DETAILED DESCRIPTION OF THE DRAWINGS

[0066] In FIG. 1 , one form of machine tool, according to the present invention, is shown at 10 . The components of the machine tool 10 are mounted upon a common support 12 . The machine tool components consist of a first spindle headstock 14 , a second spindle headstock 16 , a first turret headstock 18 , a second turret headstock 20 , and a third turret headstock 22 . The mounting positions and relative movements of the machine tool components 14 , 16 , 18 , 20 , 22 is described relative to an X, Y, Z coordinate system. For a more generic description, the Z-axis will be described as a first line, with the X-axis described as a second line, orthogonal to the first line/Z-axis.

[0067] The first spindle headstock 14 has a first spindle 24 at the working end 26 of the first spindle headstock 14 . The first spindle 24 is rotatable around a central axis 28 . The first spindle headstock 14 faces in a first direction along the first line/Z-axis, as indicated by the arrow 29 . the central axis 28 is substantially parallel to the first line/Z-axis.

[0068] The second/main spindle headstock 16 has a second spindle 30 at the working end 32 thereof that is rotatable around a central axis 34 that is parallel to the first line/Z-axis. The second spindle headstock 16 faces oppositely to the first direction, in the direction of the arrow 36 . In this embodiment, the second spindle headstock 16 is fixedly mounted to the support 12 .

[0069] The first turret headstock 18 is commonly mounted with the first spindle headstock 14 upon a base assembly 38 . The base assembly 38 consists of a base frame 40 that is selectively movable parallel and orthogonal to the first line/Z-axis and second line/X-axis, as indicated by the double-headed arrows 42 , 44 , respectively. The first spindle headstock 14 and first turret headstock 18 are thus moved simultaneously with the base frame 40 . A first turret head 46 is mounted to the first turret headstock 18 to define a first turret assembly at 48 . The first turret head 46 is pivotably mounted relative to the first turret headstock 18 for movement around a first axis 50 that is parallel to the first line/Z-axis. The first turret headstock 18 faces in the first direction, as indicted by the arrow 29 .

[0070] A second turret head 52 is mounted to the second turret headstock 20 to define a second turret assembly 54 . The second turret head 52 is pivotable relative to the second turret headstock 20 for movement around a second axis 56 that is parallel to the first line/Z-axis. The second turret headstock 20 faces oppositely to the first direction i.e. in the direction of the arrow 36 .

[0071] A third turret head 60 is mounted to the third turret headstock 22 to define a third turret assembly 62 . The third turret head 60 is pivotable relative to the third turret headstock 22 around a third axis 64 that is parallel to the first line/Z-axis. The third headstock 22 faces in the same direction, as does the second turret headstock 20 i.e. oppositely to the first direction as indicated by the arrow 36 .

[0072] The second turret headstock 22 can be translated selectively along the first line/Z-axis, second line/X-axis, and Y-axis, as seen relative to the XYZ coordinate system representation superimposed thereon. The third turret headstock 22 is translatable selectively along the first line/Z-axis, and second line/X-axis, as indicated by the double-headed arrows 66 , 68 , respectively. The second turret headstock 20 , third turret headstock 22 , and second spindle headstock 16 are relatively situated so that the central axis 34 of the second spindle headstock 16 resides between the second axis 56 and the third axis 64 on the second turret headstock 20 and third turret headstock 22 , respectively. The base frame 40 is spaced opposite to the first direction from the second spindle headstock 16 i.e. to the right thereof in FIG. 1 .

[0073] As explained in greater detail below, the first spindle headstock 14 is movable along the first line/Z-axis, as indicated by the double headed arrow 70 relative to the base frame 40 . Optionally, the first turret headstock 18 can be translated relative to the base frame 40 and first spindle headstock 14 along one or both of the first line/Z-axis and second line/X-axis, as indicated by the double-headed arrows 72 , 74 .

[0074] Referring now to FIGS. 8 and 9 , the details of the cooperation between the base assembly 38 , first turret headstock 18 , and first spindle headstock 14 will be described. The base assembly 38 consists of an elongate guide rail 76 which is mounted upon the support 12 and extends along the first line/Z-axis. A slide element 78 cooperates with the guide rail 76 , so as to be guided thereby, along the first line/Z-axis. An elongate guide rail 80 is fixed to the slide element 78 and extends along the second line/X-axis. The base frame 40 cooperates with the guide rail 80 so as to be guided thereby along the second line/X-axis.

