Abstract: In a pelletizing operation in which a synthetic thermoplastic polymeric material is reduced to particulate form, automatic startup of the flow of cooling fluid to the cutting chamber associated with the pelletizing operation is provided so as to insure that the flow of the cooling fluid is started at the time required.

Abstract: A process of manufacturing a roll of continuous synthetic thermoplastic film consisting of extruded flat film or of extruded blow-formed and flattened tubular film in which the thickness of the film is measured over the width of the film. Any striplike portion which deviates in thickness from a means thickness of the film is adjusted. The temperatures of juxtaposed temperature control sectors or the width of those portions of the slot die or of the annular die from which said striplike portions have been extruded are adjustable. When a striplike longitudinal portion having a relatively large thickness is detected in the film, the film is subsequently extruded to have a corresponding portion which has a relatively small thickness within specified thickness limits and for a length such that the two portions as superimposed in the roll have an average thickness approximately equal to the mean film thickness.

Abstract: The present invention relates to a temperature adjusting device, particularly designed for processing cylinders of extruding, injecting, drawing and the like machines for processing plastics materials in general, which comprises a flexible body, of sleeve shape, which may be arranged on the outside of the plastics material processing machine: the body is housed in an outer duct, for conveying and discharging air in a substantially transversal direction with respect to the body itself.

Abstract: This invention relates to an apparatus for regulating the heating of a thermoplastic band used in a station for thermoforming upwardly open containers, the apparatus being characterized in that, in a zone of the softened thermoplastic band, zone surrounded by a mesh of rigidified matter, the degree of deformation of this zone under the action of a predetermined mass is measured, the measured value of the degree of deformation is compared with a predetermined reference value corresponding to a good aptitude to thermoforming, and the heating of the band is regulated as a function of the value of deformation measured so that the deformation corresponds to the reference value.

Abstract: A pellet mill controller includes a plurality of temperature sensors to sense the temperature of material as it traverses the pellet mill, and a temperature sensor for sensing the temperature of the die to determine when it reaches the approximate nominal boiling point of water. As the die reaches the approximate nominal boiling point of water, the differential is measured between two of the temperature sensors and stored in the pellet mill to control the pellet mill in accordance with temperature differential control modes previously patented.

Abstract: A pipe of thermoplastic polymer, e.g. polyvinylchloride is extruded by an extruder comprising an extrusion die (2) having a moulding end part (2a) with heating elements (11) located about said end part. The wall thickness of the pipe is controlled in order to obtain a pipe of a substantially even wall thickness. For said control the wall thickness of the extruded pipe is measured at 360 points equally distributed over the circumference and moreover the average is determined in eight measuring sectors comprising 45 measuring points per sector. The average of the measuring values of one measuring sector is compared with the circumferential average of the 360 points, the deviation of the desired wall thickness in said one sector being counter balanced by the action of the heating elements. In a preferred embodiment a polyvinylchloride pipe obtained by means of a two screw extruder presents an even wall thickness over the circumference.

Abstract: Pressure is controlled in plural stages of a shaping system for a green tire in a curing press, so that each successive shaping stage is completed when a target pressure for that stage is reached. A radial tire is preferably shaped in three stages in the first of which a first target pressure in the range from 2 psig to 5 psig is the desired shaping pressure; in the second stage, a second target pressure in the range from 7-10 psig is desired; in the third stage, a third target pressure in the range from 10-15 psig is desired. A pressure transducer (PT) senses the pressure in a bladder, one PT for each bladder. A programmable controller (PC) which controls operation of the press, stores and executes a sequence of instructions which determine the optimum desired shaping pressure for each stage, computed from the type and size of the tire to be cured, the period of time the press is down before it is loaded, and the number of heats on each bladder.

Abstract: An extrusion process is controlled by feeding the material to be extruded from a supply station (5) to an extruder (1) and repeatedly weighing the supply station to calculate the throughput of the extruder. The initial line speed necessary to produce a predetermined weight/meter of extrudate is calculated and the line speed is adjusted accordingly. Subsequently, the throughput and the line speed are increased simultaneously, such that the weight/meter is maintained substantially constant until any one of a plurality of parameters such as line speed, screw speed, motor load current, extrudate temperature, melt pressure, etc reaches a predetermined maximum value. Thereafter either the line speed or extruder throughput is adjusted such as to maintain the weight/meter of the extrudate substantially constant at the desired value.

