A control device for a machine tool in which a tool used to machine a workpiece is mounted to a main spindle that is relatively movable with respect to the workpiece. The control device includes: a parameter preparing unit that stores a predetermined parameter regarding a control in advance; an evacuation unit that causes the tool to perform an evacuation operation from the workpiece; and a chip discharging unit that causes the tool to perform a chip discharging operation. The evacuation operation of the tool by the evacuation unit and the chip discharging operation by the chip discharging unit are performable at respective predetermined timings.

A hybrid threading tap includes a reamer portion and a thread cutting portion having a plurality of cutting teeth. The thread cutting portion is arranged with the reamer portion along the longitudinal axis. The reamer portion is configured to be advanced within a hole of a workpiece to plastically deform and expand the hole to an expanded hole and provide the expanded hole with a zone of residual compressive stress. The plurality of cutting teeth is configured to cut a threading into the expanded hole within the zone.

This invention, a thread chase with a lead that acts as a smooth bore guide into a threaded hole is suitable where space is confined, and the male thread chase must be exactly aligned with the female threads, “sight unseen”, or damage to female threads may result by applying force to a misaligned thread chase, particularly where the female threads are of softer metals. The lead smooth bore also prevents shavings and other debris resulting from the cleaning from the chase, from falling into the hole that is being cleaned. A recessed tapered area between the threaded portion of this case and the lead smooth bore guide collects the shavings or cleaning residue so that when the tool is withdrawn from the hole, the shavings and cleaning residual will collect in that area and not fall into the threaded hole being cleaned.

The tap tool (10) has an axis of rotation (Cr) and machines a pilot hole (6′) so that the same becomes a screw hole (6) in a state where the axis of rotation has been matched to a central axis (C6) of the pilot hole which is provided to a workpiece, wherein the tap tool (10) is characterized by being provided with: a thread section (14) having a blade section (14a) for machining a thread groove of the screw hole; pad sections (15, 16) located behind in a direction of rotation of the blade section, and engaging with the thread groove machined by the blade section during the machining of the thread groove; and a non-engagement section (17) for forming a space (20) between said section and the screw hole in a cross-sectional view where the axis of rotation and the central axis of the screw hole have been matched. The space has a size that enables simultaneous release of the engagement between the thread section and the thread groove and the engagement of the pad sections and the thread groove, in a case where the tap tool has shifted in a direction orthogonal to the axis of rotation within the screw hole, such shift being from the state where the axis of rotation and the central axis of the screw hole have been matched.

A hybrid threading tap includes a reamer portion and a thread cutting portion having a plurality of cutting teeth. The thread cutting portion is arranged with the reamer portion along the longitudinal axis. The reamer portion is configured to be advanced within a hole of a workpiece to plastically deform and expand the hole to an expanded hole and provide the expanded hole with a zone of residual compressive stress. The plurality of cutting teeth is configured to cut a threading into the expanded hole within the zone.

The invention involves the extraction process of a glow plug pencil (23) or a broken pencil (23) which is stuck in a cylinder head (13) housing (11) of a glow plug engine comprising a lower (19) and upper (17) part, so that the upper part (17) forms a shoulder (21) with the lower part (19), the pencil (23) being stuck in the lower part (19). The process is remarkable in that it includes a step (a) for drilling a bore in the pencil (23) according to the longitudinal direction of the latter which is performed with the use of a drill bit (1) comprising a drilling part (5) with flutes (7) and a shank (3) respectively having a diameter smaller and greater than the lower part diameter (19) of the housing (11) so that the shank (3) forms a shoulder (9) with the drilling part (5), and in that step a) for drilling the bore includes the drilling of the pencil (23) until the said shoulder (9) of the drill bit (1) is positioned to a stop against the shoulder (21) of the housing (11).

A thread repair tool for rethreading a blind tapped hole having damaged threads above undamaged threads of the hole, including: a shaft having a plurality of curved surfaces that extend from a top end of the shaft to a bottom end of the shaft, the plurality of curved surfaces being concave with respect to an exterior perimeter of the shaft; and wherein the shaft has a plurality of corner portions, each one of the plurality of corner portions being located in between two of the plurality of curved surfaces, a first pair of the plurality of corner portions extending from the top end to the bottom end, and a second pair of the plurality of corner portions having a threaded area proximate to the bottom end, the first pair of the plurality of corner portions being adjacent to each other and the second pair of the plurality of corner portions being adjacent to each other.

The invention involves the extraction process of a glow plug pencil (23) or a broken pencil (23) which is stuck in a cylinder head (13) housing (11) of a glow plug engine comprising a lower (19) and upper (17) part, so that the upper part (17) forms a shoulder (21) with the lower part (19), the pencil (23) being stuck in the lower part (19). The process is remarkable in that it includes a step (a) for drilling a bore in the pencil (23) according to the longitudinal direction of the latter which is performed with the use of a drill bit (1) comprising a drilling part (5) with flutes (7) and a shank (3) respectively having a diameter smaller and greater than the lower part diameter (19) of the housing (11) so that the shank (3) forms a shoulder (9) with the drilling part (5), and in that step a) for drilling the bore includes the drilling of the pencil (23) until the said shoulder (9) of the drill bit (1) is positioned to a stop against the shoulder (21) of the housing (11).

There is provided a hole machining method, using a tap tool which rotates about an axis of rotation and which includes a threaded part which has a blade for machining a threaded groove in a pilot hole, and a non-engaging part which forms a space between itself and the pilot hole in a cross-sectional view in which the axis of rotation and a center axis of the pilot hole are aligned, the method including the steps of machining a threaded groove by rotating the tap tool and advancing it toward a workpiece side in a first state in which the center axis and the axis of rotation are aligned, rotating the tap tool about the axis of rotation and moving the tap tool in an interior of the pilot hole toward the non-engaging part side in a direction orthogonal to the axis of rotation to transition the tap tool from the first state to a second state in which engagement between the threaded part and the threaded groove is released, and retracting the tap tool from the threaded hole.

A tap machining method includes: forming a female thread by cutting while synchronizing a rotation phase of a main spindle with positions of a workpiece to be machined by the tap and the main spindle in a rotation axis direction of the main spindle, the main spindle rotating while holding a tap with a tool holder mounted on a distal end portion; and adding or subtracting an angle amount of torsional deformation of the tap generated according to a cutting speed to or from the rotation phase of the main spindle during the synchronization.