Method for machining flat surfaces of a workpiece
10449610 · 2019-10-22
Assignee
Inventors
Cpc classification
B23C5/10
PERFORMING OPERATIONS; TRANSPORTING
Y02P90/02
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
G05B2219/49149
PHYSICS
B23C3/00
PERFORMING OPERATIONS; TRANSPORTING
International classification
B23C3/00
PERFORMING OPERATIONS; TRANSPORTING
B23C5/10
PERFORMING OPERATIONS; TRANSPORTING
Abstract
The invention relates to a method for machining flat surfaces (30) of a workpiece (32) using a tool (10), in particular a milling tool, which is moved in a collision-free and laterally inclined manner () relative to a flat surface (30) such that a contact point (34) is guided on the flat surface (30). The flat surface (30) is machined using a tool (10) with a cutting contour (18), which has a conically convex design, on one flank (16) of the tool (10) at a pivot angle () parallel to the flat surface (30) in order to prevent a one-sided collision completely by the tool (10) and at at least two different pivot angles (, ) parallel to the flat surface (30) in order to prevent a two-sided collision by the tool (10), wherein the flat surface (30) is separated into at least two machining segments (44, 44, 44), each of which is assigned an individual pivot angle (, ) of the tool (10) in order to prevent a two-sided collision.
Claims
1. Method for machining of flat surfaces (30) of a workpiece (32) using a tool (10) which is laterally inclined () against a flat surface (30), guided with a contact point (34) on the flat surface (30) and moved in a collision-free manner, wherein the flat surface (30) is machined using a tool (10) with a cutting contour (18), which has a conically convex design, at one flank (16) of the tool (10), and to avoid a one-sided collision completely machined by the tool (10) with a pivot angle () in parallel to the flat surface (30) and to avoid a two-sided collision by the tool (10) with at least two different pivot angles (, ) in parallel to the flat surface (30), wherein the flat surface (30) is divided into at least two machining segments (44, 44, 44) to avoid the two-sided collision collision and each of the at least two machining segments (44, 44, 44) is assigned an individual pivot angle (, ) of the tool (10) to avoid collision, wherein in case of the one-sided collision the flat surface is machined in multiple passes and the pivot angle runs continuously between a pre-defined minimum angle at a non-limited side and said pivot angle, and wherein in case of the two-sided collision the at least two machining segments of the flat surface are machined by the tool in multiple passes, with the pivot angle of the tool of the at least one machining segment being continuously interpolated with the pivot angle of the tool of the at least other machining segment, and vice versa, such that the tool swings continuously back and forth in multiple passes across the at least two machining segments between the calculated pivot angles.
2. Method according to claim 1, characterized in that the tool (10) is laterally inclined against the flat surface (30) in such a way that the contact point (34) of the cutting contour (18), which has a conically convex design, at the flank (16) of the tool (10) on the flat surface (30) is in an upper area (36) facing the shaft (12) of the tool (10).
3. Method according to claim 1, characterized in that the tool (10) is moved in multiple passes from bottom up across the flat surface (30) and is laterally inclined against the flat surface (30) in such a way that the contact point (34) of the cutting contour (18), which has a conically convex design, at the flank (16) of the tool (10) on the flat surface (30) is in an area (38) between the middle of the cutting contour (18) and an upper area (36) facing the shaft (12) of the tool (10).
4. Method according to claim 1, characterized in that the tool (10) is moved in multiple passes from top down across the flat surface (30) and is laterally inclined against the flat surface (30) in such a way that the contact point (34) of the cutting contour (18), which has a conically convex design, at the flank (16) of the tool (10) on the flat surface (30) is in an area (40) between the middle of the cutting contour (18) and a lower area (42) facing the front face (20, 22) of the tool (10).
5. Method according to claim 1, characterized in that the tool (10) is laterally inclined against the flat surface (30) in such a way that the contact point (34) of the cutting contour (18), which has a conically convex design, at the flank (16) of the tool (10) on the flat surface (30) is in a lower area (42) facing the front face (20, 22) of the tool (10).
6. Method according to claim 1, characterized in that the lateral inclination () of the tool (10) against the flat surface (30) is maintained unchanged throughout machining.
7. Method according to claim 1, characterized in that the collision freedom and possible one-sided and/or two-sided collisions with the geometry of the workpiece (32) are tested.
8. Method according to claim 1, characterized in that the tool path/s (46) of the tool (10) for the flat surface (30) and/or the at least two machining segments (44, 44, 44) is/are calculated.
