Abstract: Method and apparatus for the formation of granules of a larger size or mass of a desired range from a feed stock of smaller particles comprising feeding a meltable powdery material to be granulated, or a non-meltable powdery material with a meltable binder to the surface of a rotating spreader means in the form of a disk or bowl, at least a portion of which has been heated to a temperature above the melting point of the meltable component of the feed material wherein the rate of feeding, the energy input to the spreader means and the rotational speed of the spreader means are controlled so that there is sufficient time for at least a partial melting of the meltable component of the feed material substantially solely by contact with the heated surface of the spreader means, centrifugally spreading the material across the surface of the disk or bowl and dispersing the same from the edge thereof into an atmosphere cooler than the melting temperature to form the granulated product.

Abstract: Products having a relatively large thickness such as optical lenses for various industrial applications are molded by an injection molding machine by advancing the screw by operating an injection cylinder for filling metered quantity of a molten resin into a metal mold. The screw is rotated while it is being advanced. A plurality of position setters are provided along the stroke of the screw and their outputs are respectively compared with the output of a screw position detector by using comparators. The outputs of the comparators are used to effect a program control of screw rotation in multistages. According to a modified embodiment, during the filling step effected by screw rotation, the injection speed is varied stepwisely. The injection speed is reduced to zero for a short interval and then increased again. The number of revolutions of the screw, however, is maintained at a constant value until the injection speed is increased again.

Abstract: An integrally molded plastic structural unit includes spaced support members joined by a web section disposed therebetween, each of the support members including spaced face sections and an intermediate section therebetween. Each face section includes a stressed hard outer skin. The intermediate section includes a peripheral frame section of high density. The web section includes high density connector members extending between adjoining face sections of the spaced support members. Each of the support members includes mateable sections along at least two edges thereof, with each of the mateable sections including at least five alternating raised and recessed areas forming an asymmetrical pattern along the length of each mateable section. The pattern is the same or a reverse pattern thereof along each mateable section of the same unit and of adjacent units with which it will be assembled.

Abstract: This invention relates to a method and an apparatus for the production of ribbed pipes. According to the method a plastic material is fed through an extruder into a pipe molding space (12) defined by an extrusion sleeve (4), a mandrel (9) and chill molds (1, 2) moving in the direction of the central axis of the mandrel. When the pressure of the molding space (12) deviates from a desired value, a gap is formed between the chill molds (1,2), and plastic material is squeezed into the gap, or grooves (13) of the chill molds are filled up incompletely. In order to restore the pressure to the proper value, the pressure of the material contained in the molding space is directly measured by means of a pressure sensor (14) which adjusts the speed of the extruder or the chill molds.

Abstract: An injection molding machine utilizing brushless DC motors in its servomechanism drive systems. Brushless DC motors provide a cost effective high power drive system which has the simplicity of control of brush-type DC motors. By utilizing higher resolution encoders and controlling pressure with the servomotor velocity control loop, motor cogging and zero velocity oscillatiions are minimized.

Abstract: Apparatus for forming highly isotropic web products includes an elevator that adjustably positions a former head and an associated air and fiber supply with respect to a product condenser for varying the width and density of an isotropic web formed thereon. The process of the present invention includes selectively directing individual fibers into first and second vertical air curtains the first of which is intercepted by a backwardly inclined condenser for forming a first feed mat which is stripped to form the fiber supply for the second vertical air curtain and wherein the velocity and the height of the second vertical air curtain are controlled to control the density and width of a resultant isotropic web structure formed on a continuous belt type condenser.

Abstract: The invention relates to a blow molding machine for the blow molding of hollow articles, with an accumulator head (1) for producing a preform and with a blow mold for forming a hollow article from the preform. After completion of a blow molding sequence, a piston positioning signal is derived by a control system (15), to regulate the position of a discharge piston (4) in the accumulator head (1), from a comparative signal of the actual position and set position of the discharge piston (4). The set position is determined by integration from a previously specified speed set point profile. The control system (15) further superimposes an influx signal on the comparative signal, which corresponds to the change in volume of plastic flowing from an extruder (2) to replace the discharged contents of the accumulator head (1).

