RADIANT HEATING SYSTEM
United States Patent 3863907
A radiant heating system for maintaining the temperature of molten metals within a narrow preselected range. A radiant heater is affixed substantially centrally of a cover which is hingedly secured to a U-shaped trough so as to cover an open top end thereof. The cover is provided with heat reflecting means which extend longitudinally thereof on opposite sides of the radiant heater member. A handle cooperates with the hinge so that the cover may be moved into and out of close proximity with respect to the open end of the U-shaped trough member.
US Patent References:
Refractory-lined tundishes
Hallowell, Jr. - August 1965 - 3203689
TUNDISH-TUNDISH ROOF ASSEMBLY
Harry, Jr. et al. - August 1970 - 3525506
Refractory-lined tundishes
Hallowell, Jr. - August 1965 - 3203689
TUNDISH-TUNDISH ROOF ASSEMBLY
Harry, Jr. et al. - August 1970 - 3525506
Inventors:
Pierson Sr., Fred W. (Grand Rapids, MI)
Pierson Jr., Fred W. (Grand Rapids, MI)
Pierson Jr., Fred W. (Grand Rapids, MI)
Application Number:
05/477822
Publication Date:
02/04/1975
Filing Date:
06/10/1974
View Patent Images:
Export Citation:
Assignee:
M & T Manufacturing Company (Grand Rapids, MI)
Primary Class:
Other Classes:
432/146, 164/133, 164/335, 266/196, 432/161
International Classes:
B22D35/06; C21B7/14; B22D35/00; F27B19/00
Field of Search:
266/34R,38,40 13/33 164/66,67,133,335,337,259 432/146,152
Primary Examiner:
Dost, Gerald A.
Assistant Examiner:
Bell, Paul A.
Attorney, Agent or Firm:
Low, Warren Matthews Richard N. P.
Parent Case Data:
This is a continuation-in-part of U.S. Ser. No. 300,168 and now abandoned, filed Oct. 24, 1972.
Claims:
What is claimed is
1. A cover construction for use in conveying molten non-ferrous metal in a substantially U-shaped trough member having upwardly extending front and rear side wall members and having an open top end, said cover construction comprising:
2. said skirt means being spaced slightly outwardly from the uppermost ends to said front and side wall members to effect venting of gases from within said trough with said venting occurring substantially along the entire length of said trough member.
3. A cover construction as defined in claim 1 wherein said heat reflecting means extends along the front and rear sides of said radiant heater member and said radiant heater member is self venting by having its front and rear sides spaced inwardly from opposed sides of said heat reflecting means.
4. A cover construction as defined in claim 1 wherein said radiant heater member is a catalytic burner having a maximum temperature of about 1,800°F.
5. A cover construction as defined in claim 1 wherein said U-shaped trough member is composed of a plurality of sections positioned in end abutting relationship with each section being provided with its own cover member and its own radiant heater member.
1. A cover construction for use in conveying molten non-ferrous metal in a substantially U-shaped trough member having upwardly extending front and rear side wall members and having an open top end, said cover construction comprising:
2. said skirt means being spaced slightly outwardly from the uppermost ends to said front and side wall members to effect venting of gases from within said trough with said venting occurring substantially along the entire length of said trough member.
3. A cover construction as defined in claim 1 wherein said heat reflecting means extends along the front and rear sides of said radiant heater member and said radiant heater member is self venting by having its front and rear sides spaced inwardly from opposed sides of said heat reflecting means.
4. A cover construction as defined in claim 1 wherein said radiant heater member is a catalytic burner having a maximum temperature of about 1,800°F.
5. A cover construction as defined in claim 1 wherein said U-shaped trough member is composed of a plurality of sections positioned in end abutting relationship with each section being provided with its own cover member and its own radiant heater member.
Description:
This invention relates to a radiant heating system and cover structure for use in connection therewith and, more particularly, to such a radiant heating system for maintaining the temperature of molten metal within narrow limits of temperature from a melting furnace to a die casting machine, for example.
Heretofore, it has been the practice to insert a heat transfer tube directly into the melt in order to maintain the temperature of molten metal sufficiently high for use in a die casting machine, for example. The life expectancy of these heat transfer tubes has been relatively short, usually in the order of one year, and the system has required the use of a substantial amount of control equipment in order to maintain the desired temperature of the molten metal.
