US3873376A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for case hardening workpieces
Assignee: Daimler Benz AG
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Filing: 1973-02-16
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Granted: 1975-03-25
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Expires: 1993-02-16
Abstract
Abstract A method for case-hardening workpieces which is characterized in that certain areas at the workpiece are protected against excessive case-hardening depths by means of a cover body consisting of glass ceramic; for case-hardening transmission gears provided with shifting teeth of weaker cross section, the cover body consists of a ring with a cylindrical portion and a ring disk-shaped portion.
Inventors
- 👤 Karl Ritzka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 17:48
CPC Classifications
C; C23; C23C; C23C8/00; C23C8/04
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
130 words
A METHOD FOR CASE-HARDENING WORKPIECES IN THE WHICH PREDE TERMINED AREAS OF THE WORKPIECESARE PROTECTED AGAINST AN EXCESSIVE CASE-HARDENING DEPTH BY A COVERBODY, SAID METHOD COMPRISING PLACING ON A WORKPIECE AN INTEGRAL ALREADY-FORMED COVER BODY SHAPED TO CORRESPOND WITH THE PORTION OF THE WORKPIECE TO BE PROTECTED AND THEREAFTER CASE-HARDENING SAID WORKPIECE BY MEANS OF A GAS-CARBURIZATION INSTALLATION; SAID COVER BODYBEING FORMED OF A GLASS CERAMIC HAVING A SPECIFIC WEIGHT OF ABOUT 2.54 F/CM2, A TENSILE STRENGTH AT A TEMPERATURE OF ABOUT 25*C OF APPROXIMATELY 600 KG/CM2, A SHEARING STRENGTH OF ABOUT 240 KG/CM2, A LINEAR COEFFICIENT OF EXPANSION OF ABOUT 63 X 10-7/0C DURING A HEATING FROM ABOUT 25*C TO ABOUT 400*C, ATHERMAL CONDUCTIVITY A 25*C OF ABOUT 3.1 KCAL/SEC.CM.*C, AND A HEAT RESISTANCE OF UP TO ABOUT 1,200*C.
Claim 2
Independent Claim
130 words
A METHOD FOR CASE-HARDENING WORKPIECES IN THE WHICH PREDE TERMINED AREAS OF THE WORKPIECESARE PROTECTED AGAINST AN EXCESSIVE CASE-HARDENING DEPTH BY A COVERBODY, SAID METHOD COMPRISING PLACING ON A WORKPIECE AN INTEGRAL ALREADY-FORMED COVER BODY SHAPED TO CORRESPOND WITH THE PORTION OF THE WORKPIECE TO BE PROTECTED AND THEREAFTER CASE-HARDENING SAID WORKPIECE BY MEANS OF A GAS-CARBURIZATION INSTALLATION; SAID COVER BODYBEING FORMED OF A GLASS CERAMIC HAVING A SPECIFIC WEIGHT OF ABOUT 2.54 F/CM2, A TENSILE STRENGTH AT A TEMPERATURE OF ABOUT 25*C OF APPROXIMATELY 600 KG/CM2, A SHEARING STRENGTH OF ABOUT 240 KG/CM2, A LINEAR COEFFICIENT OF EXPANSION OF ABOUT 63 X 10-7/0C DURING A HEATING FROM ABOUT 25*C TO ABOUT 400*C, ATHERMAL CONDUCTIVITY A 25*C OF ABOUT 3.1 KCAL/SEC.CM.*C, AND A HEAT RESISTANCE OF UP TO ABOUT 1,200*C.
Claim 3
Dependent Claim
71 words
A method according to claim 1 wherein said workpieces are gears, each gear being provided with a main tooth arrangement and a shifting tooth arrangement the teeth in said shifting tooth arrangement having weaker cross-sections than the teeth in said main tooth arrangement, said cover body being shaped and sized to protect said shifting tooth arrangement but not said main tooth arrangement when said cover body is placed on said gear.
Claim 4
Dependent Claim
22 words
A method according to claim 2 wherein said cover body comprises a ring with a cylindrical portion and a ring disc-shaped portion.
Claim 5
Dependent Claim
35 words
A method according to claim 3 wherein said cover body is composed of a disc having a concentric opening therein and a cylindrical ring concentric with and attached to the outer periphery of said disc.
Claim 6
Dependent Claim
36 words
A method according to claim 4 wherein said cover body further defines tooth means adapted to engage the gaps between the teeth in said shifting tooth arrangement when said cover body is placed on said gear.
Claim 7
Dependent Claim
62 words
A method according to claim 5 wherein said cover body is sized and shaped to allow a small distance between said cover body and the teeth in said shifting tooth arrangement when said cover body is placed on said gear, whereby carburizing gas is allowed to come into contact with the surfaces of the teeth of said shifting tooth arrangement during carburization.
Claim 8
Dependent Claim
62 words
A method according to claim 4 wherein said cover body is sized and shaped to allow a small distance between said cover body and the teeth in said shifting tooth arrangement when said cover body is placed on said gear, whereby carburizing gas is allowed to come into contact with the surfaces of the teeth of said shifting tooth arrangement during carburization.
Claim 9
Dependent Claim
37 words
A method according to claim 4 further comprising removing said cover body from said gear after carburization of said gear, placing said cover body on a second gear, and carburizing said second gear in a gas-carburization installation.
Claim 10
Dependent Claim
37 words
A method according to claim 2 further comprising removing said cover body from said gear after carburization of said gear, placing said cover body on a second gear, and carburizing said second gear in a gas-carburization installation.
Claim 11
Dependent Claim
37 words
A method according to claim 1 further comprising removing said cover body from said workpiece after carburization of sAid workpiece, placing said cover body on a second workpiece, and carburizing said second workpiece in a gas-carburization installation.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-03-24 | 1978-09-23 | 1979-03-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-24 | 1982-09-23 | 1983-03-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-24 | 1986-09-23 | 1987-03-25 | $7700.00 | Window Closed / Lapsed |