JP3587360B2 - Air micrometer - Google Patents

Description

ここで、エアノズル位置のズレ量は加工精度により決定され、最大値は加工公差の上限値となる。
【００１８】
したがって、測定誤差を所定値以内に抑えるためには、エアノズル位置のズレ量を加工公差の上限値と想定して上式によりガイドクリアランスの最適値を決定する必要がある。たとえば、ワーク半径ｒが２ｍｍ、エアノズル位置のズレ量を０．０２ｍｍとした場合、測定誤差（繰り返し精度）を０．５μｍに抑えるためには、上式よりガイドクリアランスは、約２３．２μｍ以下に設定する必要がある。
【００１９】
しかし、ガイドクリアランスを小さく設定すると、挿入しにくくなるとともに、測定ヘッド３２に磨耗が生じ、却って測定誤差が生じやすくなる。
【００２０】
そこで、本実施の形態の空気マイクロメータでは、ガイドクリアランスが５〜２０μｍになるように設定している。
【００２１】
これにより、測定ヘッド挿入時の容易性を確保しつつ、繰り返し精度（繰り返し測定による測定値のバラツキ幅）が０．５μｍ以下の高精度な測定を行うことができる。
【００２２】
なお、図２において、符号４０はトップガイドである。このトップガイド４０は超硬合金製で円柱状に形成されており、測定ヘッド３２の先端部にボルト４２を介して着脱自在に取り付けられている。そして、その外径φＡは測定ヘッド３２の外径φＢよりもやや小さめに形成されている。このようなトップガイド４０を測定ヘッド３２の先端部に取り付けることにより、本実施の形態のようにガイドクリアランスを小さく設定した場合であっても、測定ヘッド３２をワーク２２を容易に挿入することができるようになる。また、測定ヘッド３２の磨耗を効果的に抑制することもできるとともに、姿勢誤差を排除して、高精度な測定を行うことができる。
【００２３】
なお、軟質ワークの場合、超硬合金製のトップガイド４０を用いると、ワーク側が磨耗してしまうので、この場合は、フッ素樹脂、ナイロン樹脂、ポリアセタール等の樹脂製のトップガイド４０を用いるのが好ましい。樹脂は摩擦が少ないので滑りが良くなり、挿入しやすくなるとともに、適度な柔らかさを有しているのでワークが傷つくのを効果的に抑制することができる。
【００２４】
また、図２、図３に示すように、各エアノズル３４、３４、…は、そのエア吹出口３４ａ、３４ａ、…に面取り加工を施さずに形成することが好ましい。このように形成することにより、容易に各エアノズル３４、３４、…の特性を合わせることができ、これにより高精度な測定が可能になる。
【００２５】
すなわち、エアノズル３４、３４、…のエア吹出口３４ａ、３４ａ、…に面取り加工を施せば測定範囲が拡大するが、高精度な測定を行うためには、各エアノズルの特性、すなわち各エアノズルの位置、穴径を正確に合わせる（寸法を同じにする）必要がある。しかし、吹出口に面取り加工を施すこととすると、吹出口の中心と面取り加工の中心とを正確に合わせて加工したり、面取りの深さを正確に合わせて加工したりしなければならず、この結果、各エアノズルの特性を合わせることが極めて困難になる。そして、各エアノズルの特性が一致しない結果、高精度な測定ができなくなる。これに対して、各エアノズル３４、３４、…の吹出口３４ａ、３４ａ、…に面取り加工を施さないこととすれば、容易に各エアノズル３４、３４、…の特性を合わせることができ、高精度な測定が可能になる。
【００２６】
なお、吹出口に面取り加工を施さないこととすると、隙間の大きさの変化に対して背圧が直線的に変化する範囲、すなわち測定可能な範囲が狭まることとなるが、繰り返し精度が０．５μｍ以下の高精度な測定を行う場合には、測定範囲を狭い範囲に限定して使用するので、測定範囲を拡大する必要はない。
【００２７】
図４は、外径測定用ジェット５０の構成を示す側面断面図であり、図５は、図４の５−５断面図である。なお、ジェット以外の構成は内径測定用のものと同じであるので、ここではジェットの構成についてのみ説明する。
【００２８】