9. Method according to claim 1, characterized in that the tool (10) is guided across the flat surface (30) or the at least two machining segments (44, 44, 44) of the flat surface (30) in multiple passes.
10. Method according to claim 1, characterized in that the tool (10) is guided across the flat surface (30) or the at least two machining segments (44, 44, 44) of the flat surface (30) in horizontal and/or diagonal passes.
11. Method according to claim 1, characterized in that the flat surface (30) or the at least two machining segments (44, 44, 44) of the flat surface (30) is/are machined using a tool (10), with its cutting contour (18), which has a conically convex design, at the flank (16) of the tool (10) being formed by a conical contour with a conical angle between the conical contour and the axis of the tool (10) and a convex bulge going out from the conical contour.
12. Method according to claim 1, characterized in that the flat surface (30) or the at least two machining segments (44, 44, 44) of the flat surface (30) is/are machined using a tool (10), with its cutting contour (18), which has a conically convex design, at the flank (16) of the tool (10) being formed as a circle segment or ellipsoid segment with a curve radius R.sub.K250 mm.
13. Method according to claim 1, characterized in that the flat surface (30) or the at least two machining segments (44, 44, 44) of the flat surface (30) is/are machined using a tool (10), with its cutting contour (18), which has a conically convex design, at the flank (16) of the tool (10) being formed as a circle segment, ellipsoid segment or curve segment with a constant or varying curve radius R.sub.K.
14. Method according to claim 1, characterized in that the flat surface (30) or the at least two machining segments (44, 44, 44) of the flat surface (30) is/are machined using a tool (10), with its cutting contour (18), which has a conically convex design, at the flank (16) of the tool (10) being formed symmetrically or asymmetrically.
15. Method according to claim 1, characterized in that the flat surface (30) or the at least two machining segments (44, 44, 44) of the flat surface (30) is/are machined using a tool (10), with its cutting contour (18), which has a conically convex design, at the flank (16) of the tool (10) directly transferring to the shaft (12) of the tool (10).
16. Method according to claim 1, characterized in that the flat surface (30) or the at least two machining segments (44, 44, 44) of the flat surface (30) is/are machined using a tool (10), with its cutting contour (18), which has a conically convex design, at the flank (16) of the tool (10) indirectly transferring to the shaft (12) of the tool (10) via a rounded transfer (24).
17. Method according to claim 1, characterized in that the flat surface (30) or the at least two machining segments (44, 44, 44) of the flat surface (30) is/are machined using a tool (10), with its cutting contour (18), which has a conically convex design, at the flank (16) of the tool (10) transferring to a flat front face (20) of the tool (10).
18. Method according to claim 1, characterized in that the flat surface (30) or the at least two machining segments (44, 44, 44) of the flat surface (30) is/are machined using a tool (10), with its cutting contour (18), which has a conically convex design, at the flank (16) of the tool (10) transferring to a spherical front face (22) of the tool (10).
19. Method according to claim 1, wherein the shape of the conically convex cutting contour is formed by a conical contour with a conical angle and a convex bulge of this contour such that the tool has a cutting contour of conical shape that does not run linearly conical but bulges in a convex shape.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Further features, advantages and details of the invention can be gathered from the following description of some preferred embodiments of the invention and are based on the drawings. The drawings are as follows:
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
(19) In the following description of different embodiments of a tool 10 formed according to the invention and of a method according to the invention for machining using a tool 10, similar parts that correspond to each other are assigned identical reference numbers. The tool 10 for example can be designed without limitation of the invention as a milling tool and/or milling cutter.
(20) In the embodiment of a tool 10 intended for the method according to the invention as shown in
(21) The phrase tool with a cutting contour, which has a conically convex design and/or conical convex design used above and below means a tool 10 with a shape that is formed by a conical angle, i.e. the angle between the tool axis 19 of the tool 10 according to the vertical line in
(22) Accordingly, the tool 10 has a cutting contour 18 of almost conical shape that does not run (linearly) conical, but bulges slightly in a slightly convex shape. This way, the surface quality at the flat surface of a workpiece can be significantly improved in particular based on the tolerance of the tool 10 regarding machine inaccuracies. At the same time, however, advantages of a purely conically shaped tool, such as a large step width (all the larger in the invention the larger the curve radius R.sub.K) or a beneficial collision-avoiding property of a purely conical cutting contour, through which the tool shaft and the tool holder are inclined far away from the plane at application, can be used.
