Nissei Plastic Industrial Co., Ltd.

Sony Corporation

Chiba Institute of Technology

Kazutoshi Takayama

Kiyoto Takizawa

Toshiyasu Koda

Yasuhiko Takeuchi

Yuji Hayashi

Mamoru Miyagawa

Kazuki Miyairi

Nobuyuki Arakawa

Yoshitoshi Yamagiwa

Minoru Yamazaki

Makoto Nakazawa

Takahiro Kobayashi

Takashi Segawa

Tetsuichi Motegi

Shuji Aiba

Moriyoshi Kaneko

Toshiyuki Kanai

The present invention provides a pressure casting method of a magnesium alloy. In the method, a molten magnesium alloy is cooled to form a partially molten state containing a solid-phase, and the partially molten state is further cooled to form a solid-phase granularly crystallized solid material. The solid material is partially-melted and pressure cast into a mold by a molding machine. A ratio of primary crystals in said solid material is set to 55 to 65%. The solid material is partially-melted in a solid-phase and liquid-phase coexisting state at a selected heating temperature so that a semi-solid having thixotropic properties and having the size of a main solid phase of 50 to 250 &#x3bc;m and a solid-phase ratio of 30 to 70% is formed. The semi-solid is pressure cast into a mold through a nozzle while maintaining the semi-solid state to form metal products having a ratio of primary crystals of 20 to 50%.

Pressure casting method of magnesium alloy and metal products thereof

An injection molding apparatus of a metal material places a heating cylinder in an inclined position. The heating cylinder includes a nozzle at a tip thereof and a screw disposed inside. In this way, the metal material in a liquid phase state can be transferred and metered accurately in a reliable manner at all times by flowing due to the inclination and a transfer force produced by rotation of the screw. A clamping apparatus is provided to oppose the injection apparatus and includes a mold having a sprue bush inside. The injection apparatus and the clamping apparatus are placed on an apparatus platform in an inclined position at the same angle with the mold in a lower end, so that the metal material in the liquid phase state in the heating cylinder flows down toward the head due to self-weight. The nozzle and sprue bush are positioned on the same straight line, thereby maintaining nozzle touch without bending the nozzle.

Method and apparatus for injection molding metal material

A method of metering a metal material in a liquid phase in molding injection provides accurate and reliable transfer of the metal material. A heating cylinder housing a rotatable and axially movable screw, is inclined with its head pointing downward, so that the metal material in the liquid phase state flows down into a front chamber due to self-weight. At the forward position after injection, the screw is forced to retract to a set position, whereby a predetermined quantity of a liquid phase material primarily stored on the periphery of the head portion of the screw is accumulated by suction due to a negative pressure in the front chamber of the heating cylinder. Further, a constant quantity of the liquid phase material can be metered each time in the front chamber by stopping and then rotating the screw at a retraction position.

Metering method of metal material in injection molding

There is provided an injection apparatus comprised of a heating cylinder which is closed by a front end member having a nozzle. The apparatus is further comprised of a plasticating screw in the heating cylinder in a freely rotating and reciprocating manner, and a plunger connected to the front end of the screw. The plunger has a conical front end in which flow channels are formed. The front end member has a measuring chamber formed therein at an internal central location thereof. The measuring chamber has a predetermined length and an internal diameter which is reduced by 8 to 15% with respect to an internal diameter of the heating cylinder. The diameter of the injection plunger is set almost equal to the diameter of the measuring chamber, whereby the injection plunger is inserted into the measuring chamber in a freely reciprocating manner. A gap is formed on the external peripheral surface of the plunger due to the difference between the heating cylinder internal diameter and the plunger diameter, and the gap functions as a plastication-accelerating block. The block is formed so as to have a distance longer than an injection stroke, whereby uniform plastication is achieved and uneven temperature in the material is eliminated. Further, the plunger advance blocks the gap, which leads to uniform density and precise measurement of the material.