同図に示すように、リング状に形成された測定ヘッド５２には、４つの取付穴５４、５４、…が放射状に形成されている。各取付穴５４、５４、…には、それぞれ測定用ニップル５６、５６、…が嵌入されている。測定用ニップル５６にはエアノズル５８が形成されており、エアノズル５８は、その先端面が測定ヘッド５２の内周面から所定量退避して形成されている。空気源１２からレギュレータ１４、Ａ／Ｅ変換器１６を介してジェット５０に供給される圧縮空気は、このエアノズル５８、５８、…から測定ヘッド５２の中心に向かって噴射される。
【００２９】
ここで、同図に示すように、測定ヘッド５２にはワーク２４が挿入されるため、その内径φＥがワーク２４の外径φＦよりも大径に形成されている。そして、本実施の形態では、測定ヘッド５２の内径φＥが、ワーク２４の公差の大径側から５〜２０μｍ大きくなるように形成されている。すなわち、ガイドクリアランス（φＥ−φＦ）が５〜２０μｍになるように設定されている。これは、上記内径測定用ジェットの場合と同じ理由からである。
【００３０】
このように、ガイドクリアランスが５〜２０μｍになるように設定することにより、ワーク挿入時の容易性を確保しつつ、繰り返し精度（繰り返し測定による測定値のバラツキ幅）が０．５μｍ以下の高精度な測定を行うことができる。
【００３１】
なお、図４において、符号６０はトップガイドである。このトップガイド６０は超硬合金製でリング状に形成されており、測定ヘッド５２の先端部にボルト６２を介して着脱自在に取り付けられている。そして、その内径φＤは測定ヘッド３２の内径φＥよりもやや大きめに形成されている。このようなトップガイド６０を取り付けることにより、ワーク２４を測定ヘッド５２に挿入し易くなるとともに、測定ヘッド５２の磨耗を効果的に抑制することができる。また、このトップガイド６０を取り付けることにより、姿勢誤差を排除して、高精度な測定を行うことができるようになる。
【００３２】
なお、軟質ワークの場合、超硬合金製のトップガイド６０を用いると、ワーク側が磨耗してしまうので、この場合は、フッ素樹脂、ナイロン樹脂、ポリアセタール等の樹脂製のトップガイド６０を用いるのが好ましい。樹脂は摩擦が少ないので滑りが良くなり、挿入しやすくなるとともに、適度な柔らかさを有しているのでワークが傷つくのを効果的に抑制することができる。
【００３３】
また、上述した内径測定用のジェットと同様に、各エアノズル５８、５８、…には、そのエア吹出口５８ａ、５８ａ、…に面取り加工を施さないことが好ましい。
【００３４】
なお、上述した実施の形態では、内径測定用、外径測定用共にエアノズルが４つ設置されているジェットを例に説明しているが、エアノズルの数はこれに限定されるものではない。
【００３５】
【発明の効果】
以上説明したように、本発明によれば、ガイドクリアランスを５〜２０μｍに設定することにより、繰り返し精度が０．５μｍ以下の高精度な測定を行うことができる。
【図面の簡単な説明】
【図１】背圧式空気マイクロメータの構成を示すブロック図
【図２】内径測定用ジェットの構成を示す側面断面図
【図３】図２の３−３断面図
【図４】外径測定用ジェットの構成を示す側面断面図
【図５】図４の５−５断面図
【図６】測定誤差の説明図
【符号の説明】
１０…背圧式空気マイクロメータ、１２…空気源、１４…レギュレータ、１６…Ａ／Ｅ変換器、１８…アンプ、２０…モニタ、２２、２４…ワーク、３０…内径測定用ジェット、３２…測定ヘッド、３４…エアノズル、３４ａ…吹出口、４０…トップガイド、５０…外径測定用ジェット、５２…測定ヘッド、５６…測定用ニップル、５８…エアノズル、５８ａ…吹出口、６０…トップガイド[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an air micrometer, and more particularly to an air micrometer capable of high-precision measurement with a repeat accuracy (variation width of measurement values by repeat measurement) of 0.5 μm or less.
