# Patent

## Title
Method for machining curved surface using lathe

## Abstract

A method for machining curved surface includes the flowing steps. A lathe is provided. The lathe includes a work table and a feeding device. The feeding device has a cutter. A workpiece is held on the work table. The work table rotates the workpiece. The feeding device controls the cutter to move backwards and forwards at a high speed to machine the workpiece circumferentially. The feeding device moves in a plane relative to the work table to machine the curved surface.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims all benefits accruing under 35 U.S.C. §119 from China Patent Application No. 201210252859.2, filed on Jul. 20, 2012, in the China Intellectual Property Office, the disclosure of which is incorporated herein by reference. The application is also related to co-pending applications entitled, “MACHINE TOOL WITH UNINTERRUPTED CUTTING” Ser. No. 13/705,843; “FEEDING DEVICE AND MACHINE TOOL USING THE SAME” Ser. No. 13/705,788; “LATHE FOR MACHINING CURVED SURFACES” Ser. No. 13/705,713; “FEEDING DEVICE AND MACHINE TOOL USING THE SAME” Ser. No. 13/705,611; “LATHE WITH TWO CROSS BEAMS” Ser. No. 13/705,585; “LATHE CONTROL SYSTEM” Ser. No. 13/705,545; “WORKPIECE HAVING NON-ROTATARY SURFACE MACHINED BY LATHE” Ser. No. 13/705,478; “LATHE FOR MACHINING CURVED SURFACES” Ser. No. 13/705,383.
BACKGROUND
1. Technical Field
The present disclosure generally relates to methods for machining curved surface, and particularly, to a method for machining curved surface using a lathe.
2. Description of the Related Art
In the related manufacturing field, a milling cutter with different cutting edges is used for machining curved surfaces. Some tracks occur on the milled surface of the workpiece because of intermitted contact and interrupted milling by the milling cutter. Then a polish process needs to be added for a better appearance.
Therefore, there is room for improvement within the art.



BRIEF DESCRIPTION OF THE DRAWING
The components in the drawings are not necessarily drawn to scale, the emphasis instead placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.
FIG. 1 is an isometric view of an embodiment of a lathe having a feeding device and a work table.
FIG. 2 is a partial, isometric view of the lathe of FIG. 1.
FIG. 3 shows an exploded and isometric view of the lathe of FIG. 2.
FIG. 4 shows an isometric view of the feeding device and the work table of the lathe of FIG. 1.
FIG. 5 is an exploded, isometric view of the feeding device of FIG. 1.
FIG. 6 is similar to FIG. 5, but viewed from another aspect.
FIG. 7 is a flow chart of one embodiment of the method for machining curved surfaces.



