JP2004061111A - Measurement instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive non-contact measurement instrument which measures the inner diameter, the straightness, the cylindricity, and so forth of a hole formed in a work. <P>SOLUTION: An air/electricity transducer 30 detects a variation in the back pressure of a gas ejected into the hole WA, when a ball 14 is inserted in an automatic centripetal state into the hole WA of the work W is moved in the longitudinal direction of the hole WA. A light-receiving part 22 receives irradiation light from an optical fiber 18 provided to the ball 14. It is constituted so that the inner diameter, the straightness, and the cylindricity of the hole WA are obtained by obtaining the the variation of the peak position A in the amount of irradiation light. Thus, the inexpensive non-contact measurement instrument 10 which measures the inner diameter, the straightness, and the cylindricity of the hole WA is provided. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a measuring device for measuring a hole formed in a work, and more particularly to a measuring device for measuring the inner diameter, straightness, and cylindricity of a hole in a non-contact manner.
[0002]
[Prior art]
Conventionally, when measuring the inner diameter, straightness, cylindricity, and the like of a hole in a cylindrical part that is widely used as an automobile part, a machine tool part, or the like, an object to be measured (hereinafter referred to as a workpiece ) Is fixed, and a contact-type detector is rotated along the inner surface of the hole and measured while moving the detector in the longitudinal direction of the hole. When the work is a small part, a work rotation type roundness measuring machine has been used.
[0003]
[Problems to be solved by the invention]
However, this roundness measuring device is a general-purpose measuring device, has various functions, and the device itself is expensive. In addition, since the contact type is used, the measurement surface is scratched, and traces of dragging the touch element remain. For this reason, when the measurement pressure is reduced, when there is a burr or a groove on the inner peripheral portion of the hole, the tentacle is caught by the burr or the groove, and the measured value is a factor of variation.
[0004]
The present invention has been made in view of such circumstances, and it is an object of the present invention to provide an inexpensive measuring device capable of measuring the inner diameter, straightness, and cylindricity of a hole formed in a work in a non-contact manner. .
[0005]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 is a measuring apparatus for measuring a hole formed in a work, wherein an injection port for holding the work and injecting gas into the hole formed in the work. , A ball inserted into a hole formed in the work, an elastic member for supporting the ball, and a light attached to the ball for conveying and emitting light emitted from a light source. A fiber, a light receiving unit that receives the irradiated light, and an elevating unit that moves the elastic member, the ball, and the optical fiber up and down, and inserts the ball into a hole formed in the work. Injecting gas into the hole to automatically center the ball and the hole, and calculating the change in the peak position of the amount of irradiation light received by the light receiving unit when the ball is moved up and down, thereby obtaining the hole. Straightforward Is characterized in that control unit is provided for determining the.
[0006]
According to the invention of claim 1, when the ball inserted into the hole is moved in the longitudinal direction of the hole in a state where the ball is automatically centered, the light receiving unit receives irradiation light from an optical fiber provided in the ball, Since the straightness of the hole is obtained by obtaining the change in the peak position of the irradiation light amount, it is possible to provide a non-contact and inexpensive hole straightness measuring device.
[0007]
According to a second aspect of the present invention, there is provided a measuring device for measuring a hole formed in a work, wherein the holding table has an injection port for holding the work and injecting gas into the hole formed in the work. A ball inserted into a hole formed in the work, an elastic member supporting the ball, a pneumatic / electrical converter for converting a change in back pressure of the injected gas into an electric signal, Attached, an optical fiber for conveying and irradiating light emitted from a light source, a light receiving unit for receiving the emitted light, the elastic member, a ball, and a lifting means for moving the optical fiber up and down, And inserting the ball into a hole formed in the workpiece, injecting gas into the hole to automatically center the ball and the hole, and moving the ball up and down, Signal from the electrical converter From the change data of the peak position of the irradiation light amount received by the light receiving portion, is characterized in that control unit is provided to determine the cylindricity of the hole.
[0008]
According to the invention of claim 2, when the ball inserted into the hole is moved in the longitudinal direction of the hole while being automatically centered, the change in the back pressure of the gas injected into the hole is measured by the pneumatic / electrical converter. In addition to detecting the irradiance from the optical fiber provided on the ball at the light receiving unit and determining the change in the peak position of the irradiating light amount, the cylindricity of the hole is determined, so that a non-contact and inexpensive hole A cylindricity measuring machine can be provided.
[0009]
According to a third aspect of the present invention, in the first or second aspect, the elastic member is a parallel spring composed of at least three linear elastic bodies. According to the third aspect of the present invention, since the ball is supported by the parallel spring made of at least three linear elastic members, the ball does not tilt even if the axis of the hole is bent, and the amount of irradiation light is reduced. A change in the peak position can be accurately detected.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of a measuring apparatus according to the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same members are given the same numbers or reference numerals.