Abstract: An apparatus for laying a mat of fibrous material which includes an upwardly inclined belt onto which the fibrous material is fed, one or more combing roller located above the belt, a stripping roller at the upper end of the belt for removing the material from the belt and passing it into a mechanism for laying the material into a mat. The angle of inclination of the incline belt and the position of the first combing roller as such that the material can build up to reach a critical angle of repose and then slide back down. A second combing roller located upstream of the first combing roller serves to comb the material to a constant depth, and the speed of the incline belt is adjustable to determine the amount of material leaving the incline belt and thus regulate the thickness of the formed mat.

Abstract: Process and apparatus for the manufacture of integral roller door structures of any desired length and width, and comprising longitudinally juxtaposed slats separated by integral hinge formations. Such a structure having slats of any desired length can be produced by a semi continuous moulding process in which a molten plastics material and a foaming agent are injected into a mould, the part of the structure so formed being allowed to solidify before removing the solidified structure partially from the mould, then closing mould about the remaining portion of the structure, thereafter moulding a further part of the structure within the mould onto the remaining portion of the previously moulded part and repeating the cycle as often as required.

Abstract: An apparatus and process for manufacturing insulation for metallic rod which includes a mechanism for housing a plurality of ingredients, scales for weighing a predetermined quantity of each ingredient, a blender for blending predetermined amounts of each ingredient into one material, a mixer to mix the dry blend of ingredients, a mill to form the blended material into strips, a dicer to transform the strips into pellets of insulation, an extruder for placing insulation around the metallic rod, a conveyor to transport the ingredients and/or material between each of the above steps, a controller for outputting commands to the blender and receiving inputs from the scales to obtain the predetermined amount of each ingredient, and a computer for verifying that the correct amount of each ingredient has been obtained. The ingredients used in the manufacture of this insulation material include plasticizers, fillers, a resin, and modifiers.

Abstract: A process for molding thermosetting plastic parts in a more efficient manner involving less cost and a higher production output, includes sequentially filling molds with a thermosetting plastic material in a continuous and uniform manner, passing the molds sequentially through an elongated heating chamber, removing the parts from the molds, and returning the molds for reuse. Also, to increase the versatility of the process, a plurality of independently driven conveyor assemblies are positioned within the heating chamber so that a number of different parts having different sizes, configurations and/or material may be fabricated concurrently with one another.

Abstract: A blow molding machine for the blow molding of hollow articles includes an accumulator head (1) for producing a preform and a blow mold for forming a hollow article from the preform. After completion of a blow molding sequence and the filling of the accumulator head (1), a piston positioning signal is sent by a control system (15) to regulate the position of a discharge piston (4) in the accumulator head (1) derived from a comparative signal of the actual position and set position of the discharge piston (4). The set position is determined by integration from a previously specified speed set point profile. The control system (15) further superimposes an influx signal on the comparative signal, which corresponds to the change in volume of plastic flowing from an extruder (2) to replace the discharged contents of the accumulator head (1).

Abstract: Continuous molding apparatus includes a raw material supplying portion, a mixing portion, a molding portion, a mixture delivery portion, a supporting portion and a control portion. Each reservoir of the raw material supplying portion is independently connected to an inlet of the mixing portion. The molding portion includes a plurality of spaced rotatable mold assemblies, each with at least two retractable mold sections. The mixture delivery portion is selectively alignable with each mold assembly sequentially in a preselected repeating cycle through an indexing mechanism.