Injection apparatus

An injection molding process wherein the times of heating to melt a resin are reduced to minimize the thermal hysteresis and to decrease the deterioration of physical properties caused by the thermal hysteresis, so that high quality information recording disks may be produced. A molding process wherein the plasticating and the injection and filling of a material resin are carried out in separate cylinders, allows constant molding for a long period of time. A material resin such as polycarbonate is supplied without predrying to an injection apparatus for a first time molding. Resin is kneaded by the apparatus while volatile components are heated to be vaporized and exhausted through a vent port. An inert gas atmosphere is provided within the cylinder to prevent the material resin from being oxidized. Since predrying can be dispensed with, the thermal hysteresis will be extremely small and the deterioration of the resin caused by such heating may be suppressed. Also, there is less chance of generation of carbonized black spots caused by foreign matter, molding failures caused by hydrolysis may be eliminated, and residual monomers can be vaporized and exhausted concomitantly.

Process for injection molding information recording disks

To avoid generation of air bubbles and silver which otherwise may be caused due to forced retraction of a dwelling plunger after a dwelling cycle is completed. A dwelling cycle is performed at the same time of metering by using an injection machine 1 and a dwelling machine 2. The injection machine 1 comprises an injection screw 11 mounted in a heating cylinder 12. The dwelling machine 2 comprises a dwelling plunger 21 slidably mounted therein and faced to a resin passage 14. An advancing motion of the dwelling plunger 14 is limited to the side surface of the resin passage while a backward movement of the dwelling plunger is limited to a position at which a desired volume of a resin trap 26 is formed for the resin to be packed in the passage between the head of the plunger and the resin passage 14. The dwelling plunger 21 is allowed to be in a free state during an injection cycle or the metering. The dwelling plunger 21 is retracted by means of a pressure of the resin to be injected or a pressure of a metered resin to from the resin trap 26. The resin in the resin trap 26 is forced into the resin passage 14 as the dwelling plunger 21 moves forward when the injection cycle is completed and the valve 16 is closed to block the resin passage 14. This provides the dwelling.

Apparatus for dwelling in injection molding

An injection apparatus capable of carrying out injection and filling of a resin and injection of a gas making use of an injection screw or injection plunger for the injection of a high-pressure gas comprises an injection screw 5 having a conical injection head 3 at the front end thereof and a ring valve 4 around a rear portion of the injection head, an injection cylinder the interior of a front end portion of which equipped with a nozzle member is formed as a tapered surface in accordance with the injection head 3 and can be closed by its contact with the injection head 3 and which contains the injection screw 5, gas flow passages 12 and 8 provided from the front end of the injection head 3 to a rear end portion of the injection screw 5, an opening/closing pin 17 inserted into the gas flow passage 12 in the injection head in such a manner that it can move together with a piston at the rear end of the injection head, and an actuation gas flow passage 10, provided inside the gas flow passage 8, for applying pressure to the piston 16 so as to close the gas flow passage 12 with the opening/closing pin 17.

Injection apparatus for molding synthetic resin hollow or foamed body

A die assembly for molding a disc such as a compact disc, a video disc or the like by employing an injection molding process. The die assembly comprises a stationary die half including as essential components a stationary platen, a base die half, and an insert die half received on the stationary platen, and a movable die half. The insert die half includes a first insert for fixing the insert die half on the stationary platen, and a first mirror surface board removably received in a cavity of the first insert. The insert die half can be easily installed and removed into/from an installation space defined by a pair of retaining members and a die receiving member and when installed, it can be certainly and easily fixed by a pair of retaining members.

Injection molding apparatus for molding a disc having a replaceable die

A disk substrate molding die is provided in which the quantity of eccentricity of a stamper can be reduced to a small value. The molding die includes a member having mounted thereon a thin plate (19) carrying thereon a recorded transfer signal and an adjusting device consisting of a plurality of pairs of adjusting blocks, each formed of movable blocks (9a) and (9b) and blocks (10a) and (10b) having adjacent surfaces inclined in the moving direction of the movable blocks and common to one another.

Growing community of inventors

Nagano-ken, Japan

Kazutoshi Takayama