JPS5870101A - Measuring device for radius of curvature - Google Patents

Abstract

PURPOSE:To obtain a measuring device which measures the radii of curvature of the arcs orcircles of the raceway tracks, etc. of ball bearings accurately and quickly by combining a measuring contactor of a 3-point type, a lever operated electric micrometer which detects the extent of the movement of a measuring stylus, etc. CONSTITUTION:Two steel balls 1 are fixed to the bottom surface of a 3-point type measuring contactor 4, and the stylus 6 of a lever operated electric micrometer head 5 is in abutment on the top end of a measuring stylus 3 at the center between the balls 1. The extent of moving in and out of the stylus 3 is detected with the stylus 6 of the electric micrometer head or the like and is displayed on an indicator 7 of the electric micrometer. To measure radii of curvature with such measuring device, an object 11 to be measured is placed on a cradle 10, and the stylus 3 is brought into contact with the surface to be measured, then the contactor 4 settles in the stablest measuring state only by the own weight of the part supported by a universal joint 8. The operator is simply required to read the value with respect to a master gage from the indicator 7 of the electric micrometer, and to determine the curvature by the equation or to calculate the curvature by inputting the output of the indicator 7 directly to a computer.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a measuring device that accurately and quickly measures the radius of curvature of an arc or circle such as a ball bearing orbit.

Conventionally, rotary shape measuring instruments such as micrometers have been generally used to measure the radius of curvature of circles, arc shapes, etc. With such a rotary measuring device, the rotation radius of the measuring needle matches the radius of curvature of the foot surface to be measured, and the center of rotation of the measuring needle, that is, the rotation center position of the reference rotating spindle, is set to the curvature of the foot surface to be measured. I had to do some work to match the center position. In other words, while rotating the reference rotating spindle, the centering and rotation radius adjustments are repeated repeatedly while increasing the measurement magnification until the relative displacement between the measuring needle and the foot surface to be measured reaches the desired accuracy. When a match is reached, the radius of curvature of the foot surface to be measured is measured, but the work is extremely complicated and time-consuming, and requires skill. Also, depending on what kind of shape is traced, individual differences in the measurer will affect the measurement result.In particular, since the orbit of a ball bearing covers about ten arcs of a circle, the measured value force may vary depending on the adjustment of the sighting radius. ``Significant change.

do. Furthermore, the reproducibility is poor when the same point is measured again by the same person, and when we actually investigated the repeat measurement error when using a Talyrond using a ball bearing outer ring with a radius of curvature of about 4, we found that the measured value The standard deviation value of is 1.5~8P
It was found that there was a large variation.

In order to solve these problems, there have been no attempts in recent years to automate the centering and radius alignment work by processing the output voltage from measurement entirely electrically; This is possible only if the relative displacement of the surface falls within a very narrow range of the measuring device's detection range, and manual centering must still be performed before it falls within that range.

In addition, conventional methods require complex mechanical devices and electrical circuits, making them expensive! Another drawback was that it could only be operated by an experienced person.

In addition, for example, if the outer ring of a ball bearing has a large flange on the outer periphery, or if the raceway is located deep from the end surface, the rotating stylus may interfere with the flange or end surface of the object to be measured. This makes measurement impossible. One possible solution to this problem would be to manufacture a special stylus that is long and curved so as not to interfere with the surroundings, but this would cause the stylus to run out, making highly accurate measurements difficult.

The present invention was made in order to solve such conventional problems, and has two fixed steel balls that smoothly move in and out at the center in a direction perpendicular to a straight line connecting the centers of the steel balls. It has a three-point measuring element with a measuring needle arranged on it, and a measuring tool equipped with a stylus metal such as a lever-set electric micrometer that detects the amount of movement of the measuring needle, and these are held in a universal joint. A simple calculation can be made from the amount of movement of the measuring needle into and out of the master gauge when the object to be measured is placed on a pedestal that is fixed to the main body of the device along with the other end of the universal joint, and the measuring point is brought into contact with the measuring surface. The present invention relates to a device for measuring the radius of curvature of circles, arcs, etc., which determines the radius of curvature of a measurement surface.

Next, the principle of measuring the radius of curvature of a circle or arc of an object to be measured according to the present invention will be explained.

As shown in Figure 1, two circles of diameter are brought into contact with an arc of radius R, the center distance between the circles is 24, and the tangents of the two circles and the tangent to the arc parallel to these tangents are If the smaller distance is '6h, then (1) or (1) equation i for the distance, 2h.
Solving for R yields equation (11).

h $2 D ””2+8h”2 ・・・・・・・・・・・・・・・
(if) FIG. 2 shows an application of the above principle to a detection section. In Figure 2, two diameter balls (1) are fixed to a plate (2) etc. at a distance of I, and two balls (11
A three-point measuring tip (3) is constructed by arranging a measuring needle (3) that smoothly moves in and out in a direction perpendicular to the tangents of the two spheres at the center of a plane passing through the center of the ball. The amount of protrusion of the measuring needle (3) with respect to the ball (1) when the measuring needle (3) of this measuring element (4) and the two balls (1) are brought into perpendicular contact with a circle or arc with a radius of curvature R ht! It is determined by equation (1).

In the case of a circle or arc with a radius of curvature R + ΔR, the amount of protrusion or △
If h changes, equation (iii) holds true.

Note that even if the surface to be measured is a convex surface, the above-mentioned series of equations hold true, and R takes a negative value.

