US2971753A - Process and an oven for the baking of enamels on articles of ferrous metal - Google Patents

Process and an oven for the baking of enamels on articles of ferrous metal Download PDF

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Publication number
US2971753A
US2971753A US519603A US51960355A US2971753A US 2971753 A US2971753 A US 2971753A US 519603 A US519603 A US 519603A US 51960355 A US51960355 A US 51960355A US 2971753 A US2971753 A US 2971753A
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Prior art keywords
articles
oven
enamelled
enamel
gases
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Expired - Lifetime
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US519603A
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English (en)
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Hermans Fernand Victo Francois
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23D—ENAMELLING OF, OR APPLYING A VITREOUS LAYER TO, METALS
    • C23D9/00—Ovens specially adapted for firing enamels
    • C23D9/04—Non-electric tunnel ovens
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23D—ENAMELLING OF, OR APPLYING A VITREOUS LAYER TO, METALS
    • C23D9/00—Ovens specially adapted for firing enamels
    • C23D9/02—Non-electric muffle furnaces
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/06—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity heated without contact between combustion gases and charge; electrically heated

Definitions

  • the present invention relates to a process for stoving enamels on articles of ferrous metal lying in a gaseous atmosphere containing combustion gases. 7 It is known that articles of ferrous metal which are raised to a temperature of several hundred degrees in the presence of air are oxidised rather rapidly if they are, at the same time, in contact with water vapour.
  • Heating in electric ovens is more expensive than heating muffle ovens by gas.
  • the latter ovens have the drawback of being of a relatively expensive construction, of necessitating periodic renewal of the muflies and of having a relatively high calorific inertia.
  • All these ovens also have the drawback that the articles being enamelled are heated by radiation from bodies, the temperature of which is necessarily higher than the temperature required for baking the enamel, so that, if the articles being enamelled are accidentally left in the oven for too long a time, defects, such as blisters or changes of colours, are sometimes produced in the enamel.
  • these ovens do not allow thick articles and thin articles to be enamelled simultaneously, because the thin articles become superheated at the moment at which the other articles only reach the melting point of the enamel.
  • ovens for enamelling articles of ferrous metal in which these articles are heated by radiation from a base-plate, below which combustion gases pass before entering the oven and quietly lick its side walls up to openings made in its roof in order to enable them to escape through a chimney.
  • the combustion gases do not come into direct contact with the articles being enamelled, notwithstanding the fact that there is no Wall separating them from the combustion gases which lick the side walls of the oven.
  • the gaseous atmosphere which is in direct contact with the ferrous articles being enamelled, undergoes hardly any movement because it is not influenced by the fiow of the combustion gases along the side walls.
  • the object of the present invention is a process for enamelling ferrous articles, whereby any trace of oxidation of the metal is obviated almost with certainty.
  • the combustion gases are made to travel, on contact with the articles being enamelled, at a minimum speed of one metre per second, preferably at about four metres per second.
  • a similar elfect is not obtained in ovens for drying articles being enamelled, in which drying gases at a relatively low temperature pass, at a low speed, in contact with the articles being dried which remain in the oven often for two or three hours.
  • the drying gases which sometimes contain a small quantity of combustion gases, are at a temperature which generally does not reach 70 C. because the workmen should be able to enter the oven.
  • the object of the low speed of travel of the drying gases is only to prevent the gases from becoming saturated with water and, consequently, from becoming incapable of removing the large quantity of water which accompanies the enamel when the latter is applied to the articles to be enamelled.
  • the enamel can be baked, even at 800 C., by passing, in contact therewith, combustion gases which contain a large quantity of water, on condition that the speed of those gases is, at least, one meter per second, preferably about four metres per second.
  • the speed of the combustion gases on contact with the articles being enamelled is such that, even with the water vapour present in these gases, the moisture, which adheres to the metal and which is formed as the result of the heating of the enamel to several hundred degrees, is carried off by these gases.
  • the water vapour contained in the latter can retard the removal of this moisture only slightly and not sufficiently for it to be possible for the metal to oxidise on contact with air before the enamel melts.
  • the speed of forced travel of the combustion gases on contact with the articles being enamelled,'which is produced in the process according to the invention, is much greater than that of the slight current of air which is, at times, admitted into mufiie ovens by the effect of natural draught, with a view to reducing the oxidation of the metal.
  • the slow renewal of the atmosphere of the mufiie has only the effect of allowing an easier removal of the moisture derived from the water of impregnation or from the water of constitution of the enamel owing to a lower content of water vapour in the air in contact with the articles of ferrous metal being enamelled in the mufiie.
  • the enamels generally employed for the treatment of ferrious articles are enamels with a titanium base, the melting point of which isabout 7 56 C. for those thatare to be applied to sheet ironand about 850 C. for those that are to be applied to cast iron. Previously, the melting point of the enamels which were available for this purpose was still higher. In the enamelling of glass, the enamels used should have a melting point that is lower than the softening point of the That is the reason why only enamels, the melting point of which generally does not exceed 550 C., are
  • One of these ways consists in employing, in the oven, jets of gas leaving the burnerswhich are used for the heating. For this purpose, it is sufiicient to'direct the burners so that the atmosphere in the ovenis set in motion on contact with the articles.
