The invention relates to a method, a tool receptacle, and an apparatus for turning a face of a workpiece with a tool. The invention relates to a workpiece having a turned front side.
For example, the workpiece is a vehicle wheel or a wheel spider for the former, having a base body made of cast or forged metal, whose side facing away from the vehicle is referred to as the front side in the context of the application. In the context of the application, the vehicle-facing side is referred to as the reverse side. The front side and the rear side are collectively referred to as the face. In the context of the application, the vehicle wheel is understood to mean the entirety of the rim and wheel spider. The wheel spider is also referred to as the wheel disk. It is known to provide surfaces that are turned on the side of the wheel facing away from the vehicle, i.e., on the side visible in the assembled state, for improvement of the aesthetic impression, wherein, for the production of such surfaces, a base body of the vehicle wheel rotates about its center axis, while on the side facing away from the vehicle, a machining is carried out by a lathe tool. For example, from DE 10 2015 004 652 A1, a turning method for turning a vehicle wheel having a center axis is known, wherein the vehicle wheel is rotated about the center axis and, for producing convex and/or concave structures on the side of the vehicle wheel facing away from the vehicle, said structures extending over defined angles of rotation, a periodic or recurring advance movement along the center axis is carried out with the tool, the period term or recurrence term of which is tuned to an instantaneous circulation term of the rotational motion.
Alternatively, the workpiece is an optical workpiece, such as an optical lens or eyeglass. For example, from DE 10 2004 037 454 A1, a process for the machining of surfaces of optical workpieces, such as optical lenses or eyeglasses, with a tool is known, wherein a workpiece is received in a workpiece receptacle rotating about an axis of a workpiece spindle in such a way that the axis of rotation of the workpiece spindle runs at a distance to a workpiece axis of the workpiece.
These workpieces have in common that they have faces on which—for aesthetic reasons or for correcting blurred vision—a workpiece contour having concave or convex portions with a high surface quality is to be provided.
It is a problem of the invention to create a method, a tool receptacle, and an apparatus for generating a workpiece contour having convex and/or concave portions on a face of a workpiece by means of turning, wherein the workpiece contour has a high, consistent surface quality. It is a further problem of the invention to create a workpiece having a machined surface.
According to a first aspect, a method for turning a face of a workpiece with a tool is created, wherein the workpiece is held in a workpiece receptacle rotating about an axis of rotation of a workpiece spindle, wherein, for producing and/or machining a workpiece contour having convex and/or concave portions on the face, the tool and the workpiece are moved back and forth relative to one another in an axial movement along the axis of rotation of the workpiece spindle, said axis being synchronized with the rotational movement of the workpiece, and wherein a blade of the tool is aligned in the cutting direction and/or transverse to the cutting direction opposite to the surface normals of the workpiece contour to be produced and/or machined, in such a way that an effective clearance angle and an effective cutting angle remain at least virtually constant opposite to the surface normals.
In the context of the application, the terms “a,” “an,” etc. are used merely as indefinite articles and not as keywords. The terms “first,” “second,” etc. serve merely to distinguish elements only and do not indicate a hierarchy of the elements. In particular, it is conceivable to machine a plurality of workpieces simultaneously and/or to machine one or more workpieces using two or more tools.
In the context of the application, the face is understood to mean a side of the workpiece to be machined, this side being aligned at least substantially perpendicular to the axis of rotation of the workpiece spindle. This is, for example, a front side of a vehicle wheel or its rear side, wherein ventilation openings on the rear side of the vehicle wheel are exposed by means of turning.
In one configuration, for a turning, the tool is arranged at an offset with respect to the axis of rotation. In order to produce convex and/or concave portions on the face, the workpiece and the tool are moved back and forth relative to one another along the axis of rotation. In one configuration, the workpiece is moved for this purpose. Alternatively or additionally, in other configurations, the tool is moved along the axis of rotation of the tool spindle. Due to the relative movement along the axis of rotation, it is possible, for example, to create a vehicle wheel that has oblique spokes for improved air cooling, as known for vehicle wheels, for example from FR 581 308.
For a high surface quality, the tool is aligned opposite to the surface normals when producing convex and/or concave structures. In one configuration, the blade is aligned by a corresponding inclination of the tool. In another configuration, only the blade is moved relative to a holder of the tool for an alignment of the blade.
With a conventional, more or less rigid clamping of the tool with respect to the rotational plane of the lathe, the cutting and clearance angles of the blade of the tool change opposite to the surface to be machined. As a result, the chip formation and chip flow conditions constantly change, which can negatively influence the surface quality.
