Jtekt Corporation

Toyoda Koki Kabushiki Kaisha

Masashi Yoritsune

Takashi Matsumoto

Yoshio Wakazono

Kazuyoshi Ohtsubo

Toshiki Kumeno

Yoshihiro Mizutani

Yasuo Niino

Ryohei Mukai

Makoto Tano

Toshiki Sakai

Hisanobu Kobayashi

In a machining method of supporting a workpiece having a cylindrical machined portion such that the workpiece is rotatable and feeding a grinding wheel in a radial direction, a start diameter that is a diameter including a measurement start point on a surface of the machined portion is measured, and, after the measurement start point passes through a machining application portion, an end diameter that is a diameter including a measurement end point is measured. An actual grinding depth at the time when the measurement start point is machined is computed by the equation, U=|D&#x2212;D|, a runout of the machined portion is computed from a relative difference in the actual grinding depth (U) between positions of the machined portion in a rotational direction, and infeed control of the grinding wheel is executed such that the runout is removed.

Actual grinding depth measurement method, machining method, and machine tool

There are provided a grinding machine and a grinding method that make it possible to achieve a high degree of accuracy of the roundness of a workpiece. As at least one of a coolant dynamic pressure and a grinding efficiency varies depending on a phase of the workpiece, a pressing force in the cut-in direction, which an eccentric cylindrical portion of the workpiece receives from a grinding wheel, varies and a degree of deflection of the eccentric cylindrical portion also varies. In the grinding machine, the degree of deflection during grinding is acquired based on the coolant dynamic pressure and the grinding efficiency, a first correction value for a command position of the grinding wheel relative to the eccentric cylindrical portion is computed, and the command position is corrected based on the first correction value.

Grinding machine and grinding method

A control unit that relatively moves a headstock and tailstock and a tool to thereby machine a peripheral surface of a workpiece in a radial direction executes control such that a relative feed speed of the tool in the radial direction in a transitional state where an amount of warpage of the workpiece in the radial direction at a machining position increases is faster than a relative feed speed of the tool in the radial direction in a steady state where an amount of warpage of the workpiece in the radial direction at the machining position is constant. By so doing, it is possible to reduce a machining time at the time of the start of machining.

Machine tool and machining method

In a grinding machine, a retraction grinding is performed after a first advance grinding. Within a rotational range for a cylindrical workpiece to rotate from a present rotational phase to a target rotational phase in the retraction grinding, target grinding resistances in respective rotational phases are generated based on residual grinding amounts in the respective rotational phases of the cylindrical workpiece. Then, the retraction grinding is performed and controlled to make a grinding resistance detected by a force sensor agree with the target grinding resistances in respective rotational phases.

In a swivel device, a swivel head provided with a plurality of tool spindles thereon is mounted on a support base to be turnable about a swivel shaft being upright on the support base. An annular space portion is formed between the support base and the swivel head in coaxial relation with the swivel shaft. The tool spindles each mounting a grinding wheel are arranged on the swivel head to extends in a horizontal plane which crosses the annular space portion at about a mid position in the vertical direction of the annular space portion. A direct drive motor is built in the annular space portion so that a driving center of the direct drive motor is at almost the same height as the horizontal plane including the axes of the grinding wheels. Thus, the swivel device can lower the positions of the rotational axes of the grinding wheels and is rigid against inclination caused by grinding resistance acting on the grinding wheels.

Swivel device and grinding machine incorporating the same

A pair of hydrostatic radial bearing devicesis mounted on right and left side surface of a front portion of a wheel slidein order to support rotatably wheel shaftsrespectively. A thrust bearing devicemounted in either one of wheel shaftssupports either wheel shaftorin a thrust direction. A shaft coupling mechanismis installed in wheel shafts. A taper cylindrical portionis projected from either one of wheel shaftsand fitted tightly with a taper inside openingformed in remaining of wheel shafts. A vertical end surfaceor Fb extending from a base of the taper cylindrical portionis fitted tightly with another vertical end surfaceorof the remaining wheel shaftor

Wheel shaft supporting apparatus for grinding machine

In a truing method and apparatus, an analyzing method is employed to calculate a truing shape from which a grinding surface having been trued with a grinding wheel being rotated at a low rotational speed during a truing operation is deformed to a desired shape due to centrifugal expansion depending on a rotational speed difference when the grinding wheel is rotated at a high rotational speed during a grinding operation. Then, with the grinding wheel being rotated at the low rotational speed, the grinding surface is trued with a truing roll to the calculated truing shape. As a result, the grinding surface of the grinding wheel being rotated at the low rotational speed is trued with the truing roll taking into consideration the centrifugal expansion of the grinding surface which takes place when the grinding wheel is rotatated at the high rotational speed during the grinding operation subsequent to the truing operation.

Truing method and apparatus

A circular or non-circular workpiece is ground in a plurality of grinding steps, including a final finish grinding step. A grinding wheel is caused to effect profile generation movement in synchronism with rotation of the workpiece and in accordance with profile data derived from the target shape of the workpiece. In each grinding step, the grinding wheel is advanced in such a manner that the grinding wheel causes cut-in movement within a predetermined cut-in angle defined on the workpiece. After completion of the final finish grinding step, the grinding wheel is retracted over a predetermined back-off angle defined on the workpiece. The retraction is effected in accordance with composite data obtained through combining the profile data and back-off data. The back-off angle is greater than the cut-in angle employed during the final finish grinding step.

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Anjo, Japan

Masashi Yoritsune