Hydrostatically actuated workholding apparatus

#This invention relates generally to machine tools and gauges and more particularly to a hydrostatic workpiece holding apparatus.

#Workholding apparatuses or workpiece holders for machining and gauging applications have been used for many years for holding cylindrical and annular workpieces for machining, grinding, measuring, or gauging thereof. It is known that a workpiece holder for machining or grinding workpieces may be hydraulically actuated and one such workpiece holder is disclosed in U.S. Pat. No. 7,967,300 assigned to Hydra-Lock Corporation of Mt. Clemens, Mich. which is the assignee of this application.

#In at least some implementations, a workpiece holder may be in the form of an arbor which may have a hydraulically expandable sleeve received on an arbor body and at least two and desirably three or more equally circumferentially spaced apart separate locators received over the sleeve and movable generally radially outward relative to the body to engage part of a bore of a workpiece to hold the workpiece for machining, grinding, gauging or measuring one or more surfaces of the workpiece. In at least some implementations the locators may be generally circumferentially and axially located by a retainer collar at least in part received over the sleeve of the arbor. In at least some implementations, the retainer collar may have an outer sleeve received over an inner sleeve. In at least some implementations, the arbor may include one or more stops to axially locate a workpiece relative to the locators and/or expandable sleeve.

#The following detailed description of the embodiments and best mode will be set forth with reference to the accompanying drawings in which:

#FIG. 1 is a side view of a pulley workpiece;

#FIG. 2 is a sectional view taken on line 2-2 of FIG. 1;

#Referring in more detail to the drawings, FIGS. 1-4 illustrate a pulley wheel 20 with a hub 22 configured to be received on and connected to a shaft for rotation therewith. The hub may have a central bore 24 essentially coaxial with a cylindrical peripheral surface 26 of the pulley wheel. The hub may have three equally circumferentially spaced apart and axially extending grooves 28 each configured to receive a roller key therein. The hub may also have two axially spaced apart and circumferentially extending oil grooves 30 each opening into the roller key grooves.

#FIG. 5 illustrates a workpiece holder 32 in the form of an arbor 34 for holding a workpiece such as the pulley wheel 20. As shown in FIGS. 6 & 7, for engaging and holding the workpiece pulley, the arbor 34 may have at least two and desirably at least three equally circumferentially spaced apart locators 36 generally radially movable into engagement with the workpiece roller grooves by an expandable sleeve 38 carried by a body 40 and expandable by a pressurized hydraulic fluid such as a hydraulic oil or grease. The locators 36 may be retained on the body by a collar 42 received over the sleeve. The collar may have an outer sleeve 44 received over an inner sleeve 46.

#The body 40 may have a series of cylindrical surfaces 48, 50, 52 with a common axis 54 and each having a diameter smaller than the diameter of the bore 24 of the workpiece, a shoulder 56 and a desirably cylindrical shank 58 for holding the arbor 34 and/or securing it in a chuck of a machine tool. The shank may be used to support the arbor such as when it may be used for carrying a workpiece for measurement or gauging purposes. To limit axial movement of the arbor into the bore 24 of the pulley workpiece and thus provide a desired axial position of the locators 36 in the bore, a stop ring 60 may be received and fixed such as by a press fit on the shoulder for engagement with an end face 62 of the hub of the workpiece.