A quill includes a fixing side quill to be fixed to a spindle housing and a leading end side quill having a whetstone mounted thereon and removably connectable to the fixing side quill. In the connecting portions between the fixing side quill and the leading end side quill, faces that are perpendicular to the axis of the quill are combined with each other. A first drive shaft is provided within the fixing side quill, and a second drive shaft, rotatable integrally with the whetstone, is provided within the leading end side quill. The first drive shaft and second drive shaft are removably connected to each other.

A quill includes a fixing side quill to be fixed to a spindle housing and a leading end side quill having a whetstone mounted thereon and removably connectable to the fixing side quill. In the connecting portions between the fixing side quill and the leading end side quill, faces that are perpendicular to the axis of the quill are combined with each other. A first drive shaft is provided within the fixing side quill, and a second drive shaft, rotatable integrally with the whetstone, is provided within the leading end side quill. The first drive shaft and second drive shaft are removably connected to each other.

In a power steering device equipped with a rack shaft constructed by joining a first member having rack teeth and a second member serving as a ball screw shaft on which a ball screw groove is formed, a grinding process of the ball screw groove is performed on the second member by causing a grindstone to rotate and move along a rotation axis of the second member, while causing the second member to rotate about an axis of the second member as the rotation axis. The grinding process is performed so as to satisfy a specified machining condition g/(5p)<w<g/p, where w is a rotational speed of the second member during grinding of the ball screw groove, g is a rotational speed of the grindstone during grinding of the ball screw groove, and p is a circumferential length of one circumference of the ball screw groove around the rotation axis.

In a power steering device equipped with a rack shaft constructed by joining a first member having rack teeth and a second member serving as a ball screw shaft on which a ball screw groove is formed, a grinding process of the ball screw groove is performed on the second member by causing a grindstone to rotate and move along a rotation axis of the second member, while causing the second member to rotate about an axis of the second member as the rotation axis. The grinding process is performed so as to satisfy a specified machining condition g/(5p)<w<g/p, where w is a rotational speed of the second member during grinding of the ball screw groove, g is a rotational speed of the grindstone during grinding of the ball screw groove, and p is a circumferential length of one circumference of the ball screw groove around the rotation axis.

In a power steering device equipped with a rack shaft constructed by joining a first member having rack teeth and a second member serving as a ball screw shaft on which a ball screw groove is formed, a grinding process of the ball screw groove is performed on the second member by causing a grindstone to rotate and move along a rotation axis of the second member, while causing the second member to rotate about an axis of the second member as the rotation axis. The grinding process is performed so as to satisfy a specified machining condition g/(5p)<w<g/p, where w is a rotational speed of the second member during grinding of the ball screw groove, g is a rotational speed of the grindstone during grinding of the ball screw groove, and p is a circumferential length of one circumference of the ball screw groove around the rotation axis.

In a power steering device equipped with a rack shaft constructed by joining a first member having rack teeth and a second member serving as a ball screw shaft on which a ball screw groove is formed, a grinding process of the ball screw groove is performed on the second member by causing a grindstone to rotate and move along a rotation axis of the second member, while causing the second member to rotate about an axis of the second member as the rotation axis. The grinding process is performed so as to satisfy a specified machining condition g/(5p)<w<g/p, where w is a rotational speed of the second member during grinding of the ball screw groove, g is a rotational speed of the grindstone during grinding of the ball screw groove, and p is a circumferential length of one circumference of the ball screw groove around the rotation axis.

The present disclosure relates to a method for dressing a multithread grinding worm, in which a flight of the multithread grinding worm is machined by means of a dressing tool. During machining of the multithread grinding worm, one of several flights of the grinding worm is eliminated, so that the number of flights of the grinding worm is reduced, thereby increasing the service life of the dressing tool and reducing the number of dressing tools to be kept in stock.

The present disclosure relates to a method for dressing a multithread grinding worm, in which a flight of the multithread grinding worm is machined by means of a dressing tool. During machining of the multithread grinding worm, one of several flights of the grinding worm is eliminated, so that the number of flights of the grinding worm is reduced, thereby increasing the service life of the dressing tool and reducing the number of dressing tools to be kept in stock.

In a thread grinder which grinds a thread grove on an inner surface of a workpiece while a rotation axis of a grinding wheel shaft is inclined with respect to an axis of a main shaft, a centering master which has a cylindrical outer surface is mounted to the main shaft. A measuring unit including two measuring instruments such that probes can contact two edges of a grinding wheel is mounted to the centering master. The origins of the measuring instruments are set by the probes contacting the cylindrical outer surface of the centering master. The measuring unit is moved in the axial direction of the centering master to bring the probes of the two measuring instruments into contact with the edges of the grinding wheel, respectively. The position of the grinding wheel shaft is adjusted such that measured values obtained by measuring instruments become same.

In a thread grinder which grinds a thread grove on an inner surface of a workpiece while a rotation axis of a grinding wheel shaft is inclined with respect to an axis of a main shaft, a centering master which has a cylindrical outer surface is mounted to the main shaft. A measuring unit including two measuring instruments such that probes can contact two edges of a grinding wheel is mounted to the centering master. The origins of the measuring instruments are set by the probes contacting the cylindrical outer surface of the centering master. The measuring unit is moved in the axial direction of the centering master to bring the probes of the two measuring instruments into contact with the edges of the grinding wheel, respectively. The position of the grinding wheel shaft is adjusted such that measured values obtained by measuring instruments become same.