Knuckle design and system of making
View Patent ↗Railcar coupling knuckles having areas of improved structure, improved surface characteristics, and reduced stress under loading, and systems and methods for shot peening railcar components such as, but not limited to, coupling knuckles. Such shot-peening systems and methods may include robotic and/or fixed-position shot-peening devices equipped with shot-emitting mechanisms for expelling shot media against desired areas of a railcar component.
1. A method of improving a transportation coupling component's resistance to failure where said coupling comprises a plurality of surface areas, comprising the step of:
providing a sand mold having a plurality of surfaces;
forming said transportation coupling component using said mold;
improving a surface quality of at least one surface area of said transportation coupling component; and
shot-peening at least one surface area of the coupling component to create a compressive surface layer on the coupling component.
2. The method of claim 1 , wherein improving the surface quality of at least one surface area of said transportation coupling component comprises the steps of:
coating at least one surface of said sand mold with substances to improve the surface quality of the transportation coupling component, such substances comprising at least one of a Zircon, Chromite, or graphitic wash.
3. The method of claim 1 , wherein the coupling component is a knuckle comprising surface imperfections and a pivot hole and improving the quality of the knuckle's surface area comprises the step of substantially removing the surface imperfections from a surface area of said knuckle by grinding, where the grinding operation is performed such that a grinding abrasive is applied to the surface of said knuckle such that resulting striation marks are aligned substantially perpendicular to said pivot hole.
4. The method of claim 1 , where the at least one area includes a throat area of a knuckle.
5. The method of claim 1 , where the at least one area includes a tail area of a knuckle.
6. The method of claim 1 where improving the quality of the coupling component's surface area comprises the steps of:
coating at least one area of the sand mold's surfaces with substances intended to reduce surface imperfections of the coupling component, such substances comprising at least one of a Zircon, Chromite, or graphitic wash; and
removing imperfections from the surface of the coupling component by a grinding abrasive applied to the surface of the coupling component such that resulting striation marks are aligned substantially parallel to a direction of stress applied to the coupling component during an intended use of the coupling component.
7. The method of claim 1 wherein the coupling component is a railcar knuckle comprising metal walls subject to high levels of stress during a normal operation of the railcar knuckle and the method also comprises the step of modifying an internal structure of the knuckle to increase a wall thickness in such areas of high stress.
8. The method of claim 7 , where modifying the internal structure of a knuckle comprises the step of:
increasing a wall thickness of the internal structure of the knuckle in an area of a pivot hole between a nose and a tail portion of the knuckle.
9. The method of claim 7 , where modifying the internal structure of a knuckle comprises the step of:
increasing the thickness of the metal walls of the internal structure of the knuckle in a nose area of the knuckle.
10. The method of claim 9 , where the step of increasing the thickness of the metal walls of the internal structure of the knuckle in the nose area of the knuckle comprises the substep of forming two internal voids in a mold core structure.
11. The method of claim 7 , where modifying the internal structure of a knuckle comprises the steps of:
increasing a metal thickness of an upper and a lower wall of a tail section of the knuckle; and
increasing a length of an internal support rib located between the upper and lower walls within the tail section of the knuckle.
12. The method of claim 1 wherein the coupling component is selected from a list comprising railcar knuckles, railcar yokes, and railcar coupler heads.
13. A shot-peening system for shot-peening one or more areas of a railcar knuckle subject to tensile stress when performing the intended coupling function of a railcar knuckle, the system comprising:
a conveyor for transporting a knuckle along a path;
a part-handling robot located along said path, the part-handling robot comprising retaining elements adapted to grasp a knuckle and present the knuckle in one or more orientations to a shot-peening device; and
a shot-peening device located along said path, the shot-peening device equipped with a shot-emitting mechanism for impacting the knuckle with shot media.
14. The shot-peening system of claim 13 , wherein the shot-emitting device is a multi-axis robot.
15. The shot-peening system of claim 13 , wherein the shot-emitting mechanism is selected from one of an air blast system or a spinning centrifugal blast wheel.
16. A shot-peening system for shot-peening one or more areas on a railcar knuckle subject to tensile stress when performing the intended coupling function of a railcar knuckle, the system comprising:
a conveyor for transporting a knuckle along a path, the conveyor including a plurality of individual carriers that travel along a track along said path, each carrier equipped with rotatable knuckle retaining elements and means for rotating a retained knuckle for presentation to a shot-peening device; and
at least one shot-peening device located in the shot-peening area, the shot-peening device equipped with a shot-emitting mechanism for impacting the knuckle with shot media.
17. The system of claim 16 , wherein the means for rotating a retained knuckle is an electric motor.
18. The system of claim 16 , wherein the means for rotating a retained knuckle includes one or more trip arms on the carrier and one or more trip dogs located along a path of travel of the conveyor.