Abstract: A method and apparatus for manufacturing one phase of a silica crucible including controlling the filling of a hollow mold of cylindrical shape, which rotates about its vertical axis, with grains of crystallized quartz. The grains of material are continuously introduced into the mold and are deposited on or near the lateral wall face of the mold in the form of a cylindrical layer, E, of internal radius R. A beam of light is directed to form a luminous spot on the summit of the layer from the commencement of its formation and the radial displacement of the spot on the layer is observed. The height at which the grains are introduced and the height of the trajectory of the luminous beam are modified as a function of the position of the luminous spot relative to determined reference points.

Abstract: An apparatus for continuously and progressively forming components from fiber-containing composite material workpieces having a deformable matrix introduces transverse bends into a workpiece that moves through the apparatus in a longitudinal or travel direction. Transverse bending of the composite material is accomplished in a kinematically admissible manner to avoid misalignment or failure of the composite material. A net bending deformation is introduced at a free transverse edge as the composite workpiece moves in a longitudinal direction, by pairs of compound roller elements between which the workpiece passes as it moves through the apparatus. the net deformation introduced at the free transverse edge is moved and distributed through the composite material workpiece during successive passes through the forming machinery, to form the final shaped component.

Abstract: Continuous molding apparatus includes a raw material supplying portion, a molding portion, a supporting portion, a mixing portion and a control portion. Each reservoir of the raw material supplying portion is connected independently with the mixing portion. The molding portion includes a plurality of spaced mold assemblies each with at least two separable mold sections. The supporting portion includes a plurality of the spaced mold assemblies each supported for independent rotation about more than one axis. The mixing portion includes an elongated mixing chamber disposed adjacent each mold assembly each with a plurality of deflector sections. A continuous method of molding a foamed product includes providing a plurality of raw material reservoirs and continuously moving raw material from each reservoir independently to a plurality of spaced mixing chambers each of which is located adjacent to an individual mold assembly including separable mold sections.

Abstract: A transfer molding process and an apparatus for carrying out the same for sealing electronic devices, such as semiconductor devices, in a resin by driving a plunger downward in a pot to inject the resin into a mold. In injecting a resin into a mold by driving the plunger downward, the rotary motion of the output shaft of an electric motor is converted into a linear motion to drive the plunger downward, the downward displacement of the plunger from the initial position is detected, and pressure applied to the plunger is varied according to the displacement of the plunger. Thus, the transfer molding process and the apparatus for carrying out the same reduces defects, such as voids and incompletely filled parts, in the resin-sealed device, and prevents burrs and the deformation of the insert during the transfer molding operation.

Abstract: A fishing line, or just a leader, has a core (11) which is coated by plastic material as it is pulled through an extruder (3) and then a quench bath (4) by a variable speed drive device (9). Very fine control can be exerted by laser devices (11, 12) before and after coating, and adjusting a selection of parameters such as drive speed, extrusion rate, pressure and temperature, and cooling. A double coating may be applied or additives mixed in the extruded plastics which will give a desired floating or sinking characteristic.

Abstract: Apparatus for producing high modulus products. A polymer morphology or powdered metal is solid-state deformed under pressure through the rollers of an extrusion rolling die, at a temperature near but below its crystalline melting point, while controlling the extrusion rate and the rate of rotation of the rollers so that the rate of extrusion of the polymer or metal is substantially the same as the rate of rotation of the rolling die surface.

Abstract: Method for controlling the processing and output feeding of plastic melt by extrusion, by means of an extrusion plant including a process unit (1) for processing the plastic material, a pump (3) for feeding the plastic melt to a die (4) or the like, and a screen pack assembly positioned between the process unit (1) and the pump (3). In the process unit (1) the melt is imparted a constant level of kinetics of extrusion, and the plastic melt pressure (P2) between the screen pack assembly (2) and the pump (3) is kept above a predetermined level. As a measure of the level of kinetics of extrusion, the pressure (P1) of the melt between the process unit (1) and the screen pack assembly (2), is used, preferably in combination with the melt pressure (P2) after the screen pack assembly (2).

