Rotatable cutting bit

Abstract

A rotatable cutting insert of improved geometry having a shank depending from a head portion and having a hard insert mounted therein, includes an insert having a conically shaped tip section, a base section contiguous with a first intermediate section, a second intermediate section contiguous with both tip and first intermediate section, and where the diameter of the second intermediate section is equal to the maximum diameter of the tip but is smaller than the diameter of the base section.

I claim:  
     
       1. A rotatable cutting bit comprising a head portion, a shank portion depending from said head portion along a longitudinal axis, said head portion having a socket at the forward end, a hard insert having coaxially aligned and integral sections, said sections comprising a base section, a tip section, a first intermediate section contiguous with said base, a second intermediate section of uniform diameter contiguous with said first intermediate and tip sections, said second intermediate section extends forwardly along the longitudinal axis from the junction with the first intermediate section to the tip section a distance of about  0 . 02  to about  0 . 05  inches, said base being fixedly mounted in said socket and having a first diameter, said tip section being conically shaped and having a maximum second diameter, said first intermediate section having a maximum third diameter, said second intermediate section having a fourth diameter equal to said maximum second diameter, said second and third diameters each being less than said first diameter, said first intermediate section has a frusto-conical shape and angles outwardly from the junction with said second intermediate section to the junction with said base section, said first intermediate section at said base forming a fillet at the junction thereof whereby said base forms a shoulder with said first intermediate section said insert is fixedly held to said head portion by brazing. 
     
     
       2. A rotatable cutting bit according to  claim 1  wherein said tip section tapers outwardly at an included angle of from about 83 degrees to about 93 degrees. 
     
     
       3. A rotatable cutting bit according to  claim 2  wherein said first intermediate section extends forwardly along the longitudinal axis from said base section to said second intermediate section a distance of from about 0.22 to about 0.28 inches. 
     
     
       4. A rotatable cutting bit according to  claim 3  wherein said second intermediate section has a cylindrical shape and extends forwardly along the longitudinal axis from the junction with said first intermediate section to the tip section a distance of about 0.02 to about 0.05 inches . 
     
     
       5. A rotatable cutting bit according to  claim 4  wherein said base section extends forwardly along the longitudinal axis a distance of from about 0.05 to about 0.11 inches. 
     
     
       6. A rotatable cutting bit according to  claim 5  wherein said first diameter is from about 0.60 to about 0.66 inches. 
     
     
       7. A rotatable cutting bit according to  claim 6  wherein said second diameter is from about 0.36 to about 0.44 inches. 
     
     
       8. A rotatable cutting bit comprising a head portion, a shank portion depending from said head portion along a longitudinal axis, said head portion having a socket at the forward end, a hard insert having coaxially aligned and integral sections, said sections comprising a base section, a tip section, a first intermediate section contiguous with said base, substantially all of said first intermediate section projects forwardly of the forward end of said head portion, a second intermediate section of uniform diameter contiguous with said first intermediate and tip sections, said second intermediate section extends forwardly along the longitudinal axis from the junction with the first intermediate section to the tip section a distance of about  0 . 02  to about  0 . 05  inches, said base being fixedly mounted in said socket and having a first diameter, said tip section being conically shaped and having a maximum second diameter, said first intermediate section having a maximum third diameter, said second intermediate section having a fourth diameter equal to said maximum second diameter, said second and third diameters each being less than said first diameter, said first intermediate section has a frusto-conical shape and angles outwardly from the junction with said second intermediate section to the junction with said base section, said first intermediate section at said base forming a fillet at the junction thereof whereby said base forms a shoulder with said first intermediate section said insert is fixedly held to said head portion by brazing. 
     
