A.k. Technical Laboratory, Inc.

Hideaki Koda

Hisashi Nakajima

Motohiro Matsuzawa

Sentaro Kobayashi

Yukio Yanagimachi

Hisao Yamaguchi

Osamu Sakai

Makoto Yoshizawa

Improvement of simplicity and durability of a stretch rod extending device and a bottom mold lifting device, equipped on a stretch blow molding machine, is achieved by applying a combination of a magnetic screw shaft and a magnetic nut member, which is able to convert rotary-linear movement smoothly without contact. The nut member and the screw shaft of the extending deviceand lifting devicecomprise a magnetic nut memberand a magnetic screw shaft, having spiral N magnetic pole and S magnetic pole alternately provided on inner peripheral surface of a cylindrical member and outer peripheral surface of a shaft at a same regular pitch. The magnetic screw shaft is inserted into the plunger, having the magnetic nut member equipped inside with keeping required clearance so as to match the magnetic pole to oppose the magnetic nut member at the same poles each other.

Stretch rod extending device and bottom mold lifting device for stretch blow molding machine

The mold opening speed is increase by upward moving a movable plate of a vertical clamping device for an injection blow molding machine by hydraulic cylinders at the both sides instead of a booster ram. The following are used: a lower base plate with an injection cavity mold set on its upper surface, a cylinder block for clamping connected to upper ends of tie bars vertically disposed at both sides of the lower base plate, an upper base plate vertically movably set above the lower base plate guided by the tie bars to rotatably hold a turntable of a neck mold below the upper base plate, a movable plate vertically movably set on the upper base plate guided by the tie bars and connected with a clamping ram at the center of the upper surface, and an injection core inserted into a cavity of an injection cavity mold through the upper base plate, turntable, and neck mold and attached to the under face of the movable plate. An upper base plate vertically moving cylinder and a movable plate upward moving cylinder are set to both ends of the lower base plate and movable plate so as to be vertically faced each other and both piston rods are longitudinally connected to the upper base plate.

Clamping device for injection blow or injection stretch blow molding machine

A required preform is molded by rapidly cooling molten resin which has been injected and filled into an injection mold. The preform is held by its neck portion with a neck mold and is mold-released in a high temperature state. A bottle having a thin body portion is molded by stretch blowing laterally and longitudinally within a blow mold. Among the thickness and length of a stretched portion of the preform which are set according to the volume and weight and body portion thickness of the bottle , the thickness is set to be thinner than the usually set thickness. The length is set to be long inversely proportional to the thickness setting. The preform is mold-released at a higher temperature than usual and is stretch-blow molded before its outer surface temperature reaches its peak. By reducing the thickness of the stretched portion of the preform and, on the contrary, increasing the length thereof, it is possible to stretch blow mold a hollow molded product with a usual geometry in which the body portion thickness is below 0.2 mm, even in a hot parison method which carries out mold-release at high temperature.

Injection stretch blow molding method

When a desired preform is to be molded from a molding material which is a polyester resin composed of a blend of PET and PEN by compressing and melting the molding material by the rotation of a screw in a heating cylinder and injecting and filling the molten material into a mold, a plastication zone,for the molding material is formed between a compression zone,of the injection screw,and a metering zone,at an end of the screw. In the plastication zone,the molding material is subjected to melting, relaxation, kneading and relaxation steps in order to melt and remove an unmolten material until the molten material reaches the metering zone,To prevent a molded article from becoming opaque and the production of a gel-like unmolten granular material when a polyester resin composed of a blend of PET and PEN is used as a molding material.

Injection screw for injection molding a preform of a polyester resin

A wide mouthed container of synthetic resins for a paint, wax and the like, formed thinly in the body portion thereof by injection stretch blow molding is provided. A mouth portion of the wide mouthed container is of large diameter and comprises an internal wall integral with a body portion having a bottom, a belt shaped external wall integrally formed on the outside of the internal wall via a joint portion of required width to be in H-shape, and an upper and lower annular grooves between both the walls sectioned by the joint portion. The body portion is stretch blow molded thinly from the underside of the internal wall to a position where the lower edge of the external wall touches the body portion to form the side surface of the body portion on the same level as said external wall and to form the lower annular groove into a hollow in the lower part of the mouth portion. A plurality of ribs for preventing the deformation of the joint portion in stretching the body portion are integrally formed aslope onto a corner between the under surface of said joint portion at its external wall side and the inner surface of the external wall to provide a required number of the ribs in the lower annular groove at a regular interval.