Abstract: The plastic molded article is produced by heating a mold by contact with a preheated salt bath. The salt bath is readily maintained at a uniform temperature and is self-insulating for energy efficiency. A noncontact infrared sensor monitors the mold cavity temperature while in the salt bath, and the mold is removed from the bath when the proper mold temperature is reached. A charge of plastic powder is introduced into the mold by clamping the mold to a powder slush box with the mold cavity confronting the opening of the box. The mold and box are then simultaneously rotated to pour the plastic charge into the mold. The plastic charge forms a skin on the cavity surface and additional plastic material may be built up to provide additional thickness. The mold and box are then separated; the mold is then postcured and cooled, whereupon the finished article may be removed from the mold.

Abstract: The calender rolls of the present invention are comprised of relatively thin-walled hollow shells which are supported at each end by shafts having bores which extend into the cavities formed in the rolls. Fittings located at the ends of the shafts are rotatable relative to them so that by tying the fittings together they do not rotate along with the rolls. The fittings at one of the ends of the rolls are connected to a source of wet steam through a pressure regulator and the fittings at the other ends carry probes which extend through the shafts and curve downwardly towards the bottoms of the rolls. A valve regulates the amount of material which flows out of the cavities through the probes. The method by which the rolls are used comprises introducing wet steam into the cavities, maintaining its pressure at a constant level.

Abstract: A method of supplying material to an article forming mold of an injection molding machine. The method comprises initially mixing a granular thermoplastic resin with a granular filler in a dry state and then heating the dry mixture in the chamber in which the feed screw of an injection molding machine rotates. The heating is controlled to initially convert the dry resin to a molten mass while simultaneously heating the filler with the filler remaining as a heated solid. After such initial heating the molten resin/heated filler is retained at a lower temperature prior to molding and then is further heated for ejection from the chamber.

Abstract: Method of adjusting the lip opening of an extrusion die for stratiform material, with the characteristic that it consists in the combination of, on the one side, the control of the heating of bar shaped elements (9) which act upon at least one of the lips (6-7) of the lip opening (5), in function of the thickness of the formed material, and on the other hand, the common cooling of several bar shaped elements (9) by forcing a cooling medium along these elements (9).

Abstract: A method of producing a compressive stress in a mass comprised of plastic material having a tendon therein, at least a portion of the length of the tendon being contained in thermoplastic material within the mass, the method comprising the steps of heating the tendon to a temperature sufficient to soften the thermoplastic material in an annular region surrounding the tendon, applying a tractive force to the heated tendon, thereby placing the heated tendon under tensile stress, and securing the heated tendon to the mass in a manner that causes the tensile force in the tendon to produce a compressive stress in the mass and prestressed plastic bodies produced according to this method.

Abstract: A method for foaming and sintering of foamable plastic employing a control method based on the detection of the softening time point during the sintering steam application in the sintering process step. The softening time point is detected by analysis of a change in the rising speed of the pressure or temperature, and the related pressure and temperature values are used for determining the maximum dismission temperature and pressure of the sintered product. The sintering time is determined in relation to the softening time point and the quality demanded. A feed back control to the prefoaming and drying process step is provided. A feed back control by means of a quality measurement at the sintered part to the sintering is provided. Incremental controls are provided for adaptive process optimization.

Abstract: A moisture control system is provided for a pelletizing process wherein the moisture content of the pellets leaving the pelletizing process is constantly monitored and differences between the measured moisture content of the pellets and a set point indicating the desired moisture content of the pellets are used to regulate variable process controls in the pelletizing process so that the pellets leaving the pelletizing process will have the proper moisture content. Also, a system for protecting a viewing window of an instrument from contaminants is provided.

Abstract: An extruder control system and method controls melt temperature to maintain viscosity of the melt at the die. A constant volumetric flow to the die is delivered by a gear pump, the die is a fixed orifice, and pressure between the gear pump and the die is indicative of viscosity. Changes in pressure are sensed and compensating changes in temperature are effected to return the pressure and, hence, the viscosity to its previous value.

Abstract: A method of producing a thermoplastic foil with reduced thickness tolerances in which close to the head the temperatures of the mass flow emerging from the heat at various regions corresponding to tempering sectors are detected, the temperature measurements are averaged and the averages are used to form a set point value with which the individual averages are compared and the comparison used to generate a correction signal which is applied to the temperature controller of the respective sector.

