JP2595323Y2 - Shape measuring instrument - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shape measuring instrument for measuring a shape, and more particularly to a measuring instrument having a structure which can be used for a non-contact shape measuring probe, can measure at high speed and with high accuracy, and is relatively resistant to disturbance. For this reason, it is used in the mass production measurement department of electrical parts and mechanical elements, and is also widely used for measurement of general shapes.

[0002]

2. Description of the Related Art Conventionally, probes used for measuring a planar shape or a straight shape are roughly classified into a contact type using a stylus and a non-contact type for measuring without contacting an object to be measured. In any case, there are few things that can measure the line shape or the surface shape instantaneously. Although it is slightly discontinuous measurement, it is called a span gauge that measures point length measuring instruments arranged at equal intervals in a line, and optical interference using optical flat which is limited to optical and flat There is a measurement in.

FIG. 7 shows an example of a contact type span gauge. This is achieved by arranging dial gauges 105, 106, 107, 108, and 109 on a measuring plate 104 supported by three fulcrums 101, 102, and 103 at predetermined intervals on a straight line. 106, 10
7, 108, 109 stylus 115, 116, 117, 1
18 and 119 are brought into contact with each other, and five points at relative positions are measured by the respective dial gauges 105, 106, 107, 108 and 109.

FIG. 8 shows an example using an optical flat. When a transparent optical flat 202 having an excellent planar shape is placed on the DUT 201 and irradiated with light of a single wavelength,
Interference fringes occur depending on the distance between the transparent optical flat 202 and the object 201 to be measured. The interval between the interference fringes corresponds to the wavelength of the light to be irradiated, and by counting the number of interference fringes or grasping the arrangement pattern of the interference fringes, the DUT 201
Is to measure the surface shape.

[0005]

However, the above measuring instrument has the following problems. With a span gauge, the dial gauge has a certain size, and cannot be measured below the width of the dial gauge, and cannot be measured unless the pitch is usually about 20 mm or more, and can be measured only intermittently.

In the span gauge, an error occurs when the dial gauge is carried, an impact occurs when the dial gauge comes into contact with an object to be measured, an error occurs due to contact friction between the object to be measured and the dial gauge, and slip displacement. On the other hand, since the optical flat has a measurement range of about 1/4 to about 10 times the wavelength of light, it cannot be measured on an object to be measured having a large dynamic range (high / low width).

On the other hand, the optical flat enables measurement of only the object to be measured which reflects light. Furthermore, a curved surface cannot be measured with an optical flat.

[0008]

In view of the above-mentioned problems, the present invention provides a multipoint heater module provided with a number of heaters inside a slit that opens in a predetermined linear shape.
Injecting air from the slit toward the object to be measured and impulse heating each heater, and measuring a resistance value of each heater cooled according to a distance from the object after a predetermined time. Thus, a shape measuring instrument configured to measure the shape of the object to be measured close to the opening of the slit in a line shape.

In addition, the above-mentioned predetermined linear shape may be defined as a straight line, an inner circumference of the inner cylinder measurement surface, an outer circumference of the outer cylinder measurement surface, and a straight line orthogonal to the orthogonal measurement plane at a predetermined angle. It may be on a straight line intersecting the measurement plane, on a free curve, or on a function curve such as a parabola. Further, in order to enable three-dimensional measurement of the object to be measured, a plurality of slits that open in a predetermined linear shape are arranged side by side in a direction perpendicular to the line, and inside these slits, a multipoint with a large number of heaters is provided. A heater module is provided, air is blown out from the slit toward the object to be measured, and each heater is impulse-heated, and after a predetermined time, the resistance indicated by each heater is cooled according to the distance from the object to be measured. By measuring the values, a shape measuring instrument was configured to three-dimensionally measure the shape of the measured object close to the opening of each slit.

[0010]

According to the present invention, from the opening of the slit to the object to be measured, the heater cooled by the air jetted from the slit toward the object to be measured is subjected to impulse heating and the resistance value of the heater after a predetermined time is measured. Are sequentially measured, and the shape of the object to be measured approaching the opening of the slit is grasped linearly.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on embodiments shown in the accompanying drawings. In FIG. 1, the air supply holes 1 are formed in the longitudinal direction along the lower surface of the alumina ceramic upper member 2 and the upper surface of the alumina ceramic lower member 3 whose shape is hardly changed even when the temperature of the rectangular parallelepiped rises. A side member 4 made of alumina ceramic is fixed to side surfaces of the upper member 2 and the lower member 3 with mounting bolts 5.

