Tool making
AssigneeNissan European Technology Centre Limited
InventorKevin J. Puddephatt
Life of this patent
Estimating the term…
Abstract
A trial tool for injection moulding is made by subjecting a cast Zn alloy tool blank to rapid EDM, using a first electrode and a relatively large EDM gap, to produce a coarse surface closely approximating to the required shape, and then subjecting the coarse tool to slow EDM, using a second electrode and a smaller EDM gap, to produce a trial tool having an operative surface of the required shape. A production tool is then made by subjecting a cast steel tool blank to rapid EDM, using the second electrode, and then subjecting the coarse production tool to slow EDM, using a third electrode.
Claims30
A method of making forming tools having an operative surface of a predetermined shape, comprising the sequential steps of:
- (a) subjecting a tool blank to EDM using a first electrode having an operative surface whose shape is complementary to said predetermined shape and which is spaced from the tool blank by a first EDM gap arranged to effect comparatively rapid EDM of the tool blank, thereby to produce a tool having a coarse surface whose shape approximates said predetermined shape;
- (b) subjecting said tool to EDM using a second electrode having an operative surface whose shape is complementary to said predetermined shape and which is spaced from said tool by a second EDM gap, the EDM second gap being smaller than the first EDM gap and being arranged to effect comparatively slow EDM of said tool, thereby to produce from the coarse surface an operative surface whose shape is complementary to that of the second electrode;
- (c) subjecting a further tool blank to EDM using the second electrode, which is spaced from the further tool blank by an EDM gap arranged to effect comparatively rapid EDM of the further tool blank, thereby to produce a further tool having a coarse surface whose shape approximates to said predetermined shape;
- and
- (d) subjecting said further tool to EDM using a third electrode having an operative surface whose shape is complementary to said predetermined shape and which is spaced from said further tool by an EDM gap arranged to effect comparatively slow EDM of said further tool, thereby to produce from the coarse surface an operative surface whose shape is complementary to that of the third electrode.
A method of making a forming tool having an operative surface of a predetermined shape, comprising the sequential steps of:
- (a) subjecting a tool blank to comparatively rapid EDM using a first electrode, said first electrode having a shape that is complementary to said predetermined shape, said electrode being spaced from the tool blank by a first EDM gap, thereby producing a tool having a coarse surface whose shape approximates said predetermined shape;
- and
- (b) subjecting said tool to comparatively slow EDM using a second electrode, said second electrode having a shape that is complementary to said predetermined shape, said second electrode being spaced from said tool by a second EDM gap, said second EDM gap being smaller than said first EDM gap, thereby producing from said coarse surface an operative surface whose shape is complementary to that of the second electrode.
Dependencies are inferred from the claim text.