     
       9. A rotatable cutting bit comprising a head portion, a shank portion depending from said head portion along a longitudinal axis, said head portion having a socket at the forward end, a hard insert having coaxially aligned and integral sections, said sections comprising a base section, a tip section, a first intermediate section contiguous with said base, a second intermediate section of uniform diameter contiguous with said first intermediate and tip sections, said second intermediate section extends forwardly along the longitudinal axis from the junction with the first intermediate section to the tip section a distance of about  0 . 02  to about  0 . 05  inches, said base being fixedly mounted in said socket and having a first diameter, said tip section being conically shaped and having a maximum second diameter, said first intermediate section having a maximum third diameter, said second intermediate section having a fourth diameter equal to said maximum second diameter, said second and third diameters each being less than said first diameter, said first intermediate section has a frusto-conical shape and angles outwardly from the junction with said second intermediate section to the junction with said base section at an included angle of from about 17 to about 23 degrees, said first intermediate section at said base forming a fillet at the junction thereof whereby said base forms a shoulder with said first intermediate section said insert is fixedly held to said head portion by brazing. 
     
     
       10. A rotatable cutting bit comprising a head portion, a shank portion depending from said head portion along a longitudinal axis, said head portion having a socket at the forward end, a hard insert having coaxially aligned and integral sections, said sections comprising a base section, a tip section, a first intermediate section contiguous with said base, a second intermediate section of uniform diameter contiguous with said first intermediate and tip sections, said second intermediate section extends forwardly along the longitudinal axis from the junction with the first intermediate section to the tip section a distance of about  0 . 02  to about  0 . 05  inches, said base being fixedly mounted in said socket and having a first diameter, said tip section being conically shaped and having a maximum second diameter, said first intermediate section having a maximum third diameter, said second intermediate section having a fourth diameter equal to said maximum second diameter, said second and third diameters each being less than said first diameter, said first intermediate section has a frusto-conical shape and angles outwardly from the junction with said second intermediate section to the junction with said base section at an included angle of from about 17 to about 23 degrees, said first intermediate section at said base forming a fillet at the junction thereof whereby said base forms a shoulder with said first intermediate section said insert is fixedly held to said head potion by brazing, said braze flowing over and around said base section. 
     
     
       11. A rotatable cutting bit comprising a head portion, a shank portion depending from said head portion along a longitudinal axis, said head portion having a socket at the forward end, a hard insert having a coaxially aligned and integral sections, said section  sections comprising a base section, a tip section, a first intermediate section contiguous with said base, a second intermediate section of uniform diameter contiguous with said first intermediate and tip sections, said second intermediate section extends forwardly along the longitudinal axis from the junction with the first intermediate section to the tip section a distance of about  0 . 02  to about  0 . 05  inches, said base being fixedly mounted in said socket and having a first diameter of from about 0.60 to about 0.66 inches, said tip section having a maximum second diameter being from about 0.35 to about 0.44 inches and being conically shaped with an included angle from about 83 degrees to about 93 degrees, said first intermediate section having a maximum third diameter, said second intermediate section having a maximum fourth diameter equal to said maximum second diameter, said second and third diameters each being less than said first diameter, said first intermediate section has a frusto-conical shape angling outwardly from the junction with said second intermediate section to the junction with said base section at an included angle of about 17 to about 23 degrees, said first intermediate section and said base forming a fillet at the junction thereof whereby said base forms a shoulder with said intermediate section, said insert is fixedly held to said head portion by brazing. 
     
     
       12. A rotatable cutting bit according to  claim 11  wherein said first intermediate section extends forwardly along the longitudinal axis from said base section to said second intermediate section a distance of about 0.22 to about 0.28 inches. 
     
     
       13. A rotatable bit according to  claim 12  wherein said second intermediate section extends forwardly along the longitudinal axis from said first intermediate section to said second section a distance from about 0.02 to about 0.05 inches. 
     
     
       14. A rotatable cutting bit according to claim  13   12 wherein said base section extends forwardly along the longitudinal axis a distance of from about 0.05 to about 0.11 inches. 
     