Abstract: To obtain from a product melt a product strip of uniform gage in the nip between two rotating rolls in a continuous cooling and solidifying of metal oxides by cotinuous casting, the gage of the nip, which is preset by the respective product strip, is measured between the rolls. One of the rolls is prestressed against the other by a force. The deviation of the measured gage from a set value is determined and the roll speed is regulated by means of this deviation.

Abstract: A method of extruding ceramic bodies in a downward direction is disclosed, which includes the steps of supporting an extruded body being downwardly extruded through an extruding die to prevent deformation of the extruded body, and cutting the extruded body in a given length. An apparatus for effecting this extruding method is also disclosed, which includes an extruding unit provided with a die at a bottom thereof, a unit for holding the extruded body being downwardly extruded, and a cutter for cutting the extruded body in the given length.

Abstract: The present invention incorporates a conductor contact apparatus, a conductor defect detector, and a relay or equivalent added to the emergency stop circuit of a conductor insulation extruder apparatus in order to detect conductor defects and shut-down the extrusion apparatus before the conductor defect can cause the extruder to become blocked, interrupting normal production operations. The defect detector is especially adapted to detect variations in the cross-sectional area (or apparent cross-sectional area) of a conductor being insulated.

Abstract: A control apparatus for an injection molding machine injects a melted resin within a housing into a cavity of a mold through a nozzle section of a nozzle at a housing and by movement of a screw. A nozzle opening changing mechanism variably changes a throttled path area of the nozzle while a mold temperature sensing mechanism sensing the temperature of the mold. A control mechanism controls the nozzle opening changing mechanism in accordance with the sensed temperature of the mold temperature sensing mechanism.

Abstract: A film manufacturing method which utilizes a trough storing a liquid therein. The liquid surface of the liquid forms a developing region in which a monomolecular film of organic molecules is developed. The developed monomolecular film is compressed by a barrier to a predetermined surface pressure. A workpiece having a build-up surface is moved by a vertical moving mechanism in a direction perpendicular to the developing region through the monomolecular film while being moved ahead of the build-up surface in a horizontal direction by a horizontal moving mechanism, so that the monomolecular film is built up on the build-up surface.

Abstract: A distinctive apparatus for forming an absorbent body includes a forming chamber, and a fiber delivering mechanism for providing a flow of fibrous material within the forming chamber. A forming layer, which is located in the forming chamber and is movable therein, receives deposit of the fibrous material thereon. A conduit mechanism supplied a flow of dispersed bodies of high-absorbency material, which enter the forming chambers and intermix with the flow of fibrous material thereon. A regulating mechanism controls a velocity of the flow of high-absorbency material into the flow of fibrous material to thereby form a selected distribution of high-absorbency material within the fibrous material deposited onto the forming layer.

Abstract: A plasticized resin is extruded from an extruding machine into an accumulator into which the resin is stored by an amount exceeding the amount required for one resin molding operation. The stored resin, in operation, is fed through a flexible hose towards a gear pump under controlled pressure conditions. The resin is measured by the gear pump and the displacement and the rotational speed of the gear pump are controlled by a suitable controller such as microcomputer to exactly measure the plasticized resin to be charged into the mold cavity in a predetermined distributing mode. The clamping of the mold can be effected by a clamping force less than that required by a conventional press-molding machine.

Abstract: Shaping device and method for shaping extrudable material including at least one extrusion nozzle for feeding extrudable material and being supported in a carrier common to all nozzles, motors for moving either the carrier or a movable support surface for receiving extruded material directly from the nozzles and a programmable computer for controlling the motors.

Abstract: Continuous strands of color concentrate are metered into the feed zone of a screw-melter polymer extruder where they are cut into pellets by the shearing action of the flights of a rotating screw against the extruder housing. These pellets are mixed within the extruder with a thermoplastic polymer to be colored and this mixture is then melted and extruded into a useful article, for example, a fiber for textile or carpeting end-use.Additionally, color concentrates can be first formed into continuous strands and stored conveniently on a spool for subsequent metering into the polymer extruder.