[0002]
[Prior art]
For example, in the case of measuring an inner diameter, an air micrometer inserts a measurement head formed in a columnar shape into a workpiece, and measures by injecting compressed air from 2 to 6 air nozzles formed on the outer periphery of the tip of the measurement head. I do. That is, when the measurement head is inserted into the work and compressed air is injected from the air nozzle, the back pressure of the air nozzle changes according to the size of the gap between the work and the measurement head. Is used to measure the inner diameter of the workpiece.
[0003]
By the way, since the air micrometer performs measurement by inserting the measurement head into the workpiece as described above (in the case of measuring the inner diameter), the measurement head needs to be formed with a smaller diameter than the inner diameter of the workpiece.
[0004]
On the other hand, the air micrometer is generally designed to measure up to a maximum measurement range of 100 μm, and for this reason, the guide clearance (the size of the gap between the workpiece and the measurement head) exceeds the measurement range. ing.
[0005]
[Problems to be solved by the invention]
However, if the guide clearance is large, there is a drawback that when the measuring head is inserted into the workpiece, a positional deviation between the center of the workpiece and the center of the measuring head is likely to occur, and a measurement error is likely to occur.
[0006]
The present invention has been made in view of such circumstances, and an object of the present invention is to provide an air micrometer capable of high-precision measurement with a repetition accuracy of 0.5 μm or less.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 inserts a measuring head formed in a columnar shape into a hole formed in a workpiece, and blows out air from a nozzle formed in the outer peripheral portion of the measuring head. In the air micrometer for measuring the inner diameter of the hole with an accuracy of 0.5 μm or less, a cylindrical top guide having an outer diameter smaller than the measuring head is attached to the tip of the measuring head. , characterized in that setting the difference between the outer diameter of the inner diameter and the measuring head of the workpiece to 5μm or 20μm or less.
According to a second aspect of the present invention, in order to achieve the above object, a measuring head formed in a columnar shape is inserted into a hole formed in a workpiece, and is formed at a constant interval on the outer periphery of the measuring head. In the air micrometer that blows out air from a plurality of nozzles and repeatedly measures the inner diameter of the hole with an accuracy of 0.5 μm or less, each nozzle is formed without chamfering the blowout port, and The difference between the inner diameter of the workpiece and the outer diameter of the measuring head is set to 5 μm or more and 20 μm or less.
[0008]
According to the present invention, it is possible to perform highly accurate measurement with a repeatability of 0.5 μm or less while ensuring ease of insertion into a workpiece.
[0009]
According to a third aspect of the present invention, in order to achieve the above object, a workpiece is inserted into the inner peripheral portion of the measurement head formed in a ring shape, and air is discharged from the nozzle formed in the inner peripheral portion of the measurement head. In an air micrometer that repeatedly measures the outer diameter of the workpiece with an accuracy of 0.5 μm or less, a ring-shaped top guide having a larger inner diameter than the measuring head is provided at the tip of the measuring head. is attached, it is characterized in that setting the difference between the outer diameter of the inner diameter of the measuring head workpiece to 5μm or 20μm or less.
According to a fourth aspect of the present invention, in order to achieve the above object, a workpiece is inserted into the inner peripheral portion of the measuring head formed in a ring shape, and the inner peripheral portion of the measuring head is formed at a constant interval. In the air micrometer that blows out air from a plurality of nozzles and repeatedly measures the outer diameter of the workpiece with an accuracy of 0.5 μm or less, each nozzle is formed without chamfering the blowout port, The difference between the inner diameter of the workpiece and the outer diameter of the measuring head is set to 5 μm or more and 20 μm or less.
