Material and process of manufacture of steel components for screw gun clutches

Abstract

A process for manufacturing highly wear and fatigue resistant steel components for power tools includes melting and mixing together a readily available base steel and alloying elements. The molten steel is cast into near-net-shape in an investment casting process. This method is cost competitive with forming the same component from steel with fewer alloying elements. In particular, clutch plates for a drill/driver or screw gun can be formed in this manner from a steel containing relatively large amounts of nickel and chromium, such as SAE 9310 steel, or from a steel containing a relatively large total amount of molybdenum and tungsten, such as AISI M2 steel.

1 . A method of making a highly wear and fatigue resistant component comprising: 
 providing a quantity of base steel;    providing a quantity of alloying elements to be added to the base steel to form a desired alloyed grade of steel;    combining and melting the quantity of base steel and the quantity of alloying elements to produce a molten alloyed steel; and    casting the molten alloyed steel in a near-net-shape investment casting process to form Me a component whereby no further machining is necessary to form the component.    
   
   
       2 . (canceled)  
   
   
       3 . The method of  claim 1  wherein the alloying elements include: 
 about 1%-3.5% nickel by weight; and    about 0.4%-1.4% chromium by weight.    
   
   
       4 . The method of  claim 1  wherein the alloying elements include: 
 at least about 3% nickel by weight; and    at least about 1% chromium by weight.    
   
   
       5 . The method of  claim 1  further comprising: 
 case hardening the component after it is cast.    
   
   
       6 . The method of  claim 5  further comprising 
 subjecting the component to a cryogenic treatment after case hardening.    
   
   
       7 . The method of  claim 6  wherein the cryogenic treatment includes cooling the component in a medium with a temperature less than about −180 degrees Fahrenheit.  
   
   
       8 . (canceled)  
   
   
       9 . The method of  claim 1  wherein the alloying elements include: 
 a total amount of molybdenum and tungsten of about 5%-11% by weight.    
   
   
       10 . The method of  claim 1  wherein the alloying elements include: 
 at least a total amount of molybdenum and tungsten of 9% by weight.    
   
   
       11 . The method of  claim 10  wherein the alloying elements include: 
 at least approximately 0.5% vanadium by weight; and    at least approximately 3% chromium by weight.    
   
   
       12 . (canceled)  
   
   
       13 - 20 . (canceled)  
   
   
       21 . The method of  claim 1  further comprising pre-radiusing an edge of the component.  
   
   
       22 . The method of  claim 21  further comprising case hardening the component, wherein case hardening occurs after pre-radiusing the edge.  
   
   
       23 . The method of  claim 1  wherein the base steel comprises SAE 1010 steel.  
   
   
       24 . The method of  claim 5  wherein case hardening comprises carburizing the component.  
   
   
       25 . The method of  claim 5  wherein case hardening comprises nitriding the component.  
   
   
       26 . The method of  claim 5  further comprising heat treating the component after case hardening.  
   
   
       27 . The method of  claim 5  wherein case hardening comprises hardening the component to about 62-65 Rockwell C.  
   
   
       28 . A method of making a component for a power tool comprising: 
 providing a quantity of base steel;    melting the quantity of base steel;    providing a quantity of alloying elements, wherein the alloying elements comprise at least one element selected from the group consisting of nickel, chromium, molybdenum, tungsten, and vanadium;    combining the quantity of alloying elements with the base steel to produce a molten alloyed steel; and    casting the molten alloyed steel in a near-net-shape investment casting process to form a clutch.    
   
   
       29 . The method of  claim 28  wherein the clutch comprises a lug having an edge.  
   
   
       30 . The method of  claim 29  further comprising pre-radiusing the edge of the lug.  
   
   
       31 . The method of  claim 28 , further comprising case hardening the clutch.  
   
   
       32 . The method of  claim 31  further comprising heat treating the clutch after case hardening.  
   
   
       33 . The method of  claim 28  wherein the alloying elements comprise about 1%-3.5% nickel by weight and about 0.4%-1.4% chromium by weight.  
   
   
       34 . The method of  claim 28  wherein the alloying elements include a total amount of molybdenum and tungsten of about 5%-11% by weight.  
   
   
       35 . The method of  claim 28  wherein the alloying elements include at least approximately 0.5% vanadium by weight and at least approximately 3% chromium by weight.