Method of ball bearings contact angle

FIELD: physics, measurement.

SUBSTANCE: invention is related to nondestructive check and may be used for determination of points of ball contact with ball bearing rim and calculation of ball bearing contact angle. Measurements may be performed on assembled ball bearing. Method includes determination of point of ball bearing contact with rim contact surface and estimation of ball bearings contact angle by displacement of contact point from design position. At that contact surface of rim in the field of design point of its contact with ball is radiated with ultrasonic beam, and contact point is determined by minimum value of reflected acoustic signal amplitude.

EFFECT: provision of possibility of direct determination of contact points of ball with ball bearing rim and calculation of angle in it, and determination of size and shape of area of contact of ball with rim.

4 cl, 3 dwg

 

The invention relates to non-destructive testing and can be used to determine the points of contact of the ball with the rim of the bearing and calculation of the contact angle of the bearing, which is an important parameter affecting the quality and durability of the bearing. Measurements can be made on the already assembled bearing.

Angle contact ball bearing is one of the most important parameters of the bearing, as set by its design. The deviation angle contact ball bearing from the calculated values leads to the reduction of the maximum permissible loads on the bearing, reduce its reliability and durability. In addition, when the Assembly of several ball bearings it is essential that they all have the same contact angle. In this case the maximum permissible load of the node is almost equal to the sum of the maximum permissible loads of the individual bearings.

The definition of area of contact of the ball with the rim of the bearing in accordance with the calculated (design) position is extremely important to check the quality of production raceways. This parameter greatly affects the durability of the bearing.

Most known methods for determining the contact angle contact ball bearings are based on the indirect measurement pairs the meters are not reliable, because we have a big error.

For example, a known method for determining the angle of contact of ball bearings. namely, that fix one of the rings of the bearing, and the other sequentially load alternating axial force, the register offset of the loose ring and its axial displacement determine the contact angle. At the same time. to determine the contact angle in angular contact bearings with an incomplete profile of the rings, the first axial loading is performed in the direction of the wide end of the fixed ring, and then fix the position of the rolling bodies (USSR Author's certificate No. 322597, MKI G01b 5/24).

However, this method is characterized by the use for determining the contact angle of indirect data, which reduces the reliability and accuracy of the measurements.

Also known a method of measuring the contact angle of ball bearings than that described what to improve accuracy and productivity in addition to axial register radial offset in alternating radial load (USSR Author's certificate No. 1320687, MKI G01M 13/04 was investigated).

The disadvantage of the described method is that the determination of the contact angle in it is not direct and is based on indirect data.

Besides, there are known a method of measuring the contact angle of ball bearings. different from the previous is, for the measurement of the contact angle of the folding roller bearings, at the time of measuring the radial displacement determines the zero position of the rolling ring. Axial load create in the direction of increasing angle contact ball bearing, measurement of axial displacement is produced from the zero position of the rings (USSR Author's certificate No. 1548682, MKI G01M 13/04 was investigated).

The drawback of this method lies in the fact that it is indirect.

Also known is a method to determine the offset in the axial and radial loading not only the contact angle, and axial and radial clearance (RF Patent No. 2232310, IPC 7F16C 19/38).

The disadvantage of this method, like the previous one, is that it is based on indirect data.

These technologies are designed to determine the quality of the bearing angle contact ball bearing. However, these methods do not allow to determine the exact location of the area of contact of the ball with the rim of the bearing and its shape. The definition of these parameters allows for more reliability to conclude about the quality of the bearing, including characterization of its wear resistance and durability.

Object of the invention is to provide a method for determining the contact angle of ball bearings that allow more reliability to determine the reliability of the bearing.

the technical result consists in the possibility of direct detection of the contact points of the balls with the rim of the bearing and calculation of the contact angle in it. In addition, the proposed method allows to determine the size and shape of the area of contact of the balls with the rim.

The problem is solved in that in the method for determining the angle contact ball bearing, comprising determining the touch point of the ball with the contact surface of the rim and finding angle contact ball bearing according to the displacement of the touch point from the calculated position, according to the decision, the contact surface of the rim in the area of computational point of contact with ball is irradiated with an ultrasonic beam, and the touch point is determined by the minimum value of the amplitude of the reflected acoustic signal. In addition, determine the touch point of the ball with the outer and inner rim of the bearing and the contact angle is determined by the distance between the projections of these points on the image plane. The inner surface of the rim is placed in the focal plane of the focused ultrasonic beam, and determining the touch point is carried out by its point-by-point scanning. Angle contact ball bearing is determined by one of the following formulas:

α=arcsin(C / D)

where α - angle contact ball bearing; - the distance between the projections of the points of contact of the ball with the inner and outer rims on the image plane; α0 - the estimated angle contact ball bearing; Δ - displacement of the projection of the point of contact of the bead with the rim on the image plane; R is the radius of the ball; And the distance from the projection point of contact of the ball with the rim on the image plane to the edge of the rim; And0- estimated distance from the projection point of contact of the ball with the rim on the image plane to the edge of the rim.

The proposed method is as follows.

