HIGH SPEED MULTI-AXIS MACHINE TOOL

Abstract

An apparatus and method are provided for three dimensional planing of a workpiece. The apparatus includes a base, a displaceable machine table supported on that base, a displaceable spindle supported on the base adjacent the machine table, a cutting tool held in a chuck carried on the spindle and a control module. The control module includes a controller and a plurality of actuators to provide precise displacement of the machine table, spindle, cutting tool and the workpiece for planing surface features into the workpiece.

Claims

1. An apparatus comprising: a base; a displaceable machine table supported on the base; a displaceable spindle supported on the base adjacent the machine table, said spindle including a chuck; a cutting tool held in said chuck on said spindle; and a control module including a controller adapted to control an X-axis actuator, a Y-axis actuator and a Z-axis actuator whereby precise relative movement of said displaceable machine table and said displaceable spindle is provided for three dimensional planing of a workpiece held on said machine table.

2. The apparatus of claim 1 wherein said X-axis actuator is held on said base and adapted to displace said displaceable machine table in an X-axis direction.

3. The apparatus of claim 2, wherein said Y-axis actuator is held on said base and adapted to displace said displaceable machine table in a Y-axis direction.

4. The apparatus of claim 3, wherein said Z-axis actuator is held on said base and adapted to displace said displaceable spindle in a Z-axis direction toward or away from said displaceable machine table.

5. The apparatus of claim 4, wherein said control module further includes a spindle actuator adapted to index, rotate and align the cutting tool held in the chuck for proper engagement and clearance with the workpiece held on the displaceable machine table.

6. The apparatus of claim 5, wherein said control module further includes a workpiece actuator parallel to one of the X-axis and the Y-axis of the displaceable machine table and adapted to index the workpiece on the displaceable machine table.

7. The apparatus of claim 6, wherein said base further includes a column supporting said displaceable spindle.

8. The apparatus of claim 7, wherein said cutting tool includes a single point.

9. The apparatus of claim 8, wherein said controller is configured to produce with said cutting tool at least one of a curved feature, a variable depth slot, a free-form slot and a pocket in the workpiece.

10. The apparatus of claim 9, further including a cryogenic cooling element for cooling said cutting tool and workpiece during machining.

11. A method of machining a workpiece, comprising: displacing a workpiece along an X-axis and a Y-axis; and simultaneously displacing a cutting tool along a Z-axis to provide a cutting stroke allowing planing of a surface feature in said workpiece.

12. The method of claim 11, further including indexing, rotating and aligning the cutting tool during reciprocation of the cutting tool along the Z-axis.

13. The method of claim 12, further including indexing the workpiece during reciprocation of the cutting tool along the Z-axis.

14. The method of claim 13, further including planing a curved feature into the workpiece using a single point cutting tool.

15. The method of claim 13, further including planing a variable depth slot into the workpiece using a single point cutting tool.

16. The method of claim 13, further including planing a free-form slot into the workpiece using a single point cutting tool.

17. The method of claim 13, further including planing a pocket into the workpiece using a single point cutting tool.

18. The method of claim 13, including using a control module, having a controller and controller-controlled actuators to displace the workpiece along the X-axis and the Y-axis and the cutting tool along the Z-axis, to control the machining process.

19. The method of claim 18, including using a controller-controlled spindle actuator to index, rotate and align the cutting tool carried on a displaceable spindle.

20. The method of claim 19, including using a controller-controlled workpiece actuator to index the workpiece on a displaceable machine table.

Description

BRIEF DESCRIPTION OF THE DRAWING FIGURES

[0020] The accompanying drawing figures incorporated herein and forming a part of the patent specification, illustrate several aspects of the apparatus and method and together with the description serve to explain certain principles thereof.

[0021] FIG. 1A is a perspective view of the apparatus adapted for three dimensional planing of a workpiece with a single point cutting tool.

[0022] FIG. 1B is a front elevational view of the apparatus illustrated in FIG. 1A.

[0023] FIG. 1C is a left side elevational view of the apparatus illustrated in FIG. 1A.

[0024] FIG. 1D is a top plan view of the apparatus illustrated in FIG. 1A.

[0025] FIG. 2 is a detailed front elevational view of the displaceable spindle of the apparatus illustrated in FIG. 2.

