Induction machine rotor slot having diverging sidewall profiles and forming method

1. An induction machine rotor formed by the process of:

providing a rotor body having an outer circumference, a central axial axis and a radial axis; and

forming opposed rotor slot first and second sidewalls having profiles diverging outwardly in a linear manner in opposite directions from the rotor radial axis and outer circumference by plunge cutting with a cutting tool into the rotor body outer circumference along a cutting path that is parallel to the central axial axis,

wherein the forming step further comprises:

forming the first sidewall with the cutting tool having a first rotational axis oriented at a first angle outwardly diverging from the radial axis; and

forming the second sidewall with the cutting tool having a second rotational axis oriented at a second angle outwardly diverging from the radial axis that is opposed from the first angle.

2. A method for forming rotor bar slots in an induction machine rotor comprising:

providing a rotor body having an outer circumference, a central axial axis and a radial axis; and

forming opposed rotor slot first and second sidewalls having profiles diverging outwardly in opposite directions from the rotor radial axis and outer circumference by cutting into the rotor body outer circumference along at least one cutting path that is parallel to the central axial axis,

wherein the forming step further comprises:

forming the first sidewall with a cutting tool having a first rotational axis oriented at a first angle outwardly diverging from the radial axis; and

forming the second sidewall with the cutting tool having a second rotational axis oriented at a second angle outwardly diverging from the radial axis that is opposed from the first angle.

3. The method of claim 2 , wherein the first and second rotational axes intersect at a common radial axis of the rotor body.

4. The method of claim 2 , wherein the first and second sidewalls are formed by plunge cutting in two passes with an identical profile tool along an identical cutting path.

5. The method of claim 4 , wherein the plunge cutting is performed with a milling machine and the cutting tool is selected from the group consisting of milling machine end cutters, slot cutters, ball cutters, torus cutters and bullnose cutters.

6. The method of claim 4 , further comprising forming a bottom wall intersecting the first and second sidewalls in the same two cutting passes.

7. The method of claim 6 , the bottom wall forming further comprising a third cutting pass with a tool concentrically aligned with the rotor radial axis and identical with the sidewall cutting paths.

8. The method of claim 2 , further comprising forming a bottom wall intersecting the first and second sidewalls, the bottom wall having a rib radially projecting outwardly toward the rotor outer circumference.

9. The method of claim 2 , wherein the rotor body is formed from a homogeneous ferromagnetic material.

10. The method of claim 2 , further comprising constructing a rotor by:

forming a plurality of rotor slots about the rotor outer circumference;

slidably inserting rotor bars into each of the respective rotor slots; and

capturing the respective rotor bars within their corresponding rotor slots with coupling means selected from the group consisting of adhesives, frictional interference fit, brazing, soldering, welding, swaging, inserted shims and diffusion bonding.