# US 4,395,025 A · Method and apparatus for the continuous furnace brazing and gas soft-nitriding treatments of iron articles

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- Number: US 4,395,025 A
- Document ID: US4395025A
- Status: Granted
- Kind: A
- Application number: 06/305,341
- Filed: 1981-09-24
- Granted: 1983-07-26
- Earliest claimed: 1978-07-12
- Assignees: Honda Giken Kogyo Kabushiki Kaisha
- Inventors: Teruoki Watanabe; Tadao Kanno; Akio Hidaka; Shunji Kobayashi
- Web page: https://patentgrep.com/patent/US4395025A

## CPC

- B23K 35/38: Selection of media, e.g. special atmospheres for surrounding the working area
- B23K 1/008: Soldering within a furnace (B23K1/012 takes precedence)
- C23C 8/06: using gases (C23C8/36 takes precedence)
- C23C 8/26: of ferrous surfaces
- C23C 8/32: of ferrous surfaces
- B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)

## Abstract

A method for continuously treating an iron member wherein the iron member is first subjected to furnace-brazing in a controlled gas environment and subsequently to a soft-nitriding treatment by addition of ammonia gas (NH.sub.3) to the controlled gas for the brazing. An apparatus for carrying out the method is also provided, and includes three partitioned chambers for brazing, annealing and soft-nitriding the iron member, each chamber being partitioned by a member such as a stainless steel film curtain at opposite sides thereof. A controlled gas feed system communicates with each of the chambers, and an ammonia gas feed system is connected to the soft-nitriding chamber.

## Claims

### Claim 1

A continuous treatment furnace for brazing and gas soft-nitriding iron parts, comprising:
a furnace body including:
a brazing chamber for brazing said iron parts in a protecting atmosphere substantially comprising a controlled gas for brazing;
a furnace cooling chamber, provided subsequent to said brazing chamber, for gradually cooling said iron parts in a protecting atmosphere substantially comprising said controlled gas; and
a gas soft-nitriding chamber, provided subsequent to said furnace cooling chamber, for gas soft-nitriding said iron parts in a gas soft-nitriding atmosphere substantially comprising said controlled gas and an ammonia gas;
a protecting gas supply line branched to feed said controlled gas to said brazing chamber, said furnace cooling chamber, and said gas soft-nitriding chamber;
an ammonia gas supply line connected to feed said ammonia gas to said gas soft-nitriding chamber;
said chambers being provided with partition walls therebetween;
each said partition wall being provided with an opening therein to permit communication between said chambers; and
a shielding steel curtain being disposed so as to cover each said opening while permitting said iron parts to be passed therethrough.

### Claim 2 (depends on 1)

A continuous treatment furnace according to claim 1, further comprising:
a conveyor extending along said furnace body so as to continuously carry said iron parts through said brazing chamber, said furnace cooling chamber and said gas soft-nitriding chamber.

### Claim 3 (depends on 2)

A continuous treatment furnace according to claim 2, wherein:
said shielding steel curtains have lower ends thereof in sliding contact with an upper surface of said conveyor.

### Claim 4 (depends on 1)

A continuous treatment furnace according to claim 1, wherein:
said gas soft-nitriding chamber is provided with an agitator means.

### Claim 5 (depends on 1)

A continuous treatment furnace according to claim 1, wherein:
said furnace body includes a front wall provided with an inlet port adjacent said brazing chamber and further includes a rear wall provided with an outlet port adjacent said gas soft-nitriding chamber; and
shielding steel curtains are disposed so as to cover said inlet port and said outlet port while permitting said iron parts to be passed therethrough.