[0075] The first turret headstock 18 is shown fixedly attached to the base frame 40 . The base frame 40 additionally supports spaced, elongate, guide rails 82 , 84 , which extend parallel to the first line/Z-axis. The guide rails 82 , 84 cooperate with a carriage 86 , that is part of the first spindle headstock 14 , to guide movement of the first spindle headstock 14 along the first line/Z-axis relative to the base frame 40 .

[0076] The first turret head 46 , as previously mentioned, is pivotable about the first axis 50 . Pivoting, indexing movement of the first turret head 46 is imparted by a drive 88 .

[0077] The first turret head 46 has an outer circumference from which a plurality of circumferentially spaced tool holders/tools 90 A, 90 B, 90 C, 90 D, 90 E, 90 F, 90 G, 90 H project. The first turret head 46 has a generally V-shaped portion, as viewed along the first axis 50 with an apex at 91 and legs 92 , 94 projecting angularly away from the apex 90 and substantially including the tools 90 A-H. The first axis 50 resides within the “V”. The tools 90 A- 90 H extend circumferentially through an angle α equal to approximately 160°. The remaining circumferential extent (360°-α) defines a void at 96 .

[0078] Conventionally, 12 tools/tool holders are equidistantly spaced around the circumference of a turret head. In the embodiment shown, 8 such tools/tool holders 90 A-H are shown with the space for the absent, remaining 4 tools defining the void 96 . The circumferential extent of the void 96 may vary substantially from that shown and will depend on a particular system configuration and desired operating characteristics. Similarly, the number of total tools/toolholders is a design consideration. For example, the void 96 may extend through a 160° circumferential angle. The purpose of the void 96 , which dictates its shape, will now be described.

[0079] The first turret head 46 is indexable through the drive 88 between, among other positions, a first angular position, shown in FIG. 9 , and a second angular position, as shown in FIG. 8 . Actually, the first and second angular portions are each within a functionally equivalent range of angular positions. In the first angular position, the first turret head 46 projects a first radial distance R1 from the first axis 50 toward the first spindle headstock 14 , as shown in FIG. 9 to allow the first turret head 46 and first spindle headstock to be placed in a first relative state as shown in FIG. 9 . In the second angular position, the first turret head 46 projects radially a second distance R2 from the first axis 50 toward the first spindle headstock 14 , as shown in FIG. 8 , to allow the first turret head and first spindle headstock to be placed in a second relative state, as shown in FIG. 8 . The distance R1 is less than the distance R2.

[0080] As seen in FIG. 9 , with the first turret head 46 in the first angular position, the void 96 functions as a receptacle to accommodate the first spindle headstock 14 . The first turret head 46 is thus allowed to move, as in conjunction with the first turret headstock 18 , along the first line/Z-axis from a position spaced along the first line/Z-axis to the left of the working end 26 of the first spindle 24 up to and past the first spindle 24 , without interference, and into coincidence along the first line/Z-axis with the remaining portion of the first spindle headstock 14 . Accordingly, the combined configuration of the first turret assembly 48 and first spindle headstock 14 can be made relatively compact along the second line/X-axis, by reducing the required spacing between the first axis 50 and the central axis 28 of the first spindle headstock 14 .

[0081] By indexing the first turret head 46 to the second angular position, the active tool/toolholder 90 is extended into coincidence along the second line/X-axis with the first spindle 24 .

[0082] Representative consecutive machining operations utilizing the inventive machine tool 10 will now be described with respect to FIGS. 1-7 . In FIG. 1 , a workpiece W 1 is chucked by the second spindle 30 . By turning the workpiece W 1 , an outer diameter processing step can be performed using a cutting tool 90 ′ on the second turret head 52 , simultaneously as an outer diameter processing step is performed by a cutting tool 90 ″ on the third turret head 60 . At the same time, the base assembly 38 can be repositioned, as from a position as in FIG. 6 , to the FIG. 1 position by movement along the first line/Z-axis and continuously moved to perform differential inside diameter drilling with representative cutting tool 90 B on the first turret head 46 . Accordingly, the two outside diameter processing steps can be performed simultaneously as the differential inside diameter drilling is performed.

