Abstract: A muffle furnace assembly for brazing aluminum heat exchanger workparts comprises a tubular muffle having a workpart conveyer extending therethrough. A pair of fans disposed inside the muffle circulate high temperature atmosphere through the workparts. The muffle is surrounded by an insulative outer shell spaced to form an interstitial cavity therebetween. High temperature combustion gasses are directed into the interstitial cavity and flow in a helical path about the muffle. Louvers are provided in the muffle, between the workparts and the fans, for regulating the amount of inert gas flow within the muffle. Inlet and exit vestibules usher workparts into and out of the furnace assembly to minimize oxygen contamination within the muffle.

Abstract: An improved convective heat transfer arrangement is disclosed achieving overall heat transfer efficiencies in the neighborhood of 30 Btu/(hr. ft.sup.2 .degree.F.). A heat transfer conduit including a heat transfer wall is axially divided into a plurality of axially extending heat transfer chambers by a plurality of transversely extending baffles. Each baffle is especially configured to have an axially extending recess formed therein through which extends an orifice opening. Heat transfer gas pumped through the conduit cascades through the heat transfer chambers forming and reforming nascent free standing jet streams through each baffle orifice which impinge the heat transfer wall to achieve very high heat transfer coefficients while efficiently utilizing the available heat in the heat transfer gas.

Abstract: Modifications are provided to a standard, batch type industrial heat treat furnace of a hot wall design which permit the furnace to be operated efficiently at high temperatures. The furnace is of a cylindrical design having a forward heat treat chamber and a rearward plenum chamber with a flat bulkhead plate in-between the chambers. The bulkhead has exit and inlet openings permitting wind mass to flow to the heat treat chamber and back to the plenum chamber. The bulkhead has a plurality of radially extending slits formed therein which permit the bulkhead to remain flat despite temperature and pressure gradients resulting in expansion/contraction of the bulkhead. Additionally, the furnace includes a closed end muffle within the heat treat chamber into which work to be heat treated is placed. A water cooled spring biasing support is provided for the closed end of the muffle to resist downward deformation of the muffle at high temperatures.

Abstract: An improved industrial furnace employing a new and unique heat transfer arrangement is disclosed. The furnace is a closed end cylindrical chamber with a circular, concentrically positioned plate dividing one side of the furnace into a fan chamber containing a fan and the other side of the furnace into a heat treat chamber containing the work. The plate has a central under-pressure opening and its outer circular edge is spaced from the cylindrical wall to define an annular space which is non-orificing. Fan rotation in the fan chamber produces an annulus of wind mass swirling at high circumferential speed which axially travels through the non-orificing space towards the closed end of the heat treat chamber at slow speed. Heating elements extend through the non-orificing space into the heat transfer chamber and are constantly impinged by the swirling annulus wind mass to effect good heat transfer therewith.

Abstract: An improved convective heat transfer arrangement is disclosed achieving overall heat transfer efficiencies in the neighborhood of 30 Btu/(hr. ft.sup.2 .degree. F.). A heat transfer conduit including a heat transfer wall is axially divided into a plurality of axially extending heat transfer chambers by a plurality of transversely extending baffles. Each baffle is especially configured to have an axially extending recess formed therein through which extends an orifice opening. Heat transfer gas pumped through the conduit cascades through the heat transfer chambers forming and reforming nascent free standing jet streams through each baffle orifice which impinge the heat transfer wall to achieve very high heat transfer coefficients while efficiently utilizing the available heat in the heat transfer gas.

Abstract: A gas fired convection cooking oven is provided with an improved air delivery and heat exchange structure for creating within the oven's cooking chamber a recirculating flow of heated air to cook food items supported therein. The structure includes a combustion box adapted to receive hot products of combustion from a gas burner, and extending into the cooking chamber through a lower portion of a vertical boundary wall thereof. Removably secured to the combustion box, and extending upwardly along the inner side of the boundary wall is a hollow baffle structure having a front mixing chamber communicating with the interior of the combustion box through spaced apart hollow legs with a discharge opening formed therebetween. Perforated skirt walls extending rearwardly from the mixing chamber define with the boundary wall a fan chamber which surrounds a motor-driven centrifugal fan impeller supported on the inner side of the boundary wall.