DETAILED DESCRIPTION
FIGS. 1 and 2 show an embodiment of a lathe 100. The lathe 100 includes a machine support 10, a work table 20, a moving device 30, a feeding device 40, and a controller (not shown). The work table 20 holds a workpiece in place and is supported by the machine support 10. The moving device 30 is movably positioned on the machine support 10 above the work table 20. The feeding device 40 is slidably mounted on the moving device 30. The controller is electrically connected with the work table 20, the moving device 30 and the feeding device 40 for controlling the lathe 100. Under the control of the controller, the moving device 30 can be driven to move with the feeding device 40, such that the feeding device 40 can be driven three-dimensionally along Cartesian coordinates, that is, along the X, the Y, and the Z axes.
The machine support 10 includes a base 11 and a pair of support bodies 13 positioned substantially parallel on the base 11. A pair of first sliding rails 131 are positioned substantially parallel on a surface of each support body 13 away from the base 11, and arranged apart from each other. In the illustrated embodiment, the first sliding rails 131 extend substantially parallel to the X-axis (a first direction). A receiving groove 133 is formed on each support body 13 between the two first sliding rails 131.
FIG. 2 shows that the work table 20 is substantially cylindrical, and rotatably positioned on the base 11 between the two support bodies 13 via the rotating driver 21. The rotating driver 21 drives the work table 20 and a workpiece placed on the work table 20 to rotate. In the illustrated embodiment, the rotating driver 21 is a direct drive motor.
FIG. 3 shows that the moving device 30 is slidably mounted on the pair of support bodies 13 above the work table 20. The moving device 30 includes two cross beams 31, four sliding bases 33, four first driving mechanisms 35, and two second driving mechanisms 37. The two cross beams 31 are positioned spaced apart on the support bodies 13 for high stability. Opposite ends of each cross beam 31 are slidably positioned on the support bodies 13 via a pair of sliding bases 33, respectively. The extending direction of the cross beam 31 is substantially parallel to the Y-axis (a second direction). A pair of second sliding rails 311 is positioned on a side surface of each cross beam 31 and extending substantially parallel to the Y-axis. Two side surfaces having the second sliding rails 311 of the cross beams 31 are positioned face to face. Two sliding bases 33 are installed on the opposite ends of the corresponding cross beam 31 to slidably connect with the first sliding rails 131. The sliding base 33 includes a first sliding block 331 slidably engaging with the first sliding rails 131. Each first driving mechanism 35 is mounted on a surface of one sliding base 33 away from the cross beam 31 and received in one receiving groove 133.
The first driving mechanisms 35 are configured to drive the cross beams 31 to move along the first sliding rails 131. Each of the first driving mechanisms 35 includes a first forcer 351 and a first stator 353. The first forcer 351 is fixedly mounted on the sliding base 31 facing the receiving groove 133. Two first stators 353 are fixedly arranged received in each of the receiving grooves 133. One second driving mechanism 37 is mounted on each of the cross beams 31 between two second sliding rails 311 to drive the feeding device 40 to move along the second sliding rails 311. Each of the second driving mechanisms 37 includes a second forcer 371 and a second stator 373. Each of the second forcers 371 are fixedly mounted on each of the opposite surfaces of the feeding device 40 facing the cross beams 31. Each of the second stators 373 is installed on each of the cross beams 31 between two second sliding rails 311. The first driving mechanisms 35 and the second driving mechanism 37 are electrically connected to the controller. In the illustrated embodiment, the first driving mechanisms 35 and the second driving mechanism 37 are linear motors with wonderful performance. In other embodiments, the first driving mechanisms 35 and the second driving mechanism 37 may be other drivers, such as hydraulic cylinders or rams. The number of the first driving mechanisms 35, the second driving mechanism 37, and the cross beam 31 may be designed according to their applications.
FIGS. 3 to 5 show the feeding device 40 is slidably positioned between the two cross beams 31, and includes a sliding saddle 41, a mounting seat 43, a tool holder 45, a feeding mechanisms 47, and a cutter 49. The sliding saddle 41 is movably assembled with the cross beams 31. The mounting seat 43 is slidably connected to the sliding saddle 41 away from the cross beam 31. The feeding mechanisms 47 are mounted and received in the mounting seat 43 to electrically connect with the controller. The tool holder 45 is slidably positioned on the mounting seat 43, and has a reciprocating motion substantially parallel to the Z-axis (the Z-axis direction, a second direction) relative to the mounting seat 43.
The sliding saddle 41 is slidably positioned between the two cross beams 31. Two second sliding blocks 411 are separately positioned on opposite surfaces of the sliding saddle 41 away from the tool holder 45, and substantially parallel to the Y-axis towards the cross beam 31. The second sliding blocks 411 are slidably engaged with the correspondingly second sliding rails 311. Each of the second forcers 371 is positioned between the two second sliding blocks 411.
The mounting seat 43 includes a frame 431 and two mounting boards 433. The frame 431 includes a first side wall 4311 and a second side wall 4313. The first side wall 4311 and the second side wall 4313 are positioned substantially parallel to each other and cooperatively define a receiving space 4315. The first side wall 4311 is slidably connected with the sliding saddle 41. Two apart guiding portions 4317 protrude from an inner surface of the first side wall 4311 facing toward the second side wall 4315 and extend substantially parallel to the Z-axis. A through groove 4318 is defined in the second side wall 4313 and extends along a direction substantially parallel to the Z-axis corresponding to the guiding portions 4317. Two sliding portions 4319 protrude from an outer surface of the second side wall 4313 at two sides of the through groove 4318. In the illustrated embodiment, the sliding portions 4319 are sliding rails, and the frame 431 is integrally formed. Two mounting boards 433 are respectively installed on two opening sides of the frame 431. Each mounting board 433 is connected substantially perpendicularly to the first wall 4311 and the second side wall 4313 to close the two opening sides of the frame 431.
