High heat transfer oven

Process of drying objects comprising:

• (a) passing said object successively along a prescribed path of travel through an essentially open interior of a housing;
• (b) disposing a plurality of fans in said open interior and in succession adjacent to the path of travel;
• (c) directing successive turbulent blasts of air from the front side of said fans toward said path of travel at spaced locations along said path of travel so as to contact each of said objects successively with such turbulent blasts of air during its travel along said path;
• (d) directing said air from said turbulent blast as return air in essentially unobstructed open paths in said interior to the back sides of said fans for redirection as blasts of air by said fans;
• (e) heating only a portion of the return air after it has been directed toward said path of travel and before said air has reached the back side of each of said fans;
• (f) commingling the heated air and the returned air;
• and
• (g) redirecting the commingled air toward said path of travel.

A high turbulence heat transfer oven for drying objects comprising:

• (a) a housing having a continuous common essentially open interior through which objects to be dried are passed along an open path of travel;
• (b) fan means disposed at spaced intervals along said path and in said common open interior of said housing for cooperating in producing a circulation of air in said interior from the front side of each of said fan means toward said objects and thence around to the back sides of said fan means, each fan means directing air against said objects;
• (c) spaced heating means along said path of travel for heating only a portion of the air as it is returned to the back sides of each of said fan means for intermixing with the air in said essentially open interior and
• (d) control means for individually, respectively controlling the amount of heat delivered by said heating means.

A high turbulence oven for drying objects comprising:

• (a) a housing having a common essentially open interior through which objects to be dried are passed along a path of travel;
• (b) fan means disposed in said open interior at spaced intervals along said path for cooperating in producing a circulation of air in said interior from the front side of each of said fans toward said objects and thence around to the back sides of said fan means, each for means directing air against said objects;
• (c) spaced heating means along said path of travel for heating only a portion of the air as it is returned to the back sides of each of said fan means for intermixing with the air in said essentially open interior;
• and
• (d) control mean for individually, respectively controlling the speed of the fan means.

An oven for drying coatings on objects passed therethrough comprising:

• (a) a housing having walls including opposed side walls and a top wall defining a generally open interior having a longitudinal path of travel through which said objects are passed;
• (b) a plurality of fan assemblies arranged in longitudinally spaced relationship along said path of travel, each of said fan assemblies having a rotatable fan with a hub and radially extending blades protruding from said hub, a shaft carrying said hub for rotation about the axis of said shaft and motor means for rotating said shaft, said axis being essentially perpendicular to the blades of said fan and said path of travel for delivering air to said objects, the space between the blades of said fan and said object being essentially unobstructed so that there is substantially no back pressure and said blades deliver air in a turbulent condition directly toward said path to impinge on said objects for providing forced convection heat transfer thereto and for reducing substantially the boundary layer of their coatings, said blades being spaced from said side walls and said top wall sufficiently that a portion of said air in said interior freely passes unobstructed to the back sides of said fans for recirculation;
• and
• (c) heating means for heating another portion of said air for returning to the back sides of said fans.

Process of drying a coating on an object, comprising:

• (a) disposing an object in a housing having walls defining a chamber;
• (b) positioning a fan within said chamber with said object in front of said fan and with the space between said fan and said object being essentially unobstructed and also with said fan being spaced from said walls sufficiently that there is essentially a free passageway for the air to return to the back side of said fan without appreciable pressure drop;
• (c) operating said fan so as to direct a blast of air toward and onto said object the coating of said object at sufficiently high velocity that high turbulence is generated in the air and the thermal barrier of said coating is reduced essentially to a minimum;
• and
• (d) progressively heating said air by passing a minor portion thereof through a heated heat exchanger to impart heat thereto as the majority of the air is recirculated to the back side of said fan;
• (e) progressively combining said minor portion of said air and said majority of said air, whereby the blast of air delivered by said fan toward said coating produces forced convection of the heat to the coating and reduced to essentially a minimum the boundary layer of said coating.