Variable stiffness rule blade, rule employing same, and method of making same
AssigneeThe Stanley Works
InventorsEdward C. Rutty, Carl C. Stoutenberg
Life of this patent
Estimating the term…
Abstract
A coilable measuring blade for coilable rules has a concavo-convex cross section which has an intermediate portion with a smaller arc and greater height extending through and beyond the normal standout length to provide greater standout length. The blade may also have an outer terminal portion of greater height to require its deflection as it enters the rule casing and thereby provide reduction of the speed with which the blade is being retracted into the casing.
Claims25
A coilable rule blade having greater standout length comprising an elongated strip of resiliently deflectable metal having a substantially uniform width in its coiled flattened state and, in its uncoiled state, a concavo-convex cross section along substantially its entire length with the arc opening in the direction of coiling, said blade being relatively free from stresses and relatively stable in the extended position, said cross section having a central segment of arcuate configuration defined by a radius R and having a depth H, the length of said blade being comprised of three portions, a first portion adjacent one end thereof with a depth H.sub.1 and radius R.sub.1, a second portion extending from said first portion with a depth H.sub.2 and a radius R.sub.2, and a third portion extending from said second portion to adjacent the other end thereof with a depth H.sub.3 and a radius R.sub.3, said second portion having a depth H.sub.2 greater than the depth H.sub.1 and H.sub.3 of said first and third portions and a radius R.sub.2 less than the radii R.sub.1 and R.sub.3 of said first and third portions, said second portion extending for a portion of the length of said blade which includes the normal breakpoint for a blade of said width and of a uniform cross section corresponding to the depth H.sub.1 and radius R.sub.1 of said first portion and which extends beyond said normal breakpoint towards said other end of said blade to provide greater standout length.
A coilable rule blade having greater standout length comprising an elongated strip of resiliently deflectable metal having a substantially uniform width in its coiled flattened state and, in its uncoiled state, a concavo-convex transverse cross section along substantially its entire length, said cross section having a central segment of arcuate configuration defined by a radius R and having a depth H, said blade having a first portion adjacent one end thereof with a depth H.sub.1 and a radius R.sub.1, a second portion extending from said first portion with a depth H.sub.2 and a radius R.sub.2, and a third portion extending from said second portion to adjacent the other end thereof with a depth H.sub.3 and a radius R.sub.3, said second portion having a depth H.sub.2 greater than the depth H.sub.1 and H.sub.3 of said first and third portions and a radius R.sub.2 less than the radii R.sub.1 and R.sub.3 of said first and third portions, said second portion extending for a portion of the length of said blade which includes the normal breakpoint for a blade of said width and of a uniform cross section corresponding to the depth H.sub.1 and radius R.sub.1 of said first portion and which extends beyond said normal breakpoint towards said other end of said blade to provide greater standout length, the radius R.sub.2 of said arcuate segment of said second portion decreasing in length, and the depth H.sub.2 increasing, from said first portion towards said third portion of said blade.
A coilable rule comprising
- A. a casing having end walls and a peripheral sidewall defining a chamber therebetween, said sidewall having an exit aperture therethrough;
- and
- B. a coiled rule blade in said chamber having one end extending outwardly of said casing aperture, said blade comprising an elongated strip of resiliently deflectable metal having a substantially uniform width in its coiled flattened state and, in its uncoiled state, a concavo-convex transverse cross section along substantially its entire length with the arc opening in the direction of coiling, said blade being relatively free from stresses and relatively stable in the extended position, said cross section having a central segment of arcuate configuration defined by a radius R and having a depth H, the length of said blade being comprised of three portions, a first portion adjacent one end thereof with a depth H.sub.1 and a radius R.sub.1, a second portion extending from said first portion and having a depth H.sub.2 and a radius R.sub.2, and a third portion extending from said second portion to adjacent the other end thereof with a depth H.sub.3 and a radius R.sub.3, said second portion having a depth H.sub.2 greater than the depth H.sub.1 and H.sub.3 of said first and third portions and a radius R.sub.2 less than the radii R.sub.1 and R.sub.3 of said first and third portions, said second portion extending for a portion of the length of said blade which includes the normal breakpoint for a blade of said width and of a uniform cross section corresponding to the depth H.sub.1 and radius R.sub.1 of said first portion and which extends beyond said normal breakpoint towards said other end of said blade to provide greater standout length for said blade.