Abstract: An extruder die for extrusion of a multilayer thermoplastic laminate, particularly in the form of a foil or plate, comprises a multicomponent block symmetric with respect to a central plane dividing a plurality of feed channels and distributing channels connected to said feed channels, at least one mouth and a central distributor channel connected to and following said mouth symmetric in relation to the axis of said extruder die as well as an outlet die following said central distributor channel. The block has on the end opposite the outlet die an additional feed channel with a round or rectangular cross section for feeding in a special plastic material which changes over into a discharge duct extending to the mouth.

Abstract: A method of controlling the heating of hot runner molds for injection molding of thermoplastic objects is disclosed, whereby the mold cavities (11, 12) receive the material to be molded via channels or runners divided into five heating zones (I through V), the temperature of each zone being controlled by means of an electric heating element (EC) associated with a thermocouple. In the event of failure of one zone's thermocouple, heat control is continued in said zone according to the power applied to the heating element of an adjacent zone.

Abstract: An extrusion die for a blow head for making blown plastic films comprises inner and outer rings, which are made of a ferrous material, particularly steel, and define between them an annular orifice. Those surfaces of the inner and outer rings which define the die orifice are covered by a layer consisting of a metallic material having a higher thermal conductivity than steel.

Abstract: A process of heating parts of a double band press used in pressing a material moving through the press involves heating a heat transfer medium and flowing it through the press parts in a first direction and, at specific time intervals, reversing the direction of flow so that it passes in the opposite direction. By periodically reversing the direction of flow, differential thermal expansion is avoided within the press parts. In a device for carrying out the proces, a supply line and a return line are connected to a device for heating the return heat transfer medium. A reversing valve is connected to the supply and return line so that the direction of flow of the heat transfer medium through the press parts can be reversed for providing a balanced heating effect.

Abstract: A method for monitoring deviations in the dimensions of profile strips during production is disclosed, as is an apparatus suitable for carrying out the method. The profile strip is formed from one or more rubber or thermoplastic material mixtures which are fed from one or more extrusion devices through nozzles into a common nozzle in an extrusion head. Pressure and temperature measuring means measure the extrusion pressure and temperature of each mixture. The profile strip thus produced then passes over weighing device which measures its weight per unit length. The measured value is transmitted to a regulating or control device and compared with a desired weight per unit length.

Abstract: A molten resin to be injected into a mold cavity in use of an injection molding machine has a temperature, i.e. viscosity difference between at the injection starting point and the injection completing point. In order to eliminate or make small this difference, a high temperature and highly pressurized gas, preferably an inert gas, is preliminarily supplied to and sealed in the mold cavity and the pressure of the supplied gas is continuously controlled in accordance with the position of the screw during the injection molding operation thereby to maintain the temperature of the supplied gas in the mold cavity to be higher than the softening temperature of the molten resin to be injected.

Abstract: A process for continuously producing an embossed thermoplastic resin sheet having a colored layer which comprises associating a molten thermoplastic resin A and a molten thermoplastic resin B having a different color from the resin A within a die for extrusion molding, extruding the associated mass through an extrusion opening to form a two-layered thermoplastic resin sheet, and thereafter embossing the sheet, wherein the temperature T (.degree.C.) of the thermoplastic resin sheet immediately before the embossing and the surface roughness R (micrometers) of said sheet immediately before the embossing expressed by a 10-point average roughness in accordance with ISO-R468 are selected so as to satisfy the following relation 1.2R+T.ltoreq.145 (1).

Abstract: A method for manufacturing molded products of polyethylene terephthalate by injection molding a material containing polyethylene terephthalate as the principal component characterized by using virgin and/or waste polyethylene terephthalate of average molecular weight of more than 10000 to which polymer such as nylon and/or inorganic fillers can be added as required, and molding said material under the following molding conditions by a general type or vent type molding machine:(a) Control of a temperature of a cylinder of the molding machine in the range of melting temperature of resin plus/minus 35.degree. C., and(b) Control of the staying hour of resin in the cylinder to be within 15 minutes.

Abstract: A melt spinning head structure is heated by use of a low melting point fusible alloy, preferably a binary-quaternary eutectic composition.

Abstract: A method and apparatus for tipping one end of an I.V. catheter includes the method steps for use of the apparatus including mounting a catheter to be tipped onto a mandrel supported on a carriage; a die having an interior molding surface, at least one portion of which is tapered according to the tip desired on the catheter, is heated; the carriage is moved along guide bars to the die such that the catheter carrying mandrel moves toward the interior molding surface to define a space, when the carriage is halted the catheter carrying mandrel is biased toward the die space with only sufficient force to cause the heated catheter to flow into the die space and as the catheter melts and flows, the mandrel engages the die thereby defining the edge of the catheter, after which the die and catheter therein are cooled; the carriage is then reversed along the guide bars such that the catheter and mandrel are withdrawn from the die, and the catheter is removed from the mandrel.