[0026] FIG. 3 is a schematic block diagram of the operation control system of the apparatus set forth in FIG. 1.

[0027] FIG. 4 is a schematic view of the various actuators used to position the cutting tool, the machine table and the workpiece.

DETAILED DESCRIPTION

[0028] Reference is now made to FIGS. 1A-1D and 2 that illustrate the new and improved apparatus 10 adapted for the three dimensional planing of a workpiece W. As illustrated, the apparatus 10 includes a base 12. A displaceable machine table 14 is supported for displacement on the base 12.

[0029] The base 12 includes a column 16. A displaceable spindle 18 is supported on the column 16 of the base 12. The spindle 18 includes a chuck 20. A cutting tool 22 is releasably held in the chuck on the spindle. The cutting tool 22 includes a single point 24 for cutting the workpiece W.

[0030] The operation control system 26 of the apparatus 10 is schematically illustrated in FIGS. 3 and 4. The operation control system 26 includes a control module 28. The control module 28 includes a controller 30 adapted to control an X-axis actuator 32, a Y-axis actuator 34, a Z-axis actuator 36, a spindle actuator 38 and a workpiece actuator 40.

[0031] More specifically, the controller 30 may comprise a computing device in the form of a dedicated microprocessor or an electronic control unit (ECU) running appropriate control software. The controller 30 may include one or more processors, one or more memories and one or more network interfaces communicating with each other over one or more communication buses.

[0032] The various actuators 32, 34, 36, 38 and 40 may comprise state-of-the-art actuators. For example, the X-axis actuator 32 and the Y-axis actuator 34 may comprise linear direction servomotors (for example: SGLFW2 Model linear servomotor from Yaskawa Electric Corporation coupled to an absolute linear encoder system such as the RESOLUTE RTLA-S absolute linear encoder system from Reinshaw PLC). The Z-axis actuator 36, the spindle actuator 39 and the workpiece actuator 40 may all comprise rotary servomotors (for example, Yaskawa SGM7A-25A). Using nanometer position and/or velocity feedback between the controller 30 and the actuators 32, 34, 36, 38 and 40, extremely high dynamic performance is achieved.

[0033] The X-axis actuator 32 is held on the base 12 and is adapted to displace the displaceable machine table 14 in the X-axis direction (note action arrow X in FIG. 1C). FIG. 4 schematically illustrates the X-axis table 42 supported by the X-axis actuator 32 riding on the magnetic track 44 held on the base 12 (note action arrows X).

[0034] The Y-axis actuator 34 rides on the magnetic track 46 supported on the X-axis table 42 and is adapted to displace the Y-axis table 48 of the displaceable machine table 14 in the Y-axis direction (note action arrow Y in FIG. 1B: that is, in and out of the two dimensional view of FIG. 4). The Z-axis actuator 36 is held on the column 16 of the base 12 and is adapted to displace the displaceable spindle 18 in a Z-axis direction toward or away from the displaceable machine table (note action arrow Z in FIGS. 1B and 4). As should be appreciated, the Z-axis actuator moves the cutting tool 22 held in the chuck 20 in a manner defining the cutting stroke of the cutting tool 22. Here, reference is made to FIG. 4 schematically illustrating the rotary servomotor of the Z-axis actuator 36 that rotates the ball screw 50 moving the ball screw nut 52 and the spindle 18 attached thereto along the Z-axis table 54 toward and away from the workpiece W.

[0035] The spindle actuator 38 on the spindle axis S is a rotary servomotor adapted to index, rotate and align the cutting tool 22 held in the chuck 20 for proper engagement and clearance with the workpiece W held on the displaceable machine table 14. More particularly, the workpiece W may be firmly held in a chuck or clamping device of a type known in the art (56) on the upper face of the machine table 14 or by other appropriate means useful for such a purpose.

[0036] The workpiece actuator 40 is a rotary servomotor mounted on the displaceable machine table 14 along the workpiece axis P that runs parallel to one of the X-axis X and the Y-axis Y of the displaceable machine table and is adapted to index the workpiece W on the machine table 14. More particularly, the workpiece actuator 40 rotates the workpiece into a desired cutting position.