[0083] The workpiece W 1 is identified in FIG. 2 as W 1 (P 1 ) after the processing of FIG. 1 is performed. With the workpiece W 1 (P 1 ) remaining chucked by the second spindle 30 , the rotation of the second spindle 30 can be halted. The second turret head 52 and third turret head 60 can be indexed to actively situate drilling tools 90 ′A and 90 ″A so as to simultaneously drill the stationary workpiece W 1 (P 1 ). At the same time, the same or different tool 90 B on the first turret head 46 can be operated to perform a face drilling operation on the stationary workpiece W 1 (P 1 ). All three drilling operations can thus be performed simultaneously on the workpiece W 1 (P 1 ).

[0084] In FIG. 3 , the workpiece W 1 is identified as W 1 (P 2 ) after being processed as shown in FIG. 2 . In FIG. 3 , the workpiece W 1 (P 2 ) is chucked by the first and second spindles 24 , 30 , respectively. The first turret head 46 is indexed to the first angular position so as to create a gap G between the first turret assembly 48 and the first spindle headstock 14 so that they can be relatively overlapped along the first line/Z-axis without interference therebetween. This allows the first spindle headstock 14 to be advanced along the first line/Z-axis towards the workpiece W 1 (P 2 ) chucked by the second spindle 30 so that the first spindle 24 can simultaneously chuck the workpiece W 1 (P 2 ). The second turret head 52 and third turret head 60 can then be indexed to actively situate the cutting tools 90 ′B, 90 ″B, respectively thereon, operatively at the held workpiece W 1 (P 2 ). By then simultaneously rotating the first and second spindles 24 , 30 , one or both of the cutting tools 90 ′B, 90 ″B, can be used to sever the moving workpiece W 1 (P 2 ). By reason of overlapping the first turret headstock 18 and first spindle headstock 14 along the first line/Z-axis, the first turret head 52 can be situated to perform the cutting operation as shown in FIG. 3 without interference from the first turret head 46 . For the same reason, chucking of the workpiece W 1 (P 2 ) by the first spindle 24 is made possible by the lack of interference between the first spindle headstock 14 and the first turret head 46 .

[0085] In FIG. 4 , the workpiece W 1 is identified as W 1 (P 3 ), after being cut off in a process shown in FIG. 3 and held by the first spindle 24 , which is thereafter moved away from the second spindle 30 . This retracting movement of the first spindle 24 is accomplished by moving the base assembly 38 which thereby simultaneously shifts the first turret assembly 48 therewith. The first spindle headstock 14 may additionally be retracted relative to the base assembly to speed up the reconfiguration process. Backside processing of the workpiece W 1 (P 3 ) can then be continued by rotating the first spindle 24 and utilizing a cutting tool 90 ′C and a cutting tool 90 ″C indexed to an operative position respectively by the second turret head 52 and the third turret head 60 . The backside processing may take place immediately after the cutting operation described with respect to FIG. 3 .

[0086] In FIG. 5 , simultaneously operation on the workpiece W′(P 3 ) which is the remaining portion of the workpiece W 1 chucked in the second spindle 30 after processing as in FIG. 3 , and the workpiece W 1 (P 4 ), which is the workpiece W 1 chucked by the first spindle 24 after processing as in FIG. 4 . The workpiece W′(P 3 ) is chucked and rotated by the second spindle 30 and simultaneously processed by tools 90 ′D, 90 ″D indexed to an active position respectively by the second turret head 52 and third turret head 60 and by a tool 90 C on the first turret head 46 . The workpiece W 1 (P 4 ) chucked by the first spindle 24 is rotated and processed by the tool 90 C carried by the first turret head 46 .

[0087] To accomplish this, the base assembly 38 is shifted towards the left in FIG. 5 from the FIG. 4 position. The first spindle headstock 14 is shifted oppositely along the first line/Z-axis i.e. to the right relative to the base frame 40 . As an example, back drilling may be performed by the tool 90 C on the workpiece W 1 (P 4 ). On the workpiece W′(P 3 ) held by the second spindle 30 , outside diameter turning operations may be performed by the tools 90 ′D, 90 ″D. At the same time, differential inside diameter machining may be performed on the workpiece W′(P 3 ) by the tool 90 C, utilizing the translatory movement of the first turret headstock 18 along the first line/Z-axis. All of the above described operations may be performed on the two workpieces W′(P 3 ) and W 1 (P 4 ) simultaneously.

