Specification "Method for Machining of Rotary Parts"
The present invention relates to a method for machining of rotary parts that includes at least one working step in which at least one surface of the workpiece clamped in an apparatus is ground.
In the automobile industry, the machining of rotary parts, for instance crankshafts or the like, is associated with high production complexity. As a rule all relevant surfaces of such a rotary part are subjected to at least one grinding step. Other work steps on the workpiece, such as for instance adding an end-face bore, require high precision for rotary parts of this type, for instance crankshafts. Adding such a bore has therefore taken place on a separate special-purpose machine in the past. According to the prior art, a special-purpose machine, a discrete work sequence, and, associated with this, re-clamping of the workpiece is thus necessary for such a work step. This leads to high capital and production costs.
The object of the present invention is comprised in simplifying a method for machining rotary parts of the type described in the foregoing for reducing production costs while attaining high process reliability and obtaining high-quality workpieces.
This object is attained using an inventive method for processing rotary parts of the type described in the foregoing, the method having the characterizing feature of the main claim. It is inventively provided that by means of a boring tool at least one end-face bore is added to the workpiece clamped in for the grinding step in the same clamping apparatus. In accordance with the invention it is thus no longer necessary to re-clamp the workpiece into a special-purpose machine provided for that purpose with its own work sequence. The boring, for instance adding an end-face suitable bore to a rotary part, for instance a crankshaft flange, occurs in the same clamping apparatus. This can occur in a clamping device suitable for this. For instance, during a grinding process the workpiece can be clamped at least at both ends in a clamping apparatus and for the boring process the clamping apparatus can be released at least at one end and a chuck for a boring tool can be arranged there, which then performs the desired end-face boring. Preferably at least one fine bore or precision bore is added to the end-face of the workpiece.
In accordance with one preferred further development of the invention, it can be provided that after releasing a clamping apparatus at least at one end of the clamping, additional guidance for the workpiece is created on its circumference using a guide element suitable therefor, for instance a guiding steady. The grinding process undertaken on the workpiece in the clamping apparatus preferably includes at least one CBN grinding by means of a grinding wheel.
In the past as a rule production of crankshafts has been very complex regardless of performance class. For instance, inter alia the fitted bearings for almost all crankshafts are turned and burnished by means of a separate machine and work sequence. In accordance with one further development of the invention, this turning and burnishing work sequence for the fitted bearing can be omitted and can be replaced by grinding the fitted bearing. For instance, the fitted bearing can be ground in the flange/pin grinding operation, which always takes place. In this manner the production costs for producing such rotary parts, in particular crankshafts, can be reduced considerably.
According to the prior art, crankshafts typically undergo finish machining, regardless of the requirements for the crankshaft. This includes for instance polishing of the main bearing, crank pin, flange, and pins on the crankshaft. In accordance with a further development of the invention, this polishing step can be omitted and can be replaced by a suitable grinding process, in particular CBN grinding. In this case roughness can be attained for instance on the order of magnitude of about 2 jam. Further fineness for rz can be attained in an optimizing process, for instance when problems occur in the area of an oil channel bore, a groove in the bearing, or the like. If the finish machining for the rotary part is omitted, especially in the case of crankshafts, this likewise leads to a further considerable reduction in production costs.
The subject-matter of the present invention is furthermore a rotary part, in particular a crankshaft, that is produced in accordance with a method of the type specified in the foregoing. The features cited in the subordinate claims relate to preferred further developments of the
invention that attains the object. Further advantages of the invention result from the following detailed description.
The invention is described in greater detail in the following using exemplary embodiments and with respect to the attached drawings.
Fig. 1 is a schematic, simplified view of a crankshaft clamped in for various work steps; Fig. 2 is an enlarged detailed view of a portion 11 of Fig. 1.
We refer first to Fig. 1. The drawing is a schematically highly simplified depiction of a machine for machining rotary parts, in particular crankshafts. This machine includes a first drive unit 17 and a second drive unit 16 so that the rotary part 10 can be machined from both ends. Moreover, a clamping apparatus is provided, including a first chuck 11 for clamping the rotary part 10 at its one end and a second chuck 12 for clamping the rotary part at its other end, the clamping apparatus being embodied such that the rotary part 10 can be rotated about its axis 18 by means of the drive units 16, 17. It can be useful to provide additional guide elements for instance on the circumference for guiding the workpiece, especially when one side of one of the clamping apparatuses is released in order to perform a boring procedure in the end-face area. For this, the inventive machine has a guiding steady 14 that provides guidance and support on the circumference of the workpiece.
