Gear cutting – milling – or planing – Planing – Process
Reexamination Certificate
1998-08-26
2001-08-21
Wellington, A. L. (Department: 3722)
Gear cutting, milling, or planing
Planing
Process
C409S299000, C409S258000, C409S244000, C029S081021, C408S229000
Reexamination Certificate
active
06276881
ABSTRACT:
TECHNICAL FIELD
This invention relates to a method for manufacturing a plurality of longitudinally extending slots in the bore of a component. One example of such a component is the sleeve element of an automotive power steering rotary valve. More particularly the invention is directed towards a method of minimising burring of the slot edges of the. sleeve component.
BACKGROUND ART
The prior art most closely related to that of the present invention is that covered by U.S. Pat. No. 5,328,309 (Bishop et al), U.S. Pat. No. 5,292,214 (Bishop et al). These prior art references relate to “slotting machines” which machine the slots in the bore of power steering valve sleeves. The design of these machines calls for each of the slots to be scooped out of the bore of a turned blank by a finger-like cutting tool mounted on a cutting spindle which angularly reciprocates about an axis in a series of progressively deeper cutting and return strokes so forming slots in the form of (usually) closed chambers, which are arcuate or partially arcuate in longitudinal section. The sleeve is held in a work holding collet, in turn mounted in a work holding spindle, having a rotational axis perpendicular to and offset with respect to the cutting spindle axis. By accurately indexing the work holding spindle upon completion of each slot, the required number of slots are precisely machined in the sleeve, usually 4, 6, 8, 10 or 12 slots for most automotive applications.
A problem associated with slotting is a tendency for bore material to burr at the edges of each slot being machined. Once an array of slots have been machined in the bore of a sleeve, a bore finishing operation can be performed by use of a boring tool. Such a method is disclosed in U.S. Pat. No. 5,390,408 (Bishop et at). However in this operation, the boring tool has been found to push the burrs on the slot edges in the direction of rotation, resulting in burr material overhanging each slot from one of its edges. On a typical slot width of say 4.5 mm, the burr overhang size may for instance be in the order of 30-70 &mgr;m.
A problem with slot edge burrs is that they affect the “boost control” and increase the noise generated during operation of the power steering valve. It has been found that the aforesaid limitations on slot machining of sleeves have imposed limitations on design of steering gear valves, and an object of the invention is to alleviate the situation by minimising the resultant burr on the sleeve edges.
SUMMARY OF INVENTION
In a first broad aspect the present invention is a method for machining at least one longitudinal extending slot in a bore of a component, comprising the steps of gripping said component in a gripping means of a workholding device, performing a cutting operation in which said slot is cut in said bore by a cutting tool, characterised by further machining the edges of said slot by inserting a deburring means into said bore and imparting relative angular reciprocation between said deburring means and said component.
In a second broad aspect the present invention is a method for machining an angularly disposed array of parallel longitudinally extending slots in a bore of a component, comprising the steps of gripping said component in a gripping means of a workholding device mounted on an indexable workholding spindle, performing a cutting operation in which said array of slots are cut in said bore by a cuting tool, characterised by further machining the edges of each slot by inserting a deburring means into said bore of the component and imparting relative angular reciprocation between said deburring means and said component whilst said component remains gripped in said gripping means.
In a third broad aspect the present invention is an apparatus for machining an angularly disposed array of parallel longitudinally extending slots in a bore of a component, said apparatus comprising gripping means for gripping said component in a workholding device mounted to an indexable workholding spindle, slotting means for cutting an array of slots within the bore, characterised in that said apparatus further comprising a deburring means for machining the edges of each slot by inserting said deburring means into said bore and imparting a relative angular reciprocation between said deburring means and said component whilst said component remains gripped in said gripping means.
Preferably the deburring means is a mandrel which is rotationally guided by the boric of the component during said relative angular reciprocation, the mandrel incorporating at least two cutting edges, a first cutting edge arranged lo deburr a first edge of at least one slot for clockwise angular rotation of the mandrel, and a second juxtaposed cutting edge to deburr a second edge of said at least one slot for anticlockwise angular rotation of the mandrel.
Preferably said component is a sleeve and said slot is a sleeve slot.
Preferably the mandrel is substantially cylindrical and comprises on its outside surface at least one land lying circumferentially between two flutes, said first and second cutting edges disposed along the lines of intersection of the land and the two flutes, the land arranged to circumferentially underlap the sleeve slot immediately prior to said angular reciprocation.
In a first preferred embodiment the first and second cutting edges of said land are substantially parallel, and arranged also parallel to the axis of the substantially cylindrical mandrel.
In a second preferred embodiment the first and second cutting edges of said land are substantially parallel, and arranged skew to the axis of the substantially cylindrical mandrel, hence forming a substantially helical land.
In a third preferred embodiment the first and second cutting edges of said land arts non-parallel, hence forming a tapered land.
REFERENCES:
patent: 644595 (1900-03-01), Grabler
patent: 1475311 (1923-11-01), Miller
patent: 1941790 (1934-01-01), Davis
patent: 2640379 (1953-06-01), Graves
patent: 3341918 (1967-09-01), Mansfield et al.
patent: 3495483 (1970-02-01), Janik
patent: 4140432 (1979-02-01), Heule
patent: 4246728 (1981-01-01), Leasher
patent: 4535519 (1985-08-01), Kajikawak et al.
patent: 4554817 (1985-11-01), Dier
patent: 4614014 (1986-09-01), Ferguson
patent: 4689864 (1987-09-01), Fukuma et al.
patent: 4768268 (1988-09-01), Ishihara et al.
patent: 5390408 (1995-02-01), Bishop et al.
patent: 5597273 (1997-01-01), Hirsch
patent: 5720585 (1998-02-01), Musso
patent: 6032350 (2000-03-01), Roeske
patent: 6-191420 (1994-12-01), None
Arent Fox Kintner Plotkin & Kahn
Bishop Steering Pty Limited
Cadugan Eric E
Wellington A. L.
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