Abstract: The cooking module for a linear tunnel oven for bakery products includes a cooking chamber having a hearth, in the form of a conveyor belt, that is mobile and permeable to a gaseous heat-transfer fluid, a roof, and a heating device in the hearth and on the roof to cook the products. The heating device in the hearth includes a plurality of orifices for blowing the fluid. The belt is mobile above a sliding surface having openings for the fluid to pass through, and is mobile between two positions, a convection position where the openings coincide with the orifices to let the fluid pass through, and a second position known as a radiation position, where openings are offset from these orifices, the surface forming a screen for the fluid blown through the orifices.

Abstract: A method and apparatus for measuring quench characteristics of a fluid. The apparatus includes a probe with an energy input device electrically connected to a display unit to monitor temperature, media flow characteristics and media heat transfer characteristics. The method includes continuously measuring thermal energy transfer in a quenching media by measuring the surrounding fluid's heat transfer relative to input probe energy.

Abstract: A hot-stamping furnace includes a housing defining a heating chamber partitioned into compartments configured to have different temperatures. The heating chamber includes an opening that is at least partially covered by a door movably mounted on the housing. The door is configured to extend over only a portion of the opening when in a closed position. A detachable panel extends from an edge of the door such that the panel extends over a portion of the opening that the door does not extend over.

Abstract: A through-type furnace for substrates comprises a furnace with a channel and a transport system for the transport of the substrates through the channel. The channel is bounded by a base, a front side wall, a rear side wall and a top part. The base contains a plurality of first holes which are connectable to a protective gas source so that protective gas can be supplied during operation. The front side wall of the channel comprises a longitudinal slit which extends parallel to the passage direction and which is bounded by a bottom edge and an upper edge. The transport system comprises at least one clamp for transporting the substrates through the channel. The clamp is movable back and forth along the longitudinal slit of the channel. Such a through-type furnace is in particular suitable for use in a soft solder die bonder.

Abstract: A blow moulding machine for blow moulding a container having an integrally formed handle; said container blow moulded from a previously injection moulded preform; said preform comprising a body portion and said integrally formed handle; said machine including a preform loading station at which said preform is oriented by a preform orienting apparatus.

Abstract: In a method for heat treating a metal tube or pipe for a nuclear power plant, the tube or pipe being accommodated in a batch-type vacuum heat treatment furnace, when the tube or pipe is laid down on and is subjected to heat treatment on a plurality of metal cross beams arranged along a longitudinal direction of the tube or pipe, it is possible to suppress scratches to be formed on the outer surface of the tube or pipe and attributable to heat treatment, and to reduce the discoloration on the outer surface of the tube or pipe by holding the tube or pipe and the metal cross beams in indirect contact with each other by virtue of a heat resistant fabric having a thickness of 0.1 to 1.2 mm interposed in between.

Abstract: In a method for heat treating a metal tube or pipe for a nuclear power plant, the tube or pipe being accommodated in a batch-type vacuum heat treatment furnace, when the tube or pipe is laid down on and is subjected to heat treatment on a plurality of metal cross beams arranged along a longitudinal direction of the tube or pipe, it is possible to suppress scratches to be formed on the outer surface of the tube or pipe and attributable to heat treatment, and to reduce the discoloration on the outer surface of the tube or pipe by holding the tube or pipe and the metal cross beams in indirect contact with each other by virtue of a heat resistant fabric having a thickness of 0.1 to 1.2 mm interposed in between.

Abstract: Embodiments of the present invention include a heating method and apparatus in which a plurality of heated regions is superimposed in order to improve energy density control.

Abstract: A method for heating an elongated metal product includes heating at a first heating location with at least one burner the metal product, and conveying combustion products from the burner through at least one channel, isolated from the metal product, from the first heating location to at least a second heating location arranged along a conveyor path for the combustion products to impinge upon an opposite surface of the metal product when the metal product passes the second heating location. A device for heating the elongated metal product is also provided.

Abstract: An industrial oven system for curing composite material parts can include an oven compartment configured to receive a composite material structure therein that extends along a majority of the length and/or width of the compartment, the compartment having an inner wall that defines a cavity between proximal and distal ends of the compartment. A shroud can be disposed circumferentially between the inner wall of the compartment and an outer wall of the composite material structure. The shroud defines a first longitudinal annular channel between the inner wall and an outer surface of the shroud, and defines a second longitudinal annular channel between the outer wall of the composite material structure and an inner surface of the shroud.

