Patent Application
20110123285
The present invention relates to a multiaxis machining apparatus and in particular to a multiaxis machining apparatus suitable for forming a free-form surface.
There is a multiaxis machining apparatus having a workbench and a machining head, wherein the workbench can be rotated centering around a vertical axis and a horizontal axis, and the machining head moves a cutting tool facing a work in directions of three axis (Patent Document 1: Unexamined Japanese Patent Application Publication No. 2005-74568). Such multiaxis machining apparatus performs cutting work in a form of a line by moving the cutting tool forward and backward in a depth direction (for example, a X direction) while moving the cutting tools in a longitudinal direction (for example, Y direction) with respect to a cutting surface of the work, then the cutting tools is shifted relatively by one pitch in a lateral direction (for example, a Z direction) with respect to the cutting surface. By repeating the above operation, a discretionary curved surface can be formed on the work. In this case, it is disirable to change an attitude of the cutting tool so that a tip section of the cutting tool maintains an optimum cutting angle with respect to the cutting surface of the work.
Patent Document 1: Unexamined Japanese Patent Application Publication No. 2005-74568
Incidentally, in the above multiaxis machining apparatus, if the workbench is rotated so that the tip section of the cutting tool maintains the optimum cutting angle, the tip section displaces from a cutting point. Thus in order to position the tip section of the cutting tool at the cutting point, operation to move the cutting tool in an opposite direction has to be carried out. The operation requires each mechanical elements to be operated, thus there is a possibility that the cutting accuracy is deteriorated. Also, compensation of the control system is required, which causes complication of the control system.
Thus, the present invention is to provide a multiaxis machining apparatus where the attitude of the tip section of the work tool such as the cutting tool can be changed and the compensation of the tip position is not necessary when the attitude of the cutting tool is changed, in other words a control system is simplified.
In order to resolve the above problems, the multiaxis machining apparatus of the present invention is provided with a) a tip position drive device to rotate the working tool centering around more than three rotation axes which intersect each other with the cutting tool being retained, and to maintain the tip section of the cutting tool at the intersection of more than three axes, and b) a position drive device to displace the cutting tools relatively with respect to a cutting object.
In the above multiaxis machining apparatus, since the position drive device displaces the cutting tool relatively with respect to the cutting object, a desirable free-form surface on the cutting object can be formed. When this occurs, since the tip position drive device rotates the cutting tool centering around three rotation axes which intersect at the tip section, the attitude of the tip section of tool can be changed discretionary, with the position of the tip section being maintained. Whereby, the cutting angle of the tip section of the cutting tool can be maintained without the position of the tip section being adjusted in accordance with adjustment of cutting angle of the tip section of the cutting tool.
In a specific embodiment of the present invention, the above multiaxis machining apparatus is characterized in that more than three rotation axes are orthogonal each other. In the above case, the cutting tool can be rotate centering around the three axes so as to direct the tip section of the cutting tool in a desirable direction.
Another embodiment of the present invention is characterized in that the tip position drive device rotates the cutting tool centering around the three axes within a rotation angle of 180°. In this case, the tip of the cutting tool is not rotated unnecessarily in the configuration.
Yet another embodiment of the present invention is characterized in that the axis of the cutting tool is disposed along one rotation axis amount three rotation axes. In the above case, attitude adjustment of the cutting tools based on the axis of the cutting tool is possible. Incidentally, the axis of the cutting tool means, in a front end section including the tip section of the cutting tools, an axis extending on a line segment connecting a tip with a center of an arc of a cutting edge which includes the tip. In case of a cutting tool having a sharp tip which does not form the arc section at the front end of the tip, the axis of the cutting tool is a bisector between a pair of edge lines extending from the front end to the rear end.
Further another embodiment is characterized in that with respect to at least one rotation axis which intersects with one of the above rotation axes on which the tip position drive device supports the axis of the cutting tool, the cutting tool is supported in a rotation manner in a double support state at a position where the axis of the cutting tool is interposed. In the above case, since the cutting tool is supported in the double support manner at an asymmetric position with respect to a force applied to the cutting tool, generation a moment can be suppressed with supporting rigidity being greatly enhanced.