A coilable rule comprising
- A. a casing having end walls and a peripheral sidewall defining a chamber therebetween, said sidewall having an exit aperture therethrough;
- B. a coiled rule blade in said chamber having one end extending outwardly of said casing aperture, said blade comprising an elongated strip of resiliently deflectable metal having a substantially uniform width in its coiled flattened state and, in its uncoiled state, a concavo-convex transverse cross section along substantially its entire length with the arc opening in the direction of coiling, said blade being relatively free from stresses and relatively stable in the extended position, said cross section having a central segment of arcuate configuration defined by a radius R and having a depth H, the length of said blade being comprised of three portions, a first portion adjacent one end thereof with a depth H.sub.1 and a radius R.sub.1, a second portion extending from said first portion and having a depth H.sub.2 and a radius R.sub.2, and a third portion extending from said second portion to adjacent the other end thereof with a depth H.sub.3 and a radius R.sub.3, said second portion having a depth H.sub.2 greater than the depth H.sub.1 and H.sub.3 of said first and third portions and a radius R.sub.2 less than the radii R.sub.1 and R.sub.3 of said first and third portions, said second portion extending for a portion of the length of said blade which includes the normal breakpoint for a blade of said width and of a uniform cross section corresponding to the depth H.sub.1 and radius R.sub.1 of said first portion and which extends beyond said normal breakpoint towards said other end of said blade to provide greater standout length for said blade, the radius R.sub.2 of the arcuate segment of said second blade portion decreasing in length and the depth H.sub.2 increasing from said first portin towards said third portion of said blade;
- and
- C. a coiled power return spring within a reel in said chamber and having its outer end engaged with the inner end of said blade which is coiled about said reel.
A coilable rule comprising
- A. a casing having end walls and a peripheral sidewall defining a chamber therebetween, said sidewall having an exit aperture therethrough;
- B. a coiled rule blade in said chamber having one end extending outwardly of said casing aperture, said blade comprising an elongated strip of resiliently deflectable metal having a substantially uniform width in its coiled flattened state and, in its uncoiled state, a concavo-convex transverse cross section along substantially its entire length with the arc opening in the direction of coiling, said blade being relatively free from stresses and relatively stable in the extended position, said cross section having a central segment of arcuate configuration defined by a radius R and having a depth H, the length of said blade being comprised of three portions, a first portion adjacent one end thereof with a depth H.sub.1 and a radius R.sub.1, a second portion extending from said first portion and having a depth H.sub.2 and a radius R.sub.2, and a third portion extending from said second portion to adjacent the other end thereof with a depth H.sub.3 and a radius R.sub.3, said second portion having a depth H.sub.2 greater than the depth H.sub.1 and H.sub.3 of said first and third portions and a radius R.sub.2 less than the radii R.sub.1 and R.sub.3 of said first and third portions, said second portion extending for a portion of the length of said blade which includes the normal breakpoint for a blade of said width and of a uniform cross section corresponding to the depth H.sub.1 and radius R.sub.1 of said first portion and which extends beyond said normal breakpoint towards said other end of said blade to provide greater standout length for said blade, the radius R.sub.2 of the arcuate segment of said second blade portion increasing and its depth H.sub.2 decreasing, at a rapid rate adjacent said third portion;
- and
- C. a coiled power return spring within a reel in said chamber and having its outer end engaged with the inner end of said blade which is coiled about said reel.
In a method for making a coilable rule blade, the steps comprising
- A. providing a length of resiliently deflectable metal strip having a width W;
- B. forming a first portion of said length into a concavo-convex cross section having a central segment of arcuate configuration defined by a radius R.sub.1 and having an overall depth H.sub.1 ;
- C. forming a second portion of said length into a concavo-convex cross section having a central segment of arcuate configuration defined by a radius R.sub.2 and having an overall depth H.sub.2, said radius R.sub.2 being less than, and said depth H.sub.2 being greater than, R.sub.1 and H.sub.1, respectively;
- and
- D. forming a third portion of said depth extending from said second portion into a concavo-convex cross section having a central segment of arcuate configuration defined by a radius R.sub.3 and having an overall depth H.sub.3, said radius R.sub.3 being greater than, and said depth H.sub.3 being less than, R.sub.2 and H.sub.2, respectively.
In a method for making a coilable rule blade, the steps comprising:
- A. hot forming a length of resiliently deflectable strip having a width W into a concavo-convex cross section having a central segment of arcuate configuration defined by a radius R.sub.1 and having an overall depth H.sub.1 ;
- B. quenching and tempering said strip;
- C. further forming an intermediate portion of the length said strip into a concavo-convex cross section having a central segment of arcuate configuration defined by a radius R.sub.2 and having an overall depth H.sub.2, said radius R.sub.2 being less than, and said depth H.sub.2 being greater than, R.sub.1 and H.sub.1, respectively;
- and
- D. stress relieving said intermediate portion, the arcs of the several portions opening in the direction of coiling and said blade being relatively free from stresses and relatively stable in an extended position.
Dependencies are inferred from the claim text.