Patent EP-2302433-A2 (EP)
Title: Drawer for holding a lens in a laser machining head and laser machining head
Inventor: SPOERL GEORG
IPC: G02B7/02
Filed: 2010-09-10
Abstract: The slot (18) comprises an adjusting unit, over which the lens is relocatable relative to the slot and which comprises a linear adjusting device (64, 66, 68) with a synchronous linear motor for relocating the lens (90, 92) in a longitudinal direction of the laser beam. The lens is a focusing lens for focusing the laser beam on the workpiece to be processed. The linear motor is a regulated permanent magnet synchronous linear motor, which comprises a stator (70) with two permanent magnets and an actuator (72) with a coil, and comprises N number of permanent magnets and M number of coils. The slot (18) comprises an adjusting unit, over which the lens is relocatable relative to the slot and which comprises a linear adjusting device (64, 66, 68) with a synchronous linear motor for relocating the lens (90, 92) in a longitudinal direction of the laser beam. The lens is a focusing lens for focusing the laser beam on the workpiece to be processed. The synchronous linear motor is a regulated permanent magnet synchronous linear motor, which comprises a stator (70) with two permanent magnets and an actuator (72) with a coil, and comprises N number of permanent magnets and M number of coils as pair of N/M that is equal to 2/3, 4/3, 10/6 or 14/6. The regulated permanent magnet synchronous linear motor is formed as linear step motor. The two permanent magnets are arranged next to each other and are alternatively poled. The pole axis of the coil is arranged along the pole direction of the two permanent magnets. The linear adjusting device has a linear guide, which is oppositely arranged to the synchronous linear motor. A support is mounted between the linear guide and the synchronous linear motor for receiving a lens holder and is led in an adjustment direction of the linear guide and the synchronous linear motor. The linear guide has a guide rod and a guide bush, in which the guide rod is slidably mounted. The linear guide is implemented as ceramic slide bearing. The support has a cylindrical recess with an internal thread and the lens holder is cylindrically formed with an external thread, where the lens holder is screwed with its external thread into the internal thread of the support. The lens holder has a hollow-cylindrical recess with a shoulder section, on which the lens is mounted. The adjusting unit is formed to relocate the lens vertical to the longitudinal direction of the laser beam. The slot comprises a front plate and a frame, which includes the linear adjusting device. The frame is pivotably mounted in a fixed axial position on the front plate of the slot around a shaft, which runs in a distance parallel to the longitudinal direction of the laser beam. The shaft is fixedly connected to the frame and is laterally guided past between the arms, which projects from the rear side of the front plate. The frame is pulled with the help of springs against the rear side of the front plate. The springs are guided around the frame and are fastened with their ends at the rear side of the plate. The adjusting unit is formed for exactly relocating the lens by the screws projecting through the front plate. An independent claim is included for a laser processing head for processing a workpiece using a laser beam.