JP5537064B2 - Inner diameter measuring device - Google Patents

Description

  The present invention relates to an apparatus for measuring the inner diameter of a measurement object, and more particularly to an inner diameter measurement apparatus corresponding to a cylindrical measurement object having conductivity.

  Conventionally, various methods have been proposed as an apparatus for measuring the inner diameter of a measurement object. In the inner diameter measuring device disclosed in the following Patent Document 1, a measuring head is inserted into the measuring object, and the inner diameter of the measuring object is measured by the amount of displacement of the contact provided on the measuring head; It has become.

  On the other hand, in the inner diameter measuring device disclosed in Patent Document 2 below, the measuring head inserted into the measuring object is provided with a reflecting mirror and a lens without contacting the inner surface of the measuring object. The inner diameter is optically measured.

  On the other hand, the inner diameter measuring device disclosed in Patent Document 3 below is a method in which the inner surface of the measurement object is not contacted as in Patent Document 2, and is a measurement inserted into the measurement object. The head serves as a probe, and is a method of measuring the inner diameter of the measurement object with ultrasonic waves.

JP 2005-257395 A JP 2002-39724 A JP 2003-75142 A

  By the way, in the above prior art, since it is necessary to insert a measuring head inside the measuring object, the measuring object having a small inner diameter is excluded from the measuring object due to the structure of the measuring head. have. In addition, an apparatus that measures the inner diameter using ultrasonic waves has a problem in that measurement cannot be performed with high accuracy.

  When the use of the measurement object is, for example, a component constituting an optical waveguide, a transmission line, etc., since such a component has a small inner diameter and requires high-precision measurement, it is mentioned in the above prior art. It can be said that the device is unsuitable.

  The present invention has been made in view of the above-described circumstances, and provides an inner diameter measuring device capable of measuring an inner diameter of a measurement object having a small inner diameter and capable of measuring the inner diameter with high accuracy. The task is to do.

  In order to solve the above-mentioned problems, the inner diameter measuring device according to the present invention as claimed in claim 1 is a device for measuring the inner diameter of a cylindrical conductive measuring object, wherein the measuring object is externally mounted. A coaxial transmission line device in which a coaxial transmission line is formed by assembling as a conductor, two coaxial cables respectively connected to both ends of the coaxial transmission line device, and the coaxial transmission line device connected via the coaxial cable And measuring the characteristic impedance value of the coaxial transmission line, and calculating to obtain the inner diameter of the measurement object based on the characteristic impedance value and the known outer diameter value of the inner conductor in the coaxial transmission line device, And an inner diameter calculation output means for outputting the calculation result.

  According to the present invention having such characteristics, attention is paid to the fact that the characteristic impedance value is different depending on the inner diameter of the measurement object, and this is used for inner diameter measurement. That is, the present invention uses the characteristic impedance value for the inner diameter measurement. Further, a known outer diameter value of a component that becomes an inner conductor when the measurement target is an outer conductor is used for inner diameter measurement. The inner diameter of the measurement object is measured with high accuracy by performing a predetermined calculation based on the characteristic impedance value and the known outer diameter value of the inner conductor.

  According to the present invention, the inner diameter can be measured by forming the inner conductor thin even if the inner diameter of the measurement object is small (the inner conductor only needs to have a function as a conductor in the coaxial transmission line). Since various functional parts as in the prior art are not assembled, it is easy to form such that it can be inserted into a measurement object having a small inner diameter).

  According to the present invention, since it is based on the characteristic impedance value, it is possible to grasp the variation in the inner diameter of the measurement object by the change in the characteristic impedance value.

  An inner diameter measuring apparatus according to a second aspect of the present invention is the inner diameter measuring apparatus according to the first aspect, wherein the coaxial transmission line device is inserted into a predetermined position inside the measurement object serving as the outer conductor. Two of the inner conductor having a known outer diameter value, the inner contact connected to the end of the inner conductor and the outer contact connected to the end of the measurement object, and the connection to the coaxial cable And an SMA connector.

  According to the present invention having such characteristics, in measuring the characteristic impedance value using the measurement object as an outer conductor, the coaxial transmission line device side, in addition to the measurement object, is inserted into the measurement object. What is necessary is just to provide a conductor and two SMA connectors.

