COMPUTER CONTROLLED MACHINE TOOL ASSEMBLY WITH MULTIPLE TAIL

UNITS

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

[0001] This patent application claims the benefit of U.S. Provisional Patent Application No. 60/938,580 filed May 17, 2007, herein incorporated by reference for all purposes.

FIELD OF THE INVENTION

[0002] This invention pertains to computer controlled machine tools, such as automatic lathes, and, more particularly, to the tail units for such machine tools.

BACKGROUND OF THE INVENTION

[0003] Figure 1 is a side view illustrating one example of a conventional computer numerically controlled (CNC) lathe 10. In this example, the CNC lathe 10 has one main spindle 20 with a chuck 22 for mounting and rotating a workpiece in a z axis. The main spindle is attached to a spindle head stock 2OA. Note: A chuck is a "hand" for grabbing the workpiece and is used when a cutting process is performed on the workpiece, usually for a lathe and a machining center (computer controlled milling machine). Lathe 10 also includes a turret 30 that revolves to process the necessary cutting tools or cutlery for cutting the workpiece mounted to chuck 22. Note: A turret is a rotational base in which a metal cutting tool can be attached. Turret 30 is mounted on a processing base or turret head stock 32 that, in this example, is able to move along an X axis, which is axis Xl, and a Z axis in order to engage the workpiece being held by chuck 22 and rotated by spindle 20 mounted in spindle head stock 2OA. Figure 2 is a simplified end view of lathe 10 illustrating a relationship between spindle 20, which is fixedly attached to the machine base 12 by bolts, in this example, and turret 30, which can move in the Xl axis to engage the workpiece held by chuck 22. In this example, lathe 10 includes a tailstock 42 mounted on tailstock post 44 that prevents a run off from the revolving center concentric to the direction of the main spindle when cutting a long cylindrical workpiece accurately, which is mounted in alignment with main spindle 20 with movement along an x-axis X2. The spindle 20, turret 30 and turret head stock 32, and tailstock post 44 are mounted on a machine base 12.

[0004] The conventional CNC lathe 10 operates by cutting a workpiece using a cutting tool as the workpiece is rotated. Chuck 22 holds the workpiece while spindle 20 rotates. Turret 30 rotates to present a cutting tool to the workpiece and turret head stock 32, in this example, moves to bring the cutting tool into contact with the rotating workpiece under precise computer control.

[0005] Figure 3 is a top view of lathe 10 further illustrating that spindle 20 and tailstock 42 share a common axis X2 about which spindle 20 rotates. Generally, the tailstock 42 is installed on the same axis as spindle 20 and chuck 22, where spindle 20 rotates on a rotational axis, which is the x-axis in this example. A center pushing tailstock 42 is typically used when working on a long workpiece, called a shaft type workpiece. One end of the shaft type workpiece is gripped by chuck 22 for rotation by spindle 20. The other end of the shaft type workpiece, e.g. the shaft type workpiece's tip, is engaged by tailstock 42, which is used to hold onto the workpiece so that it will not vibrate when the shaft type workpiece is rotated by spindle 20.

BRIEF SUMMARY OF THE INVENTION

[0006] In one embodiment, a machine tool assembly has a first spindle (120) configured to rotate in a first axis (X2) and a first chuck (122) for holding a first end of a workpiece. A first spindle headstock (124) holds the first spindle (120) and is fixedly attached to a base (112). A first turret (130) is mounted on a first turret headstock (132) that is connected to the base (112) and provides for movement along a parallel axis (Xl) and a first perpendicular axis (Z) relative to the first axis (X2). A second spindle (140) configured to rotate in the first axis (X2) having a second chuck (142) for holding a second end of the workpiece. A second spindle headstock (144) holds the second spindle (140) and is movably connected to the base (112) to provide movement of the second spindle (140) along the first axis (X2). In a further refinement of this embodiment, the second spindle headstock (144) is movably connected to the base (112) to provide movement of the second spindle (140) in a second perpendicular axis (Z2). In still another refinement, the assembly further includes a tailstock (342) movably connected to the base (112) along with the second spindle headstock (354) to provide movement of the second spindle (350) and the tailstock (342) along the first axis (X2) and the second perpendicular axis (Z2). In yet

another refinement, the assembly further includes a second turret (360) movably connected to the base (112) along with the second spindle headstock (354) to provide movement of the second spindle (350), the tailstock (342), and the second turret (360) along the first axis (X2) and the second perpendicular axis (Z2).