By aligning the blade in the cutting direction and/or transverse to the cutting direction, it is possible to reduce a change in the chip formation and chip flow conditions during a revolution and thus increase a surface quality.
In one configuration, the blade of the tool is aligned transverse to the cutting direction opposite to the surface normals of the workpiece contour to be produced. Here, “transverse to the cutting direction” is understood to mean a direction which, in a plane perpendicular to the surface normals of the workpiece contour to be produced, includes an angle, in particular an angle of approx. 90°, with the cutting direction. By aligning transverse to the cutting direction, changes in the chip formation and chip flow conditions can be reduced during a machining or production of convex or concave structures in the radial direction.
Alternatively or additionally, in one configuration, for producing a workpiece contour having convex and/or concave portions on the face extending over defined angles of rotation, the tool and the workpiece are moved back and forth relative to one another in an axial movement along the axis of rotation of the workpiece spindle, said axis being synchronized with the rotational movement of the workpiece, wherein the blade of the tool is aligned in the cutting direction opposite to the surface normals of the workpiece contour to be produced.
In a further development, a rotational speed of the workpiece is varied during a revolution in such a way that a constant cutting speed within the scope of a tolerance range is realized. By varying the rotational speed, it is taken into account that, due to the concave or convex portions in the circumferential direction, a distance to be traversed with the tool over a defined angle of rotation changes.
In one configuration, it is provided that the tool is held stationarily in the radial direction of the workpiece spindle during a revolution, in such a way that the tool is guided relative to the workpiece along a circular tool path, also referred to as a machining track, which runs concentrically to the axis of rotation of the workpiece spindle. In another configuration, for generating a tool path that does not run concentrically to the axis of rotation of the workpiece spindle, the tool is moved back and forth during a revolution in the radial direction of the workpiece spindle.
Here, it is provided in a further development that the tool is aligned opposite the surface normals of the tool path. In other words, the tool is twisted such that it lies in the direction of the machining track. Thus, with tool paths that do not run concentrically to the axis of rotation of the workpiece spindle, and thus are not circular, the conditions during machining are improved. The tool path specifies the cutting direction, wherein, in the case of convex or concave portions, the tool is aligned in the cutting direction or transverse to the cutting direction.
In configurations of the method, the workpiece is held concentrically to the axis of rotation in the workpiece receptacle. In other configurations, the workpiece is held off-centered in the workpiece receptacle, wherein a workpiece axis is offset with respect to the axis of rotation.
In the case of an off-centered arrangement of the workpiece, compensation weights or the like are provided in one configuration. Alternatively or additionally, two or more workpieces are held off-centered in the workpiece receptacle, wherein the workpiece axes of the workpieces are offset with respect to the axis of rotation. As a result, two or more workpieces can be machined simultaneously.
In a further development, it is provided that the off-centered workpiece is rotated about the workpiece axis. In this way, contours with portions that are not concentric to one another can be created without a re-clamping of the workpiece.
According to a second aspect, a tool receptacle for a tool for turning a face of a workpiece is created, wherein the workpiece is held in a workpiece receptacle rotating about an axis of rotation, and wherein the workpiece comprises on the face a workpiece contour to be produced or machined, said contour having convex and/or concave portions, wherein the tool receptacle is designed in order to align a blade of the tool in the cutting direction and/or transverse to the cutting direction opposite to the surface normals of the workpiece contour to be produced and/or machined, in such a way that an effective clearance angle α and an effective cutting angle γ remain at least virtually constant opposite the surface normals.
According to a third aspect, an apparatus for turning a face of a workpiece with a tool is created, comprising a workpiece receptacle rotating about an axis of rotation of a workpiece spindle, said receptacle being designed in order to hold the workpiece, and a tool receptacle designed in order to hold the tool, wherein, for producing or machining a workpiece contour having convex and/or concave portions on the face, the workpiece receptacle and/or the tool receptacle is designed in order to move the tool and the workpiece back and forth relative to one another in an axial movement along the axis of rotation of the workpiece spindle, said axis being synchronized with the rotational movement of the workpiece, wherein the tool receptacle is further designed in order to align a blade of the tool in the cutting direction and/or transverse to the cutting direction opposite to the surface normals of the workpiece contour to be produced and/or machined, in such a way that an effective clearance angle and an effective cutting angle remain at least virtually constant opposite to the surface normals.
In one configuration, the tool receptacle is a support structure having six degrees of freedom, wherein, for a movement of the tool receptacle, a suitable kinematics is provided, being selected in particular from the group comprising a hexapod, a quadropod, and a multi-axis robot kinematics. Depending on the configuration, the tool receptacle is arranged laterally next to the workpiece receptacle or opposite to the workpiece receptacle.