Further, a slit 11 is formed between the lower surface of the upper member 2 and the upper surface of the lower member 3 and between the inner surface of the side member 4 and the inner surface of the lower member 3 to form a fixed gap stop. I have. When air controlled at a constant pressure is supplied to the air supply hole 1,
It is set so that a uniform air flow rate can be obtained with no load.

Inside the side member 4 facing the slit 11 of the lower member 3, a line type thermal transfer heater module 1 is provided.
2 are arranged. After cooling the line-type thermal transfer heater module 12 in contact with the slit 11 at a uniform air flow rate in the slit 11, the air is blown downward. When the blown air is applied to the object 13, the flow rate pattern corresponding to the shape changes.

This line type thermal transfer heater module 12
In the example, the heater is manufactured by dividing the heater into eight blocks of 216 heaters each having a pitch of 0.125 mm × 1728 and a length of 216 mm. The line type thermal transfer heater module 12 is used for a facsimile or the like. A heating time of 0.5 msec was applied to the line type thermal transfer heater module 12 at an applied voltage of 24 volts.
The resistance value after a lapse of sec was measured by passing a small constant current of about 1 mA to the heater.

By measuring the resistance value of the heater when about 100 msec has elapsed after the heating, the flow rate of air as a medium for cooling the heater can be grasped. According to the embodiment, the total flow rate in a state where there is nothing in front of the slit 11 is 3.65 l / min, and when the measured object 13 is 0.2 mm before the all slits 11, 2.77 l / min. 0.
At 1 mm, it was 1.38 l / min. At this time, the average resistance of all heaters is 321 Ω, 0.2 m
The value was 693Ω when the object 13 was present at m, and 1221Ω when it was 0.1 mm. Table 1 shows this relationship.

[Table 1]

In Table 1, the change of the resistance value after 100 msec from the heating with respect to the approaching distance of the object 13 is a good linear change from 0.1 mm to 0.2 mm. Thus, by measuring the resistance value of each heater, the approach distance of each part of the DUT 13 to the slit 11, that is, the linear shape of the DUT 13 can be measured. In measuring the heater resistance value, a differential (bridge) measurement method is used between the heater and the heater that is not heated at all, and compensation is made for changes in the temperature of the jet air and the slit body.

The differential (bridge) measurement method with the adjacent heater is a method of measuring two elements under the same conditions (temperature, humidity, air flow rate, etc.) and calculating the difference between the two elements. (Subtracted value) is stable against changes in conditions. Conventionally, the circuit (Wheatstone bridge) shown in FIG. 2 has been used as a resistance measuring means, and the galvanometer (G) in the figure has been used.
When the variable resistor (R _S ) is adjusted so that is equal to ZERO, the resistance value (R _X ) can be obtained by the following equation.

[0018]

(Equation 1)

Even in such a circuit, when the temperature coefficients of all the resistors in the figure are the same, each potential (a, b) at the bridge point does not fluctuate with temperature, and the galvanometer No current flows and stable measurement is possible. In recent years, instead of galvanometers, the method of converting the potential at each bridge point into a digital value and subtracting it from the value has been widely adopted.This method is a common-sense method for measuring resistance, voltage, and current. ing.

According to the embodiment, the measuring speed is 0.5
Since 216 pieces are heated and measured in series at a heating time of msec and a measuring time of 0.02 msec, 0.52 ×
One line can be measured in about 0.12 seconds at 216 = 112.32 msec. This is because continuous measurement (fastest) with a conventional straightness measuring device is about 15 seconds,
The measurement speed improved more than twice. As the measurement resolution, 0.1966 mm in Table 1 is 16 bits (6553 mm).
6), 0.00003 mm (0.0
3 μm), and the variation is 2σ = 0.3 μm.
Repeat reproducibility of less than m was obtained, and by performing appropriate correction, the total accuracy was 0.42 μm, which was high measurement accuracy for non-contact measurement.

Instead of the object to be measured, a calibration object whose shape is known in advance is approached, and each element is corrected with the resistance value of each heater at this time, thereby performing high-precision measurement. Also, the shape of the measurement surface having the slit opening is varied, and the measurement relative to the measurement surface, that is, the measurement of the roundness when ejected in the directions of the inner circle and the outer circle is divided into two and the right angle is divided. When arranged at a free angle or at a free angle, it is possible to measure squareness or free angle, and further developed three-dimensionally to measure relative to the measurement surface, that is, to measure flatness if it is a surface shape, whether it is a cylindrical shape For example, measurement of cylindricity, measurement of surface perpendicularity or free surface angle when divided into two, and measurement of surface perpendicularity or free surface angle, and curvature / distortion for free curved surface or function curved surface (aspherical surface, etc.) And so on.

