CA1105210A - Coins and similarly disc-shaped articles - Google Patents
Coins and similarly disc-shaped articlesInfo
- Publication number
- CA1105210A CA1105210A CA324,816A CA324816A CA1105210A CA 1105210 A CA1105210 A CA 1105210A CA 324816 A CA324816 A CA 324816A CA 1105210 A CA1105210 A CA 1105210A
- Authority
- CA
- Canada
- Prior art keywords
- core
- intermediate metal
- copper
- thickness
- coating
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- 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
- B23K20/00—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating
- B23K20/24—Preliminary treatment
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Adornments (AREA)
- Electroplating Methods And Accessories (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A blank suitable for minting to form a coin or simi-larly disc-shaped article has an appropriately disc-shaped steel core completely encased by a copper coating electroplated thereon. The blank is produced by first electroplating a thin nickel or zinc coating onto an appropriately disc-shaped steel core such that the nickel or zinc coating completely encases the steel core, and then electroplating a copper coating onto the nickel or zinc coating.
A blank suitable for minting to form a coin or simi-larly disc-shaped article has an appropriately disc-shaped steel core completely encased by a copper coating electroplated thereon. The blank is produced by first electroplating a thin nickel or zinc coating onto an appropriately disc-shaped steel core such that the nickel or zinc coating completely encases the steel core, and then electroplating a copper coating onto the nickel or zinc coating.
Description
~1~52~
This invention relates to coins and similarly disc-shaped articles, such as medals, or medallions.
The metallic composition of coins has varied over the years owing to the escalating cost of the metals or alloys from which coins have conventionally been made. For example, gold coins are now virtually extinct, and silver coins may frequent-ly contain copper ana/or other metals to reduce the metallic value of the coin compared to its face value, while still giving it a silver-like appearance. Another kind of coinage in fre-quent use is copper coinage, which is made of copper or a copper alloy. As compared to silver and gold coinage, of course, coppercoinage is usually used for coins of lower value in a monetary system.
With the increasing cost of metals, the value of the metal of which a coin is made may increase so much that it approaches or even exceeds the face value of the coin, with the result that it can be advantageous to melt down such coins and obtain the current price of their contained metals. It is primarily for this reason that, for example, coins made of silver have now been replaced by coins made of other metals or alloys of similar appearance and lower intrinsic values, such as nickel or nickel alloys.
Until now, this problem has not become particularly significant with respect to copper coinage, since the value of the copper or copper alloy of which the coins are made has remained small compared to the face value of the coins. How-ever, with the escalating cost of copper and its alloys, this problem has now become relevant with respect to copper coinage, with the result that it is now desirable to find some alternative composition or construction for copper coins. Because most countries are reluctant to change the appearance of their coins, it is at the same time necessary to preserve the copper-like q~
l~SZ~
appearance of such coins, as was done in the case of silver coins, where the silver-like appearance of the coins was pre-served by a suitable choice of metal or alloy for at least the faces of the coin.
According to the present invention, blanks suitable for minting into coins or similarly disc-shaped articles are produced by loading a plurality of appropriately disc-shaped steel cores into a perforated container, placing the container i`n an intermediate metal electroplating bath, said intermediate metal being selected from the group consisting of nickel and zinc, electroplating an intermediate metal coating onto the cores while moving the container angularly about a horizontal axis unti`l the intermediate metal coating has a thickness of at least about 0.005 mm on each opposed face of each core and a th.ickness of the peripheral edge of each core measured radially i`n the range of from about 2 to about 4 times the face thickness, placi`ng the container in a copper electroplating bath, electro-plating a copper coating onto the cores while moving the con-tainer angularly about a horizontal axis until the copper coating has a thickness of at least about 0.05 mm on each opposedface of each core and a thickness on the periPheral edge of each core measured radially in the range of from about 2 to about 4 times the face thickness, the ratio of the two thicknesses being adjusted by varying the ratio of the diameter of the core pieces with the diameter of the electroplating container, the current densi.ty and the number of blanks in the container, removing the plated cores .from the contaïner, and heating the plated cores to form a layer of interdiffused copper and intermediate metal and a layer of interdiffused intermediate metal and steel with consequent metallurgical bonding of the copper coating to the intermediate metal coating and of the intermediate metal coat-ing to each steel core and to decrease the hardness of each steel core to less than about 65 on the Rockwell 30T hardness scale.
.,., 2 -ll~SZl~
The blank is subsequently minted by applying the required insignia to one or both faces of the blank by means of an appropriately designed die or dies. Where a coin is to be produced, the size of the core and the thickness of the copper coating will of course be such as to produce a blank of the same size as a conventional copper coin which it is intended the coin according to the present invention should replace.
