Nsk Corporation

Hiroyuki Matsuzaki

Takashi Maeda

Takeo Kawamata

Hisakazu Tadokoro

Chuichi Sato

A rolling bearingcomprises raceshaving a racewayand rolling elementshaving a rolling contact surface, wherein at least the racewayof the raceshas a machined surface, and a surface layeris formed on the machined surface by electrochemically or chemically dissolving the machined surface, whereby contamination is substantially reduced.

Rolling-bearing and bearing unit

In the ball bearing inspection apparatus and method, the butting portion 7c of a skew drive shaft 7 rotatable coaxially with a spindle rotary shaft 1 is butted against steel balls 3 which are respectively held between the respective grooves of the inner ring 4b and outer ring 4a of a ball bearing 4 to be inspected, the spindle rotary shaft 1 is rotated while applying a pre-load to the outer ring 4a by a pre-load ring 5, and the skew drive shaft 7 is rotated while controlling the rotation speed of the skew drive shaft 7 in such a manner that the respective steel balls 3, which are being rotated on their own axes and around the spindle rotary shaft 1 due to the rotation of the spindle rotary shaft 1, is caused to make a skew movement due to the butting portion 7c. Therefore, physical quantities such as vibrations, sound pressures and the like generated from the ball bearing 4 to be inspected are measured in a condition that the respective balls 3 are making their respective skew movements in addition to their rotational movements on their own axes and around the spindle rotary shaft 1.

Apparatus and method for inspecting a ball bearing

In a duplex bearing 10 in which a preload is applied to balls 14a and 14b interposed between an outer race 11 and first and second inner races 12 and 13 by tightening a nut 16, a preload jig 19 fitted to the lower end of the second inner race 13 is turned by a motor 21 and applied with an axial load by a rod 31. The rod 31 has a load detector 31 at the middle. Position sensors 24 and 25, each of which is adapted to detect an amount of displacement in the direction of axis, are provided at the ends of the outer race 11 and the second inner race 13, respectively. A rotation detecting sensor 33 adapted to detect a rotational position is provided below the lower surface of the preload jig 9. Under the condition that the axial load is applied to the extent that measuring loads are FH and FL, the amounts of average displacement XAH and XAL of the outer race 11, and the amounts of average displacement XBH and XBL are detected, and the amounts of displacement .DELTA.XH and .DELTA.XL which are the differences between those amounts are calculated, so that the aimed rigidity KA is calculated by utilizing the amounts of displacement .DELTA.XH and .DELTA.XL thus calculated.

Bearing preload measuring method and apparatus

While maintaining a shaft in a fixed state, an outer ring is rotated. Vibrations of the shaft are detected by a first vibration pickup and a second vibration pickup. Detection signals of both the vibration pickups are delivered to a frequency converter via amplifier, respectively. The frequency converter determines, by Fourier transformation, the rotation frequency of the outer ring, the revolution frequency of balls and the resonance frequency of the double-row ball bearing. A first computing assembly then calculates the contact angle and bearing rigidity, and a second computing assembly calculates the preload.

Method and instrument for measuring for measuring preload of rolling

A vibration measurement system 1 comprises a shrink-type chuck 5, a spindle 14, and a servo motor 16 as mechanical elements, and has a vibration pickup 41 attached to the outer peripheral surface of a jaw 5a holding an outer ring 4 of a roller bearing 2. A ring groove 5b is formed on the inner face of the jaw 5a holding the bearing 2, and a shell 18 with oil pressure as back pressure is fitted into the ring groove 5b. When vibration is measured, the oil pressure of the shell 18 is raised to bring bearing clearance to zero, thereby preventing so-called roller drop from causing impulsive vibration.

Vibration measurement system for a rolling bearing

While maintaining an outer ring in a fixed state, an inner ring is rotated. Radial vibrations of the outer ring are detected by a vibration pickup, and detection signals are delivered to a frequency converter via an amplifier. The frequency converter determines, by Fourier transformation, the rotation frequency of the inner ring and the revolution frequency of balls. The processor then calculates the contact angle of a rolling bearing on the basis of these rotation frequency and revolution frequency.

Method and instrument for measuring contact angle of rolling bearing

While maintaining a shaft in a fixed state, an outer ring is rotated. Vibrations of the shaft are detected by a first vibration pickup and a second vibration pickup. Detection signals of both the vibration pickups are delivered to a frequency converter via amplifier, respectively. The frequency converter determines, by Fourier transformation, the rotation frequency of the outer ring, the revolution frequency of balls and the resonance frequency of the double-row ball bearing. The first computing device then calculates the contact angle and bearing rigidity, and the second computing device calculates the preload.

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Kanagawa, Japan

Hiroyuki Matsuzaki