Abstract: A method of manufacturing a multi-layer resin material by employing a plurality of kinds of thermoplastic resin. Resins for inner and outer layers are supplied into a feed block of a feed block type T-die coextrusion apparatus where they are laid up another, and are then sent to the T-die side. In this case, a resin which is practically similar to the resin for the outer layer is supplied as an auxiliary resin to both lateral edges of the multi-layer resins within the feed block. Thus, the sheet extruded from the T-die slit has lateral edges which are made of a single resin.

Abstract: Control apparatus for an injection molding machine having a sensor provided for the injection molding machine for producing a signal representing the quality of the molded product or a molding condition of the injection molding machine, a set value memory device in which a permissible range of the signal is set, a judging member for judging as to whether the signal lies in the permissible range, a production lot data memory device containing control data for the injection molding machine with respect to a lot now being produced, and a destination table showing a destination of the data corresponding to a result of judgment of the judging member, a controller for controlling the injection molding machine in accordance with the control data stored in the production lot memory device, and another memory device for storing a plurality of sets of the production lot data regarding various lots or production conditions, and a storing device for determining a destination of the production lot data based on the result

Abstract: Forming an optical fiber so as to have a relatively constant bend loss characteristic includes apparatus for continuously bending the optical fiber downstream from a preform from which it is drawn and continuously detecting light withdrawn from the fiber at the bend so created to determine the fiber bend loss characteristic, the fiber bend loss characteristic being maintained constant by using feedback control to vary a drawing speed of the fiber and hence a diameter of a core of the fiber.

Abstract: A method of degassing thermoplastic plastic melts over a wide range of viscosities in a degassing extruder including a plurality of sequential degassing sections. Each degassing section includes at least one screw section having flights formed thereon. Each section includes a degassing region and a metering section downstream thereof. The height and length with which the flights are filled in the degassing regions in the individual degassing sections is controlled by the comparison of a pressure gradient measured in the metering region of that section with a desired pressure gradient and on the basis of this, the melt is conveyed with substantially the same throughput capacity in each degassing section. As a result of these measures, the degassing is effected in all of the degassing sections with optimally partially filled screw threads and with an optimum filling length of the worm threads, which is independent of the viscosity of the melt.

Abstract: The invention regards a universal machine for making cakes in usual bakeries all the way from a finished dough to baking. The machine extrudes soft or thick dough, makes portions and forms cakes for arranging on baking plates and baking, and extrudes cream and jam and similar materials. The machine is also suitable for making licorice, confectionery and any kind of forming and making portions of viscous, extrudable materials. The machine includes automatic measurement of thickness and control of thickness of the dough-cake by use of a photocell, and the photocell is fitted with runners, scale of measurement and patterns of thickness, so that the thickness of each cake is measured and cut independently. The machine is fitted with automatic measurement of frequency and control of frequency of cakes, relying upon the control of thickness. The machine has many cylinders utilizing the automatic control of thickness.

Abstract: Disclosed are processes and apparatus utilizing, choke means at least partially providing restriction to passage of material and measurement of magnitude of force(s) exterted on said choke means by passage of material, to provide: (1) an indication of characteristics of the material, and/or; (2) control of said passage of material and/or control or processes or apparatus associated with said passage of material in response to the magnitude of the measured force(s).

Abstract: A separator manufacturing apparatus includes a transfer roller (2) with a plurality of annular shaping grooves (1) having a predetermined shape in cross section which are formed in the outer circumferential surface of the transfer roller (2) in its circumferential direction, a resin feeding device (4) with nozzles (3) to feed a hot-melt type resin to the annular shaping grooves (1) of the transfer roller (2), a base paper feeding device (5) to feed a continuous paper (w) at a predetermined speed to the outer circumferential surface of the transfer roller (2) supplied with the resin to thereby form by transfer a plurality of ribs (9) on a surface of the continuous paper (w), and a fault detecting device (6, 36, 46) to detect the shape and/or a dimension of the rib (9) formed by transfer. A resin drop receiving device (53) or an annular shaping groove cleaning device (63) may be provided so that maintenance of the transfer roller (2) can be easy.