Steel is considerably less expensive than copper, and the metallic value of a coin according to the present in-vention is considerably less than the metallic value of a con-ventional copper coin of the same size and made entirely of copper and/or copper alloy. Also, the seigniorage of a coin according to the invention, that is to say the difference between the face value of the coin and the cost of producing it (including the cost of raw materials~, is sufficient for the present invention to constitute an attractive alternative process for producing coins of copper-like appearance.
Further, since the exterior of the coin is copper, its appear-ance will resemble that of a conventional copper coin, andwill not become substantially different therefrom over a period of time. If desired, alloying elements may be in-cluded in the copper coating to increase wear or corrosion resistance.
In order to produce a coin of satisfactory hardness and wear resistance for the usage which a coin experiences, while at the same time permitting the blank to be readily i~.printable with the required insignia by means of an appropriately designed die or dies, the steel is preferably a low carbon steel. Advantageously, the carbon content of the steel is less than about 0.05%, a preferred value being
This invention relates to coins and similarly disc-shaped articles, such as medals, or medallions.
The metallic composition of coins has varied over the years owing to the escalating cost of the metals or alloys from which coins have conventionally been made. For example, gold coins are now virtually extinct, and silver coins may frequent-ly contain copper ana/or other metals to reduce the metallic value of the coin compared to its face value, while still giving it a silver-like appearance. Another kind of coinage in fre-quent use is copper coinage, which is made of copper or a copper alloy. As compared to silver and gold coinage, of course, coppercoinage is usually used for coins of lower value in a monetary system.
With the increasing cost of metals, the value of the metal of which a coin is made may increase so much that it approaches or even exceeds the face value of the coin, with the result that it can be advantageous to melt down such coins and obtain the current price of their contained metals. It is primarily for this reason that, for example, coins made of silver have now been replaced by coins made of other metals or alloys of similar appearance and lower intrinsic values, such as nickel or nickel alloys.
Until now, this problem has not become particularly significant with respect to copper coinage, since the value of the copper or copper alloy of which the coins are made has remained small compared to the face value of the coins. How-ever, with the escalating cost of copper and its alloys, this problem has now become relevant with respect to copper coinage, with the result that it is now desirable to find some alternative composition or construction for copper coins. Because most countries are reluctant to change the appearance of their coins, it is at the same time necessary to preserve the copper-like q~
l~SZ~
appearance of such coins, as was done in the case of silver coins, where the silver-like appearance of the coins was pre-served by a suitable choice of metal or alloy for at least the faces of the coin.
According to the present invention, blanks suitable for minting into coins or similarly disc-shaped articles are produced by loading a plurality of appropriately disc-shaped steel cores into a perforated container, placing the container i`n an intermediate metal electroplating bath, said intermediate metal being selected from the group consisting of nickel and zinc, electroplating an intermediate metal coating onto the cores while moving the container angularly about a horizontal axis unti`l the intermediate metal coating has a thickness of at least about 0.005 mm on each opposed face of each core and a th.ickness of the peripheral edge of each core measured radially i`n the range of from about 2 to about 4 times the face thickness, placi`ng the container in a copper electroplating bath, electro-plating a copper coating onto the cores while moving the con-tainer angularly about a horizontal axis until the copper coating has a thickness of at least about 0.05 mm on each opposedface of each core and a thickness on the periPheral edge of each core measured radially in the range of from about 2 to about 4 times the face thickness, the ratio of the two thicknesses being adjusted by varying the ratio of the diameter of the core pieces with the diameter of the electroplating container, the current densi.ty and the number of blanks in the container, removing the plated cores .from the contaïner, and heating the plated cores to form a layer of interdiffused copper and intermediate metal and a layer of interdiffused intermediate metal and steel with consequent metallurgical bonding of the copper coating to the intermediate metal coating and of the intermediate metal coat-ing to each steel core and to decrease the hardness of each steel core to less than about 65 on the Rockwell 30T hardness scale.
.,., 2 -ll~SZl~
The blank is subsequently minted by applying the required insignia to one or both faces of the blank by means of an appropriately designed die or dies. Where a coin is to be produced, the size of the core and the thickness of the copper coating will of course be such as to produce a blank of the same size as a conventional copper coin which it is intended the coin according to the present invention should replace.