Figure 1 illustrates the crankshaft 10 clamped for a grinding process and clamped at both ends using the chuck 11, 12. For the grinding process, a grinding wheel 15 for instance can be used that can be rotatably driven about an axis 19 and that can be advanced in the direction toward the workpiece 10 by means of an appropriate apparatus 20 (see double-headed arrow in Fig. 1).
Referring now to Fig. 2, the machining of the workpiece 10 from the end-face shall be explained in greater detail. Fig. 2 depicts an enlarged detail from the left-hand end area of the crankshaft 10. It is evident that the chuck 11 was withdrawn, the clamping elements 1 la being released, so that there is no longer the original clamping at the left-hand end of the crankshaft 10 in the drawing. It can also be seen
in a comparison with Fig. 1 that due to the chuck 11 withdrawing there is a certain distance between the chuck 11 and the end-face surface 21 of the crankshaft. Only one tool, for instance a fine-bore tool 13, can be clamped into the chuck 11 specially embodied therefor, and it adds an end-face precision bore to the flange 22 of the crankshaft 10. Since the clamping was released, the guide steady 14 now supports the crankshaft 10 in this end area. The other end area of the crankshaft 10 remains clamped in the second chuck 12 as illustrated in Fig. 1, even during machining with the fine-bore tool 13. In the position in which the crankshaft 10 is clamped as illustrated in Fig. 2, the boring can be performed simply by advancing the fine-bore tool 13. After the bore has been added to the end-face surface 21 of the flange 22 of the crankshaft 10, the fine-bore tool is withdrawn, it is removed from the chuck 11, and if necessary the crankshaft 10 can be re-clamped using the clamping elements 1 la for further machining processes, for instance grinding of the surface or the like. The advantage of the inventive method is thus that work steps on the surface, such as grinding and boring processes in the end-face area, can take place on the same machine, in principle in the same clamping.
Legend
10 Tool
11 Clamping apparatus
lla Clamping elements
Clamping apparatus
Boring tool
Guide element
Grinding wheel
Drive unit
Drive unit
Axis
Axis
Apparatus
End-face surface
Flange

AMENDED CLAIMS
Filed with International Office on 2 February 2006 (2/2/06) [original claims 1-14 replaced with claims 1-12]
1. Method for machining of rotary parts that includes at least one working step in which at least
one surface of the workpiece, with each end clamped in a chuck, is ground, and including at
least one additional working step in which the clamping is released at the one end area of
said workpiece and a bore is added there by means of a boring tool while the clamping at the
other end area of said workpiece is maintained, characterized in that said end-face bore is
executed by a boring tool (13) arranged in the released chuck (11).
Method in accordance with claim 1, characterized in that it includes at least one CBN
grinding by means of a grinding wheel (15).
Method in accordance with claim 1 or 2, characterized in that at least one fine bore or
precision bore is added to the end-face of said workpiece.
Method in accordance with any of claims 1 through 3, characterized in that at least after the
release of one clamping apparatus additional guidance is provided for said workpiece on its
circumference using a guide element (14), preferably a guiding steady.
Method in accordance with any of claims 1 through 4, characterized in that said machined
rotary part is a crankshaft.
Method in accordance with claim 5, characterized in that an end-face suitable bore is added to
the crankshaft flange (22).
Method in accordance with any of claims 1 through 6, characterized in that the machining of
the surface of said workpiece occurs using grinding, preferably CBN grinding, leaving a
certain roughness without subsequent finish machining.
Method in accordance with claim 7, characterized in that the finish grinding of said
workpiece occurs in said apparatus and subsequent polishing of said workpiece is not
provided.
Method in accordance with any of claims 5 through 8, characterized in that the machining of
the fitted bearings of said crankshaft occurs using grinding in the same apparatus.
Method in accordance with claim 9, characterized in that the grinding of said fitted bearings
occurs in the same work step as the grinding of flanges and/or pins of said crankshaft.
Method in accordance with claim 9 or 10, characterized in that the grinding of said fitted
bearings occurs without prior burnishing.
Method in accordance with any of claims 1 through 11, characterized in that the machining
of all relevant surfaces of a crankshaft occurs in the same apparatus, preferably in one
clamping.