Further, yet another embodiment is characterized in that, the tip position drive device is provided with a first supporting section to support the axis of the cutting tool centering around the first rotation axis representing one of the above-mentioned rotation axes, a second supporting section to support the first support section centering around a second rotation axis which intersects with the first rotation axis, a third supporting section to support the second supporting section centering around a third rotation axis which intersects with the first and the second rotation axes, wherein the second supporting section supports the first supporting section in a double supporting state at a position where the axis of the cutting tool is interposed. In the above case, only the second supporting section can be supported in the double supporting state which can prevent the third supporting section from increasing in size and acquire moving range of each rotation axis readily. Whereby, the tip position drive device can be made compact and light weight, and supporting rigidity and stability of the cutting tool are enhanced.
Further, yet another embodiment is characterized in that the rotation axis is supported by a static pressure bearing. In this case, since the cutting tool can be rotated smoothly with high accuracy, a highly accurate cutting can be realized, thus a highly accurate transfer optical surface and an optical surface such as the free-form curve can be created.
Further, yet another embodiment is characterized in that the static pressure bearing is a hydraulic static pressure bearing. The hydraulic static pressure bearing can enhance rigidity among the static pressure bearings and is superior in dumping characteristic. Thus the cutting tool can be rotated smoothly with high accuracy and high rigidity without shimmering despite of its compactness, and cutting work of a transfer optical surface having a large degree of freedom and high accuracy becomes possible. In particular, in case of multiaxis machining apparatus having an axis configuration where a plurality of axes are cumulated, it is desired to enhance rigidity of each axis and to accurately control action of each axis. In respect to the above objects, the hydraulic bearing is suitable compared to an air bearing.
2 Cutting tool
2
a Tip of the cutting tool
10 Work retaining section
11 Chuck
12 Elevation member
13 Elevation device
20 Tool retaining section
21 First tool rotation device
28
a Chuck
21
c Turntable
22 Second tool rotation device
22
a Elevation member
22
b Turntable
23 First stage device
24 Second stage device
28 Third tool rotation device
28
a Chuck
30 Control device
31 Work position adjusting section
32 Tool angle adjusting section
61 Sensors
DP Cutting point
DS Cutting surface
M1 to M5 and M7 to M8 Rotation drive devices
RA Rotation axes
W Work
Wa Work surface
a, b and c Rotation axes
A multiaxis machining apparatus related to a first embodiment of the present invention will be described with reference to the drawing.
As
The work holding section 10, having a chuck 11 to hold a work W representing a cutting object and a motor, is provided with a rotation drive device M7 to support the chuck 11 rotatably centering around a rotation axis RA, an elevation member 12 to descend and ascend along with the rotation derive device M7 and the chuck 11, while supporting the rotation drive device M7, and an elevation drive device 13 to guide the elevation member 12 in the Y direction. Meanwhile, the rotation drive device M7 enables lathe turning of the work W.
The elevation drive device 13 is configured with a guide post 13a, standing on a base 1 to extend in the Y direction, inserted in an elevation member 12 in a sliding manner, a screw rod 13b, having an end section supported rotatably with the base 1, screwed with the elevation member 12, and a rotation drive device M1 to rotate the screw rod 13b in a clockwise and an anticlockwise directions.
In the elevation drive device 13, when the rotation drive device M1 is driven to rotate in one direction, the screw rod 13b rotate in one direction, accordingly, the elevation member 12 moves in the Y direction to negative or positive direction. Whereby, a work W fixed onto the elevation member 12 via the rotation drive device M7 and the chuck 11, moves in the Y direction to negative or positive direction. Here, the work W fixed on the chuck 11 is supported at a discretionary position centering around the rotation axis RA by operating the rotation drive device M7, or rotated at a desirable speed centering around the rotation axis RA.
Incidentally, the elevation drive device 13 can be a guide post, having a cross-section in a shape of a rectangular, penetrating a center section of the elevation member 12, instead of the guide post 13a in a shape of a circular cylinder. Also, in the elevation drive device 13, can be configured that instead of the screw rod 13b, a rod having a rack formed on the surface thereof is used, and a pinion is disposed at the elevation member 12 to mesh with the rack, the pinion is rotated in a clockwise or anticlockwise directions by a motor disposed at the elevation member 12. Also, it can be configured that installing a cylinder is installed on the base 1, and an end of a piston in the cylinder is connected with the elevation member 12.