Injection stretch blow molded wide mouthed container for a paint container and the like

When a desired preform is to be molded from a molding material which is a polyester resin composed of a blend of PET and PEN by compressing and melting the molding material by the rotation of a screw in a heating cylinder and injecting and filling the molten material into a mold, a plastication zone 13 for the molding material is formed between a compression zone 12 of the injection screw 2 and a metering zone 14 at an end of the screw. In the plastication zone 13, the molding material is subjected to melting, relaxation, kneading and relaxation steps in order to melt and remove an unmolten material until the molten material reaches the metering zone 14. To prevent a molded article from becoming opaque and the production of a gel-like unmolten granular material when a polyester resin composed of a blend of PET and PEN is used as a molding material.

Process for injection molding a preform of a polyester resin

Method of molding inner thread on neck portion of preform

In a vent arrangement comprising a heating cylinder 1 containing therein a screw and provided with a vent hole 3 and a reduced pressure exhaust path 4 provided with a vacuum pump and connected to the vent hole 3 for draining volatile fractions of a material to be molded from the heating cylinder by reducing the pressure in the vent hole by means of the vacuum pump, said volatile fractions are removed by arranging in the exhaust path a filter unit 7 filled with a granular filtering material 8. The material to be molded is used for the filtering material 8. According to the above construction, it can be achieved to efficiently remove volatile matters by using the molded material as the filtering material of the filter unit arranged in the reduced pressure exhaust path of a vent arrangement.

Method of removing volatile matters from vent arrangement

There is provided a method of molding a large container including the steps of preparing a preform from an injection-molded, thick-wall, closed-end parison by repeatedly and intermittently applying an air blow pressure to the parison and releasing the air blow pressure therefrom, and stretch blow molding the preform to a thin-wall large container. The closed-end parison is released from a mold immediately after a skin layer, keeping a parison shape, is formed on the surface of the closed-end parison having a high inner temperature, and is then molded to a preform with a preform mold heated to a predetermined temperature, while the surface temperature of the parison is increased by the inner temperature. The preform is kept at a stretch blow molding temperature and is stretch blow molded into a blow mold to produce a large container.

Method of molding large containers by the process of stretch blow molding

A method of molding a preform in an injection stretch blow molding, wherein a gas is entered into the boundary between the preform and an injection core so that the gas pressure causes the preform in an injection mold to be insulated from the injection core, thereby allowing a high-temperature releasing of the preform.

Method of molding preform in injection stretch blow molding

A composite molding device is provided at the same site for preforming a closed-end parison or controlling the temperature of the closed-end parison as well as stretch blow molding the preform or temperature-controlled parison to a final product, such as a bottle. The composite molding device applied for stretch blow molding includes a clamping device, a pair of first mold halves, and a pair of second mold halves. The pair of second mold halves are removably placed between the pair of first mold halves in the clamping device so as to use the clamping device as a common clamping device.

Composite molding device for stretch blow molding

A method enabling stretch blow molding in a temperature range preferable for polyethylene and capable of releasing at a surface temperature suited to both releasing of a preform and subsequent stretch blow molding, by disconnecting the core die and the preform in advance by the use of pressure of gas. The injection molding of a predetermined preform involves filling an injection mold with molten polyethylene, releasing the preform from the cavity die and core die of the injection mold while a mouth portion of the preform is held by the lip die, and transferring the preform into a blow die to stretch blow mold into a hollow molded thin wall product. Gas forcibly enters into the boundary of the core die and the preform, before releasing the preform from the injection mold to isolate the inside wall of the preform from the core die. Releasing is effected while the inside of the preform is not completely cooled and is still at high temperature, and in a temperature range in which the surface temperature of the preform right after releasing is 80 to 90 deg. C. The step of stretch blow molding is performed within the time interval before the surface temperature of the preform which is elevated by the internal heat of the preform reaches 120 deg. C.

Method for injection stretch blow molding of polyethylene

A method for injection molding polyethylene terephthalate by employing a vent type injection unit as means for omitting preliminary drying the resin, wherein the unit does not develop a poor screw biting, and even when the molding material is an undried uncrystallized or crystallized PET, can feed a certain amount of the material at all times to injection mold a desired transparent molded form such as a preform, and use the preform to produce a thin-wall container at a low cost.

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Ueda, Japan

Hideaki Koda