[0088] In FIG. 6 , the workpiece, previously identified as W′(P 3 ) in FIG. 5 , is identified as W′(P 5 ), after processing as in FIG. 5 . The workpiece W 1 (P 4 ) in FIG. 5 is identified in FIG. 6 as W 1 (P 5 ), after processing as in FIG. 5 .

[0089] To arrive at the FIG. 6 configuration, the base assembly 38 is shifted along the first line/Z-axis, to the right in FIG. 6 from the FIG. 5 position. In this configuration, the workpiece W′(P 5 ) chucked by the second spindle 30 is processed on the outside diameter by a tool 90 ′E on the second turret head 52 . A tool 90 ″E on the third turret head 60 performs inside diameter processing of the workpiece W 1 (P 5 ) simultaneously with processing by the tool 90 ′E. The backside, inside diameter processing of the workpiece W 1 (P 5 ) can be continued by the tool 90 C on the first turret head 96 simultaneously as the workpiece W′(P 5 ) is processed by the tool 90 ′E, 90 ″E.

[0090] The processing cycle time may be kept relatively short by simultaneously performing backside processing on the workpiece W 1 (P 5 ) and simultaneous inside and outside diameter processing on the workpiece W′(P 5 ).

[0091] Further, because the first spindle headstock 14 can be translated along the first line simultaneously as the base frame 40 is moved in the same direction along the first line, the benefit of the combined speed of movement along the first line can be exploited. It is possible to perform the backside processing on the workpiece W 1 (P 5 ) without requiring complicated, simultaneous control of multiple machining components.

[0092] In FIG. 7 , an additional configuration of the machine tool 10 is shown simultaneously operating on the previously processed workpiece W 1 (P 5 ), identified as W 1 (P 6 ) in FIG. 7 after processing as in FIG. 6 , and a separate, elongate workpiece W 2 . In this configuration, the third turret assembly 62 and base assembly 38 are moved towards each other along the first line/Z-axis. Backside processing is performed on the workpiece W 1 (P 6 ) chucked by the spindle 24 by a tool 90 ″F on the third turret head 60 .

[0093] Simultaneously, front face processing is performed on the workpiece W 2 by a tool 90 ′F on the second turret head 52 , with the workpiece W 2 chucked by the second spindle 30 .

[0094] The free end 98 of the workpiece W 2 is additionally supported by a subspindle 100 on the first turret head 46 , with the first turret head 46 in the first angular position. The subspindle 100 stabilizes the workpiece W 2 to avoid chattering thereof during operation.

[0095] By reason of placing the first turret head 46 in the first angular position, the first spindle headstock 14 is allowed to be moved relative to the first turret head 46 so that the first spindle 24 can chuck the workpiece W 1 (P 6 ) situated to the left of the first turret head 46 in FIG. 7 , and the subspindle 100 thereon, without any interference between these elements. Thus, the subspindle 100 and first spindle 24 are simultaneously useable for improved overall efficiency.

[0096] While the system operation, as described with respect to FIGS. 1-7 shows the first spindle headstock 14 to be movable only along the Z-axis, more preferably, as shown in FIGS. 10 and 11 , the first spindle headstock 14 is movable relative to the base frame 40 translatingly along the second line/X-axis. As shown in FIG. 10 , the first spindle headstock 14 is movable relative to the base frame 40 selectively along the first line/Z-axis and second line/X-axis, as indicated by the double-headed arrows 102 , 104 , respectively.

[0097] One mechanism for accomplishing the above described movement of the base frame 40 and between the first spindle headstock 14 , base frame 40 , and first spindle headstock 14 is shown in FIG. 11 . The base frame/plate 40 is mounted upon the support 12 . A ball screw assembly 112 is mounted to the base frame 40 . The first rod 114 is threadably engaged wit the ball screw assembly 112 and driven by a motor 116 secured to the support 12 . By operating the motor 116 selectively in forward and reverse directions, the base frame 40 can be selectively advanced through the ball screw assembly 112 along the first line/Z-axis, as indicated by the double-headed arrow 118 .

