JPH052004U - Inner diameter measuring instrument - Google Patents

Abstract

(57) [Summary] [Structure] At least two locations on the outer circumference of the inner diameter guide 12 are provided with air nozzles 17 for ejecting pressurized air to align the inner diameter guide 12 with the hole to be measured. [Effect] When the inner diameter guide 12 is eccentric with respect to the hole to be measured, a pressure is generated between the pressurized air ejected from one air nozzle 17 and the pressurized air ejected from another air nozzle 17. Because of the difference, the inner diameter guide 12 is centered by this pressure difference. Further, the flow of the pressurized air ejected from each air nozzle 17 forms an air flow layer between the circumference of the inner diameter guide 12 and the hole to be measured, so that this air flow layer acts as an air bearing. The inner diameter guide 12 can be easily inserted, and the inner diameter guide 12 can be stabilized. Therefore, it is possible to prevent the measurement error due to the eccentricity and the looseness of the inner diameter guide 12, and to improve the accuracy of the measured value as much as possible.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to an inner diameter measuring device, and more particularly to an inner diameter measuring device for measuring the inner diameter of an annular body such as a bearing race.

[0002]

[Prior Art]

 As shown in FIG. 4, an inner diameter measuring instrument 50 of this type is generally provided with an inner diameter guide 51 having a circular cross section to be inserted into the hole H to be measured and an outer periphery of the inner diameter guide 51 so as to be capable of expanding and contracting. A pair of gauge heads 52 facing each other in the diameter direction of the inner diameter guide 51 are provided. In order to provide a clearance C for facilitating insertion into the hole H, the diameter of the inner diameter guide 51 is set to be smaller than the inner diameter of the hole H by about several tens of microns. Although not specifically shown, inside the inner diameter guide 51, a coil spring for urging each of the measuring elements 52 outward in the radial direction of the inner diameter guide 51 and an amount of displacement of each of the measuring elements 52 are electrically connected. It has a built-in operating transformer for converting to output. Then, when measuring the diameter d of the hole H, the inner diameter guide 51 is inserted into the hole H to bring the respective measuring elements 52 into contact with the inner wall of the hole H, and the respective measuring elements 52 are displaced. The diameter of the hole H was measured based on the obtained output voltage of the working transformer.

[0003]

[Problems to be solved by the device]

 As described above, in the conventional structure, since the tracing stylus 52 is in contact with the inner diameter, the eccentricity of the tracing stylus 52 is suppressed in the direction in which the tracing stylus 52 expands and contracts. However, in the direction orthogonal to the direction in which the tracing stylus 52 expands and contracts, there is no member that performs any centering action, so there is backlash between the inner diameter guide 51 and the hole H by the radial clearance C, and measurement error occurs. There was a problem that it became easy to occur.

In particular, as shown in FIG. 4, when the inner diameter is measured with the inner diameter guide 51 along one inner peripheral surface of the hole H, as is apparent from FIG.

[0005]

[Equation 1]

Dm: measured value dr: true diameter of the hole H ε: deviation between the true diameter dr and the measuring position Δr: difference between the radius of the measured value dm and the true radius, and the measured value dm is calculated from the above equation. However, there is a problem in that the accuracy is reduced by 2 × Δr compared to the true diameter dr.

The present invention has been made in view of the above problems, and an object thereof is to provide an inner diameter measuring instrument capable of improving measurement accuracy as much as possible.

[0008]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, the inner diameter measuring device of the present invention has an inner diameter guide having a circular cross section to be inserted into a hole to be measured and an outer circumference of the inner diameter guide so as to extend and contract in the diameter direction of the inner diameter guide. In the inner diameter measuring instrument equipped with a pair of measuring elements protruding in this state, pressurized air is jetted to at least two locations on the outer circumference of the inner diameter guide to align the inner diameter guide with the hole to be measured. It is characterized by having an air nozzle.

[0009]

[Action]

 According to the inner diameter measuring device having the above configuration, when the inner diameter guide is inserted into the hole to be measured while the pressurized air is ejected from each air nozzle, when the inner diameter guide is eccentric to the hole to be measured. Causes a pressure difference between the pressurized air ejected from one air nozzle and the pressurized air ejected from another air nozzle, the inner diameter guide ejects from all air nozzles due to this pressure difference. The pressure of the generated compressed air moves in a balanced manner and stops at a position concentric with the hole to be measured, so that the inner diameter guide can be aligned with the hole to be measured.

Further, since a layer of air flow is formed between the inner diameter guide and the hole to be measured by the flow of the pressurized air ejected from each air nozzle, this layer of air flow serves as an air bearing. It works, and the inner diameter guide can be easily inserted.

