Alloys or metallic compositions – Ferrous – Nine percent or more chromium containing
Patent
1995-03-03
1997-03-25
Yee, Deborah
Alloys or metallic compositions
Ferrous
Nine percent or more chromium containing
420 49, 420 52, 420 56, 420 57, 420 58, 148610, C22C 3840, C22C 3842, C22C 3844, C21D 800
Patent
active
056141491
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to stainless steels for coins exhibiting proper magnetism or various weak magnetism through coining work and a method of producing coins of stainless steel. More particularly, it relates to a stainless steel for coins usable as a starting material for coin requiring a precise coining work through cold press, which is soft and excellent in workability before the coining work and is hard and excellent in wear resistance after the coining work, and exhibiting weak magnetism of various levels usable as a material for coins for gaming machines, medals and the like, as well as a method of producing coins by using this stainless steel.
BACKGROUND ART
Recently, the demand for stainless steel as a material for coin, medal or the like has increased. The stainless steel for coins is required to have not only excellent corrosion resistance but also good coining workability and wear resistance. That is, the materials for the coin or medal should be soft for facilitating the work during the coining work and should be hard for providing the wear resistance in use after the coining work.
As conventional stainless steel for coins, there are known a strong magnetic ferritic stainless steel as disclosed in JP-A-63-47353, and a non-magnetic austenitic stainless steel as disclosed in JP-A-4-66651.
However, only the strong magnetic ferritic stainless steel has hitherto been used as a material for game coins. Because, when the non-magnetic austenitic stainless steel is used as a material for coins and medals in a game machine, it is difficult to distinguish from currency (money) made of non-magnetic material such as white copper, brass or the like and hence the elimination of forged currency can not be conducted. For instance, if the coin (medal) for the game is used as a currency (money) in a game machine provided with a simple mechanically selecting mechanism instead of an expensive electronically selecting mechanism, discrimination between the coin and the currency is impossible. For this end, the non-magnetic austenitic stainless steel is not used as a material for the game coin.
Another problem with game coins resides in the fact that each of the many game shops desires to have a game coin inherent to each shop. In this case, the size of the coin is actually changed in each shop in order to distinguish the coins made from the same strong magnetic ferritic stainless steel between the shops. However, discrimination through coin size is impractical due to the regulation of the game machines. Furthermore, in order to distinguish the slight difference between coin sizes, an expensive selecting machine having a high selection precision should be used.
In order to solve the above problems, there have recently been proposed gaming coins being adsorbed or not adsorbed through intensity of magnet (maximum energy product BHmax). This coin is made from a weak magnetic material having a middle adequate magnetism between strong magnetism and non-magnetism and enables the discrimination in accordance with the intensity of magnetism. Such a weak magnetic material for the coin is very useful for distinguishing from the currency of non-magnetic material and the gaming coin of strong magnetic material and conducting the discrimination of the coins among many game shops.
As the conventional weak magnetic material, there is used a specific material obtained by incorporating a slight amount of iron powder into brass. However, it is not easy to uniformly disperse the iron powder into the brass. Even if uniform dispersion is attained, directionality is caused in the iron powder by subsequent rolling work and hence there is a problem causing the scattering of the magnetism. Furthermore, the surface of the material is subjected to Ni plating, so that it is expensive, low in work curing and soft, and hence it is easy to cause scratches after the coining.
Heretofore, it has been well-known that meta-stable stainless steels such as JIS-SUS 304 (austenitic stainless steel) and the like produce strain induced ma
REFERENCES:
patent: 3914506 (1975-10-01), Nishio et al.
patent: 3926685 (1975-12-01), Gueussier et al.
patent: 4090813 (1978-05-01), Minato et al.
patent: 4097311 (1978-06-01), Ishibashi et al.
patent: 4172716 (1979-10-01), Abo et al.
patent: 4222773 (1980-09-01), Degerbeck
patent: 4363952 (1982-12-01), Onishi et al.
patent: 4378246 (1983-03-01), Hoshino et al.
patent: 4812287 (1989-03-01), Nakayama et al.
patent: 4837108 (1989-06-01), Kimura et al.
patent: 4846904 (1989-07-01), Arai et al.
patent: 4858682 (1989-08-01), Odelstam
patent: 4933143 (1990-06-01), Adachi et al.
patent: 4964924 (1990-10-01), Yoshitake et al.
patent: 4999159 (1991-03-01), Uematsu et al.
patent: 5000801 (1991-03-01), Honkura et al.
patent: 5035579 (1991-07-01), Yada et al.
patent: 5035855 (1991-07-01), Utsunomiya et al.
patent: 5087414 (1992-02-01), Maniar
English Language Abstract of JP 4-66651.
English Language Abstract of JP 4-272158.
English Language Abstract of JP 57-17940.
English Language Abstract of JP 60-32710.
English Language Abstract of JP 2-141556.
English Language Abstract of JP 63-47353.
Metals Handbook Ninth Edition, vol. 3, Properties and Selection: Stainless Steels, Tool Materials and Special Purpose Metals, American Society for Metals, Metal Park, Ohio, pp. 95-97.
Metals Handbook Tenth Edition, vol. 1, Properties and Selection: Irons, Steels, and High-Performance Alloys, American Society for Metals, Materials Park, Ohio, pp. 841-846.
International Search Report.
Abe Hiroshi
Fujiwara Yoshito
Taniuchi Toshihiko
Tsuda Masaomi
Asahi Seiko Co. Ltd.
Nippon Yakin Kogyo Co. Ltd.
Yee Deborah
LandOfFree
Stainless steels for coins and method of producing coins of stai does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Stainless steels for coins and method of producing coins of stai, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Stainless steels for coins and method of producing coins of stai will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2200924