(23) The flat surface 30 or the at least two machining segments 44, 44, 44 of the flat surface 30 is/are machined using a tool 10 that has a cutting contour 18, which has a conically convex design, at the flank 16 of the tool 10 formed by a conical contour with a conical angle between the conical contour and the axis of the tool 10 and a convex bulge going out from the conical contour.
(24) A cutting contour 18, which has a conically convex design, at the flank 16 of the tool 10 that is designed as a circle segment or ellipsoid segment with a large curve radius R.sub.K, in particular R.sub.K250 mm, most preferably 500 mm, has turned out to be of special advantage.
(25) Furthermore, the cutting contour 18, which has a conically convex design, at the flank 16 of the tool 10 can be designed in a beneficial manner as a circle segment, ellipsoid segment or curve segment with a constant or varying curve radius R.sub.K.
(26) In the present embodiment according to
(27) As shown in
(28) The cutting contour 18, which has a conically convex design, also transfers to a flat front face 20 and/or front side and/or front of the tool 10, virtually merging into it.
(29) The embodiment of the tool 10 intended for the method according to the invention, which is shown in
(30) In
(31) Additionally,
(32) When used at the machine, the tool 10, as shown schematically in
(33) The method according to the invention is suitable very beneficially for machining flat surfaces 30 and/or planes of a workpiece 32 using the tool 12 in the form of, in particular, a milling tool. The blade 14 of the tool 10 has a conically convex designed shape that is used to achieve an efficient and collision-free 5-axis processing of the flat surfaces.
(34) The method according to the invention is made up of the following individual process steps, which are explained in more detail purely by way of example based on the particularly exemplary design of the tool 10 according to the invention with a spherical front face 22 and a rounded transfer 24, without being limited to these:
(35) In a first step, the lateral inclination of the tool 10 to the flat surface 30 and/or plane, i.e. the inclination away from the flat surface 30, is determined according to
(36) As
(37) The conically convex shape 18 of the blade 14 specifies the inclination angle to a relatively small interval. Any inclination angle within this interval can be chosen and determines the precise position of the contact point 34 at the tool 10.
(38) Beneficial contact points 34 are presented by selection of the corresponding inclination angles in
(39) In
(40) In
(41) In
(42) In
(43) The selection and determination of the inclination angle and therefore of the contact point 34 can be used in beneficial but nevertheless different manners in many situations.
(44) In order to bring out transfer areas between flat surfaces 30 and/or planes more precisely, it is of benefit to choose the contact point 34, as shown in
(45) In multipass machining of a flat surface 30 and/or plane from bottom up, in turn, a contact point 34 in or above the center, as shown in
(46) Vice versa, a contact point 34 in or below the center, as shown in
(47) In order to bring out transfer areas between flat surfaces 30 and/or planes more precisely, it may be of benefit to choose the contact point 34, as shown in
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(49) The flat surface 30 is machined, as shown in
(50) The transfer area between the flat surface 30 and the flat surface 30 above, as shown in
(51) For the transfer area between the flat surface 30 and the flat surface 30 below and/or bottom surface, as shown in
(52) The application or adaption of the blade 14 to a flat surface 30 and/or plane requires only a relatively small inclination angle . Machining of the lateral flat surface 30 of the workpiece 32 is possible without any problems. In particular vertical flat surfaces 30 and/or planes (also within pockets) are thus accessible very easily, with only slight stress on the pivot axes. This is another benefit of the method according to the invention and the tool 10 as compared to conventional methods, in which the tool must be turned by 90, in order to be able to place it on such a flat surface 30. Thus, the problem of positioning the tool 10 in the limited work space of the machine at large workpieces 32 or parts can be mostly solved.
(53) In a second step of the method according to the invention, possible collisions of the shaft 12 or of the holder 26, and/or, if applicable, also of the machine spindle 28 of the tool 10, with the surrounding geometry of the workpiece 32 according to
(54) Based on the chosen lateral inclination of the tool 10, it is therefore reviewed whether complete machining of the flat surface 30 is possible, i.e. whether the blade 14 of the tool 10 can be moved along the entire surface 30 and/or plane (pursuant to multipass machining, for example), without the shaft 12 or the holder 26 of the tool 10 or the machine spindle 28 colliding with the surrounding component geometry. Tool 10, holder 26 and workpiece 32 and/or part are preferably present in the form of CAD models, so that a collision test by common methods for cut calculation is possible.