[0010]
According to the present invention, it is possible to perform highly accurate measurement with a repeatability of 0.5 μm or less while ensuring the ease of inserting a workpiece.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of an air micrometer according to the present invention will be described in detail with reference to the accompanying drawings.
[0012]
FIG. 1 is a block diagram showing a configuration of a back pressure type air micrometer 10. As shown in the figure, the compressed air supplied from the air source 12 is adjusted to a constant pressure by the regulator 14 and is injected from the air nozzle 34 of the jet 30 through the throttle installed in the A / E converter 16. The The A / E converter 16 converts a minute change in pressure (back pressure) between the air nozzle 34 and the throttle into an electrical signal by a built-in bellows and a differential transformer, and outputs the electrical signal to the amplifier 18. The amplifier 18 calculates the inner diameter of the workpiece based on this electric signal and displays it on the monitor 20.
[0013]
FIG. 2 is a side sectional view showing the configuration of the inner diameter measuring jet 30, and FIG. 3 is a sectional view taken along the line 3-3 in FIG.
[0014]
As shown in the figure, the measurement head 32 is formed in a columnar shape, and four air nozzles 34, 34,... Each of the air nozzles 34, 34,... Is formed by retracting a predetermined amount from the outer peripheral surface of the measurement head 32. The air passages 36, 38,. It is communicated via…. Compressed air supplied from the air source 12 to the jet 30 via the regulator 14 and the A / E converter 16 passes from the air nozzles 34, 34,... Be injected.
[0015]
Here, as shown in the figure, since the measurement head 32 is inserted into the workpiece 22 to perform measurement, the outer diameter φB is formed smaller than the inner diameter φC of the workpiece 22. In the present embodiment, the outer diameter φB of the measuring head 32 is formed to be 5 to 20 μm smaller than the smaller diameter side of the tolerance of the work 22. That is, the guide clearance (φC−φB) is set to 5 to 20 μm. This is due to the following reason.
[0016]
In the air micrometer, the measurement error δ caused by “the displacement amount of the air nozzle position with respect to the center of the measurement head” and “the displacement of the center position of the measurement head with respect to the workpiece center due to the guide clearance” is expressed by the following equation (FIG. 6). reference).
[0017]
[Expression 1]

Here, the deviation amount of the air nozzle position is determined by the machining accuracy, and the maximum value is the upper limit value of the machining tolerance.
[0018]
Therefore, in order to suppress the measurement error within a predetermined value, it is necessary to determine the optimum value of the guide clearance by the above equation assuming that the deviation amount of the air nozzle position is the upper limit value of the machining tolerance. For example, if the workpiece radius r was 0.02 mm 2 mm, the deviation of the air nozzle located, in order to suppress the measurement error (repeatability) to 0.5μm, the guide from the above equation clearance about 23.2Myu m or less Must be set below.
[0019]
However, if the guide clearance is set to be small, it is difficult to insert the guide clearance, and the measurement head 32 is worn, which tends to cause a measurement error.
[0020]
Therefore, in the air micrometer of the present embodiment, the guide clearance is set to 5 to 20 μm.
[0021]
Thereby, it is possible to perform highly accurate measurement with a repeat accuracy (variation width of measurement values by repeat measurement) of 0.5 μm or less while ensuring ease when the measurement head is inserted.
[0022]
In FIG. 2, reference numeral 40 denotes a top guide. The top guide 40 is made of a cemented carbide and is formed in a cylindrical shape, and is detachably attached to the tip of the measuring head 32 via a bolt 42. The outer diameter φA is slightly smaller than the outer diameter φB of the measuring head 32. By attaching such a top guide 40 to the tip of the measurement head 32, the workpiece 22 can be easily inserted into the measurement head 32 even when the guide clearance is set small as in the present embodiment. become able to. In addition, it is possible to effectively suppress wear of the measuring head 32, and it is possible to perform high-precision measurement by eliminating the posture error.
