JPH116705A - Screw hole measuring method and apparatus and measuring instrument - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a method, an apparatus, and a measuring instrument capable of accurately calculating an effective diameter by measuring a pilot hole diameter of a screw hole. SOLUTION: The probe 27 having air ejection ports 29A and 29B at its tip end for ejecting air in a direction perpendicular to the longitudinal direction of the probe 27 is inserted into a screw hole SH,
The screw hole for calculating the effective diameter of the screw hole SH by detecting the average value of the peak value of the back pressure of the air by moving the tracing stylus 27 in the axial direction while blowing air from the air outlets 29A and 29B. In the measurement method, a relational expression or a data table indicating the relationship between the prepared hole diameter of the screw hole SH, the effective diameter of the screw hole SH, and the back pressure of the air is stored in a memory in advance, and measured by the prepared hole diameter measurement unit. A screw hole measuring method and apparatus for calculating an effective diameter based on the relation between the pilot hole diameter of the screw hole SH and the back pressure of the air based on the relational expression or the data table.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring, for example, a peak diameter, a valley diameter, and an effective diameter of a screw hole, and a measuring instrument. The present invention relates to a method and apparatus capable of accurately calculating an effective diameter, and a measuring instrument.

[0002]

2. Description of the Related Art As a prior example relating to the present invention, there is, for example, JP-A-8-210835.

[0003] In the above-mentioned prior art, the probe having a spout for ejecting air in a direction perpendicular to the longitudinal direction of the probe at the tip is inserted into a screw hole, and the air spouted from the spout is inserted. By measuring the back pressure, the distance between the tracing stylus and the screw hole is detected to calculate the peak diameter, the valley diameter, the effective diameter, and the like.

[0004]

In the configuration of the prior art as described above, when the jig is used to measure while keeping the axis of the measuring element and the screw hole coincident, the crest diameter of the screw hole,
This is useful because the valley diameter, the effective diameter, and the like can be accurately calculated.

However, when measuring a screw hole simply without using a jig or the like, the axis of the tracing stylus and the axis of the screw hole may not coincide with each other, resulting in variations in measured values. Also,
Since the pilot hole diameter of the screw hole is not measured, a measurement error may occur due to a pilot hole diameter error when calculating the effective diameter.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems.
Insert the probe into the screw hole, which has an air ejection port for ejecting air in a direction perpendicular to the longitudinal direction of the probe, into the screw hole, and pivot the probe while ejecting air from the air ejection port. In the screw hole measurement method of moving in the direction and detecting the average value of the peak value of the back pressure of the air to calculate the effective diameter of the screw hole, the pilot hole diameter of the screw hole and the effective diameter of the screw hole and A relational expression or data table indicating the relationship with the air back pressure is stored in the memory in advance, and based on the measured relationship between the prepared hole diameter of the screw hole and the air back pressure, the relational expression or the data table is effective. This is a screw hole measurement method for calculating the diameter.

According to a second aspect of the present invention, the back pressure of air jetted in a direction perpendicular to the longitudinal direction of the tracing stylus from an air spout provided at the tip end of the tracing stylus inserted into the screw hole is electrically controlled. A pressure-voltage converter for converting into a signal, a pilot hole diameter measuring unit for measuring the pilot hole diameter of the screw hole, and a relationship indicating a relationship between the pilot hole diameter of the screw hole, the effective diameter, and the back pressure of the air. A memory in which a formula or data table is stored in advance, and the relational expression or the data table is searched based on the pilot hole diameter measured by the pilot hole diameter measuring unit and the back pressure of the air detected by the pressure-voltage converter, and the screw is searched. A screw hole measuring device comprising: an arithmetic processing unit that calculates an effective diameter of a hole.

According to a third aspect of the present invention, there is provided a casing body having a pair of positioning flanges which can be inserted into a screw hole and are movable in a radial direction which approach and separate from each other, and detect a moving amount of the positioning flange. A measuring device is provided, and at the tip of a measuring element movably provided between the pair of positioning flanges, an air ejection port for ejecting air in a direction orthogonal to the longitudinal direction of the measuring element is provided, and the air This is a screw hole measuring device provided with a pressure-voltage converter for converting a back pressure into an electric signal.

[0009]

According to the first aspect of the present invention, the probe having an air ejection port at a tip end for ejecting air in a direction perpendicular to the longitudinal direction of the probe is inserted into a screw hole, and the air is removed. In the screw hole measurement method of moving the probe in the axial direction while ejecting air from the ejection port and detecting the average value of the peak value of the back pressure of the air to calculate the effective diameter of the screw hole, A relational expression or data table indicating the relationship between the pilot hole diameter of the hole, the effective diameter of the screw hole, and the back pressure of the air is stored in the memory in advance, and the relationship between the measured pilot hole diameter of the screw hole and the back pressure of the air is measured. , The effective diameter is calculated based on the relational expression or the data table, so that the effective diameter can be accurately calculated even if there is a difference in the size of the pilot hole diameter in the screw hole. Things.