[0037] Advantageously, the controller 30 is configured to produce a number of different cutting features in the workpiece W with the cutting tool 22. Those cutting features include, but are not necessarily limited to a curved feature, a variable depth slot, a free-form slot and a pocket. A cryogenic cooling element 42, schematically illustrated in FIG. 3 may be used to provide cooling to the cutting tool 22 and the workpiece W during the planing operation. Such a cryogenic cooling system 58 may provide external cooling to the cutting tool 22 and the workpiece W by means of a closed-loop delivery system, of a type known in the art, including a cryogenic fluid circulated by a pump 60 under the control of the controller 30.

[0038] Potential applications for this new machine tool are the production of biomedical implants, turbine blades and impellers. All of these high value, high precision components feature geometries that make them difficult-to-machine using conventional multi-axis milling machines. The new apparatus 10 allows for the use of significantly stiffer/more rigid cutting tools, since rotational symmetry is not required. Therefore, material removal rates can be increased by orders of magnitude, while tool-wear, dimensional tolerances and surface integrity (i.e., surface and sub-surface material microstructural changes induced by the cutting process) are all improved significantly. The ability to design and use novel cutting tool geometries in particular allows for much greater control over the geometry of the uncut chip, which allows for much greater control over surface integrity and thus the quality of making components; this is especially meaningful in the context of the potential applications in the biomedical and aerospace industries.

[0039] Toward this end, the apparatus 10 may be used in a new and improved method of machining a workpiece W. That method may be broadly described as including the steps of: (a) displacing a workpiece W along an X-axis X, by means of the X-axis actuator 32, and along a Y-axis Y, by means of the Y-axis actuator 34 and (b) simultaneously displacing a cutting tool 22 along a Z-axis Z, by means of the Z-axis actuator 36, to provide a cutting stroke allowing machining of a three-dimensional surface feature in the workpiece.

[0040] As should be appreciated from the above description, the method may also include indexing, rotating and aligning the cutting tool 22, by means of the spindle actuator 38, during reciprocation of the cutting tool along the Z-axis Z. Further, the method may include indexing the workpiece, by means of the workpiece actuator 40, during reciprocation of the cutting tool 22 along the Z-axis Z.

[0041] The method may further include the steps of: (a) planing a curved feature into the workpiece W using a single point cutting tool 22, (b) planing a variable depth slot into the workpiece W using a single point cutting tool 22, (c) planing a free-form slot into the workpiece W using a single point cutting tool 22 and/or planing a pocket into the workpiece W using a single point cutting tool 22.

[0042] Still further, the method may include the step of using a control module 28, having a controller 30 and a plurality of controller-controlled actuators 32, 34 and 36, respectively, to displace the workpiece W along the X-axis X and the Y-axis Y and the cutting tool 22 along the Z-axis Z to control the machining process. Further, the method may include using a controller-controlled spindle actuator 38 to index, rotate and align the cutting tool 22 carried on the spindle 18. Additionally, the method may include the step of using a controller-controlled workpiece actuator 40 to index the workpiece W on the displaceable machine table 14.

[0043] In summary, numerous benefits and advantages are provided by the apparatus 10 and the associated method of machining a workpiece W. The use of linear servo motors in two perpendicular axes (i.e., the x and y axis of the machine tool) enables accelerations on the order of 5 G and top speeds up to 800 sfm. These figures exceed prior shaper tools by orders of magnitude, particularly with respect to the dynamic/interpolated motion capability of the newly developed machine tool. Most importantly, the addition of a secondary (i.e., y) axis enables curved slots to be produced. Addition of a high resolution (100 nanometer positioning steps) vertical (i.e., z) axis enables high precision machining at speeds that have so far only been achieved in rotary machine tools, e.g. grinders and state-of-the-art milling machines.

[0044] The high speed, multi-axis planing method disclosed in this document is a newly developed machining process with great application potential in the aerospace and defense industries. By virtue of the nature of this new process, several other emerging and existing technologies can finally be leverage to their full potential. External cryogenic hybrid cooling/lubrication enables improved tool-life and surface integrity, while new tool designs with significantly higher stiffness in the feed direction enable previously unachievable metal removal rates in difficult geometries such as narrow slots and deep cavities/pockets.

[0045] The foregoing has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the embodiments to the precise form disclosed. Obvious modifications and variations are possible in light of the above teachings. All such modifications and variations are within the scope of the appended claims when interpreted in accordance with the breadth to which they are fairly, legally and equitably entitled.