     
       15. A rotatable cutting bit comprising a head portion, a shank portion depending from said head portion along a longitudinal axis, said head portion having a socket at the forward end, a hard insert having a coaxially aligned and integral sections, said section  sections comprising a base section, a tip section, a first intermediate section contiguous with said base, a second intermediate section of uniform diameter contiguous with said first intermediate and tip sections, said second intermediate section extends forwardly along the longitudinal axis from the junction with the first intermediate section to the tip section a distance of about  0 . 02  to about  0 . 05  inches, said base being fixedly mounted in said socket and having a first diameter of from about 0.60 to about 0.66 inches, said tip section having a maximum second diameter being from about 0.36 to about 0.44 inches and being conically shaped with an included angle from about 83 degrees to about 93 degrees, said first intermediate section having a maximum third diameter, said second intermediate section having a maximum fourth diameter equal to said maximum second diameter, said second and third diameters each being less than said first diameter, said first intermediate section has a frusto-conical shape angling outwardly from the junction with said second intermediate section to the junction with said base section at an included angle of about 17 to about 23 degrees, said first intermediate section extends forwardly along the longitudinal axis from said base section to said second intermediate section a distance of about 0.22 to about 0.28 inches, said first intermediate section and said base forming a fillet at the junction thereof whereby said base forms a shoulder with said intermediate section, said insert is fixedly held to said head portion by brazing. 
     
     
       16. A rotatable cutting bit comprising a head portion, a shank portion depending from said head portion along a longitudinal axis, said head portion having a socket at the forward end, a hard insert having a coaxially aligned and integral sections, said section  sections comprising a base section, a tip section, a first intermediate section contiguous with said base, a second intermediate section of uniform diameter contiguous with said first intermediate and tip sections, said base being fixedly mounted in said socket and having a first diameter of from about 0.60 to about 0.66 inches, said tip section having a maximum second diameter being from about 0.36 to about 0.44 inches and being conically shaped with an included angle from about 83 degrees to about 93 degrees, said first intermediate section having a maximum third diameter, said second intermediate section having a maximum fourth diameter equal to said maximum second diameter, said second and third diameters each being less than said first diameter, said first intermediate section has a frusto-conical shape angling outwardly from the junction with said second intermediate section to the junction with said base section at an included angle of about 17 to about 23 degrees, said first intermediate section and said base forming a fillet at the junction thereof whereby said base forms a shoulder with said intermediate section, said second intermediate section extending forwardly along the longitudinal axis from said first intermediate section to said second section a distance from about 0.02 to about 0.05 inches, said insert is fixedly held to said head portion by brazing. 
     
     
       17. A rotatable cutting bit comprising a head portion, a shank portion depending from said head portion along a longitudinal axis, said head portion having a socket at the forward end, a hard insert having a coaxially aligned and integral sections, said section comprising a base section, a tip section, a first intermediate section contiguous with said base, a second intermediate section of uniform diameter contiguous with said first intermediate and tip sections, said second intermediate section extends forwardly along the longitudinal axis from the junction with the first intermediate section to the tip section a distance of about  0 . 02  to about  0 . 05  inches, said base being fixedly mounted in said socket and having a first diameter of from about 0.60 to about 0.66 inches, said base section extends forwardly along the longitudinal axis a distance of from about 0.05 to about 0.11 inches, said tip section having a maximum second diameter being from about 0.36 to about 0.44 inches and being conically shaped with an included angle from about 83 degrees to about 93 degrees, said first intermediate section having a maximum third diameter, said second intermediate section having a maximum fourth diameter equal to said maximum second diameter, said second and third diameters each being less than said first diameter, said first intermediate section has a frusto-conical shape angling outwardly from the junction with said second intermediate section to the junction with said base section at an included angle of about 17 to about 23 degrees, said first intermediate section and said base forming a fillet at the junction thereof whereby said base forms a shoulder with said intermediate section, said insert is fixedly held to said head portion by brazing. 
     
     
       18. A rotatable cutting bit according to  claim 1  wherein said second intermediate section extends forwardly along the longitudinal axis from the junction with said first intermediate section to the tip section a distance of about  0 . 03  inches. 
     
     
       19. A rotatable cutting bit according to  claim 8  wherein said second intermediate section extends forwardly along the longitudinal axis from the junction with said first intermediate section to the tip section a distance of about  0 . 03  inches. 
     
     
       20. A rotatable cutting bit according to  claim 9  wherein said second intermediate section extends forwardly along the longitudinal axis from the junction with said first intermediate section to the tip section a distance of about  0 . 03  inches. 
     