[0011]

【Example】

 Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. In FIG. 1, which is a perspective view of an inner diameter measuring device 10 according to an embodiment of the present invention, a flange 11a is integrally formed in a portion of the apparatus body 11 near the tip of the intermediate portion, and a portion from the flange 11a to the tip is formed. The inner diameter guide 12 has a circular cross section. The inner diameter guide 12 is about several tens of microns larger than the inner diameter of the hole H in order to provide a clearance C as the hole to be measured H for facilitating insertion into the inner circumference of the ring R (see FIG. 2). It has a small diameter. On the outer circumference of the inner diameter guide 12, a pair of measuring elements 13 are provided so as to extend and contract in the diameter direction of the inner diameter guide 12. Although not specifically shown, inside the inner diameter guide 12, coil springs for urging each of the measuring elements 13 outward in the radial direction of the inner diameter guide 12 are provided inside the inner diameter guide 12, as in the conventional electric micrometer. An operating transformer and the like for converting the amount of displacement of the probe 13 into an electrical output are contained. The operation transformer is electrically connected to a micrometer amplifier 15 via a wiring 14 that passes through the inside of the apparatus body 11. The micrometer amplifier 15 is for displaying the inner diameter of the hole H (see FIG. 2) on the basis of the output voltage of the operating transformer obtained by the displacement of each probe 13.

Further, two pairs of air nozzles 17 are provided on the outer circumference of the inner diameter guide 12 so as to face each other in a direction orthogonal to the direction in which each of the measuring heads 13 faces. Each air nozzle 17 is for ejecting pressurized air of a constant pressure supplied from an air pump 19 as a pressurized air supply source through a pipe 18 passing through the inside of the apparatus body 11. Next, the operation of the inner diameter measuring device 10 will be described with reference to FIG.

As shown in the drawing, when the inner diameter guide 12 is inserted into the hole H with the pressurized air ejected from each air nozzle 17, when the inner diameter guide 12 is eccentric with respect to the hole H, Since a pressure difference is generated between the pressurized air ejected from one air nozzle 17 and the pressurized air ejected from another air nozzle 17, the inner diameter guide 12 causes all the air nozzles 17 to be affected by this pressure difference. It moves so that the pressure of the pressurized air ejected from the machine is balanced. Here, since the pressurized air of the same pressure is ejected from each air nozzle 17, the inner diameter guide 12 stands still at a position concentric with the hole H, and as a result, the inner diameter guide 12 is aligned with the hole H. can do.

Further, the flow of the pressurized air ejected from each air nozzle 17 forms an air flow layer between the periphery of the inner diameter guide 12 and the hole H, so that this air flow layer is used for air bearing. As a result, it becomes easier to insert the inner diameter guide 12, and the inner diameter guide 12 can be stabilized. Therefore, it is possible to prevent the measurement error due to the eccentricity of the inner diameter guide 12 and the backlash, and to improve the accuracy of the measured value as much as possible.

FIG. 3 shows an embodiment in which the air nozzles 17 are provided at three locations at intervals of 120 degrees in the circumferential direction. Even when the embodiment of FIG. 3 is adopted, it is possible to obtain the same effect as that of the embodiment described with reference to FIGS. It is needless to say that the above-described embodiments are merely preferable specific examples of the present invention and various design changes can be made without changing the gist of the present invention.

[0016]

[Effect of the device]

 As described above, according to the inner diameter measuring device of the present invention, when the inner diameter guide is inserted into the hole to be measured while the pressurized air is ejected from each air nozzle, the inner diameter guide is inserted into the hole to be measured. When it is eccentric, a pressure difference is generated between the pressurized air ejected from one air nozzle and the pressurized air ejected from another air nozzle. The pressure of the pressurized air ejected from the air nozzle moves equilibrium and stops at the position where it becomes concentric with the hole to be measured, and as a result, the inner diameter guide can be aligned with the hole to be measured.

Further, since a layer of air flow is formed between the inner diameter guide and the hole to be measured by the flow of the pressurized air ejected from each air nozzle, this layer of air flow serves as an air bearing. This makes it easier to insert the inner diameter guide and stabilizes the inner diameter guide. Therefore, according to the present invention, the eccentricity and play of the inner diameter guide can be eliminated, and the measurement accuracy can be improved as much as possible.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

2 is a schematic cross-sectional view of an inner diameter guide and a ring in the embodiment of FIG.

FIG. 3 is a schematic cross-sectional view of an inner diameter guide and a ring in another embodiment.

FIG. 4 is a cross-sectional view of a conventional inner diameter measuring device.

5 is an enlarged schematic view of an essential part of FIG. 4. FIG.

[Explanation of symbols]

 10 Inner Diameter Measuring Instrument 12 Inner Diameter Guide 13 Air Nozzle 17 Stylus C Clearance H Measured Hole

Claims (1)

[Claims for utility model registration] [Claim 1] The inner diameter guide having a circular cross-section inserted into the hole to be measured and the outer circumference of the inner diameter guide in a state of being opposed to each other so as to be expandable and contractible in the diameter direction of the inner diameter guide. In an inner diameter measuring instrument having a pair of protruding measuring elements, air nozzles for ejecting pressurized air to align the inner diameter guide with a hole to be measured are provided at at least two locations on the outer circumference of the inner diameter guide. An inner diameter measuring instrument characterized in that