Abstract: A method of mixing polymers, especially rubber by (i) deforming the polymer until it is estimated to attain a first predetermined viscosity, (ii) adding filler and deforming the polymer-and-filler mixture until it is estimated to attain a second predetermined viscosity, (iii) adding oil or plasticiser, and deforming and resulting mixture until it is estimated to attain a third predetermined viscosity, and then (iv) discharging the resulting mixture from the process, where the estimating of each predetermined viscosity is attained by measuring: (1) the mixing torque applied by a mixer during the process at last twice at a fixed mixer-rotor speed and corrected by a reference batch temperature; (2) the rate of change of the torque and (3) the time, or the deforming energy, necessary to reach the torque characteristic of the respective predetermined viscosity. In addition, the ram pressure applied to the mixing chamber is monitored and increased or decreased in response to the cyclic ram movement during mixing.

Abstract: A magnetic audio or video tape is smoothed and/or otherwise treated by causing it to pass through one or more calenders wherein a large-diameter primary calender roll is heated from within and the major part of its peripheral surface is surrounded by the running tape. The primary roll rotates about a fixed axis and is surrounded by a cluster of two or more smaller-diameter secondary calender rolls each of which has a viscoelastic peripheral layer and each of which can be individually biased against the adjacent portion of the running tape with a selected force. The magnetic film on the tape is out of contact with the secondary rolls as well as with the guide rollers which cause the tape to advance toward the peripheral surface of the primary roll and thereupon toward a takeup reel.

Abstract: Apparatus for making injection molded polymeric articles, comprising a vibratory pneumatic cooling assembly adapted to dissipate thermal energy from the polymeric articles after they are ejected from the mold cavities through use of an oscillating perforated vibratory grid adapted to maintain the articles in relative motion while at least partially supporting them on a substantially uniform cushion of air. A method for employing the apparatus of the invention to substantially reduce the cycle time required for injection molding polymeric articles is also provided.

Abstract: A novel process for providing a thermoplastic polymer having novel thermal characteristics including the critical step of masticating the polymer, either continuously or discontinuously, until the melt index of the polymer is substantially increased.

Abstract: A mold for molding articles of plastic or other like materials, having a plurality of vertically extending internal passages, is connected by inlet and return conduits into a closed loop that includes a heat exchanger partially filled with a liquid supply of a cooling fluid or a heating fluid. For cooling the heat exchanger is positioned with its liquid level above the top of the mold, the inlet conduit connects the lower part of the heat exchanger, below the liquid level, to the lower ends of the mold passages, and the return conduit connects the upper ends of the mold passages to the upper part of the heat exchanger; for heating these relationships are reversed. In operation the fluid changes its physical state at critical points in the mold passages, going from liquid to vapor for cooling and from vapor to liquid for heating; circulation in the closed loop is in response to the effect of gravity. Operation of the heat exchanger is controlled to maintain a controlled pressure in the closed loop.

Abstract: Disclosed is heat exchange apparatus for controlling the temperature of a resin after leaving an extruder and prior to extrusion through a die in an extrusion process, comprising a heat exchanger having an inlet and outlet for an extruded heat-plastified resin and an inlet and an outlet for a heat exchange medium to be circulated in heat exchanging relationship with the extruded resin; a selective heater for receiving the heat exchange medium from the heat exchanger, the heater heating the heat exchange medium to a predetermined temperature during a start-up phase of the heat exchange device; a cooler adapted for receiving a portion of the heat exchange medium from the heater, the cooler including an inlet and an outlet for the heat exchange medium and an inlet and an outlet for a cooling medium to be circulated in heat exchanging relationship with the heat exchange medium; control means interposed between the heater and the cooler for selectively directing a portion of the heat exchange medium to said cooler

Abstract: A moulding apparatus and a method of moulding for components of unvulcanized elastomeric material which forms a spew free component and provides for handling the component for subsequent use. The apparatus as shown in the Figures comprises a first mould member having a mould cavity for part of the component and a feed port for material and a second complementary mould member which includes a detachable component carrying insert. The two mould members and are relatively movable to provide two different volumes for the mould cavity, the change to the smaller volume being used to return some material through the feed port and to complete moulding of the component.