     
       21. A rotatable cutting bit according to  claim 10  wherein said second intermediate section extends forwardly along the longitudinal axis from the junction with said first intermediate section to the tip section a distance of about  0 . 03  inches. 
     
     
       22. A rotatable cutting bit according to  claim 11  wherein said second intermediate section extends forwardly along the longitudinal axis from the junction with said first intermediate section to the tip section a distance of about  0 . 03  inches. 
     
     
       23. A rotatable cutting bit according to  claim 15  wherein said second intermediate section extends forwardly along the longitudinal axis from the junction with said first intermediate section to the tip section a distance of about  0 . 03  inches. 
     
     
       24. A rotatable cutting bit according to  claim 16  wherein said second intermediate section extends forwardly along the longitudinal axis from the junction with said first intermediate section to the tip section a distance of about  0 . 03  inches. 
     
     
       25. A rotatable cutting bit according to  claim 17  wherein said second intermediate section extends forwardly along the longitudinal axis from the junction with said first intermediate section to the tip section a distance of about  0 . 03  inches. 
     
     
       26. A rotatable cutting bit according to  claim 1  wherein the hard insert having an overall axial length, and the second intermediate section extends forwardly along the longitudinal axis from the junction with the first intermediate section to the tip section a distance that ranges between about  3 . 4  percent and about  11 . 4  percent of the overall axial length of the hard insert. 
     
     
       27. A rotatable cutting bit according to  claim 26  wherein the second intermediate section extends forwardly along the longitudinal axis from the junction with the first intermediate section to the tip section a distance that ranges between about  5  percent and about  9  percent of the overall axial length of the hard insert. 
     
     
       28. A rotatable cutting bit according to  claim 26  wherein the second intermediate section extends forwardly along the longitudinal axis from the junction with the first intermediate section to the tip section a distance that ranges between about  5 . 5  percent and about  6 . 5  percent of the overall axial length of the hard insert. 
     
     
       29. A rotatable cutting bit according to  claim 8  wherein the hard insert having an overall axial length, and the second intermediate section extends forwardly along the longitudinal axis from the junction with the first intermediate section to the tip section a distance that ranges between about  3 . 4  percent and about  11 . 4  percent of the overall axial length of the hard insert. 
     
     
       30. A rotatable cutting bit according to  claim 29  wherein the second intermediate section extends forwardly along the longitudinal axis from the junction with the first intermediate section to the tip section a distance that ranges between about  5  percent and about  9  percent of the overall axial length of the hard insert. 
     
     
       31. A rotatable cutting bit according to  claim 29  wherein the second intermediate section extends forwardly along the longitudinal axis from the junction with the first intermediate section to the tip section a distance that ranges between about  5 . 5  percent and about  6 . 5  percent of the overall axial length of the hard insert. 
     
     
       32. A rotatable cutting bit according to  claim 9  wherein the hard insert having an overall axial length, and the second intermediate section extends forwardly along the longitudinal axis from the junction with the first intermediate section to the tip section a distance that ranges between about  3 . 4  percent and about  11 . 4  percent of the overall axial length of the hard insert. 
     
     
       33. A rotatable cutting bit according to  claim 32  wherein the second intermediate section extends forwardly along the longitudinal axis from the junction with the first intermediate section to the tip section a distance that ranges between about  5  percent and about  9  percent of the overall axial length of the hard insert. 
     
     
       34. A rotatable cutting bit according to  claim 32  wherein the second intermediate section extends forwardly along the longitudinal axis from the junction with the first intermediate section to the tip section a distance that ranges between about  5 . 5  percent and about  6 . 5  percent of the overall axial length of the hard insert. 
     
     
       35. A rotatable cutting bit according to  claim 10  wherein the hard insert having an overall axial length, and the second intermediate section extends forwardly along the longitudinal axis from the junction with the first intermediate section to the tip section a distance that ranges between about  3 . 4  percent and about  11 . 4  percent of the overall axial length of the hard insert. 
     
     
       36. A rotatable cutting bit according to  claim 35  wherein the second intermediate section extends forwardly along the longitudinal axis from the junction with the first intermediate section to the tip section a distance that ranges between about  5  percent and about  9  percent of the overall axial length of the hard insert. 
     
