Marker for a magnetic theft protection system and method for its production
AssigneeVacuumschmelze GmbH & Co. KG
InventorsOttmar Roth, Hartwin Weber
Life of this patent
Estimating the term…
Abstract
Disclosed are markers for a magnetic theft protection system, which markers contain at least one oblong alarm strip made of an amorphous ferromagnetic alloy and at least one activation strip made of a molybdenum-free semi-hard magnetic alloy consisting essentially of NiaMbFeRest, wherein M is one or more of the elements from the group including Cr, W and V, and wherein a and b are weight percentages such that 15% by weight≦a≦25% by weight, and 2% by weight≦b≦8% by weight. The activation strip has a coercive force Hc of 10 A/cm to 25 A/cm and a remanence Br of at least 0.9 T.
Claims24
A marker for a magnetic theft protection system, comprising:
- (a) at least one oblong alarm strip comprising an amorphous ferromagnetic alloy;
- and
- (b) at least one oblong activation strip consists essentially of a molybdenum-free semi-hard magnetic alloy of formula NiaMbFeRest, wherein M is one or more of the elements selected from the group consisting of Cr, W and V, and wherein a and b are weight percentages, such that 15% by weight ≦a≦25% by weight, and 2% by weight ≦b≦8% by weight, and wherein said activation strip has a coercive force Hc of 10 A/cm to 25 A/cm and a remanence Br of at least 0.9 T.
A method for the production of an activation strip for a marker for a magnetic theft protection system that comprises at least one oblong alarm strip comprising an amorphous ferromagnetic alloy, and at least one oblong activation strip, said method comprising:
- (a) melting a molybdenum-free semi-hard magnetic alloy consisting essentially of NiaMbFeRest, wherein M is one or more of the elements from the group including Cr, W and V, and wherein a and b are weight percentages, such that 15% by weight ≦a≦25% by weight, and 2% by weight ≦b≦8% by weight, in a vacuum or an inert gas atmosphere;
- (b) casting said melted alloy to produce an ingot;
- (c) hot forming of said ingot at temperatures above approximately 800° C. to produce a first strip;
- (d) process annealing of said first strip at a temperature of approximately 1100° C. to form an annealed first strip;
- (e) rapidly cooling said annealed first strip to form a cooled annealed first strip;
- (f) cold forming said cooled annealed first strip to a reduction in cross-section of approximately 65% to form a second strip;
- (g) process annealing said second strip at a temperature of approximately 650° C. to form an annealed second strip;
- (h) cold forming said annealed second strip to reduce cross-section to form a third strip, wherein the reduction in cross-section is selected such that said third strip has a remanence Br>0.9 T;
- and
- (i) tempering said third strip at a defined temperature and for a defined time, said temperature and time being selected to produce an activation strip having a coercive force Hc of 10 A/cm to 25 A/cm.
A method for the production of a marker for a magnetic theft protection system, comprising:
- (a) providing at least one oblong alarm strip comprising an amorphous ferromagnetic alloy;
- (b) providing at least one oblong activation strip consisting essentially of a molybdenum-free semi-hard magnetic alloy having formula NiaMbFeRest, wherein M is one or more of the elements from the group including Cr, W and V, and wherein a and b are weight percentages, such that 15% by weight ≦a≦25% by weight, and 2% by weight ≦b≦8% by weight, and wherein said activation strip has a coercive force Hc of 10 A/cm to 25 A/cm and a remanence Br of at least 0.9 T;
- and
- (c) placing said at least one oblong alarm strip on said at least one oblong activation strip to produce said marker.
An oblong activation strip suitable for a marker for a magnetic theft protection system, comprising an alloy consisting essentially of a molybdenum-free semi-hard magnetic alloy of formula NiaMbFeRest, wherein M is one or more of the elements selected from the group consisting of Cr, W and V, and wherein a and b are weight percentages, such that 15% by weight ≦a≦25% by weight, and 2% by weight ≦b≦8% by weight, and wherein said activation strip has a coercive force Hc of 10 A/cm to 25 A/cm and a remanence Br of at least 0.9 T.
Dependencies are inferred from the claim text.