Abstract: Heat treatment processes for hardening a workpiece such as a turbine blade include attaching a spacer to a workpiece surface, wherein the spacer comprises an inner profile mirroring the workpiece surface and an outer profile effective to generally uniformly distribute heat to the workpiece surface, heating the spacer to uniformly heat the workpiece surface at a temperature effective to form an austenitic microstructure in the workpiece surface, cooling the workpiece surface at a rate effective to transform the austenitic microstructure to a martensitic microstructure, and removing the spacer from the workpiece prior to or subsequent to cooling.

Abstract: The invention relates to a ring furnace (1) having a longitudinal axis and comprising elongated bays (10), a plurality of hollow partitions (3, 3?) arranged within the casing of each bay so as to be parallel to the longitudinal axis, a first end transverse wall (41) located at a first end of each bay (10), a second end transverse wall (42) located at a second end of each bay (10) and possibly one or more intermediate transverse walls (43) located between the first and second ends. The hollow partitions and transverse walls define baking pits (2) within the bays (10) for stacking carbonaceous articles therein. The baking pits have a length Lp and a width Wp, said length Lp being at least 15 times greater than said width Wp.

Abstract: In a continuous-feed thermomolding machine a foil is advanced in a transport direction at a constant travel speed through a heat station where it is exposed to a heat source such that each piece of the foil is exposed for a predetermined residence time. When the machine is stopped, a shield is positioned in the station between the foil and the source so that substantially no heat is imparted to the foil from the source. The machine is started by accelerating the foil to the travel speed while simultaneously and synchronously accelerating the shield opposite to the travel direction such that, as the shield fully retracts from the station, the foil reaches the travel speed and, before the shield has fully retracted from the station, every piece of the foil in the station exposed by the retracting shield is exposed to the source for the residence time.

Abstract: The present invention relates generally to semiconductor wafer fabrication and more particularly but not exclusively to advanced process control methodologies for controlling oxide formation using pressure. The present invention, in one or more implementations, includes a pressure stabilization system to dynamically adjust scavenger pressure in a furnace during wafer fabrication in relation to a pressure formation range, value, or one or more pressure indicators in a wafer fabrication process.

Abstract: A method for heating a zone of an elongate tubular article. A heat resistant, heat transmitting and heat dispersive shroud material is applied to the zone and a hot gas source is applied to the outside of the shroud material to cause heat to be transmitted through the shroud material to the zone.

Abstract: In an industrial glass furnace, which optionally contains recuperators, regenerators, electric boost or other devices for providing heat to glass batch material, at least one staged combustion oxy-fuel burner is mounted in the roof of the furnace to provide heat to melt the glass batch material by providing a flow of fuel to the oxy-fuel burner; providing a flow of gaseous oxidant in association with said the oxy-fuel burner; injecting the fuel and the oxidant into the furnace; and, combusting the fuel such that at least a portion of combustion is effected in the vicinity of said glass forming material to enhance convective and radiative transfer of heat to said glass forming material without substantially disturbing the glass forming material. In one embodiment, the oxy-fuel burner is adapted for injecting liquid fuels.

Abstract: In an industrial glass furnace which contains recuperators, regenerators, electric boost or other devices for providing heat to glass batch material an oxy-fuel burner mounted in the roof of the furnace provides additional heat to melt the batch material. A method of mounting and using such a roof-mounted oxy-fuel burner including the operating parameters to maximize heat transfer while minimizing the disturbance of the batch material is disclosed.

Abstract: Infrared oven for heating a plurality of preforms and comprising: a conduit through which said preforms move, a flow of outside air that flows through said conduit from an intake mouth to an exhaust mouth under the action of a blower, a plurality of infrared lamps irradiating the preforms in said conduit, in which a reflective surface is arranged downstream of said lamps and is provided with apertures through which the flow of outside air passes prevailingly. The axis of the preforms is oriented in a manner that is substantially perpendicular to the direction of flow of said outside air. The infrared lamps are arranged substantially downstream of the preforms, and are separated from each other by appropriate intervals through which said flow of outside air passes, in which said flow of outside air first passes through said intervals separating said preforms and then through said intervals provided between said infrared lamps.