The tool holder 45 slidably connects with the mounting seat 43. The tool holder 45 is substantially “T” shaped, and includes a main body 451 and a sliding board 453 protruding substantially perpendicularly from the main body 451. The main body 451 is a bar of material tapering in at both ends, and positioned outside of the mounting seat 43. Two distanced holding portions 4511 are positioned on a bottom of the main body 451 away from the sliding board 453. Four first guiding portions 4513 (see FIG. 5) are positioned on a surface of the main body 451 adjacent to the sliding board 453. The four first guiding portions 4513 are divided into two groups, each group having two first guiding portions 4513 slidably engaging with one sliding portion 4319. The sliding board 453 is located between the two groups of the first guiding portions 4513. The sliding board 453 passes through the through groove 4318 and is slidably attached to the two guiding portions 4317, dividing the receiving space 4315 into two parts. A second guiding portion 4531 is formed on an end of the sliding board 453 away from the main body 451, and received in the guiding portion 4317. In the illustrated embodiments, the first guiding portions 4513 are sliding blocks, and the second guiding portion 4531 is a sliding rail.
The feeding mechanism 47 is mounted in the mounting seat 43, and includes two drivers 471. The two drivers 471 are received in the receiving space 4315 and positioned on two sides of the sliding board 453, respectively. In the illustrated embodiment, the drivers 471 are linear motors. Each driver 471 includes a forcer 4711 and a stator 4713. Each forcer 4711 is fixed to a surface of each of the mounting boards 433. The sliding board 453 is positioned between the two forcers 4711. The forcers 4711 produce alternating magnetic fields when the forcers 4711 are supplied with an alternating electrical current. Two stators 4713 are respectively positioned on the opposite surfaces of the sliding board 453. Each stator 4713 is located between a forcer 4711 and the sliding board 453. Interactions between magnetic fields produced by the stators 4713 and the alternating magnetic fields which are produced by the forcers 4711, drive the tool holder 45 into a reciprocating motion at a high speed along the direction of the Z-axis. In other embodiments, the number of drivers 471 may be designed according to application. For example, the two drivers 471 can replace a single driver with more power, or three or more drivers can be positioned to drive the tool holder 45 to maximize the available power, and assembly of the drivers is simpler.
The cutter 49 is fixedly clamped between the two holding portions 4511 for machining curved surfaces of the workpiece.
In other embodiments, the mounting seat 43 may be fixedly positioned on the sliding saddle 41 when the lathe 100 machines one type of workpiece. In other words, the mounting seat 43 may not move along the Z-axis direction. A driving mechanism electrically connected with the controller may be positioned in the feeding device 40 to drive the mounting seat 43 to slide along the sliding saddle 41 in the Z-axis. The sliding saddle 41 may be omitted, and the mounting seat 43 can be directly slidably positioned on the cross beam 31.
In other embodiments, the forcers 4711 may be directly installed on the frame 431. The alternating magnetic fields produced by the forcers 4711 drive the stators 4713, thereby causing the tool holder 45 to undergo a reciprocating motion at high speed along the guiding portions 4317.
In assembly, the work table 20 is positioned between the two support bodies 13. The cross beams 31 are installed on the two support bodies 13 via the sliding bases 33. The first driving mechanism 35 and the second mechanism 37 are mounted on the moving device 30 and elastically connected with the controller. The sliding saddle 41 is also positioned on the cross beam 31. The two stators 4713 are fixedly mounted on two surfaces of the sliding board 453. The sliding board 453 passes through the through groove 4318 and finally slidably connects with the second guiding portion 4531. Each forcer 4711 is installed on one mounting board 433 and is received in the mounting seat 43 together with the mounting board 433. The cutter 49 is fixedly mounted between the two holding portions 4511. Finally, the feeding device 40 is positioned on the sliding saddle 41 and is electrically connected to the controller.
FIG. 7 is one embodiment of a method for machining curved surfaces of the workpiece.
In step S701, the lathe 100 is provided.
In step S702, the workpiece is placed and held on the work table 20.
In step S703, the second driving mechanisms 37 drives the feeding device 40 to move along the Y-axis and reaches a preset position above the work table 20 for machining.
In step S704, the rotating driver 21 rotates the work table 20 and the workpiece.
In step S705, the drivers 471 drives the cutter 49 to move backwards and forwards at a high speed along the Z-axis according to the depth of cutting required for each machining portion of the workpiece to machine the rotary workpiece circumferentially.
In step 706, the controller controls the moving device 30 to drive the cutter 49 to move along the X-axis, such that the rotary workpiece moves in the radial direction of the rotary workpiece for machining curved surfaces.
The feeding device 40 of the lathe 100 used in the method for machining the curved surface, is capable of moving along the X-axis and the Y-axis via the moving device 30 and feeding with high speed in the Z-axis. Because the cutting depths of periphery of the rotary workpiece along the Z-axis are different, the three dimensional curved surface will be machined. With the combination of the rotation of the work table 20 rotated by the rotating driver 21, the high speed feeding of the feeding device 40 moving backwards and forwards along the Z-axis, and the moving of the feeding device 40 along the Y-axis relative to the work table 20, the three dimensional curved surface achieves a quality appearance without the need for further surface processing.
While the present disclosure has been described with reference to particular embodiments, the description is illustrative of the disclosure and is not to be construed as limiting the disclosure. Therefore, various modifications can be made to the embodiments by those of ordinary skill in the art without departing from the true spirit and scope of the disclosure, as defined by the appended claims.