[0011]
FIG. 1 is a sectional view showing the concept of a measuring device for measuring holes formed in a work according to the present invention. As shown in FIG. 1, the measuring device 10 includes a holding table 12 for holding a work W, a ball 14 having a diameter slightly smaller than the inside diameter of a hole WA formed in the work W, and a tip portion penetrating the core of the ball 14. An optical fiber 18 fixed to the ball 14, a collimating lens 19 attached to the top of the ball 14 and facing the tip of the optical fiber 18, a light receiving unit 22 disposed above the collimating lens 19, and the other end of the optical fiber 18 , A resilient member 16 having a ball 14 fixed to the tip, an elevating means 26 connected to the other end of the resilient member 16 for vertically moving the resilient member 16, the ball 14 and the optical fiber 18, and a pneumatic / electrical conversion. It comprises a vessel 30, a control unit 40, and the like.
[0012]
As the ball 14, a steel ball having good sphericity is used, and a hole penetrating the core is formed in the ball 14, and the tip of the optical fiber 18 is inserted into this hole and fixed with an adhesive. A collimator lens 19 is attached to the top of the ball 14. The elastic member 16 whose tip is fixed to the ball 14 and supports the ball 14 is a hollow straw-like elastic body, and an optical fiber 18 is inserted into the hollow.
[0013]
The elevating means 26 includes a known linear guide, a ball screw, a stepping motor, and the like, and is controlled by the control unit 40 to move the elastic member 16, the ball 14, and the optical fiber 18 up and down.
[0014]
The holding table 12 is formed with an ejection port 12A for ejecting air toward the hole WA of the workpiece W to be measured, and an air supply port 12B communicating with the ejection port 12A. Compressed air is supplied to the air supply port 12B via the pneumatic / electrical converter 30, and the supplied air is injected from the injection port 12A toward the hole WA of the work W.
[0015]
An air / electric converter 30 (hereinafter, referred to as an A / E converter 30) is a device that converts a change in back pressure of supplied air into an electric signal using a bellows and a differential transformer, and converts the converted electric signal. Is sent to the control unit 40.
[0016]
The light projected from the light source 20 is conveyed through the optical fiber 18, converted into a parallel light by the collimating lens 19, and radiated to the light receiving unit 22. A CCD is used as the light receiving section 22 so that the peak position of the irradiation light amount is detected. Alternatively, the peak position of the irradiation light amount is calculated by the control unit 40 using a four-division photocell without using the CCD. A laser or a halogen lamp is used as a light source, and the collimated light is emitted.
[0017]
The injection port 12 </ b> A formed in the holding table 12 is a through hole, and the elastic member 16 supporting the ball 14 is inserted therethrough. A sealing material 29 is attached to the lower end of the injection port 12A to prevent air from leaking from a gap between the elastic member 16 and the injection port 12A. A seal member 28 is also attached to the upper surface of the holding table 12 to seal a gap between the work W and the upper surface of the holding table 12 when the work W is pressed and fixed to the holding table 12 by pressing means (not shown). .
[0018]
The control unit 40 controls the operation of each unit of the measuring device 10 and also performs arithmetic processing on the signal from the A / E converter 30 and the signal from the light receiving unit 22 to obtain a measured value.
[0019]
Next, the operation of the measuring device 10 thus configured will be described. First, a work W to be measured is placed on the holding table 12. At this time, the space between the lower surface of the work W and the upper surface of the holding table 12 is sealed with the sealant 28. Next, the ball 14 is raised by the lifting means 26 and inserted into the hole WA of the work W, and is positioned at a predetermined position. Next, compressed air is supplied from the air supply port 12B of the holding table 12 via the A / E converter 30, and is injected from the ejection port 12A into the hole WA of the work W. The supplied air is discharged upward through a gap formed by the hole WA and the ball 14. At this time, the ball 14 supported by the elastic member 16 is only cantilevered by the elastic member 16, and is automatically centered on the center of the hole WA by the action of the air flowing through the gap.
[0020]
In the A / E converter 30, a change in back pressure caused by the size of the gap formed between the hole WA and the ball 14 is converted into an electric signal and sent to the control unit 40. The control unit 40 calculates the inner diameter of the hole WA of the work W from the signal from the A / E converter 30. Prior to the measurement, the magnification of the A / E converter 30 is calibrated using two types of masters whose exact inside diameters of the holes are known.
[0021]
Next, the ball 14 is moved by the elevating means 26, the inner diameter of the hole WA at a plurality of positions is measured, and a simple cylindricity of the hole WA is obtained. The light emitted from the light source 20 travels through the optical fiber 18, is collimated by the collimating lens 19, is irradiated on the light receiving unit 22, and is received by the light receiving unit 22.
[0022]
Since the light receiving section 22 is constituted by a CCD or a four-divided photocell, a peak position A of the irradiation light amount as shown in FIG. 2 is obtained. FIG. 3 shows a state in which irradiation light is irradiated when the four-divided photocell 22 </ b> A is used as the light receiving unit 22. In this case, the peak position A of the irradiation light amount is calculated from the output distribution of each of the four photocells. That is, the center of the circle having the area ratio corresponding to the ratio of the output value of each photocell is obtained as the peak position A of the reflected light amount.