Rim ball bearing with external parties enter ultrasonic beam and record the amplitude of the signal reflected from various points on its inner surface. In the area of contact of the rim with the ball there is a sharp decrease in the amplitude of the reflected acoustic signal. To obtain an acoustic image of the inner surface of the rim can be used as a focused beam of ultrasound with mechanical or diffraction scan and unfocused beam with a more complex system receivers. At sufficiently high resolution, in which the contact area is more than 10 points of the raster image, it is possible to identify not only the location of the point of contact of the ball with the rim, but the shape of the contact area.

In the first case, the rim of the bearing with external parties through emersion fluid injected focused beam of ultra short is Vukovich pulses, formed so that the inner surface of the rim of the bearing has been in the area caustics. Acoustic lens while alternately operates in the generating and receiving modes. Mechanically moving the bearing, for some set of points to register the signals reflected from the inner side of the rim and build a bitmap image. The contact area of the ball bearing is characterized by a sharp decrease in the amplitude of the reflected signal.

This method of determining the contact point based on the following effect. The acoustic signal is reflected from inhomogeneities and discontinuities, in particular, from the inner surface of the rim of the bearing. In the contact area of the ball tightly against the rim, and the ultrasound passes it, almost no change. An example of the resulting bitmap image is shown in figure 1. Bright white area in the center of the image corresponds to the surface of the track ball, and a dark spot on her background - the area of touch rim and ball bearings. As can be seen from the drawing, the proposed method can effectively determine not only the location of the contact area, but also its shape. To calculate the contact angle for the location of the contact point can be accepted center of the contact area.

Angle contact ball bearing can be determined, n is the sample, for one of the following methods.

1. Identify points of contact of the ball, with both external and internal rim of the bearing. Measure the projection of the ball diameter, connecting the contact point on the image plane (C). The contact angle is determined by the formula:

where D is the diameter of the ball.

2. Measure the projection of the distance from the edge of the rim to the contact point on the image plane (figure 2). The measured distance is compared with a calculated value (A0), and calculate its offset (Δ). Knowing the radius of the ball (R) and the estimated contact angle, compute the projection of the radius conducted in the calculation of the contact point on the image plane (In0):

Knowing the displacement of the contact point from the calculated position, find the projection of the radius, drawn in real estimated contact point on the image plane (C), and calculate the real contact angle (α):

In the case of small displacement position of point of contact from design, you can use the approximate formula

Examples of specific executions.

The claimed method was investigated double-row ball bearing with a diameter of 60 mm, ball diameter 8 mm Two rigidly interconnected acoustic object the Islands were connected to the outer and inner rims of the bearing (see 3). Between the lens and the tyre was placed immersion liquid, the lenses are arranged such that the inner surface of the rim has been in the area caustics acoustic field of the corresponding emitter.

After preparations were scanned area size 5x5 mm is chosen so as to obtain image points of contact of the ball with both rims of the bearing. By comparing the images obtained using the upper and lower lenses, found the distance between the projections of the contact points on the image plane, which amounted to 1.6 mm, the contact Angle was calculated by the first method, which was an amount equal to 11,54°.

In another embodiment, use of the proposed method to the outer rim double row ball bearing, mounted on a micrometric table acoustic microscope, was summed acoustic lens. Calculated a distance from the edge of the rim to the projection of the point of contact of the ball bearing was 10 mm, ball diameter - 8 mm, and the calculated contact angle of 0.1π (18°). Between the lens and the surface of the rim was placed immersion liquid, the lens was positioned so that the inner surface of the rim has been in the area caustics acoustic field.

After preparations were scanned area size is rum 5× 5 mm is chosen so as to obtain the image of the point of contact of the ball to the rim of the bearing. The size of the contact area in figure 1 was an amount equal to about 20×200 μm. By measuring the distance from the edge of the rim to the center its projection was found by an amount equal 10,45 mm According to the formula (3) were made to calculate the true contact angle α=0,1π-0,45/(4·π)=0,0642πcorresponding to approximately 11,55°. This value differs from the estimated value of more than 7 degrees.

Thus, it was found that the contact angle of the investigated ball deviates significantly from the calculated values, which indicates poor quality of its manufacture, and consequently, low reliability and short life span.

1. The method for determining the contact angle of ball bearings, including determining the touch point of the ball with the contact surface of the rim and finding angle contact ball bearing according to the displacement of the touch point from the calculated position, with the contact surface of the rim in the area of computational point of contact with ball is irradiated with an ultrasonic beam, and the touch point is determined by the minimum value of the amplitude of the reflected acoustic signal.

2. The method according to claim 1, characterized in that the determined touch point of the ball with the outer and inner rim bearings of two the ka, and the contact angle is determined by the distance between the projections of these points on the image plane.

3. The method according to claim 1, characterized in that the inner surface of the rim is placed in the focal plane of the focused ultrasonic beam, and determining the touch point is carried out by its pointwise scanning.

4. The method according to claim 1, characterized in that the contact angle of ball bearings is determined by one of the following formulas:

α=arcsin(C/D)

or

or

where α - angle contact ball bearing; - the distance between the projections of the points of contact of the ball with the inner and outer rims on the image plane; α0- the calculated angle contact ball bearing; Δ - displacement of the projection of the point of contact of the bead with the rim on the image plane; R is the radius of the ball; And the distance from the projection point of contact of the ball with the rim on the image plane to the edge of the rim; And0- estimated distance from the projection point of contact of the ball with the rim on the image plane to the edge of the rim.



 

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