## Claims

1. A method for machining curved surfaces of a workpiece, comprising:
providing a lathe comprising a work table and a feeding device, wherein the feeding device comprises a cutter;
fixedly positioning the workpiece on the work table;
applying the work table to rotate with the workpiece;
controlling the cutter of the feeding device to move backwards and forwards along an axis substantially parallel to a rotating axis of the work table at high speed to machine the rotary workpiece circumferentially; and
controlling the feeding device to move in a plane relative to the work table to machine curved surfaces of the workpiece,
wherein the lathe further comprises a machine support and a rotating driver, and the rotating driver is positioned on the machine support to rotate the work table, the lathe further comprises a moving device, the moving device comprise at least one cross beam and at least one first driving mechanism, the at least one cross beam is slidably positioned on the machine support, the at least one first driving mechanism drives the at least one cross beam to move along a first direction, and the feeding device is slidably positioned on the at least one cross beam, the lathe further comprises at least one second driving mechanism, and the at least one second driving mechanism drives the feeding device to move along a second direction at about ninety degrees from the first direction, the feeding device further comprises a mounting seat positioned on the moving device, a tool holder engaging with the mounting seat, and a feeding mechanism; the cutter is fixed installed on the tool holder, and the feeding mechanism is mounted and received in the mounting seat for controlling the tool holder to move along the third direction relative to the mounting seat, the tool holder comprises a main body and a sliding board protruding from the main body; the mounting seat comprises a frame, at least one guiding portion is positioned in the frame, the main body is positioned outside of the mountings seat, and the sliding board slidably engages with the at least one guiding portion, the frame comprises a first side wall and a second side wall positioned substantially parallel to the first side wall, the at least one guiding portion is positioned on the first side wall and extends substantially parallel to the third direction, a through groove is defined at the second side wall corresponding to the at least one guiding portion, two sliding portions are positioned on the second side wall and at two sides of the through groove, the main body slidably connects with the two sliding portions, and the sliding board passes through the through groove.

2. The method of claim 1, wherein the feeding device further comprises a feeding driving mechanism driving the cutter to backwards and forwards along a third direction for machining the workpiece, the third direction being substantially perpendicular to the first and second direction.

3. The method of claim 1, wherein the machine support comprises a base and a pair of support bodies positioned substantially parallel on the base, a pair of first sliding rails are positioned substantially parallel on a surface of each of the pair of the support bodies away from the base, the moving device comprises at least one cross beam and at least two sliding bases, each two of the at least two sliding bases are positioned on opposite ends of each of the at least one cross beam, and each sliding base comprises two first sliding blocks to slidably engage with the pair of first sliding rails.

4. The method of claim 3, the at least one first driving mechanism comprising at least one first forcer and at least one first stator, the at least one first forcer is fixedly mounted on the at least two sliding bases facing the pair of the support bodies, the least one first stator is fixedly mounted on the two support bodies, and the interactions between the at least one first forcer and the at least one first stator drive the at least two sliding bases to move on the pair of support bodies.

5. The method of claim 4, wherein a receiving groove is formed on each of the pair of support bodies between the pair of first sliding rails, the at least one first stator is fixedly received in the receiving groove, and the at least one first forcer is slidably received in the receiving groove.

6. The method of claim 1, wherein two groups of first guiding portions are positioned on the main body to slidably engage with the two sliding portion, and a second guiding portion is positioned at an end of the sliding board away from the main body to slidably connect with the at least one guiding portion.