Stock material or miscellaneous articles – All metal or with adjacent metals – Plural layers discontinuously bonded
Reexamination Certificate
1998-09-17
2001-04-24
Jones, Deborah (Department: 1775)
Stock material or miscellaneous articles
All metal or with adjacent metals
Plural layers discontinuously bonded
C428S599000, C428S679000, C428S683000, C428S685000, C228S153000, C228S154000, C228S234100
Reexamination Certificate
active
06221505
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a lap joint welding arrangement and a related welding method.
For connecting two members, various joint arrangements have been conventionally proposed and used. Among them, a lap joint welding arrangement is widely known and used because of easiness in positioning the two members to be welded before performing the welding operation.
In this kind of lap joint welding structure, there is a possibility that a particular portion may be subjected to a concentrated stress, causing a crack in the welded portion.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a lap joint welding structure and a related welding method capable of effectively moderating or relieving a stress acting on a fused portion and preventing the fused portion from causing cracks.
In order to accomplish this and other related objects, an aspect of the present invention provides a lap joint welding structure comprising a first member and a second member having end portions overlapped and fixed by welding at a predetermined lap portion. A fused edge portion is formed at the lap portion as a fused and hardened portion merging into the first member and the second member. A front end surface of the fused edge portion slanting at an obtuse angle larger than 90° with respect to a naked outer surface of the second member not overlapped with the first member.
Preferably, second member has a rod body inserted into a bore of the first member. The first member has a rib brought into contact with the second member.
Preferably, the first member is a Ni-group alloy steel comprising the components (weight %) of C (≦0.05), Si (≦0.30), Mn (≦1.25), P (≦0.04), S (≦0.03), and Ni (40.00~50.00). The second member is a martensite-group stainless steel comprising the components (weight %) of C (≦1.20), Si (≦1.00), Mn (≦1.25), P (≦0.04), S (≦0.03), and Cr (≦18.00). A dilution rate S=B/(A+B) is equal to or less than 45%, where “A” represents a cross-sectional area of the fused edge portion merging into the first member and “B” represents a cross-sectional area of the fused edge portion merging into the second member.
Alternatively, the first member is a ferrite-group stainless steel comprising the components (weight %) of C (≦0.12), Si (≦3.00), Mn (≦1.25), P (≦0.04), S (≦0.03), Cr (≦20.00), and Al (≦5.00). In this case, the dilution rate S=B/(A+B) is equal to or less than 30%.
The fused edge portion is formed at the lap portion by irradiating a welding beam on an outer surface of the lap portion.
Another aspect of the present invention provides a welding method of forming the lap joint welding structure for connecting the first member and the second member. In a first step, the lap portion is formed by overlapping the end portions of the first member and the second member. In a second step, the welding beam is irradiated to a predetermined irradiation point on the outer surface of the lap portion offset from an end surface thereof. In a third step, the fused edge portion is formed along an outer periphery of the lap portion as the fused and hardened portion merging into the first member and the second member.
Preferably, the rod body of the second member is inserted into the bore of the first member for forming the lap portion. A distal end surface of the second member is brought into contact with the rib formed in the bore of the first member.
Preferably, the irradiation of the welding beam is performed along an entire periphery of the lap portion so that the front end surface of the fused edge portion slants at the obtuse angle larger than 90° with respect to the naked outer surface of the second member not overlapped with the first member.
Another aspect of the present invention provides a welding method of forming a lap joint welding structure for connecting first member and second members configured into the shapes different from those of the above-described members. The first member has a head portion, a stem portion, and a hole extending in the head portion and the stem portion. In a first step, a lap portion is formed by inserting the second member into the hole of the first member to form a lap portion. A welding beam is irradiated to a predetermined irradiation point on an outer surface of the stem member of the lap portion. A fused portion is formed along a periphery of the lap portion as a fused and hardened portion merging into the first member and the second member.
Preferably, the first member is made of a magnetic material comprising at least one selected from the group consisting of a silicon steel, a Ni-group alloy steel, and a ferrite stainless steel. The second member is made of an anti-wear metallic material comprising at least one selected from the group consisting of an alloy tool steel, a high speed tool steel, and a martensite-group stainless steel. The dilution rate S=B/(A+B) is in a range from 15 to 45%.
Another aspect of the present invention provides a lap joint welding structure comprising the first member having the head portion, the stem portion, and the hole extending in the head portion and the stem portion. The lap portion is formed between the first member and the second member inserted into the hole of the first member. The fused portion is formed along a periphery of the lap portion as the fused and hardened portion merging into the first member and the second member.
REFERENCES:
patent: 4078919 (1978-03-01), Kado et al.
patent: 5302214 (1994-04-01), Uematsu et al.
patent: 5603853 (1997-02-01), Mombo-Caristan
patent: 5628449 (1997-05-01), Onuma et al.
patent: 60-60175 (1985-04-01), None
patent: 1-205892 (1989-08-01), None
patent: 10-328861 (1998-12-01), None
Morikawa Hiroyasu
Ohmi Yoshinori
Shirai Hideaki
Denso Corporation
Jones Deborah
Pillsbury & Winthrop LLP
Savage Jason
LandOfFree
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