A workpiece holder device for a machine tool has a holder, which has a support part and a holder part. The support part supports the holder on a support device, preferably so that the holder can rotate about an axis of rotation. The holder part is set up to hold a workpiece directly or indirectly. To avoid, or at least minimize deviations from a desired alignment of the holder part based on elastic deformation of the holder due to the weight force of the workpiece, the holder has at least one mechanical or hydraulic pretensioning device arranged on or in it. The pretensioning device can be used to pretension the material of the holder, so that the pretensioning device applies a tensile stress or a compressive stress to at least one part of the holder. This can counteract a deviation of position due to an elastic deformation of the holder.

A machine tool (1, 100) comprises a support structure (4, 104) and a machining head (8) bearing a mandrel (12). The machine further comprises at least one action device (20) contained on the support structure (4,104) and applied to it, which generates pushing or pulling actions on said support structure (4, 104) acting against the action of the weight of the head (8) thereon.

A workpiece holder device for a machine tool has a holder, which has a support part and a holder part. The support part supports the holder on a support device, preferably so that the holder can rotate about an axis of rotation. The holder part is set up to hold a workpiece directly or indirectly. To avoid, or at least minimize deviations from a desired alignment of the holder part based on elastic deformation of the holder due to the weight force of the workpiece, the holder has at least one mechanical or hydraulic pretensioning device arranged on or in it. The pretensioning device can be used to pretension the material of the holder, so that the pretensioning device applies a tensile stress or a compressive stress to at least one part of the holder. This can counteract a deviation of position due to an elastic deformation of the holder.

Examples disclosed herein relate to a machining device including one or more beams attached to a surface; a platform coupled to the one or more beams; a tool support element coupled to the platform; a first movement device which may move the platform in a first direction; a second movement device which may move the platform in a second direction; and a third movement device which may move the tool support element in a third direction.

A precision protection jig with a base is provided and includes: a platform having its two ends provided with a first end portion and a second end portion, respectively, wherein a table connects bottoms of the first and second end portions, and a connection block is appropriately positioned on inner wall surfaces of the first and second end portions; a horizontal support jig having two ends provided with two connection plates, respectively, such that the connection plates allow the horizontal support jig to be transversely connected to the connection block of the first and second end portions, respectively; and a vertical support jig having two ends connected to the horizontal support jig and the table centrally and perpendicularly, respectively, wherein the horizontal support jig exerts lateral stress upon the first and second end portions, whereas the vertical support jig produces vertical stress.

A numeric control machine tool of the type comprising: a basement; a substantially rectilinear main supporting crossmember which extends above the basement and has two axial ends structured so as to rest stably and in an axially sliding manner on two reciprocally parallel rectilinear guides present on the basement; a movable slide which is fixed protruding onto a side of the main supporting crossmember, with the possibility of moving along the body of the main supporting crossmember; a substantially rectilinear vertical movable tower, which is fixed on the movable slide in a substantially vertical position and with the possibility of translating with respect to the movable slide in a vertical direction; and a tool-hold head which is fixed on the lower end of said vertical movable tower; the main supporting crossmember being structured so as stably to support the weight of the movable slide, the vertical movable tower and the tool-holder head, and the numeric control machine tool also comprising a substantially rectilinear auxiliary supporting crossmember, which extends beside the main supporting crossmember so as to be locally facing and distanced from the side of the crossmember which supports the movable slide; and on which the movable slide rests by means of interposition of a reaction member which is structured so as to vary its height, simultaneously exercising an upward thrust on the projecting arm.