Abstract: The process is used for tempering preforms made of a thermoplastic material; the preforms are to be blow molded. The preforms are provided with a temperature profile along a circumference. The temperature profile is generated by differentially heating strip-shaped regions, which extend in the direction of a longitudinal axis of the preform. A step-by-step tempering for the purpose of temporally sequential thermal conditioning of different regions of the preform is carried out with movement phases and rest phases. A carrier device is rotated by the interactions of a gear and a matching gear for initiating rotational movements. The preform is moved, motionless with regard to the rotational direction, through the tempering zone at least along a portion of the transport path before the start of the engagement of the gear with the matching gear.

Abstract: An apparatus and method for fabricating fiber gratings from optical fibers by imposing constant or variable chiral refractive index modulation along an optical fiber. The refractive index modulation may be of single helix symmetry to produce a fiber grating enabling different propagation speed of signals with the same handedness as the structure with respect to signals with opposite handedness as the structure at a wavelength substantially equal to the pitch of the single helix, or of double helix symmetry to produce a chiral fiber Bragg grating. In several embodiments of the present invention the refractive index modulation is imposed by twisting and moving a specially prepared optical fiber through a heater that heats a small region of the fiber to a temperature sufficient to allow the fiber to twist in that region as it moves through the heater.

Abstract: For reflow soldering, radiant heating is applied to one surface of a printed circuit board on which electronic components are placed and onto which cream solder is supplied and at the same time hot air is blown locally and roughly perpendicular to to-be-connected points on said one surface of the printed circuit board. This reflow method permits secure soldering even if the hot air is set at a temperature not exceeding the heat resistance of the electronic components, which is possilbe because of its combination with the radiant heat. Moreover, this reflow method can permit soldering in such a manner that only the to-be-connected points are heated selectively, because the hot air is blown locally and roughly perpendicular to the points to be connected. Thus, this reflow method prevents heat damage to other sections than the to-be-connected points and ensures that the solder at the to-be-connected points is melted.

Abstract: A method in which a (display) device having a part (41) comprising a first wall (43) and a second wall (44) is manufactured, which part (41) is warmed up during the temperature treatment by unilateral irradiation with heat by means of heat radiators (35). The method is characterized in that the temperature treatment further comprises measures which cause a fluid (53) to be fed past the outer surface of the first wall (43) to remove heat from said outer surface and/or measures which cause a fluid to be fed past the inner surface of the second wall (44) to supply heat to said second surface. In an embodiment, the inner surface of the second wall (44) is provided with a heat-absorbing coating (48). Preferably, the heat radiators (35) emit electromagnetic radiation having a wavelength below 3 .mu.m.

Abstract: A method and apparatus which allows blow-molded plastic containers to be manufactured at high rates of production independent of ambient environmental conditions. The method and apparatus eliminate the need to make adjustments to blow-molding oven operating parameters when environmental conditions change and reduce defects such as caused by water spots. The method includes the steps of flowing ambient air over cooling coils to remove moisture, heating the air to a constant pre-determined temperature and delivering the conditioned air to the blow-molding oven. The apparatus includes a variable speed blower which forces ambient air at a predetermined volumetric flow rate over cooling coils and an electric heater to provide the blow molding oven with a constant volumetric flow rate of constant temperature and low humidity air.

Abstract: The loader device comprises a cartridge-carrying carousel provided with a set of cartridge-holders in which sealed closed cartridges are mounted in removable manner, each cartridge being designed to contain a sample for processing in a space furnace, the device further comprising a control mechanism for imparting indexed rotary drive to the cartridge-holders. The carousel is mounted to one side of the furnace in such a manner that its axis of rotation is parallel to longitudinal axis of the furnace. Each cartridge-holder of the carousel co-operates with a transfer mechanism that includes a translation arm extending perpendicularly to the axis of rotation of the carousel to enable each cartridge to be brought successively into a working position in which the axis of the cartridge is in alignment with the longitudinal axis of the furnace. The control mechanism for imparting rotary drive to the cartridge-holders and the transfer mechanism are activated alternately by a single electric motor.

Abstract: A heating device including a first exothermic member disposed below a subject to be heated for preventing heat radiation from the subject while heating the subject from below, a second exothermic member disposed above the subject for preventing heat radiation from the subject while heating the subject from above, and a base or sandwiching and supporting body for bearing the subject sandwiched between the first exothermic member and the second exothermic member while securing a space under the first exothermic member. The heating device is convenient to carry about and capable of easily heating a food or the like without rapidly generating a great amount of heat.

