Abstract: A coordinate measuring machine (CMM) is disclosed having improved manufacturability and low cost while maintaining high performance standards. The CMM includes a polymer composite gantry-style base incorporating a three-point support configuration in the X, Y, and Z axes. The X-beam is hollow, has a horizontal cross-sectional orientation, uses a passive ventilation technique, and is attached to the bearing at one end by a compliant mount. The Z-axis probe shaft incorporates a combined counterbalance/drive assembly and a compliant secondary rail guide mechanism. The X-axis and Y-axis drive screws have angular alignment capability using a spherical washer configuration. This combination of features serves to minimize non-repeatable errors and enhance the manufacturability of the CMM, providing substantial improvements in CMM design and construction.

Abstract: A coordinate measuring machine is described including a vertical probe shaft mounted on an X-axis carriage in turn mounted on a Y-axis carriage for movement along three orthogonal axes, in which the Y-axis carriage is guided and supported on a first guide beam fixed extending along one side of a machine base with air bearings mounted to the lower end of one upright engaging all four sides of the first guide beam. The Y-axis carriage is also supported on a second guide beam fixed extending along the other side of the base, with air bearings mounted to the lower end of the other upright engaging only the top and bottom surfaces. A lower crossmember beam connects the lower ends of the upright to increase stiffness of the Y-axis carriage. A cast aluminum table is supported on the base with three cast in support features projecting from the underside, configured to minimize thermal distortion, with a steel plate bonded into a recess in the upper surface.

Abstract: A coordinate measuring machine (10) having laser interferometers (80, 176, 196) arranged to measure "X" and "Y" carriage and probe motions, in which fiber optic cables (66,72) are used to deliver a laser beam from a laser beam generator (60) to at least some of the interferometers (2176, 196) in order to simplify the optical system and avoid the need for precision alignment of optical components in directing the beam from the laser generator (60) to the various interferometers (176, 196). The laser generator (60) is mounted either on or off the machine base (12). A special clamp (76) and adjustment flexure (74) is used to mount and align the fiber optic cable couplings (96) to beam splitters (64) dividing the laser beam from the laser generator (60) for use along each axis.

Abstract: A coordinate measuring machine (10) having a three point support for a work supporting table (24) mounted over a base (12) constructed of a thermally dissimilar material. A first fixed support, (26A) and a laterally compliant second support (26B) are located at the front of the machine. The second front support (26B) is comprised of a pair of webs (28) oriented to be compliant in the lateral direction to allow relative thermal growth between the table (24) and base (12) while being rigid in the longitudinal direction to prevent rotation of the table (24) about the fixed front support (26A). Stacked crossed roller bearings (38A, 38B) provide a frictionless third point of support at the rear of the table (24).

Abstract: A coordinate measuring machine (10) having laser interferometers (80, 176, 196) arranged to measure "X" and "Y" carriage (52, 16) and probe shaft (56) motions, in which fiber optic cables (66, 72) are used to deliver a laser beam from a laser beam generator (60) to at least some of the interferometers (17). A special clamp (76) and adjustment flexure (74) is used to mount and align the fiber optics (66, 72) to beam splitters (64) dividing the laser beam from the laser generator (60) for use along each axis. The adjusting flexure (74) comprises a series of plate sections (120, 122, 124) interconnected with a pair of webs (142, 164) allowing tilting about two orthogonal axes with a pair of adjusting screws (148). A pair of locking straps (154) secure the plates (120, 122, 124) in the adjusted position. A double clamp (76) having axially spaced clamping jaws (102, 104) is connected to the flexure (74) and provides a stable securement of the optical coupling (96) to the flexure (74).

Abstract: A mounting bracket arrangements for an optical component (10) which must be precisely oriented on a base structure (12) and held securely against vibrations, the arrangement including a bracket assembly (14) having first and second bracket plates (24, 26) extending orthogonally with respect to each other. The component (10) is secured to subplate (20) in turn attached to the first bracket plate (24) with a pivot screw (38) and a pair of locking screws (34, 36) so as to enable pivoting adjustment, secured by tightening all of the screws. The second bracket plate (26) is attached to the base structure (12) by a pivot screw (56) and a pair of locking screws (52, 54) so as to enable pivoting adjustment, thereafter secured by tightening all of the screws. A torque plate (50, 62) is installed beneath each set of locking screws to prevent disturbing the adjusted position as the locking screws are tightened.

Abstract: A coordinate measuring machine (10) having a horizontal probe shaft assembly (20) in which a cover system is provided for the X and Y axis ways (46, 108) and carriages (50, 106), including inwardly slanted X-axis cover members (26) mounted atop granite exposed way members (24) defining a gap through which the Y column (88) moves, a pair of upstanding side covers (32) mounted over the Y-axis column (88) defining a gap through which the probe shaft assembly (20) moves in its vertical movement. a recirculating cover belt (28) fills the X-axis gap and pleated upper and lower covers (34, 36) cover the vertical gap lying between the side covers (32) at the front and rear, while a top cap (38) atop side covers (32) and end caps (30) are fit over the X-axis cover members (26), X-axis way members (24) and base portion (18).