[0023]
In the case of a soft work, if the top guide 40 made of cemented carbide is used, the work side is worn out. In this case, the top guide 40 made of resin such as fluororesin, nylon resin, polyacetal is used. preferable. Since the resin has less friction, the slipping is improved and the resin is easily inserted, and since the resin has an appropriate softness, it is possible to effectively prevent the workpiece from being damaged.
[0024]
2 and 3, each air nozzle 34, 34,... Is preferably formed without chamfering the air outlets 34a, 34a,. By forming in this way, it is possible to easily match the characteristics of the air nozzles 34, 34,..., Thereby enabling highly accurate measurement.
[0025]
In other words, the chamfering process is performed on the air outlets 34a, 34a,... Of the air nozzles 34, 34,..., The measurement range is expanded. , It is necessary to match the hole diameter accurately (same dimensions). However, if chamfering is performed on the air outlet, the center of the air outlet and the center of the chamfering must be precisely matched, or the chamfering depth must be accurately adjusted, As a result, it becomes extremely difficult to match the characteristics of the air nozzles. As a result, the characteristics of the air nozzles do not match, and as a result, highly accurate measurement cannot be performed. On the other hand, if no chamfering is performed on the air outlets 34a, 34a,... Of each air nozzle 34, 34,..., The characteristics of the air nozzles 34, 34,. Measurement is possible.
[0026]
If chamfering is not performed on the air outlet, the range in which the back pressure changes linearly with respect to the change in the size of the gap, that is, the measurable range is narrowed, but the repeatability is 0. In the case of performing highly accurate measurement of 5 μm or less, the measurement range is limited to a narrow range, so it is not necessary to expand the measurement range.
[0027]
4 is a side sectional view showing the configuration of the outer diameter measuring jet 50, and FIG. 5 is a sectional view taken along the line 5-5 in FIG. Since the configuration other than the jet is the same as that for measuring the inner diameter, only the configuration of the jet will be described here.
[0028]
As shown in the drawing, the measurement head 52 formed in a ring shape has four mounting holes 54, 54,. .. Are fitted into the mounting holes 54, 54,..., Respectively. An air nozzle 58 is formed in the measurement nipple 56, and the air nozzle 58 is formed with its tip end surface retracted from the inner peripheral surface of the measurement head 52 by a predetermined amount. Compressed air supplied from the air source 12 to the jet 50 via the regulator 14 and the A / E converter 16 is jetted toward the center of the measuring head 52 from the air nozzles 58, 58,.
[0029]
Here, as shown in the figure, since the workpiece 24 is inserted into the measuring head 52, the inner diameter φE is formed larger than the outer diameter φF of the workpiece 24. In this embodiment, the inner diameter φE of the measuring head 52 is formed so as to be 5 to 20 μm larger than the larger diameter side of the tolerance of the workpiece 24. That is, the guide clearance (φE−φF) is set to 5 to 20 μm. This is for the same reason as in the case of the inner diameter measuring jet.
[0030]
As described above, by setting the guide clearance to be 5 to 20 μm, the accuracy of repeatability (variation width of measured values by repeated measurement) is 0.5 μm or less while ensuring the ease of workpiece insertion. Measurements can be made.
[0031]
In FIG. 4, reference numeral 60 denotes a top guide. The top guide 60 is made of cemented carbide and is formed in a ring shape, and is detachably attached to the tip of the measuring head 52 via a bolt 62. The inner diameter φD is slightly larger than the inner diameter φE of the measuring head 32. By attaching such a top guide 60, it becomes easy to insert the workpiece 24 into the measurement head 52, and wear of the measurement head 52 can be effectively suppressed. Further, by attaching the top guide 60, it becomes possible to eliminate the posture error and perform highly accurate measurement.
