Claims
- 1. A method of producing a thread rolled sintered cylindrical metal product which comprises:
- forming a sintered cylindrical powder metal (P/M) blank of density ranging from about 75% to 92% of the actual density of said metal having a selected diameter larger than the final pitch diameter of a predetermined roll threaded product produced therefrom and not exceeding the outside diameter of said predetermined roll threaded product,
- the P/M blank diameter selected being substantially inversely related to the density of said blank, the P/M diameter selected being correlated to produce a substantially full thread,
- and then thread rolling said sintered P/M blank using a threading die of the same thread gage as the predetermined roll threaded product to be produced,
- whereby a thread rolled P/M product is produced having a porous core and highly densified threads, the density of the threads at the surface and sub-surface thereof from the root to the crest being at least about 95% of the actual density, with the density of the core ranging from about 75% to 92% of the actual density of the metal forming the product.
- 2. The method of claim 1, wherein the product after thread rolling is resintered by subjecting it to an elevated sintering temperature.
- 3. The method of claim 2, wherein the product is made of a metal hardenable by heat treatment, and wherein said product is hardened by heat treatment.
- 4. A method of producing a thread rolled sintered cylindrical powder metal product which comprises:
- forming from a heat treatable steel composition a sintered cylindrical powder metal (P/M) blank of density ranging from about 75% to 92% of the actual density of said steel having a selected diameter larger than the final pitch diameter of a predetermined roll threaded product produced therefrom and not exceeding the outside diameter of said predetermined roll threaded product,
- the P/M blank diameter selected being substantially inversely related to the density of said blank, the P/M blank diameter selected being correlated to produce a substantially full thread, and then thread rolling said sintered P/M blank using a threading die of the same thread gage of the predetermined roll threaded product to be produced,
- whereby a thread rolled P/M steel product is produced having a porous core and highly densified threads, the density of the threads at the surface and sub-surface thereof being at least about 95% of the actual density, with the density of the core ranging from about 75% to 92% of the actual density of the steel forming the product.
- 5. The method of claim 4, wherein the steel product after thread rolling is hardened by heat treatment.
- 6. The method of claim 4, wherein the steel product after thread rolling is resintered at an elevated sintering temperature and thereafter hardened by heat treatment.
- 7. The method of claim 4, wherein the heat treatable steel contains at least about 65% iron, about 0.3 to 1.5% carbon and the balance steel alloying ingredients.
- 8. A method of producing a thread rolled sintered cylindrical powder metal product which comprises:
- forming from a heat treatable steel composition a sintered cylindrical powder metal (P/M) blank of density ranging from about 75% to 92% of the actual density of said steel having a selected diameter larger than the final pitch diameter of a predetermined roll threaded product produced therefrom and not exceeding the outside diameter of said predetermined roll threaded product,
- the P/M blank diameter selected being substantially inversely related to the density of said blank, the P/M diameter selected being correlated to produce a substantially full thread,
- said selected blank diameter being determined by the following approximate formula: ##EQU3## and then thread rolling said sintered P/M blank using a threading die of the same thread gage of the predetermined roll threaded product to be produced,
- whereby a thread rolled P/M product is produced having a porous core and highly densified threads, the density of the threads at the surface and sub-surface thereof from the root to the crest being at least about 95% of the actual density of the steel, with the density of the core ranging from about 75% to 92% of the actual density of the steel forming the product.
- 9. The method of claim 8, wherein the steel product after thread rolling is hardened by heat treatment.
- 10. The method of claim 8, wherein the steel product after thread rolling is resintered at an elevated sintering temperature and thereafter hardened by heat treatment.
- 11. The method of claim 8, wherein the heat treatable steel contains at least about 65% iron, about 0.3 to 1.5% carbon and the balance steel alloying ingredients.
- 12. As an article of manufacture, a sintered thread rolled P/M product, said thread rolled product being characterized by a porous core and highly densified threads, the density of the threads at the surface and sub-surface thereof from the root to the crest being at least about 95% of the actual density, with the density of the porous core ranging from about 75% to 92% of the actual density of the metal forming the product.
- 13. The article of manufacture of claim 12, wherein the density of said threads is at least about 98%, and wherein the density of the core ranges from about 80% to 92%.
- 14. As an article of manufacture, a sintered thread rolled P/M product formed of a heat treatable steel composition containing at least about 65% iron, about 0.3 to 1.5% carbon and the balance steel alloying ingredients, said thread rolled product being characterized by a porous core and highly densified threads, the density of the threads at the surface and sub-surface thereof from the root to the crest being at least about 95% of the actual density, with the density of the porous core ranging from about 75% to 92% of the actual density of the steel composition forming the product.
- 15. The article of manufacture of claim 14, wherein the density of said threads is at least about 98%, and wherein the density of the porous core ranges from about 80% to 92%.
- 16. The article of manufacture of claim 14, wherein said sintered thread rolled product is in the heat treated hardened state.
Parent Case Info
This is a continuation, of application Ser. No. 055,508 filed July 9, 1979, now abandoned.
US Referenced Citations (6)
Non-Patent Literature Citations (1)
Entry |
Brodski, A. M.; "Small Thread Rolling Dies" in Machines & Tooling, vol. XLIII, Nailly 1972, pp. 54-57. |
Continuations (1)
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Number |
Date |
Country |
Parent |
55508 |
Jul 1979 |
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