In accordance with the present invention, a radiant heating means is disposed in a cover for a U-shaped trough in close proximity to the upper surface of molten metal disposed in the trough in order to maintain a desired temperature for the molten metal. The cover is provided with heat reflecting means which extend longitudinally of the cover on opposite sides of the radiant heater member.
An inert atmosphere is established and maintained over the molten metal within the trough and it has been found that a predictable, easy to balance, heat is obtained. Thus it is possible to maintain the temperature of the molten metal within very narrow temperature limits, such as 775°-800°F., with no adjustment or control equipment of any kind. It has also been found that the amount of scrap has dropped significantly, such as to 0.5 percent, by use of the instant radiant heating system.
The inherent advantages and improvements of the present invention will become more readily apparent upon considering the following detailed description of the invention and by reference to the drawings in which:
FIG. 1 is a fragmentary exploded perspective view illustrating the radiant heating system of the present invention;
FIG. 2 is a side elevational view taken in vertical cross section along line 2--2 of FIG. 1;
FIG. 3 is a fragmentary rear elevational view of a portion of the apparatus shown in FIG. 1; and,
FIG. 4 is a fragmentary perspective view, partially exploded, showing a portion of a cover construction shown in FIG. 1.
Referring now to FIGS. 1 and 2 of the drawings, there is illustrated a trough support member indicated generally at 10 having legs 12 and leg brace members 13. The trough support 10 is provided with adjustable height means by the use of suitable bolt and nut assembly members with the head of the bolt resting on the floor and the nut being suitably secured as by welding to the angle leg members 12. The adjustable height means permits the attitude of the trough support member and the trough to be adjusted to establish a gravity flow of metal in the trough. The trough support member is provided with a top support member 16 on which trough means, indicated generally at 18, are placed. Trough cover means are indicated generally at 20 and the trough means 18 are retained on the top support member 16 by use of suitable trough-retaining means 22 which may take the form of suitable stud members welded to the top support member 16.
As seen best in FIG. 2, the trough means 18 comprises a trough shell which consists of steel side wall members 24 and a steel bottom member 26. Next to the steel trough shell are placed felt side wall lining members 28 and felt bottom lining member 30. A cast silica member 32 overlays the felt members and provides a surface which is contacted by the molten metal. Tie down members 34 are suitably secured as by welding to the inside of the steel side wall members and provide a hold-down for the felt side wall lining members and the cast silica member 32. These tie down members are spaced adequately along the top of the U-shaped trough to preserve a unitary structure. It is customary to make at least one of the cast silica members 32 T-shaped so that the molten metal may be delivered sideways to a die casting machine, for example.
The trough means 18 are provided with connecting flanges 36 which are provided with felt insulator material 38 to establish a joint between adjacent trough means 18. Joints are also provided between adjacent sections of the cast silica member by the use of suitable gasket means, not shown.
The trough cover means 20 is illustrated best in FIGS. 2 and 3 and includes a pair of insulation means 40 made from felt. A steel frame member 42 provides a skirt which extends along opposite longitudinal sides of the U-shaped trough member 18. A cover shield means 44 made from silica provides a heat reflecting means which extend longitudinally of the cover construction and are positioned on opposite sides of radiant heater member 46. The radiant heater member 46 extends substantially centrally of the cover and is supported at its ends by a radiant holder member 48. A silica plate member is disposed externally of the radiant holder member 48 and with the use of suitable nut and bolt assemblies, not shown, hold the cover member in place as a rigid self-contained unit.
A handle member 52 is attached on one side of the U-shaped trough member and secured as by welding, to the steel frame member 42. Disposed on the opposite side of the U-shaped frame member is a hinge means 54 having a hinge axis 55 which is secured in a hinge extension member 56 which is part of the radiant holder member 48.
As seen best in FIGS. 2 and 3, hinge support members 58 are secured to one of the external steel side wall members 24 in order to support the hinge means 54. The cover construction of the present invention can be used with radiant natural gas atmospheric burners or with a pre-mix blower.