  According to the first aspect of the present invention, since the inner diameter is obtained by calculating based on the characteristic impedance value or the like, it is not as large as in the prior art, and the measurement with a small inner diameter is performed. Even if it is a target object, there exists an effect that an internal diameter measurement can be performed. Moreover, according to this invention, there exists an effect that the internal diameter of a measuring object can be measured with high precision.

  According to the second aspect of the present invention, there is an effect that a better form of the coaxial transmission line device can be provided.

It is a basic lineblock diagram showing the inside diameter measuring device of the present invention. It is a block diagram of the internal diameter measuring apparatus in an Example.

  Hereinafter, description will be given with reference to the drawings. FIG. 1 is a basic configuration diagram showing an inner diameter measuring apparatus of the present invention.

  In FIG. 1, reference numeral 1 indicates an apparatus for measuring an inner diameter D1 of a conductive measuring object 2 having a cylindrical shape, that is, an inner diameter measuring apparatus of the present invention. An inner diameter measuring device 1 of the present invention is connected to a coaxial transmission line device 3 in which a coaxial transmission line is formed by assembling a measurement object 2 as an inner diameter measurement target as an outer conductor, and to both ends of the coaxial transmission line device 3. Two coaxial cables 4 and an inner diameter calculation output means 5 connected to the coaxial transmission line device 3 via the coaxial cables 4.

  The coaxial transmission line device 3 is configured so that the characteristic impedance value of the coaxial transmission line can be measured by the inner diameter calculation output means 5. Specifically, since the measurement object 2 is assembled as an outer conductor, the apparatus is configured so as to include an inner conductor in addition to the measurement object 2 (for details, see the section of an embodiment described later). I will explain with a better example.) As the inner conductor, one whose outer diameter value is known in advance is used.

  The inner diameter calculation output means 5 is configured to measure the characteristic impedance value of the coaxial transmission line in the coaxial transmission line device 3. Further, the inner diameter calculation output means 5 performs a calculation for obtaining the inner diameter D1 of the measurement object 2 based on the measured characteristic impedance value and the known outer diameter value of the inner conductor in the coaxial transmission line device 3. It is configured to be able to. Further, the inner diameter calculation output means 5 is configured to output the above calculation result.

  Hereinafter, embodiments will be described with reference to the drawings. FIG. 2 is a configuration diagram of the inner diameter measuring apparatus in the embodiment. In addition, the same code | symbol shall be attached | subjected to the same structural member as FIG.

  In FIG. 2, an inner diameter measuring device 1 for measuring an inner diameter D1 (see FIG. 1) of a measurement object 2 includes a coaxial transmission line device 3, two coaxial cables 4, and an inner diameter calculation output means 5. It is configured. The inner diameter measuring device 1 is configured to be able to measure the inner diameter D1 of the measuring object 2 having various inner diameters.

  The coaxial transmission line device 3 includes a measurement object 2 as an outer conductor, an inner conductor 6 inserted into a predetermined position (center axis position) of the measurement object 2, and two SMA connectors 7. Has been. A coaxial transmission line is formed in the coaxial transmission line device 3.

  The measurement object 2 is formed in a cylindrical shape. The measurement object 2 has an internal penetration portion formed by cutting, for example. In the present embodiment, it is assumed that the inner diameter D1 is measured using the inner diameter measuring device 1 in order to confirm the processing accuracy of the cutting process (in order to confirm the finished state). The measurement object 2 is formed to have a length of at least about 15 mm to 30 mm.

  The inner conductor 6 is a conductive conductor and is formed in an extremely thin and straight cylindrical shape. The inner conductor 6 is formed so that the outer diameter D2 has a predetermined value. The outer diameter value (outer diameter D2) is used when performing calculation to obtain the inner diameter D1 of the measurement object 2.

  The SMA connector 7 is interposed between the internal contact 8 inserted and connected to the end of the inner conductor 6, the external contact 9 connected to the end of the measurement object 2, and the internal contact 8 and the external contact 9. An insulator 10 and a connection portion 11 for the coaxial cable 4 are provided. The SMA connector 7 is basically the same as a known one (SMA: SUB-MINIATURE A). In the present embodiment, although not particularly illustrated, the external contact 9 is formed in a shape that can correspond to the measuring object 2 having various inner diameters D1.