[0007] In an embodiment of a multiple turret machine tool assembly, the assembly includes a first spindle (120) configured to rotate in a first axis (X2) and having a first chuck (122) for holding a first end of a workpiece. A first spindle headstock (124) holds the first spindle (120) and is fixedly attached to a base (112). A first turret (230) is mounted on a first turret headstock (232) that is connected to the base (112) and provides for movement along a first parallel axis (Xl) and a first perpendicular axis (Z) relative to the first parallel axis (X2). A second turret (242) mounted on a second turret headstock (244) that is connected to the base and provides for movement of the second turret along a second parallel axis (X3) parallel to the first axis (X2).

[0008] An embodiment of a method calls for gripping a first end of the workpiece with a first chuck (122) and rotating the workpiece in a first axis (X2) using a first spindle (120) as well as cutting the workpiece using a first turret (130) mounted on a first turret headstock (132) that is connected to the base (112) and provides for movement along a parallel axis (Xl) and a first perpendicular axis (Z) relative to the first axis (X2). The method further calls for gripping a second end of the workpiece with a second chuck (142) and rotating the workpiece in the first axis (X2) using a second spindle (350) as well as cutting the first end of the workpiece using the first turret (130). A refinement of the method calls for providing the second spindle (350) with computer controlled motion parallel to the first axis (X2) and perpendicular to the first axis (X2). A further refinement of the method calls for mounting a tailstock (342) with the second spindle (350) and the step of cutting the workpiece using a first turret (130) includes stabilizing the workpiece using the tailstock (342). A still further refinement of the method calls for mounting a second turret (360) with the second spindle (350) and cutting the workpiece using the second turret (130).

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a side view illustrating one example of a conventional computer numerical controlled (CNC) lathe 10;

[0010] Figure 2 is a simplified end view of the lathe 10 of Figure 1 illustrating a relationship between a spindle 20, which is fixed in this example, and turret 30, which can move in the Xl axis to engage the workpiece held by a chuck 22;

[0011] Figure 3 is a simplified top view of the lathe 10 of Figure 1 illustrating a relationship between a spindle 20 and a tailstock 42, which are aligned in a common axis X2 to engage a workpiece held by a chuck 22;

[0012] Figure 4 is a simplified top view of an exemplary embodiment of a machine tool assembly 100 in accordance with one aspect of the present invention;

[0013] Figure 5 is a simplified top view of another exemplary embodiment of a machine tool assembly 200 in accordance with another aspect of the present invention; and

[0014] Figure 6 is a simplified top view of yet another exemplary embodiment of a machine tool assembly 300 in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0015] Exemplary embodiments of computer controlled lathes are shown with various tail units providing for added processing capability over conventional lathes. In one exemplary embodiment of a machine tool assembly 100, such as a computer controlled lathe, in accordance with the present invention is shown in Figure 4. The machine tool assembly 100 of Figure 4 includes a secondary spindle 140 instead of a tailstock. The secondary spindle 140 is positioned on the same axis X2 as main spindle 120 and may be used for secondary processing.

[0016] This secondary spindle 140 is used for a second cutting step after a first cutting step has been performed on a workpiece using the main spindle 120. After the first cutting step on the workpiece is complete, secondary chuck 142 of secondary spindle 140 grips the workpiece so that the lathe 100 can process the other end of the workpiece that had been gripped by main chuck 122 of main spindle 120. Secondary spindle 140 is mounted on secondary spindle stock 144, which provides computer controlled motion along the axis X2 so that secondary chuck 142 can engage the workpiece while the workpiece is gripped by

main chuck 122. The main chuck 122 is then disengaged so that secondary spindle 140 can rotate the workpiece as it is held by secondary chuck 142.