[0023]
As described above, by utilizing the automatic centripetal action of the air of the ball 14 and moving the ball 14 in the longitudinal direction of the hole WA of the workpiece W to obtain the displacement of the peak position A of the irradiation light amount, the straightness of the hole WA is obtained. The degree is calculated. The straightness component of the hole WA is calculated from the straightness data when the ball 14 is moved in the longitudinal direction of the hole WA and the inner diameter data of the hole WA by the A / E converter 30 at each position in the longitudinal direction of the hole WA. Is required. These measurement values are all calculated and obtained by the control unit 40.
[0024]
Next, a modified example of the embodiment according to the present invention will be described. When the hole WA of the work W is bent, the ball 14 is slightly inclined because the ball 14 is automatically centered while being supported by the elastic member 16 in a cantilever manner. When the ball 14 is slightly tilted, the direction of irradiation of the light from the optical fiber 18 is tilted, and the peak position of the irradiation light amount on the light receiving unit 22 is slightly shifted, so that a slight error occurs in the straightness measurement. For this reason, there is a modified example as shown in FIG. 4 for measuring straightness with higher accuracy.
[0025]
FIG. 4 shows a case where a parallel spring composed of three piano wires arranged at equal intervals on a circumference around the optical fiber 18 and parallel to each other is used as the elastic member 16. . Since the elastic member 16 holding the ball 14 forms a parallel spring with three piano wires, as shown in FIG. 4, even if the hole WA of the work W is bent, the ball 14 may be inclined. Therefore, no error occurs in the detection of the peak position of the irradiation light amount on the light receiving section 22. In FIG. 4, the illustration of the A / E converter 30, the light source 20, and the control unit 40 is omitted.
[0026]
In the above embodiment according to the present invention described, but using compressed air for automatic centripetal action of internal diameter measurement and the ball 14 to be measured hole WA, not limited thereto, N ₂ gas or Ar gas or the like, It can be selected as appropriate.
[0027]
Also, a collimating lens 19 is provided at the top of the ball 14 to make the light emitted from the optical fiber 18 a parallel light, but a lens is formed at the fiber tip without providing the collimating lens 19 as a separate component. An optical fiber 18 with a lens may be used.
[0028]
【The invention's effect】
As described above, according to the measuring device for measuring the hole of the present invention, the inner diameter of the hole is measured by detecting the change in the back pressure of the gas due to the size of the gap between the hole and the ball inserted into the hole. When the ball moves along the hole, the straightness of the hole is determined from the displacement of the peak position of the amount of light emitted from the optical fiber attached to the ball by using the automatic centripetal action between the hole and the ball due to the gas flow. Since the measurement is made and the cylindricity of the hole is calculated from both the measurement data, an inexpensive hole measuring device capable of measuring the inside diameter, straightness, and cylindricity of the hole without contact is obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a hole measuring device according to an embodiment of the present invention. FIG. 2 is a graph illustrating an irradiation light amount in a light receiving unit. FIG. 3 is a plan view illustrating irradiation light on a four-divided photocell. FIG. 4 is a cross-sectional view of a measurement when a parallel spring is used as an elastic member.
DESCRIPTION OF SYMBOLS 10 ... Measuring device, 12 ... Holder, 12A ... Injection port, 14 ... Ball, 16 ... Elastic member, 16A ... Parallel spring, 18 ... Optical fiber, 19 ... Collimating lens, 20 ... Light source, 22 ... Light receiving part, 26 ... Elevating means, 28, 29 ... sealing material, 30 ... A / E converter (pneumatic / electrical converter), 40 ... control unit, A ... peak position of light quantity, W ... work, WA ... hole

Claims (3)

In a measuring device for measuring a hole formed in a work,
A holding table provided with an injection port for holding the work and injecting gas into holes formed in the work,
A ball inserted into a hole formed in the work,
An elastic member supporting the ball,
An optical fiber attached to the ball, for conveying and irradiating light emitted from a light source,
A light receiving unit that receives the irradiated light;
Lifting means for moving the elastic member, the ball, and the optical fiber up and down,
Inserting the ball into the hole formed in the work, injecting gas into the hole to automatically center the ball and the hole, and irradiating the light receiving portion when the ball is moved up and down. A measuring device, comprising: a control unit that obtains a change in a peak position of a light amount and thereby obtains the straightness of the hole. In a measuring device for measuring a hole formed in a work,
A holding table provided with an injection port for holding the work and injecting gas into holes formed in the work,
A ball inserted into a hole formed in the work,
An elastic member supporting the ball,
A pneumatic / electrical converter for converting a change in back pressure of the injected gas into an electric signal;
An optical fiber attached to the ball, for conveying and irradiating light emitted from a light source,
A light receiving unit that receives the irradiated light;
Lifting means for moving the elastic member, the ball, and the optical fiber up and down,
The ball is inserted into a hole formed in the work, and gas is injected into the hole to automatically center the ball and the hole, and when the ball is moved up and down, And a control unit for obtaining the cylindricity of the hole from the signal of the light receiving unit and the change data of the peak position of the irradiation light amount received by the light receiving unit. The measuring device according to claim 1, wherein the elastic member is a parallel spring including at least three linear elastic bodies.

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