  The inner diameter calculation output means 5 includes a characteristic impedance measuring device 12, an inner diameter calculation device 13, and an inner diameter display device 14.

  The characteristic impedance measuring device 12 is a device for measuring the characteristic impedance value (Zo), and is configured to employ the TDR method (in this embodiment, a known network analyzer is used). Note that TDR is an abbreviation for Time Domain Reflectometry, and in this embodiment, a method of applying a high-speed pulse or the like to the coaxial transmission line and observing the reflected waveform returned is adopted. It shall be). A coaxial cable 4 is connected to each port of such a characteristic impedance measuring device 12.

  The inner diameter calculation device 13 is configured to be able to input the characteristic impedance value obtained by the characteristic impedance measurement device 12. Further, the inner diameter calculation device 13 can perform calculation for obtaining the inner diameter D1 of the measurement object 2 based on the input characteristic impedance value and the known outer diameter value (outer diameter D2) of the inner conductor 6. It is configured as follows. It is assumed that the inner diameter calculation device 13 stores a known outer diameter value (outer diameter D2) of the inner conductor 6 in advance. Regarding the above calculation, an inner diameter D1 of the measurement object 2 is calculated by substituting a predetermined value into the following mathematical formula. The inner diameter calculation device 13 has a so-called microcomputer function.

  In the following equation, Zo represents a characteristic impedance value, Ke represents a relative dielectric constant (here, 1), D1 represents an inner diameter of the measurement object 2, and D2 represents a known outer diameter of the inner conductor 6.

  The inner diameter display device 14 is provided as a device that can display the inner diameter D1 of the measurement object 2 calculated by the inner diameter calculation device 13 on the screen. It should be noted that an apparatus that prints out without displaying a screen may be used.

  Since the inner diameter calculation output means 5 uses the above network analyzer as the characteristic impedance measuring device 12, in the case of such a device, it is possible to sort 1Ω or less by the above Zo. Since the change in the inner diameter of 1Ω corresponds to about 10 μm, the present invention can obtain a resolution less than this (the conventional technology cannot obtain an accuracy of 1/100, In addition, it is not possible to grasp changes due to location with a small inner diameter).

  As described above, according to the inner diameter measuring apparatus 1 of the present invention, a predetermined calculation is performed based on the characteristic impedance value and the known outer diameter value (outer diameter D2) of the inner conductor 6, thereby obtaining the inner diameter D1 of the measurement object 2. Therefore, it is a measurement method different from that of the conventional technique, and even a measurement object 2 having a small inner diameter D1 can be measured, and can be measured with higher accuracy than in the past.

  It goes without saying that the present invention can be variously modified without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Inner diameter measuring device 2 ... Measurement object 3 ... Coaxial transmission line device 4 ... Coaxial cable 5 ... Inner diameter calculation output means 6 ... Inner conductor 7 ... SMA connector 8 ... Internal contact 9 ... External contact 10 ... Insulator 11 ... Connection part DESCRIPTION OF SYMBOLS 12 ... Characteristic impedance measuring device 13 ... Inner diameter calculating device 14 ... Inner diameter display apparatus D1 ... Inner diameter D2 ... Outer diameter

Claims (2)

A device for measuring the inner diameter of a cylindrical conductive measuring object,
A coaxial transmission line device in which a coaxial transmission line is formed by assembling the measurement object as an outer conductor;
Two coaxial cables respectively connected to both ends of the coaxial transmission line device;
It is connected to the coaxial transmission line device via the coaxial cable and measures the characteristic impedance value of the coaxial transmission line, and based on the characteristic impedance value and the known outer diameter value of the inner conductor in the coaxial transmission line device An inner diameter calculation output means for calculating the inner diameter of the measurement object and outputting the calculation result;
An inner diameter measuring device comprising: The inner diameter measuring device according to claim 1,
The coaxial transmission line device is
The inner conductor inserted at a predetermined position inside the measurement object to be the outer conductor and having the known outer diameter value;
Two SMA connectors having an internal contact connected to the end of the inner conductor and an external contact connected to the end of the measurement object, and having a connection to the coaxial cable;
An inner diameter measuring device comprising:

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