The tool retaining section 20 is provided with a first tool rotation device 21, a second tool rotation device 22 and a third tool retaining section 28. The tool retaining sections 21, 22 and 28 represent tip position drive devices to adjust attitude of a tip 2a of a cutting tool 2. The first tool rotation device 21 rotates the tool 2 centering around the rotation axis a, the second tool rotation device 22 rotates the cutting tool 2 centering around the rotation axis b and the third tool rotation device 28 rotates the cutting tool 2 centering around the rotation axis c. The rotation axes a, b and c intersect orthogonally at one point. The intersection point of the rotation axes a, b, and c coincides with the tip 2a i.e. a front end of the cutting tools 2. Incidentally, the rotation axis b extends in parallel to the Y direction and the rotation axes a and c maintain a state where they intersect orthogonally within X and Z planes.
The first tool rotation device 21 supporting the cutting tool 2 via the third tool rotation device 28, is configured with an arm 21b to fix an front end of the third tool rotation device 28 at an front end thereof, a turntable 21c, supporting the arm 21b, disposed rotatable centering around the rotation axis a, and a rotate drive device M2 having a motor whose axis is connected with the axis of the turntable 21c to rotate the turntable 21c in the clockwise and the anticlockwise direction.
In the turntable 21c, a bearing enabling the turntable 21c to rotate smooth and accurate rotation is installed. The turntable 21c is disposed so that the extended line of the rotation axis a contacts with the tip 2a of the cutting tool 2 mounted on the chuck 28a. Also, the turntable 21c rotates in a range of rotation angle of ±90° with a position where the axis of the cutting tool 2 is horizontal as a center. Whereby, the tip 2a can be changed its attitude in a vertical direction within the range of 180° with a lower limit of 90° downward and an upper limit of 90° upward.
The bearing installed in the turntable 21c is, for example, a static pressure bearing such as a hydraulic static pressure bearing. With the above bearing, highly accurate and smooth rotation of the cutting tool 2 around the rotation axis a is realized. In particular, incase of the hydraulic static bearing, enhancement of rigidity can be facilitated and the turntable 21c can be downsized because of superior damping characteristic, and the cutting tool 2 can be smoothly rotated without simmering with high accuracy and high rigidity.
Incidentally, a rotation mechanism of the turntable 21c is not limited to the rotation drive device M2 described in the forgoing. For example, a rotation mechanism of the turntable can realized by disposing tooth on the circumference of the turntable 21c, disposing a pinion and a motor to drive the pinion at a support pillar 22a to be described, mashing the tooth of the pinion and the tooth of the turntable 21c and rotating the pinion through the motor.
The second tool rotation device 22 is configured with a support pillar 22a to support an upper section of the rotation drive device M2, a turntable 22b supporting the support pillar rotatable centering around a rotation axis b, and a rotation drive device M3 having a motor whose axis is directly connected with the axis of the turntable 22b to rotate the turntable 22b in clockwise and anticlockwise directions via the axis.
In the turntable 22b, there is disposed a bearing which enables the turntable to turn smoothly with high accuracy. The turntable 22b is disposed so that an extended line of the rotation axis b contacts with the tip 2a of the cutting tool 2 which is mounted on the chuck 28a. Also, the turntable 21c rotates in a range of rotation angle of ±90° with a state where the axis of the cutting tool 2 is within Y and Z planes as a center. Whereby, the tip 2a can change its attitude in a lateral direction within the range of 180°.
The bearing installed in the turntable 22b is, for example, a static pressure bearing such as a hydraulic static pressure bearing.
Incidentally, a rotation mechanism of the turntable 22b is not limited to the rotation drive device M3 described in the forgoing. For example, a rotation mechanism of the turntable can realized by disposing tooth on the circumference of the turntable 22b, disposing a pinion and a motor to drive the pinion at a frame body of the first stage device 23, meshing the tooth of the pinion with the tooth of the turntable 21c and rotating the pinion through the motor.
The third tool rotation device 28 is provided with a chuck 28 to mount the cutting tool 2 detachably, a rotation drive device M8, having a motor, to support the chuck 28a rotatably centering around the rotation axis c. The rotation drive device M8 is provided with a bearing which enables the chuck 28a to rotate smoothly with high accuracy. The chuck 28a is configured so that the attitude of the cutting tool 2 and the position of the tip 2a can be adjusted in a way that the rotation axis c can be adjusted to be parallel to the axis of the cutting tool 2. Incidentally, the cutting tool 2 fixed on the chuck 28a is retained at a discretionary rotation position centering around the rotation axis c by operating the rotation drive device M8. In the above case, the cutting tool 2 is not rotated unnecessarily. Namely, the rotation drive device M8 can rotate the cutting tool 2 in a rage of 180° centering around the axis of the cutting tool 2.