Abstract: A method of molding foaming plastics in consecutive process cycles. The method includes directing foaming plastics to molding means for molding and sintering. The molding means are appropriate to form different molded items. The molding means communicates via an installation means with a supplying means. The supplying means serves to supply under the control of a control means, steam for heating, cold water for cooling, vacuum for providing suction and compressed air as needed to the molding means. The molding means has at least one pressure sensor means and/or temperature sensor means. The pressure sensor means and/or the temperature sensor means are connected to the control means.

Abstract: Beautifying patterns on the surface of extruded polymer products are produced by forcing molten polymer through a die which is coated with a controlled pattern of low surface energy material. Melt fracture of the polyethylene as it emerges from the die is produced at gaps in the coating material which may be silicon, inorganic or fluorine containing polymers.

Abstract: A machine for fabricating sulfur concrete pipe includes a centrifuge for centrifuging a mixture of the constituents of the sulfur concrete. The centrifuge includes a port for the direction of heat therethrough for heating the mixture. The centrifuge also includes a flexible cylindrical wall which may be directed radially inwards for compacting the mixture in response to a fluid pressure exerted on a side of said flexible cylinder opposite from said mixture. Thermometers are provided for measuring the temperature of applied heat at different points within said centrifuge, and a computer is responsive to the measured temperatures for computing future values of temperature to be applied to said mixture in accordance with a predetermined relationship based on past temperature and time of centrifuging.

Abstract: A controlled temperature hot melt adhesive dispensing system including three closed loop temperature control arrangements along a flow path for hot melt adhesive extending from an upstream adhesive source to a downstream adhesive dispenser. As disclosed, each closed loop temperature control arrangement includes a comparator which compares the temperature sensed by a temperature sensor with a setpoint temperature to produce a control signal for a heater in the temperature control arrangement. The temperature control loops are located along the adhesive flow path so that the second closed loop temperature controller is upstream from the first closed loop temperature controller; and the third closed loop temperature controller is upstream from both the first and second temperature controllers. A first feedback circuit scales and integrates the control signal from the first location to produce a first feedback circuit output which adjusts the setpoint temperature at the second location.

Abstract: There is provided a hydraulic motor-driven extruder having raw rubber stock fed from coiled continuous strips into the extrusion portion thereof. The extruder includes a screw shaft and housing having decreasing diameter as material is transported toward the discharging extremity thereof. Surrounding this screw extruder there is provided heating bands of controlled temperature to impart additional heat. On discharge from the extruder the prepared rubber is deposited within an expandable cavity for selecting the desired volume of prepared rubber material. Once measured the prepared rubber is lifted from the cavity for insertion into the molding press.

Abstract: This invention is directed to a reaction amount measurement apparatus capable of measuring the reaction amount and also to a reaction amount measurement and controlling apparatus capable of measuring and controlling the reaction amount with high accuracy. The apparatus comprises at least one temperature detector disposed in the interior, the outer surface of the reaction system or in a vessel, a computer having an operation function for calculating the reaction amount in accordance with the temperature signal of the temperature detectors, and a comparison function for generating an output signal to terminate reaction when the reaction amount has exceeded the set amount, a timer for getting the operation and comparison performed at given intervals.

Abstract: There is disclosed a method for controlling an extrusion line for foamed insulation cables. In this method, a foaming insulation compound composed of a polyolefin resin and a foaming agent is supplied to an extruder, and extruded and coated as a foamed insulation onto a continuously fed cable conductor at a temperature higher than a decomposition temperature of the foaming agent to produce a cable that is subsequently passed through a cooler unit for controlling the outside diameter and electrostatic capacity of the foamed insulation.

Abstract: A method of manufacturing an electrochemical cell for determining the cencentration of a component of a measurement gas, which comprises a solid electrolyte body, and a pair of electrodes which are disposed on the solid electrolyte body and spaced apart from each other, such that one of the electrodes is exposed to the measurement gas via a porous ceramic diffusion layer having a predetermined diffusion resistance to the component of the measurement gas, so that an atmosphere adjacent to the above one electrode is controlled by means of reaction of the pair of electrodes by application of an electric current thereto, the method comprising the steps of: preparing an unfired or calcined laminar structure of the electrochemical cell such that an unfired or calcined layer of the above one electrode is covered by an unfired or calcined layer of the porous ceramic diffusion layer; starting a firing process to fire the laminar structure at predetermined elevated temperatures; applying an electric voltage or current

Abstract: A worm press extruder or the like includes a worm shaft which conveys a flow medium within a housing cylinder. In order to provide the medium with an appropriate pressure and temperature the worm shaft cooperates with a constriction plate so as to define a gap therebetween. The gap is controlled by heat responsive unit e.g. a bolt of high thermal expansion coefficient which is connected to a stationary portion of the housing as well as to another housing portion which is movable with respect to the stationary housing portion by lever means. Consequently, when the temperature of the bolt is changed its length is altered thus causing the other housing portion which is associated with the constriction plate to shift towards the stationary housing portion. Since the worm shaft is supported by the stationary housing portion and cannot move axially with respect to the latter, the movement of the constriction plate causes a modification of the gap.