     
       37. A rotatable cutting bit according to  claim 35  wherein the second intermediate section extends forwardly along the longitudinal axis from the junction with the first intermediate section to the tip section a distance that ranges between about  5 . 5  percent and about  6 . 5  percent of the overall axial length of the hard insert. 
     
     
       38. A rotatable cutting bit according to  claim 11  wherein the hard insert having an overall axial length, and the second intermediate section extends forwardly along the longitudinal axis from the junction with the first intermediate section to the tip section a distance that ranges between about  3 . 4  percent and about  11 . 4  percent of the overall axial length of the hard insert. 
     
     
       39. A rotatable cutting bit according to  claim 38  wherein the second intermediate section extends forwardly along the longitudinal axis from the junction with the first intermediate section to the tip section a distance that ranges between about  5  percent and about  9  percent of the overall axial length of the hard insert. 
     
     
       40. A rotatable cutting bit according to  claim 38  wherein the second intermediate section extends forwardly along the longitudinal axis from the junction with the first intermediate section to the tip section a distance that ranges between about  5 . 5  percent and about  6 . 5  percent of the overall axial length of the hard insert. 
     
     
       41. A rotatable cutting bit according to  claim 15  wherein the hard insert having an overall axial length, and the second intermediate section extends forwardly along the longitudinal axis from the junction with the first intermediate section to the tip section a distance that ranges between about  3 . 4  percent and about  11 . 4  percent of the overall axial length of the hard insert. 
     
     
       42. A rotatable cutting bit according to  claim 41  wherein the second intermediate section extends forwardly along the longitudinal axis from the junction with the first intermediate section to the tip section a distance that ranges between about  5  percent and about  9  percent of the overall axial length of the hard insert. 
     
     
       43. A rotatable cutting bit according to  claim 41  wherein the second intermediate section extends forwardly along the longitudinal axis from the junction with the first intermediate section to the tip section a distance that ranges between about  5 . 5  percent and about  6 . 5  percent of the overall axial length of the hard insert. 
     
     
       44. A rotatable cutting bit according to  claim 16  wherein the hard insert having an overall axial length, and the second intermediate section extends forwardly along the longitudinal axis from the junction with the first intermediate section to the tip section a distance that ranges between about  3 . 4  percent and about  11 . 4  percent of the overall axial length of the hard insert. 
     
     
       45. A rotatable cutting bit according to  claim 44  wherein the second intermediate section extends forwardly along the longitudinal axis from the junction with the first intermediate section to the tip section a distance that ranges between about  5  percent and about  9  percent of the overall axial length of the hard insert. 
     
     
       46. A rotatable cutting bit according to  claim 44  wherein the second intermediate section extends forwardly along the longitudinal axis from the junction with the first intermediate section to the tip section a distance that ranges between about  5 . 5  percent and about  6 . 5  percent of the overall axial length of the hard insert. 
     
     
       47. A rotatable cutting bit according to  claim 17  wherein the hard insert having an overall axial length, and the second intermediate section extends forwardly along the longitudinal axis from the junction with the first intermediate section to the tip section a distance that ranges between about  3 . 4  percent and about  11 . 4  percent of the overall axial length of the hard insert. 
     
     
       48. A rotatable cutting bit according to  claim 47  wherein the second intermediate section extends forwardly along the longitudinal axis from the junction with the first intermediate section to the tip section a distance that ranges between about  5  percent and about  9  percent of the overall axial length of the hard insert. 
     
     
       49. A rotatable cutting bit according to  claim 47  wherein the second intermediate section extends forwardly along the longitudinal axis from the junction with the first intermediate section to the tip section a distance that ranges between about  5 . 5  percent and about  6 . 5  percent of the overall axial length of the hard insert. 
     
