초록 ▼

A concave cutter bit which has a bit body that contains a concavity in the axially forward end thereof. A plurality of cutter inserts are brazed to the bit body at the periphery of the open end of the concavity. The cutter inserts are spaced-apart in such a fashion so that a gap exists between adjac

A concave cutter bit which has a bit body that contains a concavity in the axially forward end thereof. A plurality of cutter inserts are brazed to the bit body at the periphery of the open end of the concavity. The cutter inserts are spaced-apart in such a fashion so that a gap exists between adjacent cutter inserts that is of sufficient size to prevent the formation of a continuous braze joint between any adjacent cutter inserts.

대표청구항 ▼

1. A rotatable cutter bit that is rotatable about its central longitudinal axis, the cutter bit comprising: a bit body having opposite forward and rearward ends, the bit body containing a concavity in the forward end thereof wherein the concavity is symmetric about the central longitudinal axis,

1. A rotatable cutter bit that is rotatable about its central longitudinal axis, the cutter bit comprising: a bit body having opposite forward and rearward ends, the bit body containing a concavity in the forward end thereof wherein the concavity is symmetric about the central longitudinal axis, the concavity having an open end; a plurality of cutter inserts being secured by brazing to the bit body at the periphery of the open end of the concavity; and adjacent cutter inserts being spaced-apart so that a gap therebetween is sufficient in size to prevent the formation of a continuous braze joint between the adjacent cutter inserts. 2. The rotatable cutter bit of claim 1 wherein the bit body contains a channel about the entire periphery of the open end of the concavity, the channel defining a longitudinal surface and a transverse surface, and each cutter insert forming a braze joint with the longitudinal surface and the transverse surface. 3. The rotatable cutter bit of claim 1 wherein each one of the cutter inserts is made of cobalt cemented tungsten carbide, and the bit body is made from steel. 4. The rotatable cutter bit of claim 3 wherein the cemented tungsten carbide comprises about 90.5 weight percent tungsten carbide and about 9.5 weight percent cobalt. 5. The rotatable cutter bit of claim 1 wherein the braze alloy comprises about 50 weight percent silver, about 20 weight percent copper, about 28 weight percent zinc, and about 2 weight percent nickel. 6. The rotatable cutter bit of claim 1 wherein the bit body having a generally cylindrical shank near the rearward end thereof, the shank containing a groove therein, and a retainer being carried in the groove in the shank. 7. A cutter bit-block assembly comprising: a block containing a bore therein; a cutter bit having a bit body with opposite axially forward and rearward ends, the bit body having a central longitudinal axis, the axially forward end of the bit body containing therein a concavity with an open end, the concavity is symmetric about the central longitudinal axis, the bit body having a peripheral surface completely surrounding the open end; the bit body having a retainer that engages the bore of the block so as to retain the cutter bit to the block so that the cutter bit is rotatable about its longitudinal axis; and a plurality of cutter inserts secured to the peripheral surface in a spaced-apart fashion so that a gap exists between each adjacent one of the cutter inserts, each one of the gaps is sufficient in size to prevent the formation of a continuous braze joint between the adjacent cutter inserts. 8. The cutter bit-block assembly of claim 7 wherein the bit body contains a channel at the periphery of the open end of the concavity, the channel defining a longitudinal surface and a transverse surface, and each cutter insert forming a braze joint with the longitudinal surface and the transverse surface. 9. The cutter bit-block assembly of claim 8 wherein each cutter insert having a top surface, a bottom surface, an external side surface, an internal side surface, and opposite end surfaces, each cutter insert being secured in the channel so that the end surfaces of each one of said cutter inserts does not contact the end surfaces of either one of the two adjacent said cutter inserts; and the bottom surface of each cutter insert forming a braze joint with the transverse surface of the channel and the internal side surface of each cutter insert forming a braze joint with the longitudinal surface of the channel. 10. The cutter bit-block assembly of claim 7 wherein cutter bit is rotatable with respect to the block. 11. A rotatable cutter bit for impinging a substrate, the cutter bit comprising: an elongate bit body having a central longitudinal axis, the bit body having an impingement end, the impingement end having a peripheral region generally symmetric about the central longitudinal axis, a plurality of cutter inserts connected to the bit body at the peripheral region thereof, the cutter inserts being spaced-apart so as to define a spatial gap between any two adjacent cutter inserts. 12. The cutter bit of claim 11 wherein the bit body contains a cavity at the impingement end thereof, and the cavity has an open end defined by the peripheral region. 13. The cutter bit of claim 12 wherein the cavity is concave in shape. 14. The cutter bit of claim 4 wherein the peripheral region includes a transverse surface generally perpendicular to the longitudinal axis of the bit body, and the cutter inserts being connected to the transverse surface. 15. The cutter bit of claim 14 wherein the cutter inserts being connected to the transverse surface by brazing, and a spatial gap existing between each adjacent cutter inserts that is sufficiently large so as to prevent the formation of a continuous braze joint between the adjacent cutter inserts. 16. The cutter bit of claim 14 wherein the peripheral region further includes a longitudinal surface generally parallel to the longitudinal axis of the bit body, and the cutter inserts being connected to the longitudinal surface. 17. The cutter bit of claim 16 wherein the cutter inserts being connected to the longitudinal surface by brazing, and a spatial gap existing between each adjacent cutter inserts that is sufficiently large so as to prevent the formation of a continuous braze joint between the adjacent cutter inserts. 18. A rotatable cutter bit comprising: a bit body having opposite forward and rearward ends, the bit body containing a concavity in the forward end thereof, the concavity having an open end; a plurality of cutter inserts being secured by brazing to the bit body at the periphery of the open end of the concavity; adjacent cutter inserts being spaced-apart so that a gap therebetween is sufficient in size to prevent the formation of a continuous braze joint between the adjacent cutter inserts; the bit body contains a channel at the periphery of the open end of the concavity, the channel defining a longitudinal surface and a transverse surface, and each cutter insert forming a braze joint with the longitudinal surface and the transverse surface; each cutter insert having a top surface, a bottom surface, an external side surface, an internal side surface, and opposite end surfaces, each cutter insert being secured in the channel so that the end surfaces of each one of said cutter inserts does not contact the end surfaces of either one of the two adjacent said cutter inserts; and the bottom surface of each cutter insert forming a braze joint with the transverse surface of the channel and the internal side surface of each cutter insert forming a braze joint with the longitudinal surface of the channel. 19. The rotatable cutter bit of claim 1 comprising seven of the cutter inserts, and each of the cutter inserts being generally arcuate in shape. 20. The rotatable cutter bit of claim 19 wherein each one of the cutter inserts has an included angle of about 44 degrees 30 minutes.