Abstract: A gas-lance apparatus and method for injecting a rate-enhancing gas between a flame and a thermal load to augment combustion of fuel undergoing combustion in the flame. A fan-shaped main jet is introduced between the flame for producing a low pressure field of the rate-enhancing gas between the flame and the thermal load. The low pressure field deforms the flame into the shape of the main jet and draws the flame toward the thermal load. The main jet decays along its length due to entrainment of combustion-environment gas in the main jet. In order to delay such decay, a fan-shaped booster jet of rate-enhancing gas is introduced between the main jet and the thermal load. The booster jet has a higher velocity than the main jet and is positioned adjacent to the main jet.

Abstract: A method and system for providing a controlled gaseous environment at the opening to a receiver and around a free liquid stream downwardly entering the receiver opening. The method comprises laminarly emitting at least two gas flows to extend and intersect over the receiver opening thereby forming an upward plume enveloping the free liquid stream.

Abstract: Preforms are thermally treated in a continuous-run oven equipped with infrared lamps. The portions of the oven exposed to infrared radiation are cooled by an air flow, whose temperature is kept constant by mixing air at ambient temperature with hot air. The latter is obtained by recycling at least part of the cooling air flow, which becomes heated as it carries away excess heat. A recycling mechanism in the form of a plenum box 13 equipped with a pivotable shutter 16 for adjusting the proportions of recycled hot air and ambient temperature air makes it possible to keep the temperature of the cooling air constant.

Abstract: A core 6 is disposed inside of and spaced from a hollow plastic preform 1 subjected to external infrared radiation 4 including a first wavelength B.sub.1 that is absorbed by and heats the plastic, and a second wavelength B.sub.2 that propagates through the wall 2 of the preform. The propagated radiation 12 is converted into the first wavelength by the surface 7 of the core, and reemitted at 13 back towards the preform to heat its internal surface 8 to a higher temperature than its external surface 10. The preform may be axially rotated with the core stationary to implement uniform angular heating. Alternatively, the core may be irregularly configured and/or surface treated, with both the core and preform rotated in synchronism.

Abstract: Apparatus is provided for decreasing temperature differentials within rectangular metal blooms being heated in a furnace. The apparatus includes elongated internally cooled members located above the blooms adjacent an exit end of the furnace. The longitudinal axes of the internally cooled members are parallel to each other and to the longitudinal axes of the blooms, the latter axes being aligned so as to extend transversely with respect to the direction of movement of the blooms from an entry to an exit end of the furnace.

Abstract: An apparatus for flame treating an exterior surface of a plastic container such as a barrel includes a carriage mounted on a frame for rotatably supporting a plastic container, a first treatment station attached to the frame for flame treating a facing end of the container and a second treatment station attached to the frame for flame treating the sides of the container. The carriage is attached to a cable driven by a first actuator for moving the carriage from a starting position for loading the container onto the carriage past the first station to the second station and back to the starting position. The carriage, a burner at the second station and a roller for rotating the container at the second station are all adjustable for accommodating various diameter containers.

Abstract: A process and apparatus for heating injected, cold preform blanks to blow molding temperature on a conveyor path wherein they are thereafter fed to a blow mold, the preform blanks being first heated to a temperature below the blow moulding temperature, then cooled and later reheated to a temperature slightly above the blow molding temperature, whereupon the preform blanks are allowed to equalize in temperature inside and out or are caused to do so by slightly cooling their outsides. The spacing on the holders on the conveyor chain, on which are mounted the preform blanks, is selectively adjustable to avoid heat radiation losses. The neck portions of the mounted preform blanks are surrounded completely by protective sheathings so that such neck portions are not heated while being conveyed to the blow mold.

Abstract: An apparatus and process for positioning and for simultaneously oscillating a plurality of heater probes within a plurality of heat exchanger tubes mounted in a tubesheet of a nuclear steam generator is disclosed herein. The apparatus generally comprises a frame, a plurality of probe drivers mounted onto the frame, wherein each driver includes a pneumatically operated, bladder-type gripper for selectively gripping and ungripping the push-cable of one of the heater probes, as well as an oscillating mechanism powered by a variable voltage d.c. motor. A controller connected between the d.c. motor and a power source separately controls the frequency and the amplitude of the cycle that the oscillating mechanism moves the gripper in, and further controls the alignment between the midpoint of the oscillatory cycle and a selected point along the longitudinal axis of the tube.