[0017] In this example, a rotatable tool turret 130 is mounted on turret stock 132, which provides computer controlled x-axis motion, along axis Xl, and z-axis motion. Turret 130 is used to perform the first and second cutting steps by engaging the workpiece using cutting tools mounted in the turret 130, which is moved under computer control by turret stock 132.

[0018] Figure 5 is a simplified top view of another exemplary embodiment of a machine tool assembly 200 in accordance with another aspect of the present invention. In this embodiment, the machine tool assembly is a lathe 200 that includes a main spindle 220 that has a main chuck 222 and is mounted on a fixed position main spindle stock 224. A main turret 230 is mounted on a main turret stock 232 that provides computer controlled x-axis motion, along axis Xl, and z-axis motion. Lathe 200 also includes a secondary turret 242 mounted on a second turret stock 244, which provides x-axis motion, along an axis X3, relative to a main spindle 220. Secondary turret 242 takes the place of a tailstock and may be used to perform additional processing steps on a workpiece held by main chuck 222, such as drilling the workpiece along axis X3. For example, second turret 242 may be used to drill a deep hole into the workpiece, such as a bore hole. In some applications, a tool mounted on the secondary turret 242 may perform a drilling step on the workpiece at the same time that main turret 230 is performing a cutting step on the outer surface of the workpiece. Generally, the drilling speed when processing a workpiece is slower than the cutting of the outer diameter. This may result in a longer processing time than the time required for just cutting the outer diameter of the workpiece. However, using the computer controlled lathe 200 to simultaneously perform multiple processing steps, such as drilling out the workpiece using the secondary turret 242 while cutting the outer surface of the workpiece with main turret 230, may reduce the overall processing time required to achieve the same level of processing on a workpiece.

[0019] Figure 6 is a simplified top view of yet another exemplary embodiment of a machine tool assembly 300 in accordance with the present invention. In this embodiment, machine tool assembly 300 is a lathe having a main spindle 320 that has a main chuck 322 and is mounted on a fixed position main spindle stock 324. A main turret 330 is mounted

on a main turret stock 232 that provides computer controlled x-axis motion, along axis Xl, and z-axis motion, along an axis Zl. Lathe 300 further includes a tailstock 342 mounted on a tailstock post 344, which is mounted to a computer controlled z-axis slide motion plate 380. In addition, lathe 300 includes a secondary spindle 350 having a secondary chuck 352 and mounted on secondary spindle stock 354, which is mounted to z-axis motion plate 380. Lathe 300 also includes a secondary turret 360 mounted on a secondary turret stock 362, which is mounted to motion plate 380. Z-axis motion plate is movably connected to x-axis slide motion plate 370, which is connected to machine base 312. Mounting tailstock post 344, secondary spindle stock 354, and secondary turret stock 362 to motion plates 370 and 380 provides computer controlled x-axis motion, along axis X2, and z-axis motion, along axis Z2, respectively, relative to main spindle 320.

[0020] The resulting combination permits a variety of secondary processing steps to be performed on a workpiece under computer control. Tailstock 342 may be used to stabilize long workpieces during processing using main spindle 320. Secondary spindle 350 may be used to perform an additional cutting step on the end of a workpiece gripped by main chuck 322 during a first cutting step. Secondary turret 360 may be used to perform yet another cutting step, such as drilling on a face of the workpiece facing towards turret 360, secondary spindle 350 and tailstock 342. For example, a long workpiece may be stabilized tailstock 342 during a first cutting step while main turret 330 is used to cut the outer surface of the workpiece. The second turret 360 may be used to drill or cut the face of the workpiece facing away from main chuck 322 and toward second turret 360. The secondary chuck 352 may then be used to grip the workpiece so that a second cutting step may be performed by main turret 330 on the portion of the workpiece that was gripped by main chuck 322 during the first cutting step. The combination of lathe 300 enables a wide range of processing to be performed on a workpiece utilizing the same computer controlled equipment and may permit processing time to be reduce.

[0021] All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0022] The use of the terms "a" and "an" and "the" and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., "such as") provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0023] Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. It should be understood that the illustrated embodiments are exemplary only, and should not be taken as limiting the scope of the invention.