(55) In the following, various exemplary situations are described that occur during collision testing. The description remains limited to vertical, rectangular flat surfaces 30 and/or planes for simplification. Without being illustrated in detail, transfer to inclined and non-rectangular flat surfaces 30 and/or planes (trapezoidal or triangular or with curved contours, for example) is possible without any problems.
(56) According to
(57) According to
(58) From a certain depth onwards, the shaft 12 of the tool 10 first collides with the adjacent surface 30 according to
(59) According to
(60) Accordingly, bilateral collisions initially occur between the shaft 12 of the tool 10 and the adjacent surfaces 30, 30 according to
(61) It is not to be considered a limitation that the collision-causing surfaces 30, 30 are directly adjacent to the flat surface 30 to be machined in the illustrated cases of one-sided and two-sided collision. For example, the illustrated surfaces 30 and/or 30 could also be made up of multiple partial surfaces each, of which, if applicable, only partial surfaces that are not directly adjacent to the flat surface 30 would be affected by collisions. Equally, this also includes such cases where no collisions with directly adjacent surfaces 30, 30 occur, but with surfaces adjacent to these surfaces or even only indirectly adjacent in turn.
(62) As
(63) In a third step, the tool 10 is pivoted at an appropriate pivot angle parallel to the flat surface 30 and/or plane if collisions are determined according to
(64) In order to avoid collisions as in the illustrated examples of embodiments pursuant to
(65) Referring to
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(67) For the situations described based on
(68) Referring to
(69) In the simplest case, as shown in
(70) Then a dedicated collision-avoidance pivot angle , in parallel to the flat surface 30 according to
(71) Referring to
(72) When working with different tool orientations , , the cutting contour 18, which is approximately conical or has a conically convex design, of the tool 10 has a highly positive effect. Many machines are unable due to inaccuracies in the pivot axes to adjust the required lateral inclination identically in the two machining segments 44, 44 with the respective different pivot angles , . When using a common, flat conical blade of the tool 10, this would lead to differently designed step effects in the machining segments 44, 44. This would be particularly noticeable, since the machining segments 44, 44 are directly adjacent. The cutting contour 18, which has a conically convex design, of the blade 14 of the tool 10 designed according to the invention and/or of the method according to the invention can compensate a certain axis inaccuracy of the machine, in contrast to this, and thereby permits sensible execution of the described strategy for avoiding collisions in compliance with a required surface quality.
(73) As schematically suggested in
(74) According to
(75) As shown in more detail in
(76) According to
(77)
(78) As
(79) Based on
(80) The division of the flat surface 30 and/or plane in machining segments 44, 44, 44 and the determination of the fixed pivot angle , is only an interim step in any case.
(81) Lifting off of the tool 10 from the workpiece 32 with subsequent pivoting around between the machining segments 44, 44, 44 is no longer required for this. The continuous movement of the tool 10 also offers advantages in collision avoidance, since only the cornersi.e. where it is actually requiredwill reach the maximum pivot angle , that may potentially cause collisions with the respective opposite corners.
(82) According to
(83) In a fourth and last step, finally, the tool paths 46, 46 according to
(84) Due to the first three steps, information is available on the inclination angle against the flat surface 30 and/or plane and the pivot angle/s , in parallel to the flat surface 30 and/or plane with which the tool 10 must be guided in each machining segment 44, 44, 44 of the flat surface 30. The tool paths 46, 46 are calculated based on this. The position information included in this always refers to a specific fixed reference point at the tool 10, usually the center of the front face 22 or another point on the axis of the tool 10.
(85) Calculation of the tool paths 46, 46 is based on a specific pattern.
(86) According to
(87)
(88)
(89) Such horizontal tool paths 46, as presented in
(90) However, in principle, any other, for example diagonal, patterns are possible for the tool paths 46, 46 according to
(91) According to
(92) In all patterns of the tool paths 46, 46, the distance between the individual passes is a variable value. Obviously, it should not be any larger than the length of the almost conical blade 14, but may be smaller. Different parameters, such as the infeed, the revolutions, the surface accuracy to be achieved, or the selection of the contact point 34, can be introduced in the selection. The material of the workpiece 32 may also play a role here.
(93) In the description of the first step of the method according to the invention according to
(94) The invention is not limited to the illustrated embodiments of the method according to the invention according to