A machine tool (10) for machining workpieces (18) has a main spindle (12) which carries a tool holder (14) at its end and is mounted in such a way that it can rotate about an axis of rotation (22) and can move along the axis of rotation (22). A preferably electromagnetic feed device (32) is also provided, which exerts a force (FZ) acting along the axis of rotation s on the main spindle (12). A screw gear (52), which connects a drive (20) for driving the main spindle to the main spindle (12), drives the main spindle (12) in rotation and simultaneously moves it along the axis of rotation (22). The screw-and-nut gearing (52) has a thread (64, 66a, 66b) formed on a first component (54) and a cam (70a, 70b) formed on a second component (12) that cooperates with the thread (64, 66a, 66b). One of the two components (54) is rotated by the drive (20) via a drive gear (57) and is immovably mounted along the axis of rotation (22). The other of the two components is the main spindle (12).

A linear actuator includes a screw shaft comprising a screw thread and having a longitudinal axis A, a nut movable along the screw shaft from a retracted position to an extended position, and a plurality of rollers movable with the nut. Each roller includes a cylindrical surface configured to roll along one or more flanks of the screw thread, such that rotation of the screw shaft causes the rollers to roll along the flank(s) so that the nut translates in an axial direction along the screw shaft. The screw thread has a variable lead angle. The actuator can be part of a power door opening system of an aircraft.

To achieve a compact construction shape with a long service life, a focus adjustment apparatus for an image detection system is provided which comprises an objective having at least one lens and which comprises a motor device for the positional adjustment of the objective, wherein the lens is provided on a movable lens holder, wherein the movable lens holder is connected to a threaded unit of the motor device via a support unit provided in the movable lens holder such that the support unit can be rolled with the lens holder along a main axis of the threaded unit in accordance with a rotation of the threaded unit and such that an axis of rotation of the support unit is directed perpendicular to the main axis of the threaded unit.

A linear actuator includes a screw shaft comprising a screw thread and having a longitudinal axis A, a nut movable along the screw shaft from a retracted position to an extended position, and a plurality of rollers movable with the nut. Each roller includes a cylindrical surface configured to roll along one or more flanks of the screw thread, such that rotation of the screw shaft causes the rollers to roll along the flank(s) so that the nut translates in an axial direction along the screw shaft. The screw thread has a variable lead angle. The actuator can be part of a power door opening system of an aircraft.

A spot welding apparatus (10) according to the present invention includes: a circular cylindrical cam (12) having an outer circumferential surface, in which a spiral-shaped large lead cam groove (12a) inclined at a steep angle and a spiral-shaped small lead cam groove (12b) inclined at a gentle angle are formed; and a pressurizing shaft (13) including a plurality of rollers (R1, R2) insertable into the respective cam grooves (12a, 12b) and configured to move along an axis of rotation of the circular cylindrical cam (12) when the circular cylindrical cam (12) rotates. When the rollers (R1, R2) are inserted into the large lead cam groove (12a), a roller (R1, R2) located at one end side of a row comes into contact with one of two sides surfaces of the cam groove (12a) and a roller (R1, R2) located at another end side of the row comes into contact with the other one of the two side surfaces of the cam groove (12a), and when the rollers (R1, R2) are inserted into the small lead cam groove (12b), each of the rollers (R1, R2) comes into contact with at least one of one side surface and the other side surface of two side surfaces of the cam groove (12b).

There is provided a ball screw mechanism for which a return of a sphere, such as a conventional circulating ball screw, need not to be considered, and that can prevent vibration and noise and avoid an increase in heat by ensuring smooth movement of a sphere without causing ball jam or the like of a sphere on a screw shaft. The present invention includes a screw shaft 2 that has a spiral groove 2a and extends linearly, a housing 30 that surrounds a periphery of the screw shaft 2, and a plurality of spheres 4 and ball bearings 5 that transmits thrust of the screw shaft 2 to the housing 30. Each ball bearing 5 includes an outer ring 7 attached and fixed to the housing 30 at regular intervals along the spiral groove 2a of the screw shaft 2, and an inner ring 6 provided with a concave spherical contact surface 5a in contact with the sphere 4 on a side surface facing the screw shaft 2. Each inner ring 6 is rotatably disposed about rotation axes N.sub.1 to N.sub.4 orthogonal to a rotation axis O of the screw shaft 2. The spheres 4 are arranged, each in contact with the contact surface 5a of each of the ball bearings 5, at regular intervals adjacent to each other in the spiral groove 2a of the screw shaft 2.

There is provided a ball screw mechanism for which a return of a sphere, such as a conventional circulating ball screw, need not to be considered, and that can prevent vibration and noise and avoid an increase in heat by ensuring smooth movement of a sphere without causing ball jam or the like of a sphere on a screw shaft. The present invention includes a screw shaft 2 that has a spiral groove 2a and extends linearly, a housing 30 that surrounds a periphery of the screw shaft 2, and a plurality of spheres 4 and ball bearings 5 that transmits thrust of the screw shaft 2 to the housing 30. Each ball bearing 5 includes an outer ring 7 attached and fixed to the housing 30 at regular intervals along the spiral groove 2a of the screw shaft 2, and an inner ring 6 provided with a concave spherical contact surface 5a in contact with the sphere 4 on a side surface facing the screw shaft 2. Each inner ring 6 is rotatably disposed about rotation axes N.sub.1 to N.sub.4 orthogonal to a rotation axis O of the screw shaft 2. The spheres 4 are arranged, each in contact with the contact surface 5a of each of the ball bearings 5, at regular intervals adjacent to each other in the spiral groove 2a of the screw shaft 2.

The present invention relates to a linear module. The linear module according to an example of the present invention comprises a base plate; a screw disposed on the base plate and arranged in the longitudinal direction of the base plate; a carrier block including a hollow part surrounding a portion of the screw; a carrier block rail disposed on one side of the carrier block and arranged in the longitudinal direction of the base plate; a long rail disposed on the base plate and arranged in the longitudinal direction of the base plate; and a roller guide disposed between the carrier block rail and the long rail and to reduce the frictional force between the carrier block rail and the long rail when the carrier block moves in the longitudinal direction of the base plate.

A linear actuator includes: a screw shaft that has a screw thread and a longitudinal axis A and a nut movable along the screw shaft from a retracted position to an extended position. The actuator also includes a plurality of rollers movable with the nut, each of which includes a cylindrical surface configured to roll along one or more flanks of the screw thread, such that rotation of the screw shaft causes the rollers to roll along the flank(s) so that the nut translates in an axial direction along the screw shaft. The screw thread includes one or more detents (e.g., grooves) configured to lock the nut in one or more axial positions.

A bearing screw transfer device which converts a rotational motion of a screw shaft into a linear motion by the medium of a bearing is disclosed. The bearing screw transfer device has a first driving bearing and a second bearing which run along a screw groove of a rotating screw shaft, thereby converting a rotational force of the screw shaft into a translational force of an operating plate disposed on an upper portion of the screw shaft, wherein a two-surface screw groove is formed on the screw shaft, and an outer ring of the first driving bearing runs in contact with one surface of the two-surface screw groove, and an outer ring of the second driving bearing runs in contact with the other surface of the screw groove.