In order to supply natural gas to the radiant heater 46, a pipe 60 is secured to the legs 12 by means of brackets 62 and connected to a suitable source of gas, not shown. A gas valve 64 which may be, for example, Niblet Model 400 of a ball type gas valve admits the natural gas from pipe 60 through flexible hose 66 to the radiant heater 46.
The heaters themselves are R322 (or equivalent) natural gas atmospheric heaters or pre-mix radiant heaters (RE-Verber-Ray Industrial Processing Type).
The arrangement provides an inert gas atmosphere which reduces the build-up of dross and substantially minimizes scrap. The ends of the silica cover shield members 44 are substantially in line with the upper ends of the U-shaped trough so as to provide a heat reflecting means for the molten metal within the cast silica member 32. The handle 52 is conveniently made from a one-half inch diameter reinforcing rod although other handle materials and sizes may be used. Handle 52 permits the cover to be lifted from a position substantially covering the U-shaped trough member to an open position shown on the right-hand side of FIG. 1. In the open position, relatively free access is had to any molten metal within trough means 18.
The mold construction of the present invention has been used to transport molten zinc, aluminum and copper though other molten non-ferrous metals may be transported. The radiant heater construction and cover permit the temperature of the molten metal to be controlled with a relatively predictable heat from the burners after an initial stable condition is reached without adjustments of any kind and to control the temperature within extremely narrow ranges, for example, from 775°-800°F. for aluminum.
The radiant heater 46 is preferably a catalytic burner which relies upon cracking and has a maximum temperature of about 1,800°F. When the burner is adjusted properly there is virtually no flame but only a red glow therefrom. Such a burner produces a temperature of about 1,350°F. at a distance one inch away from the burner. These temperatures are substantially less than the 2,700° to 3,000°F. required for steel, but are satisfactory for non-ferrous metals. Temperatures for zinc, for example, customarily range from 825°F. to 900°F.
It is to be noted that the sides of the radiant heater member 46 as seen in phantom in FIG. 2 are spaced inwardly from the most inward vertically extending wall portion of the cover shield means 44. Thus each radiant heater member 46 is self-venting.
In similar fashion and again with reference to FIG. 2, the longitudinally extending skirt 42 of the steel frame not only extends along opposite longitudinal sides of the U-shaped trough member 18 but are also spaced slightly outwardly from the uppermost ends of the front and rear side wall members 24. Thus venting to the atmosphere occurs along substantially the entire length of the U-shaped trough member 18 and along each section of the trough member.
The practical advantage and significance of the venting which occurs is that sufficient oxidation occurs so that no carbon monoxide (CO) is produced from the burner since sufficient venting is present to ensure the formation of only carbon dioxide (CO 2 ). Thus it becomes possible to use the trough construction at an "in plant" location, that is, within a building without providing for an expansive arrangement to obtain venting exteriorly of the building.
In the conveying of non-ferrous metals such as aluminum and zinc, an oxide skull or skin develops over the top of the metal in the trough. In accordance with the present invention, the metal is maintained in a quiescent condition and the gases are permitted to escape. The apparatus is not suitable for conveying steel because in that instance the skin continues to break up and more oxide is formed which is deleterious to the end products.
When zinc is being conveyed, for example, it is not unusual for the apparatus to be used continuously for seven days with the molten metal being pumped from a furnace to a casting operation. The handle structure permits periodic checking to be certain that the metal is flowing properly and permits cleaning of the trough. It also permits access to the top of the molten metal in the trough which may be skimmed with a ladle periodically. The purpose of this skimming operation is to prevent the build-up of an excess of an oxide layer which acts as an insulator and tends to defeat the purpose of the radiant heater.
It is preferred that the trough member be composed of a plurality of sections arranged in end abutting relationship with each section being vented substantially throughout its length and further with each section being provided with its own cover member and its own radiant heater member. With the associated hinge means and handle members it becomes possible to open each section individually as requisite for inspection, cleaning, and/or skimming.
While presently preferred embodiments of the invention have been illustrated and described, it will be recognized that the invention may be otherwise variously embodied and practiced within the scope of the claims which follow.
