed state as described above, the coil 15 attached to the coil substrate 14 has an inductance corresponding to the distance from the conductive plate 7. In this example, the distance between the coil holder 4 and the coil 15 also changes in the same manner as the distance between the conductive plate 7 and the coil 15. Therefore, the inductance of the coil 15 changes with the change in the distance between the coil holder 4 and the conductive plate 7. Changes at a relatively large rate. Coil as above
The inductance of 15 is led out of the lower mold 26 and the upper mold 28 through the lead wires 21 and 22 and the lead wire 23, and by measuring the magnitude of the inductance there, the upper surface 26a and the lower surface 28a at the place 29 are measured. You can know the size of the gap between. After the above measurement is completed, when the upper mold 28 is separated from the lower mold 26, the main body 2 of the gap sensor 1 is restored to its original shape, and can be reused.

Next, the principle that the coil 15 generates an inductance having a value corresponding to the distance from the conductive plate 7 will be described. When an AC voltage is applied to the coil 15 to bring the conductive plate 7 close to the coil 15,
An eddy current is generated in the conductive plate 7 by the action of electromagnetic induction caused by the AC magnetic field generated by the coil 15. At this time, when the frequency of the AC voltage is high, the penetration depth of the eddy current in the conductive plate 7 is reduced by the skin effect, so that a sufficient eddy current can flow even if the conductive plate 7 is thin. When a sufficient eddy current flows, the magnetic flux does not pass through the conductive plate 7 and reach the back side (the side of the contact 8). That is, the conductive plate 7
Has the function of an electromagnetic shield. By this action, even if another metal material is present outside the conductive plate 7, the adverse effect due to it can be eliminated. The above operation is the same in the case of the above embodiment in the relationship between the coil 15 and the coil holder 4. The coil 15 is connected to the conductive plate 7 and the coil holder 4.
When the frequency of the AC voltage is high, the magnetic flux is applied to the conductive plate 7 and the coil holder 4 even if their thickness is thin.
Does not leak out of the room. That is, a magnetic flux is formed in a space surrounded by the conductive plate 7 and the coil holder 4. coil
When the magnetomotive force (ampere turn) supplied to the coil 15 is constant, the space for forming the magnetic flux becomes narrow when the distance between the coil 15 and the conductive plate 7 is short, so that the magnetic flux decreases and the permeance decreases, and the coil becomes small. The inductance of 15 becomes smaller. Conversely, when the distance is large, the magnetic flux increases, the permeance increases, and the inductance of the coil 15 increases. Therefore, the distance between the coil 15 and the conductive plate 7 can be known by extracting the change in the inductance of the coil 15 in the form of a voltage or a frequency.

Next, FIG. 7 showing an example of the measuring circuit will be described. An oscillator 31 generates an AC signal of, for example, 1 MHz. Z1 and Z2 are bridge forming resistors, Z3 is the same coil, 32 is an AC amplifier, and 33 is a rectifier and an amplifier. In such a configuration, when an AC signal is applied from the oscillator 31 to the coil 15, an AC signal corresponding to the inductance of the coil 15 is provided to the amplifier 32.
After the signal is amplified by the amplifier 32, it is rectified and amplified by the circuit 33, and a signal corresponding to the inductance of the coil 15, that is, a signal corresponding to the size of the clearance is obtained as an output signal.

Next, FIG. 8 shows the relationship between the clearance size and the output voltage obtained by the measuring circuit. In the case of the above configuration, an output voltage having a characteristic indicated by reference character a is obtained. When the frequency of the oscillator 31 is 2 MHz,
An output voltage having characteristics as shown by b is obtained. On the other hand, when the coil holder 4 and the conductive plate 7 are formed of aluminum, an output voltage having a characteristic indicated by c is obtained, and when the coil holder 4 and the conductive plate 7 are formed of iron, an output voltage having a characteristic indicated by d is obtained. In any of these cases, the relationship between the clearance size and the output voltage is non-linear. Therefore, it is preferable to improve the linearity by using a linearizer if necessary.

FIG. 9 shows another embodiment of the present invention, in which the coil 15 is formed in a rectangular spiral shape in plan view. The other shape may be an elliptical spiral shape or a triangular spiral shape.

Next, FIG. 10 shows a different example of the structure of the signal lead-out portion. The lead-out leads 21 and 22 on one side and the other side of the substrate 20 are shown in FIG.
Are formed in the shapes as shown in the drawing, and are connected to each other at a number of connection portions 35 by through holes. When the lead conductor is formed in this way, the lead conductor has a twisted structure, which is effective in eliminating the capacitance of the parallel pattern.

