Hitachi, Ltd.

Hitachi Tool Engineering, Ltd.

Hideaki Onozuka

Koji Utsumi

Masayuki Kyoi

Masato Kobayashi

Shigeru Kikuchi

Masaya Takahashi

Toshio Yamanaka

Yoshio Koguchi

Yohei Asakawa

Hayato Takahashi

Tomu Kato

Tomu Katou

Motohiro Kikuchi

The table on which a workpiece is put can travel on a guide rail mechanism relative to a working head with a cutting tool mounted thereon. The table is connected through a nut to a ball screw part to move in an axial direction thereof as the ball screw part rotates. One end of the ball screw part is supported by a bearing and the other end is connected to a servomotor to be rotationally driven. A hollow part is provided in the table to receive therein a damper mechanism part, which comprises a spring, a damper, and a weight, the table and the weight being arranged to enable traveling separately on guide rails. Thereby, even when the workpiece is heavy, the weight can move relative to the table to effectively damp vibrations of the table in a feed direction.

Machine tool

In a cutting method of an oblique surface by a rotary tool, for analyzing in advance a stability limit depth of cut with respect to a self-excited cutting vibration in consideration of a pick feed amount and a work oblique angle and reducing the number of steps necessary for preparation and correction of NC data, a tool diameter, the number of cutting teeth and dynamic stiffness of the rotary tool, a cutting force coefficient determined by a combination of the tool and work materials, dynamic stiffness of the work, the pick feed amount, oblique angles between the tool and the work and the like are used as input values, an initial value of the stability limit depth of cut is determined based on the input values, and calculation is performed based on the initial value. In this case, the initial value is compared with the calculated value, the initial value is corrected by a certain rule, and the calculation is repeated until both the initial value and the calculated value fall in a constant error range to thereby calculate the stability limit depth of cut during the oblique cutting.

Method for estimating self-vibration of milling tool in the operating process

Disclosed herein is the structure of a damper that is capable of improving the degree of freedom in design to optimize the damping characteristics of the damper and is capable of allowing the damper to be easily optimized and manufactured for a wide variety of dynamic stiffness characteristics of a tool body, and a manufacturing method using the same. A plurality of ring-shaped elastic members are disposed at opposite ends of a weight part. The weight part is connected to the tool body via the elastic members. Consequently, the weight part is moved relative to the tool body. The plurality of elastic members are mounted while spacers are disposed between the elastic members, and the spacers are moved with respect to the weight part in the axial direction thereof. A viscous fluid is filled in the region surrounded by the outer circumferential surfaces of the spacers, the elastic members, and the inner surface of a hollow part of the tool body. Consequently, it is possible to damp the relative movement of the weight part with respect to the tool body.

Tool having damper

A method for calculating depth of cut without any milling self-excited vibration. An initial value for machining-surface-perpendicular depth of cut is set. A cutting start angle and cutting end angle for a cutting edge is obtained, based on the initial value. A machining-surface-perpendicular depth of cut that causes no self-excited vibration is calculated. The maximum depth of cut that corresponds to the stability limit of a milling self-excited vibration is calculated, by repeating the calculation while modifying the initial value until the difference between the initial value and the calculation result becomes the same as, or smaller than, a given value. As a result, the stability-limit depth of cut is preliminarily analyzed to the milling self-excited vibration in consideration of a pick feed, the gradient angle of a workpiece, and a machining-surface curvature radius, so that man-hours required for creation and modification of NC data can be reduced.

Method and program for calculating maximum depth of cut without self-excited vibration of cutting tool

An electrode comprises an electrode main body having a porosity, and the conductivity of the electrode main body at its part ranging from the arc running face to a stated depth is made higher than the conductivity at the section or the conductivity at the part ranging from the back surface to a stated depth. This brings about an improvement in circuit-break performance of a circuit breaker and also prevents the arc running face of the electrode main body from deteriorating.

Sintered body and electrode, method for surface densitication of these, process for manufacturing electrode by this method and circuit breaker

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Sagamihara, Japan

Hideaki Onozuka