Apparatus and method for machining long workpiece

1. A long workpiece machining apparatus for machining a long workpiece having a constant sectional shape while rotating the long workpiece around a horizontal axis O extending in the length direction of the long workpiece, the long workpiece machining apparatus comprising:

a base frame that is positioned below the horizontal axis O and that extends along the horizontal axis O;

a pair of clamp units that are positioned at the two ends of the base frame;

a pair of support units that are positioned in the lengthwise inside of the clamp units, that are capable of moving along movement guides disposed parallel to the horizontal axis O, that horizontally support the long workpiece in two locations, and that are capable of moving vertically; and

one or a plurality of machining units that are capable of moving over the base frame along movement guides disposed parallel to the horizontal axis O, and that are capable of machining the long workpiece; wherein

the clamp units are capable of moving from the outside of the ends of the long workpiece toward the inside;

the clamp units horizontally support the long workpiece in two locations; and

the clamp units rotate in synchronization with each other around the horizontal axis O;

each of said clamp units comprising:

a cylindrical ring that has a cylindrical inner surface and is supported so as to be rotatable around the horizontal axis O;

an intersecting flat member which is attached to the inner surface of the cylindrical ring and which has two flat surfaces extending in parallel with the horizontal axis and crossing each other; and

a holding head disposed in the cylindrical ring in a position opposite to the intersecting flat member, directly moved in a diametrical direction relative to the cylinder ring and thus toward the intersecting flat member, and freely rocked around an axis parallel to the horizontal axis O;

wherein each of said support units have a pair of free-rotating rollers that are supported at the lower ends so as to rotate freely around an axis, and that intersect with each other to form a V shape that opens upward;

the free-rotating rollers are capable of moving along the horizontal axis O in the lengthwise inside of the clamp units, and are also capable of vertical movement; and

while the free-rotating rollers are at raised positions, the V shapes are coplanar with V shapes of the upper surfaces of the intersecting flat members of the clamp units when the intersecting flat members are at bottom positions.

2. The long workpiece machining apparatus according to claim 1 , each of said machining units comprising:

a spindle for rotating rotary tools; and

a tool-moving device for moving the rotary tool in two dimensions within a plane orthogonal to the horizontal axis O.

3. The long workpiece machining apparatus according to claim 1 , comprising:

a NC control device for numerically controlling the horizontal movement positions and rotational angles of the clamp units as well as the positions of the rotary tools of the machining units; and

a sequence control device for controlling the sequence of the units.

4. The long workpiece machining apparatus according to claim 1 , comprising:

a stationary-side stopper sensor that is fixed to a first end of the base frame and that comes into contact with one end of the long workpiece and outputs a detection signal; and

a moving-side stopper sensor that is capable of moving from the other end of the base frame to the first end along the horizontal axis O, and that comes into contact with the other end of the long workpiece and outputs a detection signal.