  • the speed of the jets may easily be obtained by acting on theoutlet section of the burners and on the supply pressure.
  • Another object ofthe invention is an oven for carrying 'outthe process accordingtothe invention.
  • an oven for the discontinuous enamelling of articles comprises gas bumers which open laterallyand are arranged in'sucha manner'that the jets of combustion-gases which leave-them meet halfwayacross the width.
  • this oven comprises at least one fan, which ensures a transverse travel of the gaseous atmosphere on contact with the articles in the preheating zone, and gas burners which ensure the transverse passage of the gaseous atmosphere on contact with the articles in the baking zone.
  • Fig. 1 represents diagrammatically a vertical crosssection through a plane represented by the line 1-1 in Fig. 2 of an oven according to the invention for the intermittent baking of enamels.
  • Fig. 2 is a vertical longitudinal sectioncorresponding to the staggered line IIII of Fig. 1.
  • Fig. 3 represents diagrammatically, in plan, two'par-ts of a U-shap'ed tunnel oven according to the invention, in which the articles being enai'nelled are carried during their displacement in the oven.
  • Figures 6 and 7 are cross-sections, which correspond respectively to those of Figures 4 and 5, in a tunnel oven according to the invention, in which the articles are suspended during their displacement in the oven.
  • the discontinuous oven represented in Figures 1 and 2 comprise gas burners 2 which are fed withgas-'and-air through pipes denoted respectively by 3 and '4. These burners open laterally into the oven near the base-plate and send upwards, along the side walls 5, the jets of combustion gases formed at the outlets. These jets meet one another at about the middle of the width of the oven. The cur-rents of combustion gases are compelled to descend in the middle part of the oven towards the articles being enamelled which are carried by a grate 6.
  • the oven' represented also comprises'two flues lii' which are separated from the baking chamber by walls-14.
  • the fan 18 therefore also ensures ap'artial recirculation of the combustion gases coming into contact-With the articles being enamelled.
  • the longitudinal current of combustion gases,which is produced by the fan 18, isdis'tributed both below and above the grate '6.
  • Tests have' shown'that, when the speed of the combustion gases, on contact with'theferrous'articlesbeing enamelled; re'aehes a minimum-value of one-metre per second, appreciable oxidation of these'articles no longer ture which is formed from the layer of enamel between the instant at which the articles begin to be heated in the oven and that at which the enamel is melted.
  • the speed of the combustion gases on contact with the articles being enamelled is about four metres per second.
  • the movement of the combustion gases on contact with the articles being enamelled may be produced solely with the aid of gas jets issuing from the burners but, in certain cases, the arrangement of the articles in the oven with a view to filling it as much as possible is such that transverse currents cannot be obtained conveniently.
  • a fan for producing the movement of the gaseous atmosphere in contact with the articles in the direction which is suitable for all the faces of the latter to be capable of being licked by the gases at a minimum speed of one metre per second.
  • the tunnel oven represented by Figures 3 to 5 comprises, in the known manner, a preheating zone 19, in which the articles 20 already enamelled travel towards the outlet and give up a part of their heat to the articles 21 being enamelled which are advancing towards a baking zone 22.
  • At least one fan 23 has been provided, which ensures a transverse travel of the gaseous atmosphere on contact with the articles 20 and 21.
  • the speed of travel of this atmosphere is, at least, one metre per second in order that the moisture formed by these articles during their heating should be removed immediately by the moving atmosphere.
  • the articles being enamelled are licked by the combustion gases which, on their contacting these articles, travel at a speed which is also at least one metre per second, owing to the arrangement of the burners 2.
  • the articles 20 and 21 are carried and are displaced in preheating and baking zones which are wider than their height.
  • the burners 2 are arranged laterally about halfway up.
  • the burners which are situated on one side of the oven are so oriented that the jets which issue therefrom are directed upwards whilst the burners which are situated on the other side of the oven are so oriented that the jets which issue therefrom are directed downwards.
  • This arrangement of the burners assists the travel of the gaseous atmosphere, on contact with the articles being enamelled, at the speed required for re moving the moisture which is formed from the enamel during the heating of these articles.
  • the oven represented in Figures 6 and 7 is also a tunnel oven, but the articles being enamelled are suspended therein. height than the Width because of the dimensions of the suspended articles being enamelled.
  • a fan 23 also ensures a forced travel of the air in the preheating zone 19 on contact with the articles 21 being enamelled.
  • some of the burners 2 are arranged on one side near the base-plate, so that their jets are directed upwards, and the others are arranged on the other side near the roof so that their jets are directed downwards.
  • a process for removing combined water from porcelain enamels and for vitrifying porcelain enameling material on articles of ferrous metal by fusion of the enameling material in an oven heated by combustion gases comprising introducing said combustion gases into said oven in contact with the enamel-coated articles, circulating the combustion gases at an effective speed by applying a positive pressure to said gases during contact thereof with the enameling material being melted, removing from said oven the combustion gases as they are being circulated, and removing from said oven the combined water contained in the enameling material during the heating of the latter preceding their fusion as the circulated gases are removed from said oven, thereby preventing injurious oxidation of the metal by combined water originally contained in the enameling material.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Combustion & Propulsion (AREA)
  • General Engineering & Computer Science (AREA)
  • Tunnel Furnaces (AREA)
  • Drying Of Solid Materials (AREA)
  • Oxygen, Ozone, And Oxides In General (AREA)
US519603A 1954-07-08 1955-07-01 Process and an oven for the baking of enamels on articles of ferrous metal Expired - Lifetime US2971753A (en)