According to a second aspect of the present invention, the back pressure of air jetted in a direction orthogonal to the longitudinal direction of the measuring element from an air jet port provided at the tip of the measuring element inserted into the screw hole is electrically controlled. A pressure-voltage converter for converting into a signal, a pilot hole diameter measuring unit for measuring the pilot hole diameter of the screw hole, and a relationship indicating a relationship between the pilot hole diameter of the screw hole, the effective diameter, and the back pressure of the air. A memory in which a formula or data table is stored in advance, and the relational expression or the data table is searched based on the pilot hole diameter measured by the pilot hole diameter measuring unit and the back pressure of the air detected by the pressure-voltage converter, and the screw is searched. And an arithmetic processing unit that calculates the effective diameter of the hole, so that the effective diameter can be accurately calculated even if there is a difference in the prepared hole diameter of the screw hole.

According to a third aspect of the present invention, there is provided a casing body having a pair of positioning flanges which can be inserted into a screw hole and can move in a radial direction which approach and separate from each other, and detect a moving amount of the positioning flange. A measuring device is provided, and at the tip of a measuring element movably provided between the pair of positioning flanges, an air ejection port for ejecting air in a direction orthogonal to the longitudinal direction of the measuring element is provided, and the air Since it is provided with a pressure-voltage converter that converts back pressure into an electric signal, it is possible to measure the pilot hole diameter in the screw hole and position the measuring element so that it almost matches the axis of the screw hole. Can be done.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, a measuring instrument 1 for measuring, for example, a screw hole SH formed in a product or a work W is provided with a cylindrical casing body 3. A fluid cylinder 11 in which a ring-shaped piston 9 is reciprocally mounted between the inner cylinder 5 and the outer cylinder 7 is mounted on the distal end side. A pair of semicircular positioning flanges 15A are provided between the lid 9 and the piston 9 attached to the end of the fluid cylinder 11.
15B are provided so as to be able to approach and separate from each other in the radial direction.

The positioning flanges 15A and 15B are
An elastic member 17 such as an annular coil spring or the like always presses and presses inward so as to approach each other.
In order to move A, 15B in the outward direction away from each other, the tapered surfaces formed on the pistons 9 contact the inclined surfaces 19A, 19B formed on the surfaces of the positioning flanges 15A, 15B facing the pistons 9. In contact. Therefore, when the working fluid is supplied to the fluid cylinder 11 and the piston 9 is moved rightward in FIG. 1, the positioning flanges 15A and 15B move away from each other against the urging force of the elastic member 17 (the diameter is increased). Direction).

A pilot hole diameter measuring unit is provided for measuring the pilot hole diameter of the screw hole SH. That is, at the center of each of the positioning flanges 15A and 15B, there are provided opposed facers 21A and 21B extending in the axial direction through holes 13H provided in the center of the lid member 13. Each of the feelers 21A and 21B has a semi-circular cross-sectional shape, and is formed to be elongated so that it can be inserted into the screw hole SH.

The positioning flanges 15A, 1
In order to detect the movement of 5B, the movement amount detectors 23A, 23A
3B is attached to the lid member 13. The movement amount detectors 23A and 23B are not particularly limited as long as they can detect the movement amount (displacement amount) of the contact contacting the feelers 21A and 21B, and an appropriate sensor can be used.

With the above structure, the feelers 21A, 2A
1B is inserted into the screw hole SH, and the positioning flanges 15A, 15B are moved in the direction away from each other by the fluid cylinder 11 as described above.
By detecting the amount of movement when 1B comes into contact with the inner peripheral surface of the screw hole SH by the movement amount detectors 23A and 23B, the pilot hole diameter of the screw hole SH can be measured. The positions (corresponding to the diameters) of the feelers 21A and 21B before the feelers 21A and 21B are moved are known.

The probe body 2 is provided in the casing body 3.
5 is provided so as to be movable in the axial direction (the left-right direction in FIG. 1). The probe main body 25 is configured to reciprocate in the axial direction by driving an appropriate actuator (not shown) such as a motor, and an appropriate position detector (not shown) such as a linear sensor. With this configuration, the position of movement in the axial direction can be detected. The configuration for reciprocating the probe body 25 in the axial direction and the configuration for detecting the axial movement position include:
Since the configuration may be the same as that of the above-described prior example, a detailed description of those configurations will be omitted.