Steel is considerably less expensive than copper, and the metallic value of a coin according to the present in-vention is considerably less than the metallic value of a con-ventional copper coin of the same size and made entirely of copper and/or copper alloy. Also, the seigniorage of a coin according to the invention, that is to say the difference between the face value of the coin and the cost of producing it (including the cost of raw materials~, is sufficient for the present invention to constitute an attractive alternative process for producing coins of copper-like appearance.
Further, since the exterior of the coin is copper, its appear-ance will resemble that of a conventional copper coin, andwill not become substantially different therefrom over a period of time. If desired, alloying elements may be in-cluded in the copper coating to increase wear or corrosion resistance.
In order to produce a coin of satisfactory hardness and wear resistance for the usage which a coin experiences, while at the same time permitting the blank to be readily i~.printable with the required insignia by means of an appropriately designed die or dies, the steel is preferably a low carbon steel. Advantageously, the carbon content of the steel is less than about 0.05%, a preferred value being
2~U
of the order of 0.01%.
Many coins have raised rims around the peripheries of opposed faces, and these raised rims are preferably formed on the steel cores before the electroplating step.
In one embodiment of the invention, a batch of coin-age cores was made of low carbon steel, namely steel manu-factured by Dofasco and sold by them as ASTM A424 type I, the maximum carbon content of such steel being 0.01% by weight.
The circular steel cores of appropriate diameter were punched out of steel strip of appropriate thickness, namely about 1.2 mm and were given a raised rim around the periphery of both faces by an upsetting operation. The steel cores were loaded, as a 60 kg batch, into a perforated barrel made of polypropylene 91 cm long and 46 cm in diameter. This 60 kg batch of cores contained about 13,000 cores.
- The steel cores were than put through a cleaning cycle by lowering the barrel into successive baths providing rinses of 5% neutral detergent solution, hot water, cold water, 10% HCl and cold water respectively. In each instance, the barrel was immersed in the bath with its longitudinal axis horizontal, and was oscillated over nearly 180 about its longitudinal axis at about six to and fro cycles per minute. The barrel was then immersed in a nickel sulphamate plating bath containing about 98 grams per litre nickel, and oscillated as before. The temperature of the nickel plating bath was maintained at about 55C and the pH was maintained at about 2.1. Flexible cathode rods were mounted within the barrel, and baskets containing nickel anode pieces were supported in the plating bath externally of the barrel. A voltage of 12V was applied, giving a current of 290A.
. .
2ilO
-After 1.5 h, a 2.8 kg sample of nickel-plated cores was withdrawn from the barrel and rinsed in water.
The thickness of nickel coating on the faces of these cores was found to be 0.003 mm. After a further 1.5 h, a
of the order of 0.01%.
Many coins have raised rims around the peripheries of opposed faces, and these raised rims are preferably formed on the steel cores before the electroplating step.
In one embodiment of the invention, a batch of coin-age cores was made of low carbon steel, namely steel manu-factured by Dofasco and sold by them as ASTM A424 type I, the maximum carbon content of such steel being 0.01% by weight.
The circular steel cores of appropriate diameter were punched out of steel strip of appropriate thickness, namely about 1.2 mm and were given a raised rim around the periphery of both faces by an upsetting operation. The steel cores were loaded, as a 60 kg batch, into a perforated barrel made of polypropylene 91 cm long and 46 cm in diameter. This 60 kg batch of cores contained about 13,000 cores.
- The steel cores were than put through a cleaning cycle by lowering the barrel into successive baths providing rinses of 5% neutral detergent solution, hot water, cold water, 10% HCl and cold water respectively. In each instance, the barrel was immersed in the bath with its longitudinal axis horizontal, and was oscillated over nearly 180 about its longitudinal axis at about six to and fro cycles per minute. The barrel was then immersed in a nickel sulphamate plating bath containing about 98 grams per litre nickel, and oscillated as before. The temperature of the nickel plating bath was maintained at about 55C and the pH was maintained at about 2.1. Flexible cathode rods were mounted within the barrel, and baskets containing nickel anode pieces were supported in the plating bath externally of the barrel. A voltage of 12V was applied, giving a current of 290A.
. .
2ilO
-After 1.5 h, a 2.8 kg sample of nickel-plated cores was withdrawn from the barrel and rinsed in water.
The thickness of nickel coating on the faces of these cores was found to be 0.003 mm. After a further 1.5 h, a
3.8 kg sample of nickel-plated cores was withdrawn from the barrel, and the nickel coating thickness was found to be 0.006 mm on the core faces and 0.02 mm on the circumferential rims. Laboratory tests show that the nickel coating thickness of 0.003 mm on the first sample of cores was inadequate for subsequent copper plating.