Abstract: Curing of rubber in a mold is disclosed wherein a desired modulus or viscosity for the cured rubber product is obtained on the basis of an equation developed from a relaxation phenomenon. The cure process may be isothermal and non-isothermal and is controlled in a manner to compensate for acceleration of the cure reaction due to an increase in carbon black filler loading and the effect thereof which broadens the relaxation spectrum. Control of the curing process for the rubber material according to the equation permits response to the effect of the presence of a filler which reduces the activation energy of the viscous flow and that the presence of the filler produces a small effect on the activation energy of the cure reaction.

Abstract: A method and apparatus for regulating a dose-charged twin-screw extrusion device so as to achieve optimum quantitative discharge of a material being extruded in an automatic manner. By monitoring the screw torque and the mass temperature and modifying the dosed supply of material and/or the screw speed in accordance with the monitored values, the optimum mode of operation is ensured for the extrusion device which fully utilizes the discharge capacity of the device without risking damage either to the extrusion device itself or to the material being extruded.

Abstract: A novel method and device for precision injection molding is disclosed providing controlled cooling of a portion of the mold cavity surface during the molding cycle, or several such portions independently, and also, in the preferred embodiment controlled heating of a portion of the mold cavity surface during the molding cycle or several such portions independently, whereby high quality, high precision parts having close dimensional tolerances may be produced. Another aspect of the invention, a volume-controlled variable conductance heat pipe is disclosed, which novel heat pipe comprises housing means forming a sealed chamber, fluid, such as water or ammonia, within the chamber, wicking means and control means for controlling the thermal conductance of the heat pipe comprising means for controlling the volume of fluid in the liquid phase in the chamber.

Abstract: Apparatus is disclosed for the formation of pipe comprising one or more layers of thermoplastic resin. The apparatus comprises a die housing having a bore therethrough with a mandrel longitudinally supported within the bore by radial members extending from the inside surface of the bore to provide an annular extrusion passageway defined by the inside surface of the housing and the outer surface of the mandrel. The housing includes therein a plurality of electrically resistive heating elements longitudinally positioned parallel to the extrusion passageway to selectively heat the thermoplastic material flowing therethrough in proximity to the heated section thereby increasing the laydown of thermoplastic material. Also included in the housing is plurality of radially adjustable elements having electrically resistive heating elements therein to radially reposition a moveable discharge sleeve held therebetween thereby controlling the wall thickness of the thermoplastic material passing in proximity thereto.

Abstract: A method for controlling the state of vulcanization of a wheel tire which comprises controlling the process steps of a vulcanizing process preceeding the heating step according to a time mode, controlling the heating step according to an equivalent cure unit control mode and again controlling the process steps subsequent to the heating step according to the time mode. A vulcanization apparatus is also disclosed.

Abstract: A method of manufacturing a thermally insulated building block (54a) comprises foaming a quantity of foamable plastics material in an enclosed space (56) between a building block (54) and a closure means (52), the quantity of material being sufficient to fill the enclosed space (56). The foamable material may be injected into a cavity in the block onto an outer surface of the block (54) or onto the closure means (52) prior to locating the block (54) and closure means (52) relative to each other to form the enclosed space (56) therebetween. The block (54) is transported between upper and lower parallel endless belts (55, 50) during foaming and either belt (55, 50) may provide the closure means (52). If the lower belt (50) provides the closure means (52) the upper belt (55) maintains the block (54) in contact with the closure means (52) during foaming.

Abstract: A plastic extruder system having a barrel and a shell with heat exchange elements surrounding the barrel is disclosed. Two thermocouples are provided, one for sensing the temperature of the inner surface of the barrel and the other for sensing the temperature of the shell. A system controller, into which a desired barrel setpoint temperature can be set and stored, receives and stores the independent temperature signals from the thermocouples and controls the heat exchange elements to automatically maintain the temperature of the extruder barrel close to the desired barrel setpoint temperature.