Abstract: Disclosed is a method of controlling the temperature of a joining area between two different strip materials in a continuous strip processing line. In the case where a strip material after the joining area requires a nozzle pressure greater than that of a preceding strip material, the opening of a damper is initially gradually throttled, at a timing before the joining area passes through a predetermined location in a treating furnace, by an amount required for changing the nozzle pressure so that an optimum pressure of the preceding strip material is changed so that of the following strip material. The rotational speed of a recirculation fan is then raised to keep the nozzle pressure substantially constant, and the damper is rapidly opened to the opening before the throttling at a time the joining area passes through the predetermined location.

Abstract: A process for firing ceramic shaped bodies is disclosed, which comprises the steps of placing the ceramic shaped bodies on a truck, and firing the shaped bodies with a combustion gas. Shield members are arranged on the truck such that a jet stream of the combustion gas will not directly contact the ceramic shaped bodies and that a path for the combustion gas jet stream may be formed on the truck. The shield member may be obliquely divided into two sections at the central portion thereof.

Abstract: In a method and apparatus for depicting a circuit pattern on an article such as a semiconductor wafer, glass mask or a reticle supported by a stage in an evacuated casing with an electron beam, the article is disposed in a magazine contained in a sealable chamber communicated with the evacuated chamber. The article is contacted with a heat adjusting member to adjust the temperature thereof. After matching the level of the article with that of the stage, the article is loaded on the stage.

Abstract: Process and apparatus employing flame ashing for stripping photoresist from a substrate in the manufacture of a semiconductor device. The substrate is exposed to the flame with the photoresist to be removed being contacted directly by the flame to oxidize, or ash, the photoresist. The flame is produced by burning oxygen and a gaseous fuel, and the rate of ashing is increased by preheating the substrate. Nitrogen, a nitrogen-containing gas or an inert gas is added to the fuel to provide a cooler flame and an improved ashing rate. In one disclosed embodiment, the oxygen and the gaseous fuel are discharged through a plurality of spaced apart openings in a burner and the substrate is moved relative to the flames to successively ash different portions of the photoresist.

Abstract: A process for changing the color of partial surface areas of pigmented, hydraulically bonded construction elements by application of high temperatures thereon, wherein the said partial surface areas are subjected to temperatures of at least 1,000.degree. C., until the desired change in coloration has been achieved.

Abstract: A food preparation oven for baking foods which require less heat energy input into a first surface than into a second surface such as pizzas. A radiant panel is provided which is heated by means of hot air and which is positioned to heat one surface of the food product by radiant heat energy. The second surface of the food product is heated by means of a flow of hot air. The air is heated in a heating chamber and recirculated by means of a fan. The food product is supported on a conveyor belt and travels through the food preparation oven while it is being baked.

Abstract: Apparatus for heating a plastic pipe 18 or the like comprises a body portion having inner and outer parts 1,2 defining therebetween an annular cavity 3 which receives the end of the pipe. In use of the apparatus, hot fluid is pumped through the cavity 3 via flow passages 7-11 whereby to heat the pipe 18 sufficiently e.g. for moulding purposes. The fluid is prevented from escaping from the open end of the cavity 3 by means of compressed air supplied via ports 15.

Abstract: A heating device including a flame burner (40) and a nozzle (52) into which the flame (50) from the burner (40) is directed and in which process air is mixed with products of combustion from the flame; the nozzle (52) having hot gas discharge openings (106) through which the hot gases resulting from the mixing action are projected onto articles (10) or other material to be heated.

Abstract: Heat treatment apparatus for annealing a reactor vessel includes an envelope having a plurality of insulated compartments each supplied with heated fluid from inlet ducts having nozzles in the compartments. The heated fluid passes out of the compartments via concentric tubular exhaust ducts. Heaters supplying the heated fluid are controlled by a mini-computer to ensure that a predetermined temperature profile is maintained across the heated section of the vessel.

Abstract: The circumferential wall of the godet drum is heated via air which is heated by a heating device within the chamber of the drum. Air circulation through a closed path is aided by means of fan blades which are mounted on an interior face of the drum.