A probe 27 is provided at the tip of the probe body 25 so as to penetrate between the positioning flanges 15A and 15B and project from the tips of the feelers 21A and 21B. The tracing stylus 27 is sandwiched between the respective feelers 21A and 21B, and has a substantially rectangular cross section as shown in FIG. At the tip of the tracing stylus 27, air jets 29A and 29B for jetting air in a direction orthogonal to the longitudinal direction of the tracing stylus 27 are provided so as to be directed in opposite directions to each other. Air passages 31A and 31B are connected to 29A and 29B, respectively. The air passage 3
1A and 31B are connected to an air supply source (not shown) for supplying air at a constant pressure.

The configuration of the air outlets 29A, 29B and the like constitutes a kind of air micrometer, and the back pressure when air is injected from the air outlets 29A, 29B is determined by the pressure-voltage converters 33A, 33B ( (See FIG. 4) to convert to a voltage and to detect it.

The detection values of the pressure-voltage converters 33A and 33B are supplied to an arithmetic processing unit 39 via an amplifier 35 and an A / D converter 37. The arithmetic processing unit 39 is configured to detect the detected values of the pressure-voltage conversion devices 33A and 33B and the movement amount detector 23.
Based on the prepared hole diameter of the screw hole SH detected by A and 23B, a relational expression or a data table indicating the relationship between the prepared hole diameter of the screw hole, the effective diameter, and the back pressure of the air stored in the memory 41 in advance. It has a function of calculating the effective diameter of the screw hole SH by utilizing it. The effective diameter calculated by the arithmetic processing unit 37 is output and displayed on an appropriate output unit 43 such as a CRT or a printer.

In FIG. 4, reference numeral 45 denotes a controller which controls an actuator 47 such as a solenoid valve for controlling the supply of the working fluid to the fluid cylinder 11 and a motor for reciprocating the probe body 25.

In the above configuration, to measure the effective diameter of the screw hole SH, the following process is first performed. That is, as shown in FIG. 5, each of the positioning holes in the measuring instrument 1 is inserted into the screw holes of a plurality of master rings having a known effective diameter and a prepared hole diameter for the screw hole to be measured and having different effective diameters and prepared hole diameters. After inserting the feelers 21A, 21B of the flanges 15A, 15B, the working fluid is supplied to the fluid cylinder 11 to move the feelers 21A, 21B away from each other so as to contact the inner peripheral surface of the screw hole. Then, the pilot hole diameter of the screw hole is detected by detecting the travel distance of each feeler 21A, 21B by the travel distance detectors 23A, 23B.

Each positioning flange 15A, 15B
Are urged by the elastic member 17 in a direction to approach each other, and the feelers 2
Dimensions corresponding to the outer diameters of the first and second feelers 1A and 21B are measured in advance, and the amount of movement of each of the feelers 21A and 21B until the outer diameters of the first and second feelers 21A and 21B come into contact with the inner peripheral surface of the screw hole. It can measure the prepared hole diameter of a hole.

As described above, each feeler 21A, 21B
Is positioned in contact with the inner peripheral surface of the screw hole, the axis of the screw hole substantially coincides with the axis of the tracing stylus 27.
In this state, when the tracing stylus 27 is moved in the axial direction while blowing air toward the inner peripheral surface of the screw hole from the air spouts 29A and 29B provided at the tip of the tracing stylus 27, the air spouts 29A and 29B The back pressure of the air jetted from 29B changes according to the pitch of the screw thread in the screw hole. When the change in the back pressure is converted into a voltage by the pressure-voltage converters 33A and 33B, and the total value is displayed in relation to the position in the screw depth direction, it is represented as shown in FIG.

As shown in FIG. 6, peak values A ₁ , A ₂ , A ₃ ... Of the measured voltages are averaged for each master ring, and the average value and the known effective diameter of each master ring are measured. Is plotted on the coordinates of the total value of the output voltage and the effective diameter, straight lines A, B, and C as shown in FIG. 7 are obtained. The straight line A shows the relationship between the output voltage and the effective diameter when the pilot hole diameter is small, the straight line B shows the relationship when the pilot hole diameter is medium, and the straight line C shows the relationship when the pilot hole diameter is large. The formulas or data tables representing the straight lines A, B, and C are stored in the memory 41 in advance.

As described above, the straight lines A, B, and C are stored in the memory 41.
After storing a formula or a data table representing the formulas (the formulas or data tables representing the straight lines A, B, and C may be stored in the memory 41 before the measurement of a predetermined screw hole. The storage time is not limited to immediately before the measurement), the feelers 21A and 21B of the positioning flanges 15A and 15B are inserted into the screw holes SH to be measured,
The feelers 21A and 21B are brought into contact with the inner surfaces of the screw holes SH, and the travel distance detectors 23A and 23B detect the pilot hole diameters. The pilot hole diameters of the screw holes SH to be measured are large, medium, and small. It is determined to which one it belongs. This discrimination is performed for each screw hole diameter such as M6, M8, etc.
This is determined by classifying the pilot hole diameter into small ones and searching the arithmetic processing unit 39 for the corresponding data from the data stored in the memory 41 in advance.