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Application Number Priority Date Filing Date Title
BE530224D BE530224A (enrdf_load_html_response) 1954-07-08 1954-07-08

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US2971753A true US2971753A (en) 1961-02-14

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US (1) US2971753A (enrdf_load_html_response)
BE (1) BE530224A (enrdf_load_html_response)
DE (1) DE1017877B (enrdf_load_html_response)
FR (1) FR1134010A (enrdf_load_html_response)
GB (1) GB801741A (enrdf_load_html_response)
NL (1) NL97227C (enrdf_load_html_response)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3718496A (en) * 1970-11-16 1973-02-27 Formica Corp Textured caul plate surfaced with furnace cement

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1257530B (de) 1962-07-23 1967-12-28 Ahlmann Ag Co Emaillierofen fuer Badewannen und Saenitaetsguss
CN109974430A (zh) * 2019-05-16 2019-07-05 吉丽 一种烘干线隧道炉

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1819772A (en) * 1927-06-04 1931-08-18 William A Darrah Process of applying heat
US2010295A (en) * 1933-12-18 1935-08-06 Henry A Dreffein Conveying and supporting mechanism
US2181928A (en) * 1937-08-13 1939-12-05 Electric Furnace Co Forced circulation fuel fired furnace
US2308902A (en) * 1941-07-25 1943-01-19 Gen Properties Company Inc Method of producing heat radiating flames
US2434491A (en) * 1942-10-06 1948-01-13 Harold G Elder Method of firing metallurgical furnaces
US2480374A (en) * 1945-09-20 1949-08-30 Carnegie Illinois Steel Corp Furnace
US2492682A (en) * 1945-07-23 1949-12-27 Armco Steel Corp Processes of producing glass coated silicon steel
US2517024A (en) * 1946-06-17 1950-08-01 Anaconda Wire & Cable Co Enameling oven
US2676007A (en) * 1951-03-29 1954-04-20 Alvin W Davis Heat-treating apparatus
US2676008A (en) * 1949-12-12 1954-04-20 Munker Theo Method for the heat treatment and drying also only on the surface of substances in continuously working furnaces

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1819772A (en) * 1927-06-04 1931-08-18 William A Darrah Process of applying heat
US2010295A (en) * 1933-12-18 1935-08-06 Henry A Dreffein Conveying and supporting mechanism
US2181928A (en) * 1937-08-13 1939-12-05 Electric Furnace Co Forced circulation fuel fired furnace
US2308902A (en) * 1941-07-25 1943-01-19 Gen Properties Company Inc Method of producing heat radiating flames
US2434491A (en) * 1942-10-06 1948-01-13 Harold G Elder Method of firing metallurgical furnaces
US2492682A (en) * 1945-07-23 1949-12-27 Armco Steel Corp Processes of producing glass coated silicon steel
US2480374A (en) * 1945-09-20 1949-08-30 Carnegie Illinois Steel Corp Furnace
US2517024A (en) * 1946-06-17 1950-08-01 Anaconda Wire & Cable Co Enameling oven
US2676008A (en) * 1949-12-12 1954-04-20 Munker Theo Method for the heat treatment and drying also only on the surface of substances in continuously working furnaces
US2676007A (en) * 1951-03-29 1954-04-20 Alvin W Davis Heat-treating apparatus

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3718496A (en) * 1970-11-16 1973-02-27 Formica Corp Textured caul plate surfaced with furnace cement

Also Published As

Publication number Publication date
DE1017877B (de) 1957-10-17
BE530224A (enrdf_load_html_response) 1955-01-08
GB801741A (en) 1958-09-17
FR1134010A (fr) 1957-04-04
NL97227C (enrdf_load_html_response) 1961-03-15

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