Abstract: A method and an apparatus for measuring and controlling foam sheet blow-up in a thermoformer oven. Control of the oven operation is achieved through monitoring the measured blow-up of a material in the thermoformer oven at a sensing location in a forming station receiving the material from the over in order to regulate the thickness of the plastic material prior to its conveyance into said forming station. This is effected by varying the rate of advance and dwelling time of the material in the oven, and optionally, also concurrently regulating the temperature in the oven to optimize control over material blow-up.

Abstract: A continuous granulator of the double-screw type includes a mechanism by which the degree of kneading can be controlled, and prevents lateral communication between the screw ends. A gear pump connected after the screw cylinders delivers the material to the cutting unit.

Abstract: An automatic control for an extruder has a temperature sensor which monitors the exit temperature of the extrudate and several pressure transducers which monitor the pressure within the extruder to control the cooking of the mash inside the extruder to ensure production of high quality extrudate. The controller monitors and controls the temperature and moisture content of the mash in the extruder by controlling the input of various ingredients and also the cooling or heating of the mash near the exit of the extruder through a heat exchanger.

Abstract: A method for monitoring and controlling the wall thickness of an extruded profile of heated polymeric material that issues from an extrusion die. The die includes a plurality of discrete sectors each having a controllable heat source and a temperature sensor, and the temperature at each particular sector is controlled and adjusted in order to change the measured wall thickness corresponding with that particular sector as necessary to provide a desired wall thickness distribution. A characteristic curve for the particular material is provided as an input quantity and involves the relationship between a change in extrusion temperature versus the corresponding change in wall thickness, and that relationship is utilized to effect rapid adjustment of wall thickness by means of a temperature change in order to provide a finished article having the desired thickness profile and without having excessive material, to thereby reduce the weight and cost of the extruded article.

Abstract: A method and apparatus for machining dough that takes into account the different flow regimes exhibited by the dough during processing. As in conventional systems, the apparatus includes a hopper for extruding dough in a sheet and pairs of powered rollers for sizing the sheet. A computer controls the system. Mass flow rate is made constant throughout the system by establishing a master flow rate based upon predetermined criteria related to the product being produced, and the computer monitors the weight of the extruded sheet to maintain a constant input to the powered rollers. The flow rate is varied to remain constant by comparing the input to output, as measured by the sheet thickness at the cutter station. The gage rollers are controlled by setting a nominal roller speed, trimmed according to the tension present in the sheet upstream of the gage roll, as reflected in the position of a loop in the dough sheet between the gage roll and the pair of rolls immediately upstream of same.

Abstract: In a method and a device for making shaped objects from plastic refuse plasticized in a roller extruder under pressure and ejected from the nozzle of the extruder a plurality of molds are provided transported to the extruder, filled thereby and transported therefrom. Each mold has at the end face a plate having a filling opening. During the filling process this plate sealingly overlaps the surface surrounding the nozzle so that the mold can be filled with plasticized plastic under the pressure generated in the roller extruder.

Abstract: An extrusion molding equipment for a multi-layer parison which includes an operation position detecting device for detecting an operation position of an accumulator extruding an layer of resin material invisible from outside the parison. A pressure detecting device is provided for detecting pressure of the inner resin material in an inner resin conduit. An extrusion amount control device for the inner resin material is also provided for controlling an extrusion amount of the inner resin by the use of a signal indicating the operation position from the operation position detecting device, and a signal indicating the pressure from the pressure detecting device.

Abstract: A novel method of producing molding members for automobiles, formed at least partly of a synthetic resin material is disclosed. According to the method of the invention, synthetic resin material is extrusion molded into a continuous body with a substantially constant cross-section throughout the entire length thereof. A controlled amount of the material is removed from the predetermined location of the continuous body, synchronously with the extrusion molding of the material, such that the cross-section of the continuous body varies in the longitudinal direction of the body. The continuous body subjected to the controlled removal of the material is then cut into the predetermined length of the molding member.