Abstract: A furnace for heating pipes each having an upset portion at least at one of its opposite ends includes a housing defining a heating chamber filled with high temperature gas, and a conveying apparatus for sequentially conveying the pipes in the housing in a direction perpendicular to an axial direction of the pipes. A blowing device is provided on one side of a path of the upset portion, and a waving plate is provided on the other side of the path, whereby the upset portion, when passing through a space between the blowing device and the plate, is heated locally by the high temperature gas blown out from the blowing device and also by the reflected high temperature gas and radiant heat from the plate.

Abstract: A method for reducing the radial temperature gradient of a radiant energy emitting heated body is described. The method comprises insulating such heated body with a refractory insulating material containing an efficient absorber of the radiant energy emitted by said heated body. Specifically, materials containing trivalent dysprosium are disclosed as suitable thermal insulation for use where the heated body is at a temperature in the 1800.degree. C.-2500.degree. C. range. Also described is a crystal growth chamber for pulling unicrystalline compositions from a melt utilizing the Czochralski technique. The chamber is characterized by the placement of a refractory insulating material containing an efficient absorber of near infrared radiation around a crucible which contains the melt. Dysprosium is specifically disclosed as an efficient absorber of the near infrared radiation which is emitted by melt and crucible at the elevated temperatures employed for boule formation utilizing the Czochralski technique.

Abstract: A method of fabricating an insulating joint between a pair of end abutting rail sections of a railroad track includes the suspension of a pair of opposed fishplates at the rail joint at spaced distances outwardly of the rail sides, and simultaneously heating the rail sections and the fishplates to a predetermined temperature for activating a heat-activatable adhesive provided in fabric cuffs which are disposed between the fish surfaces and the fishplates. The fishplates are shifted along guide rods of their support assemblies inwardly toward one another into place against opposed fish surfaces of the rail sections, and are thereafter bolted in place. A device for fabricating the joint includes a box-like hood on which heaters are mounted, or a shear assembly supporting the heaters and being clamped onto the rail head. The heaters may be adjusted to accommodate various rail profiles.

Abstract: An apparatus for removing solder bonded devices from a substrate which includes a hollow housing element having an open end with a seating portion adapted to engage the flat backside of a semiconductor device, an inlet for admitting heated gases to the interior of the housing, and an outlet for the heated gases, a baffle within the housing having an end portion recessed from the seating portion of the housing wherein the baffle directs heated gas downwardly against the backside of the device when in engagement with the seating portion of the housing, and a clamping means to secure a semiconductor device in seated relation on the seating portion.A rework method for removing a solder bonded semiconductor device from a ceramic substrate leaving only a coating of solder on the pad site sufficient to solder bond another device without the need for additional pad site preparation which includes the steps of preheating the substrate and solder bonded devices to a temperature not greater than 100.degree. C.

Abstract: A quartz tube adapted for thermal processing of semiconductor substrates comprising a double-layered central tube having an external sintered crystalline quartz layer fused with a quartz layer of different quality, i.e. an internal transparent fused quartz layer. Both ends of the central tube are fused with the ends of two transparent fused quartz end tubes. The double-layered tube portion can be produced by compacting quartz particulates by means of centrifugal force within a mould and heating from the center with or without placing a fused quartz tube on its inner surface. Semiconductor substrates are processed using this quartz tube, thereby semiconductor devices having stabilized high qualities are produced at an increased yield as well as at a low cost.

Abstract: A ladle for receiving molten metal is heated by a direct flame, by applying a lid to the rim of the ladle and directing an air stream through a heat exchanger and through the lid to the ladle, mixing fuel with the air and igniting the mixture and directing the flame into the ladle chamber, and exhausting the gases of combustion from the ladle chamber back through the lid and heat exchanger. A heat shield is mounted adjacent the lid and is sized and shaped to telescopically receive the rim of the ladle, and a ring of air is moved between the heat shield and the rim of the ladle to an air pickup ring. The ring of air blocks the gases escaping from inside the ladle through any openings between the ladle rim and the lid, the heat shield blocks heat radiation from any such openings, and the ring of moving air cools the heat shield.

Abstract: A method and a circulating-air furnace for heating one end of a length of plastic pipe for the purpose of belling the end of the pipe. The circulating air is made to flow through a fan and a heater and thereinafter along the outer and inner faces of the pipe end. In order to improve the adjustability of the heating of the pipe end, the circulating air is blown as an annular shaped flow in the direction of the center axis of the pipe end towards the pipe end so that the air flow is divided onto the inner and outer faces of the pipe.