     
       50. A rotatable cutting bit comprising a head portion, a shank portion depending from said head portion along a longitudinal axis, said head portion having a socket at the forward end, a hard insert having coaxially aligned and integral sections, said sections comprising a base section, a tip section, a first intermediate section contiguous with said base, a second intermediate section of uniform diameter contiguous with said first intermediate and tip sections, said second intermediate section extends forwardly along the longitudinal axis from the junction with said first intermediate section to the tip section a fifth distance, said base being fixedly mounted in said socket and having a first diameter, said tip section being conically shaped and having a maximum second diameter, said first intermediate section having a maximum third diameter, said second intermediate section having a fourth diameter equal to said maximum second diameter, said second and third diameters each being less than said first diameter, said first intermediate section has a frusto- conical shape and angles outwardly from the junction with said second intermediate section to the junction with said base section, said first intermediate section at said base forming a fillet at the junction thereof whereby said base forms a shoulder with said first intermediate section, said insert is fixedly held to said head portion by brazing, and the ratio of the fifth distance to the first diameter ranging between about  0 . 03  and about  0 . 10 .   
     
     
       51. The rotatable cutting bit according to  claim 50  wherein the ratio of the fifth distance to the first diameter equals about  0 . 05 . 
     
     
       52. A rotatable cutting bit comprising a head portion, a shank portion depending from said head portion along a longitudinal axis, said head portion having a socket at the forward end, a hard insert having coaxially aligned and integral sections, the hard insert having an overall axial length equal to a sixth distance, said sections comprising a base section, a tip section, a first intermediate section contiguous with said base, a second intermediate section of uniform diameter contiguous with said first intermediate and tip sections, said second intermediate section extends forwardly along the longitudinal axis from the junction with said first intermediate section to the tip section a fifth distance, said base being fixedly mounted in said socket and having a first diameter, said tip section being conically shaped and having a maximum second diameter, said first intermediate section having a maximum third diameter, said second intermediate section having a fourth diameter equal to said maximum second diameter, said second and third diameters each being less than said first diameter, said first intermediate section has a frusto- conical shape and angles outwardly from the junction with said second intermediate section to the junction with said base section, said first intermediate section at said base forming a fillet at the junction thereof whereby said base forms a shoulder with said first intermediate section, said insert is fixedly held to said head portion by brazing, and the ratio of the fifth distance to the sixth distance ranging between about  0 . 03  and about  0 . 12 .   
     
     
       53. The rotatable cutting bit according to  claim 52  wherein the ratio of the fifth distance to the sixth distance ranges between about  0 . 05  and about  0 . 07 . 
     
     
       54. A rotatable cutting bit comprising a head portion, a shank portion depending from said head portion along a longitudinal axis, said head portion having a socket at the forward end, a hard insert having coaxially aligned and integral sections, the hard insert having an overall axial length equal to a sixth distance, said sections comprising a base section, a tip section, a first intermediate section contiguous with said base, a second intermediate section of uniform diameter contiguous with said first intermediate and tip sections, said second intermediate section extends forwardly along the longitudinal axis from the junction with said first intermediate section to the tip section a fifth distance, said base being fixedly mounted in said socket and having a first diameter, said tip section being conically shaped and having a maximum second diameter, said first intermediate section having a maximum third diameter, said second intermediate section having a fourth diameter equal to said maximum second diameter, said second and third diameters each being less than said first diameter, said first intermediate section has a frusto- conical shape and angles outwardly from the junction with said second intermediate section to the junction with said base section, said first intermediate section at said base forming a fillet at the junction thereof whereby said base forms a shoulder with said first intermediate section, said insert is fixedly held to said head portion by brazing, and the ratio of the fifth distance to the first diameter ranging between about  0 . 03  and about  0 . 10 , and the ratio of the fifth distance to the sixth distance ranges between about  0 . 03  and about  0 . 12 .   
     
     
       55. The rotatable cutting bit according to  claim 54  wherein the ratio of the fifth distance to the sixth distance ranges between about  0 . 05  and about  0 . 07 . 
     
     
       56. The rotatable cutting bit according to  claim 54  wherein the ratio of the fifth distance to the first diameter equals about  0 . 05 . 
     
     
       57. The rotatable cutting bit according to  claim 56  wherein the ratio of the fifth distance to the sixth distance ranges between about  0 . 05  and about  0 . 07 .