As described above, each positioning flange 15
After the feelers 21A and 21B of A and 15B abut against the inner peripheral surface of the screw hole SH to be measured, as described above, they move in the axial direction while ejecting air from the air ejection ports 29A and 29B of the tracing stylus 27. Then, an output voltage obtained by averaging a peak value obtained by converting the back pressure of the air into a voltage is detected. Corresponding straight lines A, B, and C are obtained based on the detected output voltage and the prepared hole diameters detected by the movement amount detectors 23A and 23B.
The effective diameter of the screw hole SH to be measured is calculated from the data.

As described above, according to the present embodiment, the pilot hole diameter of the screw hole is classified into large, medium, and small, and the back pressure of the air when the probe is moved in the axial direction for each pilot hole diameter. A formula or a data table showing the relationship between the average value of the peak voltage converted to the voltage and the effective diameter is created and stored in the memory, and when measuring the screw hole, the pilot hole diameter of the screw hole is detected, In addition, the probe is moved in the screw hole in the axial direction to detect the average value of the peak voltage based on the change in the back pressure of air, and the data table is searched based on the detected pilot hole diameter and voltage value. Since the effective diameter is calculated, it is possible to accurately calculate the effective diameter.

When the measuring element is moved in the axial direction in the screw hole, the feelers 21A and 21B of the positioning flanges 15A and 15B abut against the inner peripheral surface of the screw hole to place the measuring element at the center of the screw hole. , Accurate measurement can be performed.

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view showing a main part of a measuring instrument.

FIG. 2 is an explanatory right side view of FIG. 1 as viewed from the right.

FIG. 3 is an explanatory diagram showing a relationship between a tracing stylus, a tip, and a screw hole.

FIG. 4 is an explanatory diagram schematically showing a control block in the screw hole measuring device.

FIG. 5 is an explanatory diagram showing a list of master rings.

FIG. 6 is an explanatory diagram showing a change in back pressure of air when a stylus is moved in a screw hole in an axial direction.

FIG. 7 is an explanatory diagram showing a relationship among a pilot hole diameter, a back pressure of air, and an effective diameter in a screw hole.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Measuring device 3 Casing main body 11 Fluid cylinder 15A, B Positioning flange 21A, B feeler 23A, B Movement amount detector 25 Probe main body 27 Measuring element 29A, B Air outlet 33A, B Pressure voltage converter 39 Operation processing unit 41 Memory

Claims (3)

[Claims] 1. An air ejection port for ejecting air in a direction orthogonal to a longitudinal direction of a measurement element is inserted into a screw hole at an end thereof with an air ejection port, and air is ejected from the air ejection port. In the screw hole measuring method of moving the tracing stylus in the axial direction and detecting the average value of the peak value of the back pressure of the air to calculate the effective diameter of the screw hole, the pilot hole diameter of the screw hole and the screw hole The relational expression or data table indicating the relationship between the effective diameter of the air and the back pressure of the air is stored in a memory in advance, and based on the measured relationship between the prepared hole diameter of the screw hole and the back pressure of the air, the relational expression or the data is stored. A screw hole measuring method, wherein an effective diameter is calculated based on a table. 2. A method for converting a back pressure of air jetted from an air jet port provided at a tip end of a probe inserted into a screw hole in a direction orthogonal to a longitudinal direction of the probe into an electric signal. A pressure-voltage converter, a pilot hole diameter measuring unit for measuring the pilot hole diameter of the screw hole, and a relational expression or a data table indicating the relationship between the pilot hole diameter of the screw hole, the effective diameter, and the back pressure of the air in advance. Based on the stored memory, the pilot hole diameter measured by the pilot hole diameter measuring unit, and the back pressure of air detected by the pressure-voltage converter, the relational expression or the data table is searched to calculate the effective diameter of the screw hole. A screw hole measuring device, comprising: 3. A casing main body having a pair of positioning flanges which can be inserted into a screw hole and can move in a radial direction which approach and move away from each other, a moving amount detector for detecting a moving amount of the positioning flange is provided. At the distal end of the tracing stylus movably provided between the positioning flanges, an air ejection port for jetting air in a direction orthogonal to the longitudinal direction of the tracing stylus is provided, and the back pressure of the air is converted into an electric signal. A screw hole measuring device comprising a pressure-voltage converter for conversion.