Abstract: A coordinate measuring machine (10) having an improved carriage drive system including a flexible toothed belt (89) mounted on a rigid spar member (88) to be stretched along the carriage (X) axis. The spar member (88) absorbs the tension loading of the stretched flexible belt (89), while the connection (198, 152) of the spar member (88) to the base (12) precludes stressing of the machine (10) by the belt tension or by thermal stresses. A drive package (118) is mounted to one end of the carriage (40) and includes a toothed drum (126) engaging the flexible belt (89) so that upon being rotated by a drive motor (120) acting through a double reduction pulley system (254, 258, 260, 268, 272, 274) to rotate the toothed drum (126) and cause the carriage (40) to be driven along the ways (32, 34). Flexures (86a, 86b) mounting the belt (89) accommodate side to side movement as the carriage (40) is driven along the axis while being rigid to the tension exerted by the belt (89).

Abstract: A bearing arrangement for a coordinate measuring machine having a horizontal probe arm assembly (16) extending to the front of the machine and supported for movement along X,Y, and Z orthogonal axes. The bearing arrangement comprised of opposing sets of supporting or guiding and preloading air bearings (48a,b; 46a,b; 66a,b; 64a,b; 76a,b; 78a,b) for the X carriage (40), the YZ carriage (17) (17a,b; 180a,b; 182a,b; 184a,b; 204a,b), and for the probe shaft (186) (188a,b; 190a,b; 192a,b194a,b). The air bearings each ride on way surfaces formed on the base (12) a column member 160, and the probe shaft (186) and are arranged to most efficiently distribute the load and minimize the effects of inaccuracies in the way surfaces, and make more efficient the accurate machining of the way surfaces.

Abstract: A coordinate measuring machine (10) of the horizontal arm type having an improved way arrangement for a carriage (40) mounted for movement along one of the orthogonal axes (X) of the machine including a pair of angled upstanding granite way members (24,26) detachably mounted spaced apart atop a granite base member (22), extending parallel to each other and the axis of movement. The way members (24, 26) have inwardly turned opposing overhang portions (28, 30) formed with upper horizontal way surfaces (32,34) and under way surfaces (36,38). The carriage (40) is received in the space between the way members (24,26) and is formed with flanges (42,44) extending over the upper way surfaces (32, 34) with pairs of air bearings (46a,b; 48a,b) interposed.

Abstract: A coordinate measuring machine (1) of the type having a plurality of movable members, a probe (2), carriage (5), and bridge (6), each movable along an orthogonal axis adjacent member (16), in which a selectively engageable fine feed mechanism (10) is disclosed providing a limited range of precision adjustment of movement each movable member anywhere along the total range of member movement. The mechanism (10) includes a pair of opposing locking elements (18), selectively spreadable to frictionally engage a slot (20) formed in the adjacent member (16); and also including an adjustment knob (44) axially fixed relative to the locking elements in mounting plate (12) attached to a movable member or fixed member, rotation of the adjustment knob (44) allowing precision adjustment of the position of the movable member after the locking element (18) is engaged with the slot (20).

Abstract: A bridge type coordinate measuring machine (CMM) characterized by a bridge (20) that has a closed loop configuration encircling the upper surface (11) of the measuring machine base (10). The bridge (20) includes two uprights (21, 22), an upper member (23) connecting the uprights together, and a lower member (24) that connects the uprights together above the ways (12, 13) and below the upper surface (11) of said base (10). Bearings (41) acting in three perpendicular directions on each guideway (12, 13) minimize unwanted movement of the bridge (20). This arrangement increases the resonant frequency of the bridge, improves the CMM accuracy and repeatability, and provides for easy assembly of the bridge (20) onto the base (10). Bearings (41) for the bridge are offset inwardly from the vertical axis of the uprights of the bridge and a respective guideway (12, 13), along which the bearings travel, is located on each side of the base.

Abstract: A coordinate measuring machine (CMM) of the type including a bridge (26) supported for horizontal movement on a base (20) that has a table portion (18). The bridge includes cross members (28, 32) that extend above and below the table (18). The bridge (26) supports a probe (12) for vertical movement on a carriage (24) which, in turn, is supported for horizontal movement transversely to the horizontal motion of the bridge (26). The bridge (26) is guided laterally during its movement on the base by means of a rail guide (44) mounted centrally beneath the table (18), and air bearings (48) acting on the guide rail (44). This establishes accurate control over the movement of the bridge (26) on the base (20). Both the table (18) and guide rail (44) are constructed of granite, while the bridge (26) is of aluminum. This arrangement minimizes the effects of thermal expansion between on the components and increases the measuring accuracy of the CMM.