[0098] The base frame 40 in turn carries second and third base plates 120 , 122 , which follow movement of the base frame 40 along the first line/Z-axis. The second base plate 120 supports the first turret headstock 18 . A second ball screw assembly 124 is fixed to the second base plate 120 and threadably receives a second rod 126 driven by a motor 128 fixed to the base frame 40 . By operating the motor, the rod 126 and second ball screw assembly 124 cooperate to selectively translate the second base plate 120 in opposite directions along the second line/X-axis, as indicated by the double-headed arrow 128 .

[0099] The third base plate 122 in turn supports a fourth base plate 130 . The first spindle headstock 14 is operatively mounted on the fourth base plate 130 .

[0100] A third ball screw assembly 132 is attached to the third base plate 122 and cooperates with a threaded rod 134 driven by a motor 136 fixed to the second base plate 120 . By operating the motor 136 selectively in opposite directions, the third base plate 122 can be translated relative to the second base plate 120 along the second line/X-axis, as indicated by the double-headed arrow 138 , to thereby control the spacing between the first axis 50 and the central axis 28 of the first spindle headstock 14 .

[0101] The fourth base plate 130 , and the first spindle headstock 14 mounted thereon, are movable relative to the third base plate 122 in opposite directions along the first line/Z-axis, as indicated by the double-headed arrow 140 . This is accomplished by utilizing a cooperating rod 142 and fourth ball screw assembly 144 . The rod 142 is controllably driven by a motor 146 fixed to the third base plate 122 .

[0102] With this arrangement, the base frame/plate 40 can be moved along the first line/Z-axis to simultaneously reposition the first turret assembly 48 and first spindle headstock 14 . The first turret assembly 48 can be independently repositioned along the second line/X-axis relative to the base frame 40 . The first turret assembly 48 and first spindle headstock 14 can be relatively repositioned along the second line/X-axis. The first spindle headstock 14 can be independently moved relative to the first turret assembly 48 along the first line/Z-axis. With the motor 136 stationary, the second base plate 120 and third base plate 122 move unitarily to be shifted along the second line/X-axis by the motor 128 and by the motor 116 along the first line/Z-axis.

[0103] By using the plate arrangement shown, multiple variations of movement between the first turret assembly 48 and first spindle headstock 14 are possible using a relatively low profile construction. This facilitates compact and efficient overall system design.

[0104] As shown in FIG. 10 , using the FIG. 11 mechanism, another dimension of operation can be achieved compared to the corresponding setup shown in FIG. 5 , absent this additional degree of movement. Because the first spindle headstock 14 can move along the second line/X-axis, typically up to a distance of 30 mm, not only drilling operations may be performed, but also inside and outside diameter turning operations become possible with the workpiece W 1 (P 4 ) chucked by the first spindle 24 of the first spindle headstock 14 , using the tool 90 G on the first turret head 46 .

[0105] As previously noted, there are a number of advantages afforded by the inventive structure. As one example, the combined movement of the base frame 40 along the first line/Z-axis, combined with the movement of the first spindle headstock 14 in the same direction relative to the base frame 40 , allows compounding of the resultant movement of the first spindle headstock 14 relative to the other system components, such as the second turret assembly 54 , third turret assembly 62 , and second spindle headstock 16 . This construction potentially introduces cost savings in the system design and may require a lesser degree of complexity to coordinate operation of the system components. Conventional systems may utilize independent machining components that require a complex scheme of coordination. Potentially complex combinations of machining operations can be performed, using the present invention, without the generally required complex coordination of separate components in the prior art. This may be particularly true in the case of backside machining on a workpiece wherein, for example, the first spindle headstock 14 and first turret assembly 48 are relatively moved as they are moved in unison through the base frame 40 .

[0106] Additionally, by utilizing the sliding movement of the first turret assembly 48 and first spindle headstock 14 , differential inside and outside diameter machining is made possible.

[0107] The foregoing disclosure of specific embodiments is intended to be illustrative of the broad concepts comprehended by the invention.