Heretofore, it has been the practice to insert a heat transfer tube directly into the melt in order to maintain the temperature of molten metal sufficiently high for use in a die casting machine, for example. The life expectancy of these heat transfer tubes has been relatively short, usually in the order of one year, and the system has required the use of a substantial amount of control equipment in order to maintain the desired temperature of the molten metal.
In accordance with the present invention, a radiant heating means is disposed in a cover for a U-shaped trough in close proximity to the upper surface of molten metal disposed in the trough in order to maintain a desired temperature for the molten metal. The cover is provided with heat reflecting means which extend longitudinally of the cover on opposite sides of the radiant heater member.
An inert atmosphere is established and maintained over the molten metal within the trough and it has been found that a predictable, easy to balance, heat is obtained. Thus it is possible to maintain the temperature of the molten metal within very narrow temperature limits, such as 775°-800°F., with no adjustment or control equipment of any kind. It has also been found that the amount of scrap has dropped significantly, such as to 0.5 percent, by use of the instant radiant heating system.
The inherent advantages and improvements of the present invention will become more readily apparent upon considering the following detailed description of the invention and by reference to the drawings in which:
FIG. 1 is a fragmentary exploded perspective view illustrating the radiant heating system of the present invention;
FIG. 2 is a side elevational view taken in vertical cross section along line 2--2 of FIG. 1;
FIG. 3 is a fragmentary rear elevational view of a portion of the apparatus shown in FIG. 1; and,
FIG. 4 is a fragmentary perspective view, partially exploded, showing a portion of a cover construction shown in FIG. 1.
Referring now to FIGS. 1 and 2 of the drawings, there is illustrated a trough support member indicated generally at 10 having legs 12 and leg brace members 13. The trough support 10 is provided with adjustable height means by the use of suitable bolt and nut assembly members with the head of the bolt resting on the floor and the nut being suitably secured as by welding to the angle leg members 12. The adjustable height means permits the attitude of the trough support member and the trough to be adjusted to establish a gravity flow of metal in the trough. The trough support member is provided with a top support member 16 on which trough means, indicated generally at 18, are placed. Trough cover means are indicated generally at 20 and the trough means 18 are retained on the top support member 16 by use of suitable trough-retaining means 22 which may take the form of suitable stud members welded to the top support member 16.
As seen best in FIG. 2, the trough means 18 comprises a trough shell which consists of steel side wall members 24 and a steel bottom member 26. Next to the steel trough shell are placed felt side wall lining members 28 and felt bottom lining member 30. A cast silica member 32 overlays the felt members and provides a surface which is contacted by the molten metal. Tie down members 34 are suitably secured as by welding to the inside of the steel side wall members and provide a hold-down for the felt side wall lining members and the cast silica member 32. These tie down members are spaced adequately along the top of the U-shaped trough to preserve a unitary structure. It is customary to make at least one of the cast silica members 32 T-shaped so that the molten metal may be delivered sideways to a die casting machine, for example.
The trough means 18 are provided with connecting flanges 36 which are provided with felt insulator material 38 to establish a joint between adjacent trough means 18. Joints are also provided between adjacent sections of the cast silica member by the use of suitable gasket means, not shown.
The trough cover means 20 is illustrated best in FIGS. 2 and 3 and includes a pair of insulation means 40 made from felt. A steel frame member 42 provides a skirt which extends along opposite longitudinal sides of the U-shaped trough member 18. A cover shield means 44 made from silica provides a heat reflecting means which extend longitudinally of the cover construction and are positioned on opposite sides of radiant heater member 46. The radiant heater member 46 extends substantially centrally of the cover and is supported at its ends by a radiant holder member 48. A silica plate member is disposed externally of the radiant holder member 48 and with the use of suitable nut and bolt assemblies, not shown, hold the cover member in place as a rigid self-contained unit.
A handle member 52 is attached on one side of the U-shaped trough member and secured as by welding, to the steel frame member 42. Disposed on the opposite side of the U-shaped frame member is a hinge means 54 having a hinge axis 55 which is secured in a hinge extension member 56 which is part of the radiant holder member 48.
As seen best in FIGS. 2 and 3, hinge support members 58 are secured to one of the external steel side wall members 24 in order to support the hinge means 54. The cover construction of the present invention can be used with radiant natural gas atmospheric burners or with a pre-mix blower.
