A chuck (1) is provided by means of which workpieces (2) are supported individually for machining by a machine tool (3) and aligned coaxially to a centering axis (4), which serves as a reference for machining the workpiece (2) by the machine tool (3), having a chuck body (5), having at least four clamping jaws (6, 7, 8, 9) that are radially movably mounted on the chuck body (5) and are arranged in pairs in an X or Y plane and by means of which the workpiece (2) is held during the machining process to be aligned with respect to the centering axis (4), and having a pull piston (45) that is mounted in or at the chuck body (5) so as to be linearly movable and which is drivably coupled to a respective clamping jaw (6, 7, 8, 9) such that during the linear movement of the pull piston (45) the clamping jaws (6, 7, 8, 9) are radially fed in the direction of the workpiece (2) to be clamped or moved away from same in a synchronous manner, wherein the pull piston (45) is arranged coaxially with respect to the centering axis (4) inside the chuck body (5) and is axially actuated by one or more drive means (12, 13, 52, 53), on the one hand aiming at adjusting the compensatory movements between two adjacent clamping jaws running perpendicular to one another (6, 7, 8, 9) irrespective of their feed movement and operative contact with the workpiece (2) to be clamped, and on the other hand aiming at the constructional height of such chuck (1) being as small as possible. This aim is achieved in that each drive means (12, 13, 52, 53) has a linearly movable piston rod (26) or threaded spindle (55), whose respective longitudinal axis (26′ or 55′) is arranged to be perpendicular to the centering axis (4). (FIG. 1)

A hydraulic chuck device includes a cylinder portion operated by pressure oil, a chuck opened and closed by operation of the cylinder portion, a pressure oil supply controlling pressure of pressure oil supplied to the cylinder portion, and a chuck controller controlling the pressure oil supply. When controlling the pressure oil supply to cause a jaw portion to perform a clamping operation, during movement of the jaw portion from an unclamping position to a preliminary position situated before a clamping position, the chuck controller supplies pressure oil set at a first pressure into a cylinder chamber for clamping to move the jaw portion quickly, and during movement of the jaw portion from the preliminary position to the clamping positon, the chuck controller supplies pressure oil set at a second pressure lower than the first pressure into the cylinder chamber for clamping to move the jaw portion slowly.

The invention relates to a double-sided drilling fixture for die-forged pistons and a double-sided drilling process thereof. It overcomes the defects of low efficiency and accuracy of the double-sided drilling operation for die-forged pistons in the prior art. The invention comprises a die-forged piston, a fixture base assembly, an upper load-resisting assembly and a lower expansion-resisting assembly. The upper load-resisting assembly is installed on the fixture base assembly and disposed above the die-forged piston. A fixation base, whose upper surface shape is the same as internal surface shape of the die-forged piston, is installed above the fixture base assembly. The die-forged piston is sleeved on the fixation base. The invention achieves simultaneous drilling on both sides of the two rear skirt surfaces of die-forged pistons and delivers quick clamping and automatic fixation, significantly reducing the difficulty in the assembly of drilling plate and workpiece and increasing the alignment accuracy.

A workpiece holding device for holding a workpiece in a heat treatment system while the workpiece undergoes a thermal expansion and/or contraction includes at least two clamping units configured to apply a radial and/or an axial clamping force to the workpiece to hold the workpiece in the workpiece holding device in a predefined position, and at least three support units configured to support the workpiece. A first one of the at least three support units includes a first cylinder configured to support the workpiece, the first cylinder having a longitudinal axis and being configured to rotate around the longitudinal axis.

A workpiece holding device for holding a workpiece in a heat treatment system while the workpiece undergoes a thermal expansion and/or contraction includes at least two clamping units configured to apply a radial and/or an axial clamping force to the workpiece to hold the workpiece in the workpiece holding device in a predefined position and a drive unit configured to rotate the workpiece in the workpiece holding device. The at least two clamping units may be configured to adjust their position relative to the holding device to maintain the clamping force during the thermal expansion and/or contraction of the workpiece.

A workpiece holding device for holding a workpiece in a heat treatment system while the workpiece undergoes a thermal expansion and/or contraction includes at least two clamping units configured to apply a radial and/or an axial clamping force to the workpiece to hold the workpiece in the workpiece holding device in a predefined position, and at least three support units configured to support the workpiece. At least one of the support units includes a carrier and an exchangeable support element attached to the carrier, the exchangeable support element being configured to contact and rotatably support the workpiece in the predefined position.

A workpiece clamping device includes a chuck main body, multiple first chuck claws attached to the chuck main body, a second chuck claw attached to the chuck main body, and a driving source configured to move the first chuck claws and the second chuck claw to clamp a workpiece having a rectangular shape, in which the multiple first chuck claws each have a pair of first contact portions, are disposed at positions of different corners, respectively, on a rectangular workpiece, and bring each of the pair of first contact portions into contact with two sides forming the corner to hold the corner, and the second chuck claw has a second contact portion, and is configured to bring the second contact portion into contact with one side of the workpiece to hold the one side of the workpiece.

The invention relates to a double-sided drilling fixture for die-forged pistons and a double-sided drilling process thereof. It overcomes the defects of low efficiency and accuracy of the double-sided drilling operation for die-forged pistons in the prior art. The invention comprises a die-forged piston, a fixture base assembly, an upper load-resisting assembly and a lower expansion-resisting assembly. The upper load-resisting assembly is installed on the fixture base assembly and disposed above the die-forged piston. A fixation base, whose upper surface shape is the same as internal surface shape of the die-forged piston, is installed above the fixture base assembly. The die-forged piston is sleeved on the fixation base. The invention achieves simultaneous drilling on both sides of the two rear skirt surfaces of die-forged pistons and delivers quick clamping and automatic fixation, significantly reducing the difficulty in the assembly of drilling plate and workpiece and increasing the alignment accuracy.

A rim drilling and milling machine has a base (10), a column (20), a turret (30), a saddle (40), a table (50), and a fixture unit (60). The fixture unit (60) has a foundation (61) and four clamping seats defined as two first clamping seats (63A) and two second clamping seats (63B). The first clamping seats (63A) are slidably mounted on the foundation (61) along a first radial direction, and are disposed at positions diametrically opposite in the first radial direction. The second clamping seats (63B) are slidably mounted on the foundation (61) along a second radial direction perpendicular to the first radial direction, and are disposed at positions diametrically opposite in the second radial direction. The four clamping seats can clamp at four equiangular points of a wheel rim.

A hydraulic chuck device includes a cylinder portion operated by pressure oil, a chuck opened and closed by operation of the cylinder portion, a pressure oil supply controlling pressure of pressure oil supplied to the cylinder portion, and a chuck controller controlling the pressure oil supply. When controlling the pressure oil supply to cause a jaw portion to perform a clamping operation, during movement of the jaw portion from an unclamping position to a preliminary position situated before a clamping position, the chuck controller supplies pressure oil set at a first pressure into a cylinder chamber for clamping to move the jaw portion quickly, and during movement of the jaw portion from the preliminary position to the clamping positon, the chuck controller supplies pressure oil set at a second pressure lower than the first pressure into the cylinder chamber for clamping to move the jaw portion slowly.