Method to manufacture soft magnetic pressed bodies
AssigneeRobert Bosch GmbH
InventorsFriedrich Esper, Hans-Martin Wiedenmann
Life of this patent
Estimating the term…
Abstract
To permit use of less expensive iron powder material and manufacture of more complex shapes, a mixture of iron powder, of an approximate grain size of between 30 to 450 .mu.m, and containing preferably 5 to 50% of carbonyl iron powder or from 5 to 50%, by weight, of soft ferrite powder of a grain size of from 10 to 200 .mu.m, and a thermosetting resin, in which the thermosetting resin is about 50% by volume of the overall mixture, is filled into a die. Pressure is built up in the die, which is heated, permitting excess binder to escape during the build-up phase thereof, the pressure then being held so that the resin can set in the heated die. The pressures needed are substantially less than heretofore required, in the order of from between 500 to 5000 bar.
Claims16
Method to manufacture soft magnetic pressed bodies comprising a mixture of soft magnetic material and a resin binder,
- comprising the steps of
- preparing a mixture of iron powder which includes atomized, sponge or electrolytic iron powder and a liquid component consisting essentially of a liquid thermosetting resin having a viscosity of at least 1,000 cpoises;
- filling the mixture into a die;
- heating said die;
- building up pressure in said die to squeeze out excess liquid and permit escape thereof through the clearance between die walls and adjacent punch side walls during build-up of the pressure;
- and keeping the pressure for final compacting until the resin has cured.
Method of manufacturing soft magnetic pressed bodies comprising a mixture of soft magnetic materials and a resin binder,
- comprising the steps of:
- admixing iron powder having a grain size of from about 30 to 450 micrometers and a liquid component consisting essentially of a liquid thermosetting resin having a viscosity of at least 1,000 cpoises;
- filling said mixture into a die;
- heating said die;
- applying a pressure in the die of between 200 and 5,000 bar during a period of from one to thirty seconds to squeeze out excess liquid and permit escape thereof through the clearance between the die walls and punch side walls during build-up of the pressure, and
- maintaining the pressure until said resin has cured.
Dependencies are inferred from the claim text.