[0032]
In the case of a soft work, if the top guide 60 made of cemented carbide is used, the work side is worn out. In this case, the top guide 60 made of resin such as fluororesin, nylon resin or polyacetal is used. preferable. Since the resin has less friction, the slipping is improved and the resin is easily inserted, and since the resin has an appropriate softness, it is possible to effectively prevent the workpiece from being damaged.
[0033]
Further, it is preferable that the air nozzles 58, 58,... Are not chamfered at the air outlets 58a, 58a,.
[0034]
In the above-described embodiment, the jet having four air nozzles is described as an example for both inner diameter measurement and outer diameter measurement, but the number of air nozzles is not limited to this.
[0035]
【The invention's effect】
As described above, according to the present invention, by setting the guide clearance to 5 to 20 μm, it is possible to perform highly accurate measurement with a repetition accuracy of 0.5 μm or less.
[Brief description of the drawings]
FIG. 1 is a block diagram showing the configuration of a back pressure air micrometer. FIG. 2 is a side sectional view showing the configuration of an inner diameter measuring jet. FIG. 3 is a sectional view taken along line 3-3 in FIG. Side sectional view showing the configuration of the jet [FIG. 5] FIG. 5-5 sectional view of FIG. [FIG. 6] Explanatory drawing of measurement error [Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Back pressure type air micrometer, 12 ... Air source, 14 ... Regulator, 16 ... A / E converter, 18 ... Amplifier, 20 ... Monitor, 22, 24 ... Workpiece, 30 ... Jet for measuring inner diameter, 32 ... Measuring head 34 ... Air nozzle, 34a ... Air outlet, 40 ... Top guide, 50 ... Jet for measuring outer diameter, 52 ... Measuring head, 56 ... Measuring nipple, 58 ... Air nozzle, 58a ... Air outlet, 60 ... Top guide

Claims (4)

A measuring head formed in a cylindrical shape is inserted into a hole formed in the workpiece, and air is blown out from a nozzle formed on the outer peripheral portion of the measuring head so that the inner diameter of the hole is repeated with an accuracy of 0.5 μm or less. In the air micrometer to measure in
Wherein with an outside diameter than the measuring head to the tip of the measuring head is attached to small-formed cylindrical top guide that was set to the difference between the outer diameter of the workpiece inner diameter and the measuring head of the 5μm or 20μm or less Air micrometer characterized by A measuring head formed in a cylindrical shape is inserted into a hole formed in the workpiece, and air is blown out from a plurality of nozzles formed at a constant interval on the outer periphery of the measuring head, so that the inner diameter of the hole is repeated with high accuracy. In an air micrometer that measures with an accuracy of 0.5 μm or less,
An air micrometer characterized in that the nozzles are formed without chamfering the air outlet, and the difference between the inner diameter of the workpiece and the outer diameter of the measuring head is set to 5 μm or more and 20 μm or less. A work is inserted into the inner circumference of the measurement head formed in a ring shape, air is blown out from a nozzle formed in the inner circumference of the measurement head, and the outer diameter of the work is repeated with an accuracy of 0.5 μm or less. In an air micrometer that measures with accuracy,
Wherein is attached a inner diameter larger by a ring-shaped top guide than the measuring head to the tip of the measuring head, that sets the difference between the outer diameter of the inner diameter of the measuring head workpiece to 5μm or 20μm or less Features an air micrometer. A work is inserted into the inner circumference of the measurement head formed in a ring shape, and air is blown out from a plurality of nozzles formed at regular intervals on the inner circumference of the measurement head, so that the outer diameter of the work is repeated with accuracy. In an air micrometer that measures with an accuracy of 0.5 μm or less,
An air micrometer characterized in that the nozzles are formed without chamfering the air outlet, and the difference between the inner diameter of the workpiece and the outer diameter of the measuring head is set to 5 μm or more and 20 μm or less.

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