The second sample of nickel plated cores was then placed in a smaller barrel having a length of 30 cm and a diameter of 15 cm. The second barrel was then immersed in an acid copper sulphate plating bath con-taining 45 yrams per liire coppex and the barrel was continuously rotated at 6 rpm. Flexible cathode rods were mounted within the baxrel, and baskets containing copper anode pieces were supported in the bath externally of the barrel.
This plating bath was maintained at a tempera-ture of 40C and a pH of 1. The ~ckel plated cores were plated with copper for 13.5 h at a voltage of 3V and a current of 40A and, after this time, a copper coating of 0.06 mm was deposited on the nickel-plated core faces, with a copper coating of 0.14 mm having been deposited on the circumferential rims. After the copper plating, the resultant blanks were rinsed and dried.-5~
The blank~ ~ere then annealed in a pure ~y~rogen atmos-phere at a temperature of 800C for 30 min, and allowed to cool in the same atmosphere, An analysis of the annealed blanks is shown in Table 1.
. F~ I _ _ . _ ~ Nickel Copper ~¦
Cu Ni (by dif- l~eight Diameter ~hickness l~a~dness Plate on Plate on 1 _ 7._ ~ fe~ence) (g) (~m). (mm) R-30T Face (mm) Face (m~) ~.
14.4 1.7 83.9 5.44 24.81 1.3S 42 0.006 0.060 . _ .i~
... . ~ . . . . . .......................... . . . . . . . :~
Metallography showed the plating of the cores to be free from any significant defects, with there being good adhesion between the copper and nickel coatings and between the nickel coat-ing and the steel core.
Some of the blanks were minted, by applying appro-priate insignia to both faces of the blanks by means of dies, and excellent results were achieved. To provide a coin of high lustre, it may be advantageous to burnish the blanks before mint-ing, for example, by burnishing in a soap solution containing metallic media.
The barrel in the copper plating bath may be oscillated, as was the barrel in the nickel plating bath, rather then con-tinuously rotated.
It will be understood that the invention is applicable to the production of other disc-shaped articles, as well as coin blanks. Medals and medallions are examples of other disc-shaped articles to which the invention is applicable. Also, such articles may not necessarily have a circular periphery and may not necessarily be imperforate.
Other embodiments within the scope of the invention will be apparent to a person skilled in the art, the scope of the invention being defined in the appended claims.
~ 6
The second sample of nickel plated cores was then placed in a smaller barrel having a length of 30 cm and a diameter of 15 cm. The second barrel was then immersed in an acid copper sulphate plating bath con-taining 45 yrams per liire coppex and the barrel was continuously rotated at 6 rpm. Flexible cathode rods were mounted within the baxrel, and baskets containing copper anode pieces were supported in the bath externally of the barrel.
This plating bath was maintained at a tempera-ture of 40C and a pH of 1. The ~ckel plated cores were plated with copper for 13.5 h at a voltage of 3V and a current of 40A and, after this time, a copper coating of 0.06 mm was deposited on the nickel-plated core faces, with a copper coating of 0.14 mm having been deposited on the circumferential rims. After the copper plating, the resultant blanks were rinsed and dried.-5~
The blank~ ~ere then annealed in a pure ~y~rogen atmos-phere at a temperature of 800C for 30 min, and allowed to cool in the same atmosphere, An analysis of the annealed blanks is shown in Table 1.
. F~ I _ _ . _ ~ Nickel Copper ~¦
Cu Ni (by dif- l~eight Diameter ~hickness l~a~dness Plate on Plate on 1 _ 7._ ~ fe~ence) (g) (~m). (mm) R-30T Face (mm) Face (m~) ~.
14.4 1.7 83.9 5.44 24.81 1.3S 42 0.006 0.060 . _ .i~
... . ~ . . . . . .......................... . . . . . . . :~
Metallography showed the plating of the cores to be free from any significant defects, with there being good adhesion between the copper and nickel coatings and between the nickel coat-ing and the steel core.
Some of the blanks were minted, by applying appro-priate insignia to both faces of the blanks by means of dies, and excellent results were achieved. To provide a coin of high lustre, it may be advantageous to burnish the blanks before mint-ing, for example, by burnishing in a soap solution containing metallic media.
The barrel in the copper plating bath may be oscillated, as was the barrel in the nickel plating bath, rather then con-tinuously rotated.
It will be understood that the invention is applicable to the production of other disc-shaped articles, as well as coin blanks. Medals and medallions are examples of other disc-shaped articles to which the invention is applicable. Also, such articles may not necessarily have a circular periphery and may not necessarily be imperforate.
