Okuma Corporation

Okuma Machinery Works Ltd.

Fumitoshi Terasaki

Tatsuhiro Yoshimura

Takashi Nishimoto

Takeo Shirakura

Kenji Yoshimura

The present invention provides a method of machining a female screw groove in a workpiece whereby the spindle of an internal grinding wheel for machining the workpiece into a female screw is tilted relative to the screw's axis at an angle (&xgr;) smaller than the lead angle (&agr;) of the female screw. First, specifications of the female screw, data on the configuration of the thread groove, and the tilt angle are supplied to a program for calculating data on dressing of the grinding wheel wherein the locus of the groove on cross-sections normal to the axis of the grinding wheel and wheel dressing data are calculated. Second, the grinding wheel on the aforementioned spindle is shaped or dressed by simultaneous triaxial control of the rotation of the single point dresser about a b-axis, and the feed of the grinding wheel table along a z-axis and a cross slide along an x-axis based on the foregoing data. Thereupon, the female screw is machined with the dressed grinding wheel.

Method of machining a female screw and dressing a grinding wheel for female screw machining

The present invention achieves machining operation without grind-burning and grinding crack and improves the profile accuracy of a workpiece, by automatically generating X/C axis data that controls the headstock and the wheel spindle head while taking into account speed, acceleration, change in acceleration and contact arc length. Storage means 33 for storing the time taken by the workpiece to make one turn, reference X/C axis data computing element 53 for computing machining data from given angle and a set of lift points to control the grinding peripheral speed constant within a range where the machine can follow, computing element 56 for computing contact arc during grinding from the X/C axis data, storage means 53 for storing limitation value of X axis based on the contact arc while changing it according to C axis, computing means 46 for storing said reference X/C axis data and computing speed, acceleration and change in acceleration while reading the reference X/C axis data by skipping a specified number of steps, and modifying element 57 for reducing said number of steps to bring the speed, acceleration and change in acceleration within limits when any of these values exceeds the limit are provided, thereby to carry out synchronous control of the work spindle rotation and reciprocal motion of the wheel spindle head according to the modified X/C axis data.

Method of grinding and machining non-circular workpiece and apparatus

When a non-circular workpiece is to be machined by an NC cylindrical grinding machine, the latter is controlled such that the velocity of each of the main spindle and grinding head does not exceed a threshold allowable by the machine. A non-circle data pre-processing section is provided to convert a group of angle and lift points relating to the shape data into profile data to determine the complete circumferential length of the profile. The circumferential length of the profile is divided into line segments of minute and equal length at a plurality of division points. When the tool is brought into contact with the workpiece at each of the division points, a reference X/C axes data relating to the X-axis position of the tool and the rotational angle of the main spindle at this time is prepared. The reference X/C axes data are selected out to prepare temporary X/C axes data which in turn are used to determine the velocity, acceleration and rate of acceleration change in each of the main spindle and tool head. These determined values are compared with the respective thresholds. If they exceed the respective thresholds, the rate of selecting is changed. If the calculated values do not exceed the respective thresholds, the temporary X/C axes data is taken as modified X/C axes data. The machining will be carried out in accordance with the modified X/C axes data.

Method and apparatus for grinding non-circular workpiece

A method of machining a member included a screw-shaped portion which is used when the member is ground at the screw-shaped portion by means of a machine tool, in particular, a grinder. A configuration of the tool that projects corresponding to the thread-groove configuration on a section normal to the axis of the screw-shaped portion to be machined is prepared. The axis of the tool is positioned in parallel with the axis of the screw-shaped portion to be machined, and the relevent surface of the screw-shaped portion is machined by moving the tool relative to the screw-shaped portion while their axes are being kept in parallel with each other. According to the present invention, the lead of a small-diameter, deep-grooved female screw-shaped portion may be able to be machined. In addition, an ordinary NC machine tool can be used to machine leads of screw-shaped portions simply by making changes in the NC program.

Growing community of inventors

Kani, Japan

Fumitoshi Terasaki