Abstract: This invention relates to a process of producing a thermoplastic resin sheet and equipment therefore. The equipment includes a first extruder of a high kneading type, a second extruder of a low kneading type and an extrusion die. A film-shaped resin extruded from the extrusion die is cooled by a cooling device, to thereby obtain the resin sheet. Additionally, a difference between pressures at the outlets of the first and second extruders is detected, and, in response to this difference between the pressures thus detected, the operating conditions of the first extruder are automatically controlled.

Abstract: A process and apparatus for producing a reclosable container stock with adhered occludable closure strip portions, said apparatus comprising a rotatable lay-on roll having circumferential grooves therein, means to advance the closure strip portions to the lay-on roll, a rotatable casting cylinder positioned opposite the lay-on roll, means for extruding a molten plastic film onto the casting cylinder so that the film adheres to the closure strip portions, and means for cooling the resulting reclosable container stock with adhered closure strip portions.

Abstract: A plastic web is made by an extrusion apparatus having a plastics screw press, a metering pump with a volume flow depending on the rotation speed, an output die and a rolling unit with calendaring rolls. The flow of a thermoplastic material is regulated with the metering pump. The melt web issuing from the output die is cooled and calibrated. The process uses a metering pump which has substantially linear volume flow/rotation speed characteristics in the regulated range of rotation speeds and together with the rolling unit is part of a common computerized control system. The peripheral speed of the calendaring rolls is controlled so that it is proportional to the rotation speed of the metering pump. The special proportionality factor for the speed ratio is set by a computer which controls the roll speed so that no undesirable thickness variations or other product defects occur.

Abstract: The specification discloses a new method and apparatus for treating extruded TEFLON (fluoropolymer) tubing to significantly improve its dimensional and optical characteristics. Diameter tolerance is .+-.0.0002, concentricity rises to 95%, and optical clarity rises to the theoretical transmittance of the material. The tubing is first cleaned, and then heated to a transition temperature above 150.degree. C. to soften and further homogenize the tubing. The tubing is then drawn through a polished diamond die and then rapidly cooled. The cooled tubing may be further stabilized by an annealing step. Both a batch mode and a continuous mode of operation are disclosed.

Abstract: A method and associated apparatus for the injection molding of plastic articles of enhanced surface quality using fluid pressure. The method involves the initial step of injecting molten plastic at a nominal injection pressure from an injection molding machine through a flow path to a mold cavity defining the shape of the molded article. A charge of fluid pressurized at a predetermined level no greater than the nominal plastic injection pressure is communicated to the plastic flow path through an orifice of sufficiently small dimension to resist entry of the molten plastic against the pressure of the fluid charge. The pressurized charge of fluid responds to a reduction of the pressure in the plastic flow path below the predetermined level upon substantial completion of plastic injection and enters the flow path and passes into the mold cavity. The fluid is contained within the mold cavity under pressure until the article has set up, and is thereafter vented to atmosphere.

Abstract: In a method of operating an injection compression molding machine having a stationary metal mold, a movable metal mold, an oil pressure actuator for advancing the movable metal mold toward the stationary metal mold to form a mold cavity therebetween with a predetermined compression clearance .delta. left between the movable and stationary metal molds, a heating cylinder adapted to engage with the stationary metal mold, a hopper for supplying a thermoplastic resin into the heating cylinder, a screw contained in the heating cylinder for injecting molten metal into the mold cavity, an oil pressure motor for rotating the screw and a piston cylinder unit for reciprocating the screw through the heating cylinder, the molten resin is filled in the mold cavity by advancing the screw and the advancement of the movable metal mold is started when the screw reaches a predetermined set position during an injection stroke so as to reduce the compression clearance .delta.