FIG. 3 shows an embodiment of the measuring device of the present invention. 3
Two steel balls (1) are fixed to the downward direction of the point type measuring head (4), and a lever-equipped electric micrometer head (5) is attached to the upper end of the measuring needle (3) in the center between the steel balls (1). The stylus (cut) contacts the measuring needle (3), and the amount of inflow and outflow of the measuring needle (3) is detected by the stylus (6) of the electric micrometer head, etc., and is displayed on the indicator (7) of the electric micrometer. 3 points A measuring tool consisting of a type measuring head (4) and an electric micrometer head (5) equipped with a stylus (6) that detects the amount of movement of the measuring needle (3) is attached to one end of the universal joint (8). Mounted and universal (8)
The other end of is attached to the main body (9).

The main body (9) K is also attached with a v or planar pedestal α0, so that the object to be measured C11 is placed on the pedestal αQ.

To measure the radius of curvature with the measuring device of the present invention, first
Place a master gauge (not shown) whose radius of curvature is known in advance on top of the ball, place the 3-point probe (4) on top of the ball ( 1) Set the detection amount of the indicator of the lever set electric micrometer in measuring the protrusion from the tangent line to zero cents. Next, place the object to be measured Q1t'' on the pedestal α1, and place the measuring needle (3
) is brought into contact with the measuring surface, the three-point measuring head (4) will settle into the most stable foot measuring state/condition with only the weight of the part supported by the universal joint (8).

Then, read the value △hl for the master gauge from the electric micrometer indicator (7) and calculate the curvature using formula (iii), or input the output of the indicator (7) directly into a computer to calculate the curvature. .

According to the present invention, the amount of movement of the measuring needle (3) is detected by a stylus (6) such as an electric micrometer of a set of levers. It becomes possible to measure the inner surface of a certain ball bearing outer ring raceway, etc., and if the raceway is located further back, the neck of the measuring point (4) can be made longer.Movement of the measuring needle (3) The stylus (6) for detecting the amount can be used with a small tester other than the stylus of a lever-equipped electric micrometer, or by using a lever to detect the displacement of the measuring needle (3) in the linear direction after bending it 90°3. Also, for large-diameter bearings where the surface to be measured is in the outer cylinder, such as the outer ring or inner ring, there is sufficient space in the direction of the center of curvature of the surface to be measured, so use the measuring needle (3).
It is also possible to detect the moving lid directly with a dial cage or the like.

Further, in the present invention, since the measuring element (4) is held by the universal joint (8), the following effects can be achieved.

1) Since measurement is possible using only the weight of the part supported by the universal joint, the amount of elastic deformation due to the measurement load of the ball (1) at the tip of the probe is constant, and the measurement conditions are the same, so the amount of elastic deformation due to the measurement load is No measurement errors occur.

2) Also, the 3-point measuring head (4) is connected to the YY axis of the universal joint and 22
Since it moves on a spherical surface centered on the intersection point n'2 of the axes, stable measurement conditions can be maintained without lateral deterioration even on a horse-branch-shaped curved surface such as the inner raceway of a ball bearing.

3) Furthermore, by holding the object to be measured with a block-shaped pedestal, together with the universal joint (8), the repeatability of the measured value is good, and according to experiments, it is within 0.3 μm. In addition, when measuring a large number of objects in succession, the time required for each object conventionally took 10 to 15 minutes, but according to the present invention, it can be measured in about 5 seconds, allowing continuous measurement of the radius of curvature on a line. becomes possible.

Furthermore, as shown in Fig. 4, if the three-point measuring head (4) and the object to be measured (11) are structured to be able to swing and rotate relative to each other about approximately the center of curvature of the object to be measured α~, the shape of the scrap n will be reduced. Not only can it be detected, but it also has the effect of easily measuring the radius of curvature of a track in an inclined position, such as in an angular contact ball bearing.

Even if the center of curvature of the object to be measured (lI) and the center of oscillating rotation (0) are slightly misaligned, the three-point measuring head (4) is supported by the universal joint, so it can sufficiently follow the displacement. Since the contact portion of the probe (4) with the object to be measured is a spherical surface, good sliding can be obtained and a stable measurement state can be maintained.

As described above, compared to the conventional method in which the radius of curvature can be measured by repeatedly fine-tuning the rotation radius and center of rotation of the stylus, the present invention requires skill in a very short period of time and reduces individual differences. It becomes possible to measure the radius of curvature with high precision, including the shape, without the need for

[Brief explanation of the drawing]

Fig. 1 is a detailed explanatory diagram of the present invention, Figs. 2 and 4 are explanatory diagrams of the principle of the present invention applied to a detection section, and Fig. 3 is a partially cutaway perspective view of an embodiment of the present invention. It is a diagram. (1)...Steel ball (3)...Measuring needle (4)
...Three-point probe (6)...Stylus (8)...
Universal joint (9)...Main body Ql), cradle 91...Patent attorney representing the object to be measured Kawachi
Junji! PJ1 dormitory 2 days ¥3 figure

Claims (1)

[Claims] A three-point measuring head is provided with a measuring needle that can freely move in and out in a direction perpendicular to a line connecting the centers of both steel balls at the center of the interval between two fixed steel balls, and the other end of the measuring needle is in contact with the measuring needle. A measuring tool having a stylus for detecting the amount of movement of the measuring needle is fixed to the other end of a universal joint whose one end is fixed to the main body, and the measurement device is placed on a pedestal for placing the object to be measured which is fixed to the main body. A device for measuring the radius of curvature of an arc or circle, characterized by having needles placed opposite each other.