In one configuration, the blade is aligned by a corresponding inclination of the tool. In another configuration, the tool receptacle is designed in order to move the tool along one or two rectilinear feed direction(s) and to move the blade relative to a holder of the tool for an alignment of the blade. In one configuration, a setting device having a programmable control is provided for a movement of the tool and/or the blade of the tool.
In one configuration, two or more tool receptacles are provided for simultaneous turning with a plurality of tools.
In one configuration, the tool receptacle is designed in order to align the blade of the tool transverse to the cutting direction opposite to the surface normals of the workpiece contour to be produced. Depending on the configuration, the tool receptacle is designed in order to move the tool including the blade or just the blade.
Alternatively or additionally, for producing a workpiece contour having convex and/or concave portions on the face extending over defined angles of rotation, the workpiece receptacle and/or the tool receptacle are designed in order to move the tool and the workpiece back and forth relative to one another in an axial movement along the axis of rotation of the workpiece spindle, said axis being synchronized with the rotational movement of the workpiece, wherein the tool receptacle is further designed in order to align a blade of the tool in the cutting direction opposite to the surface normals of the workpiece contour to be produced.
In one configuration, the apparatus is further designed in order to vary a rotational speed of the workpiece in such a way that a constant cutting speed within the scope of a tolerance range is realized.
In one configuration, for generating a tool path that does not run concentrically to the axis of rotation of the workpiece spindle, the tool receptacle is further designed in order to move the tool back and forth during a revolution in the radial direction, wherein the tool receptacle is designed in particular in order to align the tool opposite to the surface normals of the tool path.
In one configuration, the workpiece receptacle is further designed in order to center the workpiece. Alternatively or additionally, the workpiece receptacle is designed in order to hold the workpiece off-centered in the workpiece receptacle, wherein a workpiece axis is offset with respect to the axis of rotation. Due to the off-centered clamping, it is possible to create non-rotationally symmetrical contours. In one configuration, the workpiece receptacle is designed in order to hold two or more workpieces off-centered in the workpiece receptacle, wherein the workpiece axes of the workpieces are offset with respect to the axis of rotation.
In one configuration, the workpiece receptacle is further designed in order to rotate the off-centered workpiece about the workpiece axis. This allows contours having portions that are not concentric to one another to be created without a re-clamping of the workpiece.
According to a fourth aspect, a workpiece with a machined face is obtained by a method described above. The workpiece is, for example, a vehicle wheel or a wheel spider having a base body made of cast or forged metal, or optical workpieces such as optical lenses or glasses. This list is not exhaustive.
Other advantages and aspects of the invention arise from the claims and from the description of exemplary embodiments of the invention, which are explained below by way of the schematic figures. In the figures, the same reference numbers are used for the same or similar elements. The following are shown:
The apparatus 1 comprises a workpiece receptacle 12, which is driven for machining the workpiece 2 for rotation about an axis of rotation 100 of a workpiece spindle (not shown). The workpiece receptacle 12 is designed in order to hold the workpiece 2. In the exemplary embodiment shown in
The apparatus 10 further comprises a tool receptacle 13, which is designed in order to hold the tool 3.
For a turning of a face 20 of the workpiece 2 being aligned at least substantially perpendicular to the axis of rotation 100, it is known to place the tool radially to the axis of rotation 100 and/or along the axis of rotation 100 after each revolution of the workpiece receptacle 12.
The illustrated tool receptacle 13 is further designed in order to align a blade of the tool 3 in the cutting direction and transverse to the cutting direction opposite to the surface normals of the workpiece contour to be produced.
The illustrated tool receptacle 13 comprises a hexapod for this purpose. A hexapod is advantageous, because it is suitable to hold the tool with a high rigidity for a machining. However, the invention is not limited to the use of a hexapod.
The apparatus 1 according to
In the exemplary embodiment according to
The spokes 22 are respectively configured in a ball-like manner, i.e., a workpiece contour of the workpiece 2 shown in
For an improved surface quality, the blade of tool 3 (cf.
In the arrangements shown in
The illustrated exemplary embodiments are merely exemplary, and numerous variations are possible in order to realize a turning of a face of a workpiece 2 in which the blade is aligned with the surface normals. The machining of rotationally symmetrical as well as non-rotationally symmetrical components is conceivable.
Number | Date | Country | Kind |
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21164282.2 | Mar 2021 | EP | regional |