Next, FIGS. 11 to 13 show still another embodiment of the present invention, in which a signal extraction portion is provided with a reinforcing plate 37. FIG. The reinforcing plate 37 is formed of, for example, a metal plate having a thickness of about 0.1 mm and having sufficient flexibility and sufficient strength, for example, a stainless steel plate, and has a distal end formed with a flange 10b in the connecting means 9 of the main body 2 as shown in FIG. , 11b,
In addition, the signal extraction portion substrate 20 is integrated with the reinforcing plate 37 by an adhesive means. When such a reinforcing plate 37 is provided, the lower die upper surface 26a and the upper die lower surface 28 in the state shown in FIG.
In the case of measuring the distance from “a”, the clearance of each part can be measured sequentially while moving the main body 2 back and forth and right and left via the reinforcing plate 37. It is also possible to insert the main body 2 into the gap from outside the upper and lower molds after the mold matching.

Next, FIG. 14 shows a still further embodiment of the present invention, in which a substrate 14 provided with a coil is fixedly attached to a holder 4 and a conductive plate 7 is connected to a bellows-like connecting means 39.
3 shows a structure connected to the holder 4.

[0020]

As described above, in the present invention, FIG.
When it is desired to measure the clearance between the upper mold 28 and the lower mold 26 each having a concave-convex shape, the clearance sensor 1 includes a plate-shaped coil holder, a plate-shaped conductive plate, and a planar coil. Since each is composed of three thin components, it can be applied to a very narrow gap like the above-mentioned place, that is, between the upper surface 26a of the lower die 26 and the lower surface 28a of the upper die 28. There is an effect that the clearance sensor 1 can be inserted corresponding to the narrowness.

In addition, when the clearance sensor 1 is placed in the clearance, the clearance sensor 1 has a flat surface provided inside the contact surface of the coil holder 4 so as to be along the surface facing the contact surface of the conductive plate 7. The shape of the coil 15 is such that it comes close to the contact surface of the conductive plate 7 in a planar state. This means that the change in pressure corresponding to the amount of bending of the "spring plate"
Because it was used, by repeatedly using the spring plate
"The pressure changes sequentially with the amount of bending, and the measurement error
Is different from the technical idea which has a problem such as "occurs", an inductor having a value corresponding to a change in "distance" between the "surface" of the current surface of the conductive plate 7 and the surface of the planar coil 15
Use the change in the resistance of the conductive plate.
By repeatedly using, the return force of the conductive plate weakens,
Even if the value of the biasing force changes, the biasing
There is an effect that a correct measurement value can be obtained irrespective of the change in force . Therefore, there is an advantage that a change in the size of the gap can be obtained as an accurate electric signal corresponding to a slight change in the conductive plate 7.

[Brief description of the drawings]

FIG. 1A is a perspective view of a clearance sensor, and FIG. 1B is an exploded perspective view of a main body.

FIG. 2 is a longitudinal sectional view of a main body (hatching is omitted).

3 (A), (B), and (C) each show 3 in FIG.
FIGS. 3A and 3B are enlarged views of portions A, 3B, and 3C, and FIG. 3D is a perspective view illustrating shapes of coil elements provided on one surface and the other surface of the coil substrate.

FIG. 4 is a longitudinal sectional view showing a use state of the clearance sensor.

FIG. 5 is a longitudinal sectional view showing a state where the body of the clearance sensor is compressed.

FIG. 6 is a longitudinal sectional view showing a state where the main body of the clearance sensor is further compressed.

FIG. 7 is a block diagram of a circuit for measuring inductance.

FIG. 8 is a graph showing a relationship between a clearance dimension and an output voltage of a measurement circuit.

FIG. 9 is a plan view showing an example in which the planar shape of the coil is different.

FIG. 10 is a partial view showing another example of the structure of the signal extraction unit.

FIG. 11 is an exploded perspective view showing a clearance sensor provided with a reinforcing plate.

FIG. 12 is an enlarged sectional view showing a connection structure between a reinforcing plate and a main body of the clearance sensor.

FIG. 13 is a diagram showing a use state of the clearance sensor in FIG. 11;

FIG. 14 is a longitudinal sectional view showing still another embodiment of the clearance sensor.

[Explanation of symbols]

 4 Coil holder 7 Conductive plate 15 Coil

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01B ^7/ 00-7/34

Claims (1)

(57) [Claims] 1. A plate-shaped coil holder whose outer surface is in contact with one of the distance measurement objects, and whose outer surface is in contact with the other of the distance measurement objects. Plate-shaped conductive plates are arranged side by side with their respective inner surfaces facing each other, and both are in a state in which the respective contact surfaces are biased in a direction in which the respective contact surfaces are freely movable toward and away from each other via connecting means. A planar coil which is connected and has an inductance of a value corresponding to a change in the distance to the conductive plate is provided on an inner surface of the coil holding body, which is opposed to the conductive plate on the inner surface of the conductive plate. A clearance sensor provided in a state parallel to a plate surface of a coil-shaped holding member.