A feed assembly, a boring head and an alignment device. The feed assembly may include a feed mechanism; an adjustment mechanism to adjust a feed rate of the feed mechanism; and a gage to indicate the feed rate. The boring head may include a body supportable on and for rotation with the bar; and a tool holder to support a tool to work on a workpiece and supported for radial movement on the body to adjust a radial position of the tool. An alignment device may include a clamp lockable in an axial position on the bar; an alignment member engageable with a bore of a workpiece; and an adjustment member between the locking clamp and the alignment member, the adjustment member and the alignment member include complementary threads, the adjustment member being rotatable about the axis to move the alignment member relative to the clamp along the axis.

A holder according to one embodiment has a rod shape and includes a head portion located at a front end side. The head portion includes an upper jaw portion and a lower jaw portion located at a front end, an insert pocket located between the upper jaw portion and the lower jaw portion, a first wall surface located at an upper surface of the upper jaw portion and inclined in an extending manner from one side surface side, a second wall surface located closer to a rear end side than the first wall surface and inclined upward, a concave-shaped third wall surface located closer to the rear end side than the second wall surface, and a fourth wall surface inclined upward as the fourth wall surface extends away from the third wall surface. The third wall surface is concave downward from an upper end of the second wall surface.

A boring tool holder has a base member and a cutting insert holding member. The base member has a first main surface and a second main surface opposite to the first main surface. The cutting insert holding member is contiguous to the base member on the first main surface, and disposed in a circumferential direction of the base member as viewed in a direction from the first main surface toward the second main surface. A cross-sectional area of the base member in a cross section perpendicular to the direction from the first main surface toward the second main surface and intersecting the base member is larger than a cross-sectional area of the cutting insert holding member in a cross section perpendicular to the direction from the first main surface toward the second main surface and intersecting the cutting insert holding member.

The present disclosure relates to a long boring bar device of a machine tool and, more particularly, to a long boring bar device of a machine tool, wherein a boring bar is detachably fastened to a holder, and a head tool is detachably fastened to the boring bar to automatically exchange a head tool through an automatic tool changer, thereby reducing non-processing time and improving productivity of the machine tool.

The holder includes a body having a rod shape extending from a first end surface to a second end surface and including a large-diameter portion which is a recess extending from the first end surface, a weight located in the large-diameter portion, a ring-shaped first elastic member, and a lid press-fitted into the large-diameter portion from the side of the first end surface. The inner peripheral surface of the large-diameter portion includes a first region located on the side of the first end surface and a second region located closer to the second end surface than the first region. The first elastic member comes into contact with the inner peripheral surface of the large-diameter portion in the second region to fix the weight to the inner peripheral surface. The surface roughness of the second region is greater than the surface roughness of the first region.