That is, FIG. 3 shows the roundness measurement, and the opening direction of the slit 21 for ejecting air to the cylindrical measuring device 20 in which the cylindrical object 23 is fitted is indicated by an arrow. FIG. 4 shows the cylindricity measurement, and the opening direction of the slit 31 for ejecting air to the cylindrical measuring device 30 in which the cylindrical object 33 is fitted is indicated by an arrow. Further, FIG. 5 shows the perpendicularity measurement, in which the opening direction of the slit 41 for ejecting air to the perpendicular measuring device 40 is indicated by an arrow on the measured object 43 on two intersecting measurement planes.

Further, FIG. 6 shows a flatness measurement, in which a flat measuring instrument 5 arranged on a flat object 53 is measured.
The opening direction of the slit 51 for ejecting air at 0 is indicated by an arrow. In addition, although not shown, a function curve such as a free angle, a free curve, and a parabola, and other angles, a curvature, a distortion, and the like can be measured.

[0024]

As described above, in the present invention, a multipoint heater module provided with a number of heaters is provided inside a slit that opens in a predetermined linear shape, and air is blown out from the slit toward an object to be measured. At the same time, each heater is subjected to impulse heating, and a resistance value of each heater cooled according to a distance from the object to be measured after a predetermined period of time is measured, so that the object to be measured close to the opening of the slit is measured. Since the shape is measured in a line, the shape can be measured continuously. Further, unlike the conventional span gauge, errors due to impact, contact friction and slip displacement do not occur. Further, the measurement range is not restricted unlike the measurement by the optical flat. Various objects to be measured can be measured.

In addition, the above-mentioned predetermined linear shape means not only a straight line but also an intersection at a predetermined angle on the inner circumference of the inner cylinder measurement surface, on the outer circumference of the outer cylinder measurement surface, on the orthogonal straight line of the orthogonal measurement plane. The measurement can be performed on a straight line that intersects with the measurement plane, on a free curve, or on a function curve such as a parabola. Further, as described above, the present invention arranges a plurality of slits opening in a predetermined linear shape in a direction perpendicular to this line, and provides a multi-point heater module provided with a large number of heaters inside these slits, By blowing air toward the object to be measured from the slit and impulse heating each heater, and measuring the resistance value of each heater cooled according to the distance from the object after a predetermined time. Since the shape measuring instrument is configured to three-dimensionally grasp the shape of the object to be measured close to the opening of each slit, the object to be measured can be three-dimensionally measured.

[Brief description of the drawings]

FIG. 1 is a front view and a sectional view of a shape measuring instrument according to a specific embodiment of the present invention.

FIG. 2 is a Wheatstone bridge circuit diagram.

FIG. 3 is a perspective view showing a measuring device for measuring roundness.

FIG. 4 is a perspective view showing a measuring device for measuring cylindricity;

FIG. 5 is a perspective view showing a measuring device for measuring a squareness.

FIG. 6 is a perspective view showing a measuring instrument for measuring flatness.

FIG. 7 is a diagram showing two front and side surfaces of a conventional spange.

FIG. 8 is a perspective view showing a state in which a plan view is measured using a conventional optical flat.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Air supply hole 2 ... Upper member 3 ... Lower member 4 ... Side member 11
21 · 31 · 41 · 51 · · · slit 12 · line type thermal transfer heater module 13 · 23 · 33 · 43 · 53 · DUT

Claims (2)

(57) [Scope of request for utility model registration] 1. A multipoint heater module provided with a large number of heaters inside a slit that opens in a predetermined linear shape,
Injecting air from the slit toward the object to be measured and impulse heating each heater, and measuring a resistance value of each heater cooled according to a distance from the object after a predetermined time. A shape measuring instrument configured to measure a shape of an object to be measured close to an opening of a slit in a line. 2. A multi-point heater module having a large number of heaters is provided inside a plurality of slits opening in a predetermined linear shape in a direction perpendicular to the line. By blowing air toward the heater and impulse heating each heater and measuring the resistance value of each heater cooled according to the distance from the object to be measured after a predetermined time, the opening of each slit is measured. A shape measuring device configured to measure the shape of an object to be measured close to the object.