In order to supply natural gas to the radiant heater 46, a pipe 60 is secured to the legs 12 by means of brackets 62 and connected to a suitable source of gas, not shown. A gas valve 64 which may be, for example, Niblet Model 400 of a ball type gas valve admits the natural gas from pipe 60 through flexible hose 66 to the radiant heater 46.
The heaters themselves are R322 (or equivalent) natural gas atmospheric heaters or pre-mix radiant heaters (RE-Verber-Ray Industrial Processing Type).
The arrangement provides an inert gas atmosphere which reduces the build-up of dross and substantially minimizes scrap. The ends of the silica cover shield members 44 are substantially in line with the upper ends of the U-shaped trough so as to provide a heat reflecting means for the molten metal within the cast silica member 32. The handle 52 is conveniently made from a one-half inch diameter reinforcing rod although other handle materials and sizes may be used. Handle 52 permits the cover to be lifted from a position substantially covering the U-shaped trough member to an open position shown on the right-hand side of FIG. 1. In the open position, relatively free access is had to any molten metal within trough means 18.
The mold construction of the present invention has been used to transport molten zinc, aluminum and copper though other molten non-ferrous metals may be transported. The radiant heater construction and cover permit the temperature of the molten metal to be controlled with a relatively predictable heat from the burners after an initial stable condition is reached without adjustments of any kind and to control the temperature within extremely narrow ranges, for example, from 775°-800°F. for aluminum.
The radiant heater 46 is preferably a catalytic burner which relies upon cracking and has a maximum temperature of about 1,800°F. When the burner is adjusted properly there is virtually no flame but only a red glow therefrom. Such a burner produces a temperature of about 1,350°F. at a distance one inch away from the burner. These temperatures are substantially less than the 2,700° to 3,000°F. required for steel, but are satisfactory for non-ferrous metals. Temperatures for zinc, for example, customarily range from 825°F. to 900°F.
It is to be noted that the sides of the radiant heater member 46 as seen in phantom in FIG. 2 are spaced inwardly from the most inward vertically extending wall portion of the cover shield means 44. Thus each radiant heater member 46 is self-venting.
In similar fashion and again with reference to FIG. 2, the longitudinally extending skirt 42 of the steel frame not only extends along opposite longitudinal sides of the U-shaped trough member 18 but are also spaced slightly outwardly from the uppermost ends of the front and rear side wall members 24. Thus venting to the atmosphere occurs along substantially the entire length of the U-shaped trough member 18 and along each section of the trough member.
The practical advantage and significance of the venting which occurs is that sufficient oxidation occurs so that no carbon monoxide (CO) is produced from the burner since sufficient venting is present to ensure the formation of only carbon dioxide (CO 2 ). Thus it becomes possible to use the trough construction at an "in plant" location, that is, within a building without providing for an expansive arrangement to obtain venting exteriorly of the building.
In the conveying of non-ferrous metals such as aluminum and zinc, an oxide skull or skin develops over the top of the metal in the trough. In accordance with the present invention, the metal is maintained in a quiescent condition and the gases are permitted to escape. The apparatus is not suitable for conveying steel because in that instance the skin continues to break up and more oxide is formed which is deleterious to the end products.
When zinc is being conveyed, for example, it is not unusual for the apparatus to be used continuously for seven days with the molten metal being pumped from a furnace to a casting operation. The handle structure permits periodic checking to be certain that the metal is flowing properly and permits cleaning of the trough. It also permits access to the top of the molten metal in the trough which may be skimmed with a ladle periodically. The purpose of this skimming operation is to prevent the build-up of an excess of an oxide layer which acts as an insulator and tends to defeat the purpose of the radiant heater.
It is preferred that the trough member be composed of a plurality of sections arranged in end abutting relationship with each section being vented substantially throughout its length and further with each section being provided with its own cover member and its own radiant heater member. With the associated hinge means and handle members it becomes possible to open each section individually as requisite for inspection, cleaning, and/or skimming.
While presently preferred embodiments of the invention have been illustrated and described, it will be recognized that the invention may be otherwise variously embodied and practiced within the scope of the claims which follow.