Other embodiments within the scope of the invention will be apparent to a person skilled in the art, the scope of the invention being defined in the appended claims.
~ 6
Claims (2)
1. A method for producing blanks suitable for minting into coins or similarly disc-shaped articles, comprising loading a plurality of appropriately disc-shaped steel cores into a perforated container, placing the container in an intermediate metal electroplating bath, said intermediate metal being selected from the group consisting of nickel and zinc, electroplating an intermediate metal coating onto the cores while moving the container angularly about a hori-zontal axis until the intermediate metal coating has a thick-ness of at least about 0.005 mm on each opposed face of each core and a thickness on the peripheral edge of each core measured radially in the range of from about 2 to about 4 times the face thickness, placing the container in a copper electroplating bath, electroplating a copper coating onto the cores while moving the container angularly about a horizontal axis until the copper coating has a thickness of at least about 0.05 mm on each opposed face of each core and a thickness on the peripheral edge of each core measured radially in the range of from about 2 to about 4 times the face thickness, the ratio of the two thicknesses being adjusted by varying the ratio of the diameter of the core with the diameter of the electroplating container, the current density and the number of blanks in the container, removing the plated cores from the container, and heating the plated cores to form a layer of interdiffused copper and intermediate metal and a layer of interdiffused intermediate metal and steel with consequent metallurgical bonding of the copper coating to the intermediate metal coating and of the intermediate metal coating to each steel core and to decrease the hardness of each steel core to less than about 65 on the Rockwell 30T
hardness scale.
hardness scale.
2. A blank suitable for minting into a coin or similarly disc-shaped article comprising a disc-shaped steel core, an intermediate metal coating electroplated on and encasing the core, said intermediate metal being selected from the group consisting of nickel and zinc, and said intermediate metal coating having a thickness of at least about 0.005 mm on each opposed face of the core and a thickness on the peripheral edge of the core measured radially in the range of from about 2 to about 4 times the face thickness, and a copper coating electro-plated on and encasing the intermediate coating and core, the copper coating having a thickness of at least about 0.05 mm on each opposed face of the core and a thickness on the peripheral edge of the core measured radially in the range of from about 2 to about 4 times the face thick-ness, the intermediate metal coating being metallurgically bonded to the core by a layer of interdiffused intermediate metal and steel, the copper coating being metallurgically bonded to the intermediate metal coating by a layer of interdiffused copper and intermediate metal, and the hard-ness of the steel core being less than about 65 on the Rockwell 30T hardness scale.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA324,816A CA1105210A (en) | 1979-04-03 | 1979-04-03 | Coins and similarly disc-shaped articles |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA324,816A CA1105210A (en) | 1979-04-03 | 1979-04-03 | Coins and similarly disc-shaped articles |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1105210A true CA1105210A (en) | 1981-07-21 |
Family
ID=4113911
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA324,816A Expired CA1105210A (en) | 1979-04-03 | 1979-04-03 | Coins and similarly disc-shaped articles |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1105210A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5139886A (en) * | 1990-06-21 | 1992-08-18 | Royal Canadian Mint | Coins coated with nickel, copper and nickel |
| US5151167A (en) * | 1990-06-21 | 1992-09-29 | Royal Canadian Mint | Coins coated with nickel, copper and nickel and process for making such coins |
| US6656606B1 (en) | 2000-08-17 | 2003-12-02 | The Westaim Corporation | Electroplated aluminum parts and process of production |
| US9447515B2 (en) | 2008-06-13 | 2016-09-20 | Royal Canadian Mint | Control of electromagnetic signals of coins through multi-ply plating technology |
-
1979
- 1979-04-03 CA CA324,816A patent/CA1105210A/en not_active Expired
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5139886A (en) * | 1990-06-21 | 1992-08-18 | Royal Canadian Mint | Coins coated with nickel, copper and nickel |
| US5151167A (en) * | 1990-06-21 | 1992-09-29 | Royal Canadian Mint | Coins coated with nickel, copper and nickel and process for making such coins |
| US6656606B1 (en) | 2000-08-17 | 2003-12-02 | The Westaim Corporation | Electroplated aluminum parts and process of production |
| US6692630B2 (en) | 2000-08-17 | 2004-02-17 | The Westaim Corporation | Electroplated aluminum parts and process for production |
| US9447515B2 (en) | 2008-06-13 | 2016-09-20 | Royal Canadian Mint | Control of electromagnetic signals of coins through multi-ply plating technology |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |