Abstract: There is disclosed a thermosetting resin injection molding machine comprising: a heating cylinder including a body having a device for introducing a resin material into said body, and a sleeve having an injection port for injecting the resin material; and a screw reciprocally movable in the heating cylinder, wherein the screw includes a body having a flight, and a piston portion provided at a front end of the screw body, and a diameter of the piston portion is smaller than a diameter of the flight; wherein an inner diameter of a working portion of the sleeve is smaller than an inner diameter of the heating cylinder body; wherein a length of the piston portion, a length of the working portion of the sleeve and an annular clearance between the working portion of the sleeve and the piston portion are so determined that a predetermined amount of the resin can remain for cushion molding at a front end of the piston portion during dwell after the injection of the resin material; and wherein a resin compressing port

Abstract: An injection mold system and corresponding method that equalizes pressure of flowable plastic dispensed into an injection mold cavity. A gate in communication with the mold cavity introduces a quantity of flowable plastic into the cavity at a predetermined pressure. A gas inlet in communication with the mold cavity at a mold cavity location remote from the gate introduces a gas into the mold cavity to pack the flowable plastic in the mold cavity at a pressure corresponding generally to the predetermined pressure, to thereby minimize the formation of sink marks and warpage on an injection molded part formed therein. The present invention insures formation of the part with a highly finished appearance surface and eliminates the need for painting or otherwise additional finishing of the part.

Abstract: A simulation system predicts a behavior of a molten resin in a mold in filling, packing, and cooling processes by using a fundamental equation formulated by the finite element method, and shrinkage factors in a direction of thickness and planar directions based on anisotropy of a volume shrinkage factor obtained during prediction of the filling, packing, and cooling processes, so that a warp deformation in an injection-molded article can be predicted at a higher precision. In this simulation system, the warp deformation is predicted by calculating the shrinkage factors in accordance with:.epsilon.Z=A+B.multidot.eV (1).epsilon.P=(eV-.epsilon.Z)/2 (2)wherein .epsilon.Z is a shrinkage factor in the direction of thickness, .epsilon.P is a shrinkage factor in the planar directions, eV is a volume shrinkage factor, and A and B are shrinkage coefficients.

Abstract: The knit line strength and other packing related properties both aesthetic and functional of injection molded polymeric products is improved by equipping the mold with packing pins. The packing pins are similar in construction to mold ejector pins and may also be mold ejector pins depending on mold configuration. The packing pins are sequentially actuated during or after filling of the mold to cause flow of plastic either transverse or parallel to the direction of flow in a to and from manner. The result is a kneading action in the viscous flow and an oriented layering effect in the solidified plastic much like a scarf joint at the knit line location. The irregular shape of the layers enhances the mechanical strength at the knit line in addition to increasing the likelihood that long chain molecules will re-entangle between the two melt flows at the knit line.

Abstract: A method is disclosed for the production of a molded article, using a mold assembly including a mold having a cavity, for producing a molded article from a thermoplastic resin; an insert block formed of ceramic or glass having a thermal conductivity of 2.times.10.sup.-2 cal/cm.sec..degree.C. or less, the insert block being disposed inside the mold, constituting part of the cavity, and having a thickness of 0.5 mm to 10 mm; and a cover plate for covering a peripheral portion of the insert block. The cover plate is attached to the mold and constitutes part of the cavity, wherein a clearance between the insert block and the cover plate is 0.001 mm to 0.03 mm, an amount of overlapping of the insert block and the cover plate is at least 0.1 mm. The method includes filling a molten thermoplastic resin in the cavity, and then cooling the thermoplastic resin to solidness.

Abstract: A method and apparatus for resin transfer molding composite materials that emit volatiles. The apparatus includes an RTM tool, a constant displacement injection pump, a heater connected to a power supply, one or more porous tool inserts, and one or more articulated tool inserts. The porous tool inserts are mounted within the RTM tool and allow volatiles produced during processing to flow through the inserts. The volatiles are drawn through the porous tool inserts and out through an exhaust port. The articulated tools are also mounted within the interior of the RTM tool. The articulated tools are movable in order to increase and decrease the volume of the RTM tool. As volatiles are emitted, the articulated tools are moved in order to decrease the volume of the tool. The articulate tools are also used to apply a consolidation force to the resin and fiber-reinforced preform within the tool.

Abstract: The present invention includes an in-line roller skate substantially free of the effects of differential shrinkage and a method of molding an in-line skate substantially free of the effects of differential shrinkage, the skate including a molded boot with a sole; a molded wheel frame integral with the sole; a plurality of in-line wheels rotatably attached to the wheel frame; and a mechanism for minimizing the effects of differential shrinkage.

Abstract: A mould for cast moulding a contact lens includes a first cup member having a male mould surface and a second cup member with a female mould surface. The two cup members form a piston and cylinder and are used in a pressure vessel so as to apply loading pressure to deflect the mould surfaces to maintain the surfaces in contact with a lens being cast. The mould is opened with the mould surface facing upwardly. Hydrating fluid is added to the first cup member and a cover sealed to the top of the first cup member.

Abstract: Equipment, in particular pressure gelling equipment, is provided to fill one or more casting molds with castable, liquid materials of which the components are fed by pumps through closable conduits to at least one plunger-cylinder system from where the components are moved to a mixing chamber and from there to the particular casting mold. In order to process especially abrasive casting materials of high viscosity and short pot life, the invention provides that at least one plunger-cylinder system be operated at a pressure substantially higher than are the pumps and that the mixing-chamber volume be comparatively slight.

Abstract: A method and an apparatus for injection-molding a molten resin wherein any flaw such as warpage, shrinkage or the like does not occur in products having a small thickness when the desired product of injection molded resin is molded by injecting the molten resin into a cavity of an injection molding die. The molten resin is injected into the cavity under proper control with respect to injection speed and pressure, the pressure of the molten resin being temporarily set and reduced to a preset reference value when the cavity is filled with the molten resin, and subsequently, the pressure of the molten resin filled in the cavity is released.

Abstract: When injection-molding a molten thermoplastic resin into a molding having different thicknesses, a void inducing member is set in a cavity corresponding to heavy sections. Then gas pressure is applied passing through a gas passageway to a tip end of the void inducing member, thus forming a void nucleus in the resin adjacent to the tip end of the void inducing member. The void nucleus develops to a void by shrinking force of the resin as the molten resin cools.

Abstract: A local pressurizing type injection molding apparatus including a stationary die, a movable die disposed for movement into and out of contact with the stationary diet a first local pressurizing pin extending through the movable die and having a tip facing a gate, and a second local pressurizing pin extending through the movable die and having a tip facing the cavity. The apparatus is further provided with first advancing mechanism for advancing the first local pressurizing pin, second advancing mechanism for advancing the second local pressurizing pint and a device for individually setting the points in time at which advancing movements of the first local pressurizing pin and the second local pressurizing pin are started and for individually setting the pressurizing pressures given by the first local pressurizing pin and the second local pressurizing pin.

Abstract: Reverse gating is added to a conventional compression molding machine so that when the molding cavity is filled with material in excess of the amount required to mold a part, the material flows from the cavity to a pressure chamber to be vented. Pressure in the chamber allows back flow of the material from the chamber to the molding cavity during cooling to compensate for shrinkage.

Abstract: An improved injection/compression molding process for the manufacturing of high quality concave optical lenses of thin thickness. A thermoplastic material is injected into a mold cavity of an injection/compression molding machine, the mold cavity is designed to have adjustable thickness and is initially set at a thickness greater than the lens to be produced. After the amount of the plastic injected fills the enlarged cavity, the thickness of the cavity is gradually reduced by exerting a compressional force on the thermoplastic material inside the mold cavity. During the compression stage, the injection continues and the excess thermoplastic material is squeezed into an overflow pocket inside the injection/compression mold. The injection apparatus can be switched into a pressure holding mode during and after the compression stage to prevent any backflow and post-injection shrinkage.

Abstract: Apparatus for making a plastic lens. Mold members are spaced apart to define a mold cavity. Ultraviolet light is directed through a filter and against at least one of the mold members. The mold members are cooled by air.

Abstract: A mold for manufacturing polyurethane parts using the RIM process, has two mold halves which between them enclose a mold cavity. The mold cavity is sealed off from the outside by a sealing surface. A gap of 15 to 30 mm depth and 0.15 to 0.25 mm width is provided between the mold cavity and the sealing surface.

Abstract: An injection molding die includes a fixed half die and a movable half die which has a core surface and which is provided with ejector pins. The ejector pins are held with their extremities retracted from the core surface to form recesses corresponding to compression allowances. The ejector pins are advanced toward the cavity to compress the compression allowances after a molten resin has been injected into the injection molding die in a manner which fills the cavity and the recesses. The compression with the ejector pins renders the pressure distribution int he cavity uniform, so that a molding can be formed with a high degree of accuracy and so that the injection molding cycle time can be reduced.

Abstract: An apparatus for mating a finished ophthalmic lens includes a pre-manufactured lens or lens wafer as a part of a mold for making the finished lens. A polymerizable lens material is injected between the lens or lens wafer and a conventional mold member and a trio of indexers are used to rotate the conventional mold member relative to the lens wafer, to adjust the spatial relationship between the conventional mold member and the lens or lens wafer, and to control the angular relation between them. The assembly is subjected to irradiation and the radiation cures the polymerizable lens material and fuses it to the lens wafer so that the lens or lens wafer becomes an integral part of the finished lens. The apparatus produces a finished lens in less than one hour.

Abstract: A contact lens casting mould includes two casting mould halves. A concave shaping surface (11) is constructed on a female part (1) and a convex shaping surface (21) on a male part (2). When joined together, the two casting mould halves (1 and 2) adhere by frictional connection.

Abstract: A process and apparatus for injection molding and a plastic article having a hollow rib portion is formed utilizing a spill cavity. The process includes the steps of sequentially injecting fluent plastic and gas into a mold cavity having a space defining at least one wall portion of the article and a channel defining a rib portion of the article. A quantity of fluent plastic is initially injected to substantially fill the mold cavity. A charge of pressurized gas is then injected into the channel of the mold cavity to displace a portion of the still fluent plastic into the spill cavity which is flow coupled to the channel. Preferably, the thickness of the rib portion in cross section is at least twice as large as the thickness of the wall portion in cross section along the entire length of the rib portion. Also, preferably, the channel is tapered along its length. The rib portion may be either internal or external to the article.

Abstract: The present invention relates to a filler injector for applying a filler to crevices in concrete surfaces. The injector has a transparent outer tube having scale markings thereon to indicate the pressure of any filler backing up from the surface and an adaptor connectable to a pressurized source of filler and screwed onto the outer tube. The injector also includes a check valve mounted in the adapter, an inner tube mounted inside a closed top of the outer tube and having a bore therein which can convey the filler from the adaptor to the surface, and a piston slidably mounted inside the outer tube and on the inner tube. The filler injector thus will not result in unwanted explosion, implosion, or skipping of a seam joint because of the pressure of the filler, and will provide a reading of the filling pressure on the concrete surface as the filler is being applied.

Abstract: A device for supplying plastic material into a flask under pressure and a flask with the device, which are used for preparation of a denture. The device includes a cylinder having the inside end communicated to a cavity in the flask, a piston slidably inserted in the cylinder, a spring urging the piston toward inside of the flask, a stopper restricting the outside stroke end of the piston, and a device for adjusting elastic force of the spring. The adjusting device preferably includes a spring receiver abutting against the outside end of the spring, a screw-mechanism for moving the spring receiver in the axial direction of the cylinder, and a handle member for operating the screw-mechanism.

Abstract: An apparatus for controlling a molding of a solid product in a mold cavity from molten material which solidifies in the mold cavity, in which first and second conduits are coupled to the mold cavity at spaced positions for carrying the molten material, includes first and second elements, and a controller for controlling the driving the first and second elements repeatedly during solidification of the molten material in the mold cavity so that the molten material is repeatedly moved through the mold cavity. The first element is disposed in the first conduit and the second element is disposed in the second conduit.

Abstract: A method and apparatus for controlling a casting process for obtaining a cast product from a cast substance injected into a die cavity of a pair of casting dies by a fluid-operated injecting plunger and pressurized by a fluid operated squeezing plunger after the completion of an injecting process. Actual movement of the squeezing plunger is controlled to copy a desired curve with respect to a desired movement of the squeezing plunger versus an elapse of time from the start of the actual movement of the squeezing plunger.

Abstract: A method and apparatus for moulding a fluid settable material. The apparatus includes male and female mould halves defining between them a mould cavity having an inlet thereto for the introduction of a fluid settable material; between the male and female mould halves of the cavity a seal can be interposed to seal the mould cavity from the atmosphere. At least one vacuum outlet from a mould half leads via an isolation valve to a vacuum source.

Abstract: A method and apparatus for the molding of a thermoplastic with a large cross-section is provided. The plastic is extruded into a closed mold where sufficient pressure is maintained on the plastic to offset the shrinkage to the extrudate during cooling. In particular, the mold cavity is capable of changing its volume as molten plastic is forced into it while also changing the pressure within it against which the plastic is being extruded. This is achieved by positioning a movable piston as one end of the mold, and applying pressure to the piston so that a predetermined pressure within the mold is maintained. Once the desired amount of plastic is within the cavity, pressure is maintained while it solidifies, following which the finished product is ejected.

Abstract: A manufacturing method for a molded resin article includes an injection step of injecting a resin molding material into a mold, a compression step of compressing a prescribed portion of the resin molding material, a cooling step of solidifying the resin molding material by cooling while maintaining pressure on the prescribed portion, and a removal step of removing the resulting molded resin article from the mold. The compression prevents the formation of voids in the compressed portion and increases the dielectric strength thereof. In a preferred embodiment, the molded article is a distributor rotor for an internal combustion engine.

Abstract: A gas assisted injection molding apparatus of the type in which a supply of resin is introduced into a cavity in a mold at a resin injection location and a gas injection assembly is provided to introduce gas into the mold cavity at a gas injection location removed from the resin injection location to assist the resin in filling out the mold cavity. The gas injection assembly includes a bore in the mold communicating with the mold cavity, a pin having a size to fit slidably in the bore and including a central axial passage for delivery of gas into the mold cavity through the pin, a power cylinder assembly mounting the pin for movement between an advanced gas injection position in which the pin is positioned in the bore with its forward tip in communication with the mold cavity and a retracted position in which the mold cavity is vented through the bore, and an annular edge on the pin operative to remove obstructions with each forward movement of the pin from its retracted position to its advanced position.

Abstract: An injection-compression mold having a stationary part and a movable part which are used for injection-molding a molten thermoplastic resin, at least one spring member with one end fixed to at least one of the mold parts and the other arranged so that it can abut against the opposite mold part when the mold is clamped in order that the bias force of the spring member to absorb the clamp force of a molding machine.

Abstract: A system and method of controlling hold pressure applied to molding cavities of a stacked multi-parting injection molding system having desynchronized injection periods while cyclic injection molding a plastic material. A combination of the center molding block and an injection system together provide an adjustable feed system. The feed system is adjusted to enable plastic material to be fed from the injection system through a left branch to the left molding cavity. The injection system is pressurized to inject the plastic material through the left branch to fill the left molding cavity. The injected plastic material is confined within the left branch and the left molding cavity; and the confined plastic material is hold pressurized by a movable packing element. A like sequence of steps is followed to hold pressurize the right molding cavity.

Abstract: A system and method of controlling hold pressure to cooling cavities when cyclic injection molding a thermoplastic material by utilizing a combination of a multi-parting mold system and an injection unit which together encompass a bifurcated feed system with a molten core. The mold system includes a center part that joins end parts at parting surfaces to define first and second cooling cavities. The feed system is defined by the injection unit and the center part and includes a runner orifice from the injection unit and bifurcated branches. A valve is located in the runner orifice. The first branch feeds injected thermoplastic material to the first cooling cavity, and the second branch feeds injected thermoplastic material to the second cooling cavity. The valve is closed each time after molten thermoplastic material is separately injected under pressure into each of the cooling cavities to hold pressurize the plastic material in the respective cooling cavities.

Abstract: In critical surface quality plastic molded articles, especially in optical lenses and disks, an "adaptive" mold cavity is used to automatically control melt pressure and densification during mold packing to within a predetermined range of acceptable values, while normal cycle-to-cycle molding process variations produce a corresponding minor but acceptable change in the molded-part thickness. In multicavity "adaptive" moldsets, permissible cavity-to-cavity imbalance without an overfilled cavity flashing at the parting line is increased. A resilient member (mechanical steel spring or elastomer or hydraulic cylinder) is interposed between the part-forming mold insert surface and the associated clamp plate for that half of the moldset. When the mold is initially closed, a separation distance between the A and B mold insert is less than the molded product specification's minimum acceptable part thickness.

Abstract: Apparatus for moulding a thin-walled article, such as a Petri disk, in which the moulding is effected by injecting from the side of a planar portion of the article. The moulding apparatus has a core piece (10) co-operable with a cavity (12) which together define a space (14) in which the article is to be moulded. At least one of the core (10) or the cavity (12) has a moulding surface (16, 18), corresponding to the planar portion of the finished article, which is non-planar. Preferably, the moulding surface (18) of the cavity (12) has a concave curvature, while the opposing surface (16) of the core (10) inserted therein has a convex curvature. The radius of curvature preferably being larger at the core than at the cavity. The particular configuration allows more material to be supplied to the central area corresponding to the planar portion of the finished article.

Abstract: An apparatus is disclosed for the reduction of mold cycle time. A heat recoverable member in a compressed state is placed within a channel defined relative to the surface of a mold. A hardenable liquid used to form the article then flows in an accelerated manner through the channel. Thermal energy supplied to the heat recoverable material thereafter causes the heat recoverable material to expand within the channel, thereby displacing the hardenable liquid from the channel. The temperature of gelation of the hardenable liquid and the recovery temperature of the heat recoverable material may be selected such that the channels are substantially filled by the heat recoverable material prior to the hardening of the hardenable liquid. In this manner, the heat recoverable material becomes flush with the surface of the mold prior to hardening of the liquid so as to yield an article of manufacture having a relatively planar surface.

Abstract: A molding apparatus for molding a clay pigeon includes a bypass tube having a tip disposed in a blow orifice communicating with a cavity of a metal mold in the form of the clay pigeon. The bypass tube has a diameter smaller than that of the blow orifice and compressed air, which leads molding material in the blow orifice, passes therethrough in order to supply the molding material mixture of at least sand and hardening agent to the cavity, whereby corners and details of the cavity are satisfactorily filled with the molding material supplied to the cavity.

Abstract: Apparatus for injection compression molding of thermoplastic parts. A preferred apparatus (100) includes a platen assembly 106, a toggle clamp assembly 102, a screw injection assembly 101, a hydraulic system suitable for providing power to the toggle clamp assembly 102 and the screw injection assembly 101, and a control system 88 for operatively controlling the various hydraulic devices associated with the molding apparatus. The platen assembly 106 provides for a plurality of variable-volume mold cavities 7. In one embodiment, enlarged mold cavities 7 receive plasticized resin from the screw injection assembly 101, and compression of the injected resin is provided by the toggle clamp assembly 102. In another embodiment, the platen assembly 106 includes a floating die assembly wherein pressure created by injected resin causes die inserts 5 and support pillars 15 to slide relative to a molding plate 74. Compression in this embodiment is also preferably provided by the main toggle clamp assembly 102.

Abstract: A vertical injection apparatus is incorporated with a parting mold including upper and lower mold halves and defining a cavity to be filled with a melt. The lower mold half has a vertical sleeve hole at the outer side thereof and a vertical melt passage hold communicating between the cavity and the sleeve hole. The upper mold half has a vertically extending pin hole coaxial with the melt passage hole and open to the cavity and provided with a vertically extending mold pin movable through the pin hole. At least an upper part of the melt passage hole in the vicinity of the cavity has a diameter smaller than that of the sleeve hole but slightly large than the of the mold pin. Preferably, the cavity is designed for a disk wheel having a central hole through which the mold pin is allowed to pass, and the lower mold half forms a contoured inner surface corresponding to a decorated surface of the disk wheel.

Abstract: A method and apparatus for the fabrication of optical lenses by injection/compression molding of thermoplastic includes a plurality of sleeves, each having a bore therethrough, and a plurality of mold inserts dimensioned to be received in the bore with minimal clearance for sliding fit. The mold inserts each include a precision optical surface adapted to form a front or back surface of a lens. A selected pair of mold inserts are placed in the bore of a sleeve with front and back surface forming optical surfaces in confronting relationship to define a mold cavity, and the assembly is heated to a temperature above the glass transition temperature of the thermoplastic to be molded. An injection port extends through the sleeve to the bore, and is positioned to inject thermoplastic that has been heated to a fluid state into the cavity. After injection of the thermoplastic, the mold inserts are compressed together, and excess thermoplastic is forced out of the mold cavity.

Abstract: An apparatus for injection molding a product having a partly thin portion includes a molding die including a male die and a female die for defining a cavity having a volume larger than a volume of the product. A gate is provided to permit molten resin material from an injection molding machine to be injected into the cavity. A slide block disposed in either the male die or the female die has in cross section a dimension corresponding to a dimension of the thin portion of the product. The slide block is movable between a retracted position where the volume of the cavity is substantially maintained and an advanced position to project into the cavity to form the thin portion. A drive is provided for moving the slide block to the advanced position before the resin material injected into the cavity is solidified.

Abstract: Molded bodies of thermoset material are produced from monomers, oligomers or higher pre-polymers of reactive resins by pressure reaction injection molding. The molded bodies may contain filler and/or reinforcing material. The process is carried out in a mold consisting of a first, preferably upper half mold and a second, preferably lower half mold, and an inlet socket opening downwardly into the first half mold. The mold is equipped with heating coils adapted for applying separately a lower temperature to the first half mold and a higher temperature to the second one. During the introduction and hardening phase of the reactive mixture, the first half mold is maintained at a lower temperature than the second half mold, the temperature difference amounts to about 40 to 180, and preferably 60 to 120 centigrades.

Abstract: A molding apparatus and method for producing a thermoplastic lens having a minimum of stress including a male mold and a female mold defining therebetween a molding space, one of the molds being mounted for movement towards and away from the other mold, and a gate mounted adjacent to the other mold for the passage of thermoplastic resin. The other mold defines a window width for admitting thermoplastic resin to the molding space. A compression pressure applying member such as a wedge-shaped slide member is further provided for moving the other mold toward and away from the one mold so as to compress thermoplastic resin within the molding space as well as to automatically withdraw the other mold from the one mold prior to the injection of thermoplastic resin.

Abstract: In an injection molding machine which injects molten metal into a metal mold cavity by an injection step and a succeeding pressure holding step, the injection step is controlled by the steps of filling the molten resin into the metal mold cavity at a high speed during the filling step; switching the injection operation from the filling step to the pressure holding step; concurrently operating braking means for applying a braking force to the plunger of the injection molding machine for stopping the plunger; and locking the braking means for continuously applying a constant force to the plunger until a gate seal of the metal mold cavity is completed.

Abstract: Method and apparatus for molding a plurality of lenses of thermoplastic resin of different optical power and/or mass that comprises a plurality of molding stations, each including a rigidly supported male mold and a female mold allowed to float freely within defined limits. At each molding station, a wedge-shaped slide member whose position is controlled by a hydraulic piston is movable an independent distance over the female mold between a home position allowing maximum free floating and an operative position independent for each slide member to transfer a compression force onto an injected body of molten resin at said station. The hydraulic pistons are actuated from a common manifold to allow equal compression pressure at each molding station after the slide members move their independent distances.

Abstract: An injection molding apparatus including a barrel for holding molten plastic material, a first passage connected at one end with the barrel for receiving hot plastic material from the barrel, a second passage connected with the other end of the first passage for receiving molten material from the first passage for supplying the material to a mold, a cylinder, a third passage connected at one end with the cylinder and connected at its other end with the second passage, a piston in the cylinder, movable by pressure means in one direction to maintain pressure on molten material in the cylinder, the third passage and the second passage, and movable by pressure means in the other direction to exert a suction action in the cylinder, the third passage and the second passage for drawing molten material in the second passage back into the third passage and the cylinder, and a valve means.

Abstract: A metal mold to be used for injection-molding of a flat plastic disc. The flat, annular mold cavity has a substantially continuously increasing axial thickness away from the injection gate. The gate can be in the center or on the outer periphery of the mold. A split mold type is disclosed wherein at least one of the inner opposed surfaces tapers away from an imaginary flat center plane. Alternatively, a stamper having a tapering thickness can be used in a mold having parallel opposed inner surfaces.

Abstract: A plastification and injection device for an injection molding machine includes a plunger rod on the pressurized piston coupled to a spindle on which the valve body of a directional control valve is guided axially. The spindle is axially rotatable and is coupled to a stepping motor controlled in accordance with the injection pressure and/or the injection rate. The shaft of a hydromotor driving the plastification and injection screw is guided by means of another directional control valve, the valve body of which is guided so as to slide axially on the shaft. And, this shaft is further coupled to another stepping motor. This, upon completion of the plastification process, the direction of rotation of the hydromotor is reversed in order to close the backflow and, because of the interaction of the other stepping motor and the other directional control valve, the screw moves axially by a predetermined amount to close the backflow.

Abstract: A device suitable for molding ophthalmic lenses comprises two spaced mold parts in face-to-face relationship inside a cylindrical sleeve. One or both parts comprise a rigid supporting base, a molding die of an elastically deformable material and an intermediate pad of an incompressible elastic material disposed between the base and the die and completely covering their respective surfaces.

Abstract: As in the conventional manner for molding an optical component, a molding cavity is used in combination with a relief chamber with which the molding cavity can selectively communicate. There is no communication between the relief chamber and the molding cavity while the latter is filled. The molding cavity is then placed in communication with the relief chamber. Subsequently, relative displacement of the relief chamber and the molding cavity parallel to the axis of the combination interrupts such communication. The optical component thus molded may be of any kind, such as an optical lens, specifically an ophthalmic lens.

Abstract: A pressure generating device for use in injection moulding at a high pressure or normal pressure where the pressure generating device is attached to the mould, the platens, the tie bars or other suitable parts of the injection moulding machine which device operates separately from the normal pressure generating mechanism and acts on the content of the mould cavity only, said device comprising a pressure generating part, e.g. a hydraulic cylinder (1) connected with a plunger (2) which can bring the pressure inside the cavity to the desired level during an injection cycle and a non-return flow valve (3) or any other element closing the mold cavity from the injection side, and the use of said device in injection moulding at high pressure or normal pressure.

Abstract: An apparatus and method for molding polycarbonate lenses is disclosed in which the lenses are formed in a single injection molding operation. Polycarbonate is injected into a cavity between two movable dies which are forced apart by the injected polycarbonate. These dies are then urged together forcing a portion of the injected polycarbonate back through the same port through which the polycarbonate was injected. The finished lens does not have the knit line normally associated with injection molded lenses.