Abstract: A gas fired convection cooking oven is provided with an improved air delivery and heat exchange structure for creating within the oven's cooking chamber a recirculating flow of heated air to cook food items supported therein. The structure includes a combustion box adapted to receive hot products of combustion from a gas burner, and extending into the cooking chamber through a lower portion of a vertical boundary wall thereof. Removably secured to the combustion box, and extending upwardly along the inner side of the boundary wall is a hollow baffle structure having a front mixing chamber communicating with the interior of the combustion box through spaced apart hollow legs with a discharge opening formed therebetween. Perforated skirt walls extending rearwardly from the mixing chamber define with the boundary wall a fan chamber which surrounds a motor-driven centrifugal fan impeller supported on the inner side of the boundary wall.

Abstract: An internal heat exchange tube for cooling work within an industrial furnace is positioned to extend within the furnace and is closed at its axial end which is inside the furnace. Within the tube is an open ended, thin wall inner tube formed in the shape of a helical coil. Water introduced into the inner tube distributes thermally induced, circumferential stress gradients about both tubes to prevent tube bending while achieving fast cooling of the outer tube.

Abstract: An arrangement for connecting a heat-resistant blower wheel located in a oven comprises a hollow projection formed on a wheel at its side facing toward a motor and provided with a coaxial flange, a metal disc connectable with a perpendicularly extending motor shaft, the wheel and the projection being composed of a heat-resistant material, and a disc-shaped element located between the flange and the disc in the region of their connection and formed as a springly element.

Abstract: An improved industrial furnace employing a new and unique heat transfer arrangement is disclosed. The furnace is a closed end cylindrical chamber with a circular, concentrically positioned plate dividing one side of the furnace into a fan chamber containing a fan and the other side of the furnace into a heat treat chamber containing the work. The plate has a central under-pressure opening and its outer circular edge is spaced from the cylindrical wall to define an annular space which is non-orificing. Fan rotation in the fan chamber produces an annulus of wind mass swirling at high circumferential speed which axially travels through the non-orificing space towards the closed end of the heat treat chamber at slow speed. Heating elements extend through the non-orificing space into the heat transfer chamber and are constantly impinged by the swirling annulus wind mass to effect good heat transfer therewith.

Abstract: A radiant tube furnace has a pair of regenerative burners firing alternately into opposite ends of the tube. There is a respective inlet at each end of the tube for admitting gas to the tube immediately adjacent to the wall thereof and these inlets communicate via a duct so that products of combustion are drawn from one end of the tube and introduced into the opposite end of the tube, where the burner is firing.

Abstract: Two concentric and relatively displaceable cylinders mounted on the center axis of a vacuum furnace between its load chamber and its blower serve to control the gas flows in said furnace, where said gas flows are used to heat and cool the load portions.

Abstract: An internal heat exchange tube for cooling work within an industrial furnace is positioned to extend within the furnace and is closed at its axial end which is inside the furnace. Within the tube is an open ended, thin wall inner tube formed in the shape of a helical coil. Water introduced into the inner tube distributes thermally induced, circumferential stress gradients about both tubes to prevent tube bending while achieving fast cooling of the outer tube.

Abstract: A gas-fired oven is disclosed wherein heated air is delivered to an oven's interior from a gas burner located outside the oven in a way to enhance the convection heating properties and capacity of the oven. This is accomplished by means of a conduit which receives air heated by the external gas burner and internally discharges this heated air into the return air path of a blower used to recirculate hot air within the oven. The internal discharge end of the conduit is located adjacent to the blower's return air path so that the conduit does not obstruct the recirculating air. The external gas burner may be either an atmospheric burner or a power burner. Its gas burner head is axially aligned with the conduit's exterior inlet end and spaced a short distance from this inlet. The spacing between the burner head and the conduit inlet controls the dilution air which is required to regulate the temperature of the hot air according to the oven's function such as heating food.

Abstract: A low cost, improved convective heat transfer furnace is disclosed which includes a cylindrical casing to which is attached blanket insulation and the casing is closed at its ends to define a closed end cylindrical furnace enclosure. An annular fan face plate is positioned within the enclosure to define a pressure zone on one side and a work zone on the other side. A paddle wheel fan in the work zone develops a large mass of circumferentially swirling wind which is initially formed as a stationary swirling mass without an axial force component but which under pressure travels axially in the form of a swirling annulus through the non-orificing annular space. The under pressure zone established by the central opening in the fan face plate causes the swirling wind annulus in the work zone to expand radially inwardly and uniformly impinge the complete surface of the work in an effective heat transfer manner before being recirculated back to the pressure zone.

Abstract: An ingot pusher furnace of the vertical air flow type includes adjustable side baffles hingedly connected to lower ends of respective vertical side baffles to prevent the "short circuiting" of heated gases around the ends of an ingot to be heated. The adjustable side baffles are movable from a vertical position to an angled position so that its upper ends are in closely spaced proximity with the outer faces on the end portions of the shorter length ingot so as to produce a more uniform and faster heat transfer along the entire length thereof.

Abstract: An enhanced, air-flow convection oven is disclosed, comprising an oven chamber liner circumscribed by a thermally insulated outer oven shell with a heat source in a combustion chamber between the shell and the liner. Hot air flows from the combustion chamber and into a uniquely constructed blower wheel assembly. The blower wheel assembly has a concave central plate configuration which creates a negative pressure behind the blower wheel assembly, inducing a flow of hot air from the back of the blower wheel assembly into the blower wheel assembly as the wheel rotates. This hot air is mixed with air from within the chamber to produce uniform heating throughout the chamber.

Abstract: A heat treatment furnace for treating metal workpieces has a substantially cylindrical housing. The housing surounds a heating chamber having cooling gas inlets and outlets connected to a cooling gas circulation system for circulating the gas. A plurality of nozzles forming the gas inlets are mounted on the housing on two diametrically opposite sides thereof. The two sets of nozzles simultaneously direct cooling gases towards an impact zone within the heating chamber such that cooling gases meet in the impact zone. The workpieces are also supported in the impact zone of the heating chamber. A plurality of vents forming the gas outlets are placed around the periphery of the impact zone and conduct the cooling gas out of the heating chamber and into a heat exchanger.

Abstract: A cooling system for a processing furnace provides improved cooling efficiency in a more compact arrangement than known furnace cooling systems. In the system a blower is situated within the cooling gas plenum but has its intake exterior thereto. The plenum wall and the furnace outer wall define a recirculation channel which is relatively large and free of obstructions. Heat exchanger coils are disposed within the recirculation channel adjacent the blower intake thereby providing a less restricted flow path for the cooling gas.

Abstract: A fuel fired heat treating furnace having an imperforate inner shell for containing a work load in isolation. The shell is made of a refractory material which provides a good heat exchange from the outside to the inside. A multiplicity of hot gas streams is directed under pressure against the outside of the shell by means of a circulation system which includes a plenum, a fan within the plenum and a plurality of apertured distributor tubes extending from one end of the shell to the other. Fuel burners exhaust combustion gases into the system on the discharge side of the fan where the gases mix with returning gases from the intake side of the fan and are fed into the distributor tubes.

Abstract: A gas fired convection cooking oven is provided with an improved air delivery and heat exchange structure for creating within the oven's cooking chamber a recirculating flow of heated air to cook food items supported therein. The structure includes a combustion box adapted to receive hot products of combustion from a gas burner, and extending into the cooking chamber through a lower portion of a vertical boundary wall thereof. Removably secured to the combustion box, and extending upwardly along the inner side of the boundary wall is a hollow baffle structure having a front mixing chamber communicating with the interior of the combustion box through spaced apart hollow legs with a discharge opening formed therebetween. Perforated skirt walls extending rearwardly from the mixing chamber define with the boundary wall a fan chamber which surrounds a motor-driven centrifugal fan impeller supported on the inner side of the boundary wall.

Abstract: An improved heat transfer arrangement for use in a unique multi-function, industrial heat treat furnace which employs a sealed, closed end, heat exchanger shell member containing the work. The heat transfer arrangement includes a totally contained, internal recirculation system which develops an especially configured annular jet stream that produces highly efficient, convective heat transfer with the shell member. After heat transfer between the entrained gases in the jet stream with the shell member has occurred, the jet flow is reversed at one end of the shell and impinged against the workpiece, the spent stream being reformed into the annular jet at the opposite end of the shell member.

Abstract: An improved heat transfer arrangement for use in a unique multi-function, industrial heat treat furnace which employs a sealed, closed end, heat exchanger shell member containing the work. The heat transfer arrangement includes a totally contained, internal recirculation system which develops an especially configured annular jet stream that produces highly efficient, convective heat transfer with the shell member. After heat transfer between the entrained gases in the jet stream with the shell member has occurred, the jet flow is reversed at one end of the shell and impinged against the workpiece, the spent stream being reformed into the annular jet at the opposite end of the shell member.

Abstract: Apparatus for the heat treatment of a length of continuously moving material in a plurality of treatment zones contains a fan to provide a stream of circulating air. The outer wall of the machine and fan housing is provided with an opening which can be closed by a closure device, through which the interior of the fan housing and the nozzle casing are accessible.

Abstract: A method of providing an air circulation and exhaust control system for an oven (20) includes an oven enclosure (24) having a conveyor (40) mounted therein for transporting food products through the oven. A plurality of ribbon burners (100) are mounted within the oven interior (32) adjacent the path of the conveyor to heat the interior of the oven. Heated gases generated by operation of the ribbon burners are received through inlet plenums (140) under operation of a circulation fan (146) and are discharged through discharge tubes (154) extending adjacent portions of the conveyor (40) remote from the locations of the ribbon burners (100). Exhaust gases are removed from the oven interior through discharge ports (180) by exhaust blower assemblies (184) which are operated to remove exhaust gases from the oven interior at a rate proportional to the flow rate of combustion air and gaseous fuel into the ribbon burners.

Abstract: A furnace for heat treatment in vacuo with cooling by a stream of gas wherein there is a rotating volute mounted between a heat enclosure and a turbine and wherein the rotating volute is in the form of a helical flange arranged on the outside of a hollow cylinder through which gas is directed from the enclosure to the turbine and which volute also includes a gas outlet deflector associated with the helical flange through which gas may be directed toward the heat enclosure.

Abstract: A fuel fired heat treating furnace having an imperforate inner shell for containing a work load in isolation. The shell is made of a refractory material which provides a good heat exchange from the outside to the inside. A multiplicity of hot gas streams is directed under pressure against the outside of the shell by means of a circulation system which includes a plenum, a fan within the plenum and a plurality of apertured distributor tubes extending from one end of the shell to the other. Fuel burners exhaust combustion gases into the system on the discharge side of the fan where the gases mix with returning gases from the intake side of the fan and are fed into the distributor tubes.

Abstract: A gas-fired convection oven comprises a cooking cavity having a centrifugal fan mounted on a rear wall thereof. A vertical shroud mounted adjacent to the fan forms a narrow heat exchanging chamber within the cavity. A heat exchanger comprising a generally U-shaped hollow tube extends within the heat exchanging chamber and is provided with outwardly directed jets on the leg portions thereof. A power jet burner surrounded by a secondary air passageway conduit communicate with an inlet into the heat exchanger. Means for baffling secondary air at the inlet to the heat exchanger provides for generally balanced flow of combustion products within both legs of the heat exchanger facilitating energy efficiency in the heating of the cooking cavity.

Abstract: An improved heat transfer arrangement for use in a unique multi-function, industrial heat treat furnace which employs a sealed, closed end, heat exchanger shell member containing the work. The heat transfer arrangement includes a totally contained, internal recirculation system which develops an especially configured annular jet stream that produces highly efficient, convective heat transfer with the shell member. After heat transfer between the entrained gases in the jet stream with the shell member has occurred, the jet flow is reversed at one end of the shell and impinged against the workpiece, the spent stream being reformed into the annular jet at the opposite end of the shell member.

Abstract: An oven (20) includes an oven enclosure (24) having a conveyor (40) mounted therein for transporting food products through the oven. A plurality of ribbon burners (100) are mounted within the oven interior (32) adjacent the path of the conveyor to heat the interior of the oven. Heated gases generated by operation of the ribbon burners are received through inlet plenums (140) under operation of a circulation fan (146) and are discharged through discharge tubes (154) extending adjacent portions of the conveyor (40) remote from the locations of the ribbon burners (100). Exhaust gases are removed from the oven interior through discharge ports (180) by exhaust blower assemblies (184) which are operated to remove exhaust gases from the oven interior at a rate proportional to the flow rate of combustion air and gaseous fuel into the ribbon burners.

Abstract: A continuous heat treating furnace is equipped with an automatic flow control system and contains a high-temperture treating zone internally provided with a plurality of burners, a pre-heating zone connectively disposed at one end of the high-temperature treating zone and a cooling zone connectively disposed at its other end, the pre-heating and cooling zones being partitioned into a plurality of compartments each provided on its ceiling portion with a convection fan.

Abstract: An oven for heat treating, curing, stress relieving or otherwise treating objects within the oven has side walls that can be moved into contact and out of contact with side edges of a movable floor. All interior surfaces of the oven are insulated and, when the floor is located in the oven, the side walls can be moved so that the insulation on the side walls forms a sealed relationship with the insulation along the adjacent side edges of the floor. A door of the oven can then be closed. When the door is opened, the side walls can be moved out of contact with the floor and the floor can be removed. Preferably, the side walls are moved by the operation of pneumatic cylinders.

Abstract: An indirect-fired, infrared drying oven for articles of manufacture which have been through a coating process. Tubular radiators are mounted within the enclosure to produce infrared radiation which impinges upon the coated articles. The tubular radiator operates at a sub-ambient interior pressure and is vented near the burner to directly inspirate fumes from the interior of the oven as they are given off by the drying articles. Temperatures in the radiator are sufficient to incinerate the fumes as they travel along the length of the tubular radiator. A heat exchanger is utilized near the exhaust end of the radiator to recover waste heat and return this heat to the oven enclosure, thus balancing air flow within the enclosure and maintaining a neutral pressure condition.

Abstract: An ingot pusher furnace of the vertical air flow type includes distributing means for preventing short circuiting of a gaseous medium around the ends of ingots to be heated so as to produce a more uniform heat transfer along the entire length of the ingots. The distributing means comprises a pair of air distribution baffles which force the gaseous medium contained in an enclosure to flow towards the center portions of the ingots so as to facilitate uniform heating throughout the ingots. In an alternate embodiment, the distributing means comprises a pair of movable side baffles which is movable to an angled position so that its lower ends are adjacent the ends of the ingots.

Abstract: A rethermalization oven for heating food is disclosed, characterized by uniform distribution of heat and air through a heating chamber. The oven includes a housing and partitions for defining an outer U-shaped air plenum, a rectangular heating chamber, and a burner chamber. The side panels of the partition contain a plurality of spaced horizontal slots and the rear panel of the partition contains a plurality of spaced openings and horizontal slots of progressively increasing thickness in the directions toward the top and bottom of the housing. A heating element is arranged in the burner chamber for heating the air arranged therein.

Abstract: An ingot pusher furnace of the vertical air flow type includes distributing means for preventing short circuiting of a gaseous medium around the ends of ingots to be heated so as to produce a more uniform heat transfer along the entire length of the ingots. The distributing means comprises a pair of air distribution baffles which force the gaseous medium contained in an enclosure to flow towards the center portions of the ingots so as to facilitate uniform heating throughout the ingots. In an alternate embodiment, the distributing means comprises a pair of movable side baffles which is movable to be angled position so that its lower ends are adjacent the ends of the ingots.

Abstract: A gas convection oven includes a heating chamber having a gas combustion chamber formed therein and a blower positioned within the combustion chamber for circulating air through the heating and combustion chambers. The blower defines a low pressure inlet centrally of the combustion chamber for receiving air from the heating chamber and forcing it through the combustion chamber back into the heating chamber around the outer edges of the combustion chamber. A gas burner extends into the combustion chamber and includes a distally-mounted diverter for dividing and directing flame and combustion products into two different directions. A bifurcated heat exchanger defines first and second tubular passages which are aligned with and encompass the blower and define inlets aligned with the two different directions for receiving the combustion products from the burner.

Abstract: A bakery oven, of the type employing a continuous spiral conveyor for carrying goods to be baked through an oven enclosure, employs an air distribution system to direct heated air from near the top wall of the oven enclosure to a plenum chamber, and from there through an air distribution network to at least certain ones of the tiers of the spiral conveyor. Preferably, heater elements are disposed beneath alternate ones of the tiers of the conveyor system within the oven enclosure, while the air distribution pipes are disposed beneath the remaining tiers. This arrangement serves to decrease fuel consumption for the burners, thereby increasing productivity, and further serves to decrease the stratification of heat layers within the oven enclosure, thereby providing uniform baking conditions throughout the oven enclosure.

Abstract: A furnace for preheating and homogenizing aluminum ingots prior to hot rolling same wherein the heating efficiency is improved thus reducing the time required to heat the ingots to the homogenizing temperature. The furnace comprises an elongated housing having a ceiling, a floor and a pair of side walls extending from the floor to the ceiling for defining a chamber which is divided into an upper fan section and a lower ingot heating section. A plurality of fans are disposed in the upper fan section for circulating hot gases to the ingot heating section of the chamber. Baffles are associated with the side walls of the furnace for directing the hot gases toward the lower portion of the ingot heating section so as to cause the hot gases to flow between the ingots to be heated so as to contact the entire side wall surfaces thereof improving heating efficiency.

Abstract: A furnace (10) has a preheater zone (12) into which exhaust gases from a combustion chamber (14) are recycled for preheating of articles passing through the furnace. The exhaust gases are supplied to the preheater zone (12) through jet pipes (18) which create a turbulent flow about the articles in the furnace (10). The exhaust gases are withdrawn by a fan (30) which is disposed in a duct (34) adjacent to the furnace entrance (13). To prevent the introduction of ambient air into the furnace (10), a pressure chamber (56), which is maintained at about atmospheric pressure, is provided within the preheater zone (12), with the chamber (56) pressurized by gases supplied by exhaust gases passing through a separate pipe (70) which has an adjustable valve (72) to adjust the pressure in the chamber (50). A sealing arrangement defined by the pressure chamber (56) and the articles passing through the furnace prevents the introduction of cool air through the preheater zone (12).

Abstract: A bakery oven, of the type employing a continuous spiral conveyor for carrying the goods to be baked through the oven enclosure, employs an air distribution system to direct heated air from near the top wall of the oven enclosure to a plenum chamber, and from there through a pipe distribution network to at least certain ones of the tiers of the spiral conveyor. Preferably, heater elements are disposed beneath alternate ones of the tiers of the conveyor system within the oven enclosure, while the air distribution pipes are disposed parallel to and beneath the remaining tiers. This arrangement serves to decrease fuel consumption for the burners, thereby increasing productivity, and further serves to decrease the stratification of heat layers within the oven enclosure, thereby providing uniform baking conditions throughout the oven enclosure.

Abstract: The ceramic roller-hearth kiln is divided into three zones, of which the first and last are utilized for the initial heating and the cooling of the material respectively, and the central zone, which is provided with combustion means and utilized for high-temperature firing, comprises a conduit for the forced counter-current suction of the gaseous products of combustion between said second and said first zone, from said conduit there branching two ducts for the feed and recovery of part of the hot gas to and from the first zone; the cooling zone being constituted by three successive sections comprising, respectively, direct cooling by blowing air on to the material, cooling by induction and cooling by forced ventilation, the hot air recovered from said cooling zones being fed to the head of the kiln, to flow into said forced suction conduit.

Abstract: A forced air circulation heating apparatus in which an air stream is heated at a first location in a conduit means and transported to a second location within the apparatus by the conduit means and is forced into a heating compartment and mixed with a recirculated forced air flow within the compartment. A valve or controller means can be used to vary the proportions of the heated air stream and the recirculated forced air flow which are combined within the heating compartment. The air conduit and the heating compartment can have a common wall whereby the heated air stream indirectly heats the heating compartment. A dual flow impeller fan is used to move the heated air stream and to establish the recirculated forced air flow within the heating compartment. The fan operates with a single electric motor. The heating compartment is vented to a flueway.

Abstract: A paint bake oven (10) including an outer insulated housing (12), the outer insulated housing having an inner wall surface (14). An inner housing (16) is disposed within the outer housing (12) and has an outer wall surface (18) spaced from the inner wall surface (14) to define a gas flow channel (20) therebetween. The inner housing (16) has an inner product passageway (22). A gas supply plenum (46) is disposed above the inner housings for supplying a gas flow to the gas flow channel (20). A gas exhaust passageway (38) exhausts gas from the product passageway (22). The oven (10) is characterized by including a manifold wall (28) for directing the gas flow along a flow path from the gas supply plenum (46) downwardly along the inner wall surface (20) of the outer housing (12) and then upwardly over the outer surface (18) of the inner housing (16) to uniformly distribute the gas flow over the inner housing (16).

Abstract: An air bearing and heating system for use in moving and heating integrated circuit chip carriers (12) prior to their being tested by an electronic tester (10) is the subject of this patent application. The system includes a magazine (18) having a plurality of tracks (24) spaced vertically therein. Each track (24) includes an air-permeable wall (62, 62') through which air in a plenum (52) beneath the wall (62, 62') seeps. The air forms a cushion on the surfaces (64) of the sloped tracks (24) in order to float chip carriers (12), positioned for movement down the tracks (24) therealong.The air can be heated by a heater (104) prior to the time it is introduced to form the air cushion so that the chip carriers (12) will be heated as they are floated down the tracks (24).Similarly, the system can be provided with a distribution member (28) by which carriers (12) are conveyed away from the test site (14) of the handler.

Abstract: A tangent spin furnace providing a combustion chamber of metal which is unlined with any refractory material but whose temperature is maintained below the self-destruct level by combustion air being introduced into the combustion chamber between a plurality of slats defining the combustion chamber and disposed in spaced relation to each other so that they define longitudinal slots. Thus there are slots for the introduction of combustion air between the slats so that a sweep of combustion air is maintained peripherally inside of the combustion chamber over virtually the entire inner surface thereof. Without refractory material lining the combustion chamber overheating is avoided by the cooling effect of the sweep of combustion air.

Abstract: A forced air circulation heating apparatus in which an air stream is heated at a first location in a conduit means and transported to a second location within the apparatus by the conduit means and is forced into a heating compartment and mixed with a recirculated forced air flow within the compartment. A valve or controller means can be used to vary the proportions of the heated air stream and the recirculated forced air flow which are combined within the heating compartment. The air conduit and the heating compartment can have a common wall thereby the heated air stream indirectly heats the heating compartment. A dual flow impeller fan is used to move the heated air stream and to establish the recirculated forced air flow within the heating compartment. The fan operates with a single electric motor. The heating compartment is vented to a flueway.

Abstract: A recirculating air heater for an oven is fired by a burner and connected with the oven by a return air duct and an outlet duct. The return air duct has two sets of louvers for admitting controlled amounts of return air to a combustion chamber and a burner bypass chamber in the oven. The combustion gases and return air in the combustion chamber are mixed and directed through a catalytic converter before being mixed with the return air in the burner bypass chamber and directed back into the oven. A portion of the gases directed through the catalytic converter are discharged to atmosphere and an equal amount of preheated fresh air is admitted to the heater. The inlet and exhaust ducts are provided with blowers and dampers so that the mass flow rates of fresh air and exhaust air are substantially equal. During oven preheating some of the combustion gases and heated return air are caused to bypass the catalytic converter and flow directly back into the oven.

Abstract: In order to improve the thermal efficiency of a multi-zone, indirect-heated, travelling baking oven, with a closed-circuit gas heating system which heats at least the major part of the length of the oven and which includes at least two heaters which are spaced apart in the direction of gas flow in the heating system, the gas flow is passed along the bottom of the oven to adjacent the delivery end of the oven and then back along the top of the oven, the temperature generally falling throughout the circuit so that the maximum bottom heat is adjacent the input end of the oven and the maximum top heat is adjacent the delivery end of the oven.

Abstract: A furnace is described as having a heat treatment chamber which is provided with banks of radiant heaters to heat a load that is placed within the chamber for heat treatment. The radiant heating of the load is improved by the addition of convection heating which is carried out by a plurality of nozzles that are designed to direct jets or streams of heated gas against the load positioned in the chamber.