The bearing installed in the rotation device M8 is, for example, a static pressure bearing such as a hydraulic static pressure bearing.
Further, the tool retaining section 20 is provided with a first stage device 23 and a second stage device 24. The first stage device 23 moves the cutting tool 2 in a X direction via the turntable 22b, the support pillar 22a, the rotation drive device M2, the turntable 21c, the arm 21b, the rotation drive device M8 and the chuck 28a, and the second stage device 24 moves the cutting tool 2 in the Z direction via the turntable 22b and so forth.
The first stage device 23 is configured with a moving block 23a to retain the rotation drive device M3, a frame body 23c having the guide rail 23b to guide the moving block 23a in the X direction, a rack rod 23d disposed at an end surface of the moving block 23a extending in the X direction and a rotation drive device M4 disposed at the frame body 23c having a motor provided with a pinion 23a at an axis end capable of rotating in the clockwise and anticlockwise directions. In the guide rail 23b, a bearing to enable smooth and accurate sliding of the moving block 24a is installed. In the first stage device 23, the pinion 23e and the rack of the rack rod 23d are meshed. In the first stage device 23, when the rotation drive device M4 is driven, the pinion 23e rotates in one direction, thereby the rack rod 23d is moved in the x direction toward one direction and the moving block 23a moves in the X direction being guided by the guide rail 23b, as a result the turntable 22b is moved in the X direction.
Incidentally, the guide mechanism to guide the turntable 22b in the X direction in the first stage 23 can be configured in a way that one guide rail is disposed at the frame body 23c and the moving block 23a is disposed to straddle the guide rail. Also, instead of the rack rod, a screw rod can be disposed. The screw rod meshing with the moving block 23a is directly connected with the axis of the motor, and the motor drives the screw rod. Whereby, the moving block 23d can be moved. Also, a cylinder can be installed so as to move the moving block 23a by the cylinder, where an end of a piston rod in the cylinder is connected with the moving block 12a.
The second stage device 24 is configured with a guide rail 24a to guide the frame body 23c disposed on the base 1 in the Z direction, a screw rod 24b penetrating and being meshed with the frame body 23c, and a rotation drive device M5 to rotate the screw rod 24b in the clockwise and anticlockwise direction. In the guide rail 24a, a bearing to enable smooth and accurate movement of the frame body 23c is installed. In the second stage device 24, when the rotation drive device M5 is rotated in one direction, the screw rod 24b rotates in one direction, thereby the frame body 23c namely the moving block 23a and the turntable 22b moves in the Z direction.
Incidentally, in the second stage 24, the guide mechanism to guide the frame body 23c and the turntable 22b in the Z direction can be configured in a way that one guide rail is disposed at the base 1 and the frame body 23c is disposed to straddle the guide rail. Also, instead of the screw rod 24b, a rack rod can be disposed. The end section of the rack rod is connected with the frame body 23c rotatably and a pinion and a motor to rotate the pinion are disposed on the base 1. The pinion is rotated by the motor so that rack rod moves in the Z direction via the pinion. Whereby, the frame body 23c can move in the Z direction. Further, by disposing a cylinder on the base 1, and by connecting an end of a piston rod in the cylinder with the frame body 23c, the frame body 23c and the turntable 22b can be moved in the Z direction.
As described in the forgoing, the elevation drive device 13, the first stage device 23 and the second stage device 24 serve as position drive devices to displace the cutting tool 2 with respect to the work W relatively.
Specific cutting operation under control of the control device 30 in the multiaxis machining apparatus of the embodiment will be described as follow. In the multiaxis machining apparatus the work W is mounted on the chuck 11 of the work retaining section 10. The work position adjusting section 31 configuring the control device 30 sets the work so that the cutting surface Wa locates at a correct position. The cutting tool 2 is mounted on a chuck 28a of the tool retaining section 20. When this occurs, the cutting tool 2 is set at a position so that the tip 2a maintain a desirable angle with respect to cutting surface Wa at the cutting point in the work surface Wa of the work W through the tool angle adjusting section 32 configuring the control device 30, also performs setting so that the rotation axis a of the turntable 21c, the rotation axis b of the turntable 22b and the rotation axis c of the chuck 28a coincide at a point to be orthogonal.
By driving the rotation drive device Ml of the elevation drive device 13, the work W is moved in the Y direction, and by driving the rotation drive device M5 the tip 2a of the cutting tool 2 comes in contact with the work surface Wa of the work W and moved further by an desired cutting amount. Then the work W moves continuously in the Y direction (for example, upward) and the cutting tool 2 goes forward and backward continuously in the Z direction in accordance with a shape of the work surface Wa (for example a curve line) of the work W to be processed.
In the cutting operation, the attitude of the cutting tool 2 has to be changed so that the tip 2a of the cutting tool 2 maintain an optimum cutting angle with respect to, for example, the curve line along the Y direction within the work surface Wa of the work W. Change of the attitude of the cutting tool 2 is carried out by driving the rotation drive device M2 of the first tool rotation device 21 and the rotation drive device M3 of the second tool rotation device 22. When this occurs, the cutting angle is changed while the tip 2a of the cutting tool 2 remains at the same point without the tip 2a of the cutting tools 2 displacing in the Y direction since the tip 2a of the cutting tool 2 rotates centering around, for example, the rotation axis a as
When the work surface Wa of the work W reaches at an upper most position, the frame body 23c move in the Z direction by the rotation drive device MS whereby the tip 2a of the cutting tool 2 detaches from the work surface Wa the work W. Subsequently, the elevation member 12 is moved in the Y direction downward through the rotation drive device Ml, then the work W returns so that the work surface Wa of the work W comes to a lower most position. At the almost the same time, the moving block 23a moves in the X direction by one pitch through the rotation drive device M4. When this occurs, if the work surface Wa of the work W curves within X and Y planes, the attitude of the cutting tools 2 has to be changed so that the tip 2a of the cutting tools 2 maintains an optimum angle with respect to the curve line of the work surface Wa of the work W. The change of the attitude of the cutting tool 2 is carried out by driving the rotation drive device M3 of the second tool rotation device 22 and the rotation drive device M8 of the third tool rotation device 28. When this occurs, the cutting angle is changed while the tip 2a of the cutting tool 2 remains at the same point without the tip 2a of the cutting tools 2 displacing in the X direction since the tip 2a of the cutting tool 2 rotates centering around, for example, the rotation axis b as
A multiaxis machining apparatus of the second embodiment related to the present invention will be described with reference to the drawings as follow. Incidentally, since the second embodiment is a modified version of the multiaxis machining apparatus of the first embodiment, portions thereof not described are the same as that in the multiaxis machining apparatus of the first embodiment.
A mult- of the third embodiment related to the present invention will be described with reference to the drawings as follow. Incidentally, since the third embodiment is a modified version of the multiaxis machining apparatus of the first embodiment, portions thereof not described are the same as that in the multiaxis machining apparatus of the first embodiment.
As above, the present invention has been described in line with the embodiments without the present invention being limited to the embodiments. For example, in the above embodiments, while the cutting tool 2 is moved in the X and Z directions, the work W can be moved in the X and Y directions. Also, in the above embodiments, while the work W is moved in the Y direction, the cutting tool can be moved in the Y direction.
Also, in the above embodiments, while the cutting tool 2 is an R bite having a round tip, a bite having a half circle shape and a bite having an apex can be mounted on the chuck 28a in accordance with cutting objects. The angle of the tips of the half circle bite and the apex bite with reference to the work surface Wa can be adjusted directly and precisely.
Also, in the above embodiments, the cutting tool 2 is described as a stationary tool. However, the cutting tool 2 can be a vibration cutting type tool. Namely, a vibration cutting unit to apply vibration to the cutting tools 2 is installed at the tool retaining section 20. In this case, while the tip 2a of the cutting tool 2 vibrates in a high frequency, the angle of the tip 2a with reference to the work surface Wa can be adjusted directly and precisely through the multiaxis machining apparatus in
Also, in the above embodiments, while the angle of the tip 2a of the cutting tool 2 is rotated centering around the three rotation axes a, b and c through the rotation drive devices M2, M3 and M8, the cutting tool can be rotated centering around two axes among the rotation axes a, b and c. In this case, the angle of the tip 2a of the cutting tool 2 can be adjusted with some degree of freedom.
Also, in the above embodiments, while the rotation axes a and b are orthogonal with the axis of the cutting tool, the rotation axes a and b have not to be orthogonal with the axis of the cutting tool 2, thus the axes a and b can be in a non-orthogonal state.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2007-220447 | Aug 2007 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2008/064460 | 8/12/2008 | WO | 00 | 2/24/2010 |
