Injection molding plastic parts includes furnishing resin material to a screw barrel having a rotatable screw therewithin, rotating the screw to work the resin material into a molten state, furnishing additive such as liquid color or another additive to the screw barrel interior at a first rate during screw rotation and driving the screw longitudinally from a first position to a second position to force an additive-resin material mixture resulting from screw rotation into a mold while furnishing additive with resin to the screw barrel interior at a second additive addition rate.

A method of injection molding a building product includes providing an injection mold with a plurality of gates located adjacent a perimeter of the injection mold. The method further includes commingling a first material and a second material into a flow, the second material comprising a color that contrasts with a color of the first material and injecting the commingled flow into the plurality of gates to form a building product. Thereafter, the method includes removing the building product from the injection mold. The second material extends through an interior of the building product and appears as contrasting streaks on an exterior of the building product to form a variegated grain appearance. The method also includes notching a portion of the building product, such that the building product has a substantially linear grain in an exposed portion thereof.

A method of injection molding a building product includes providing an injection mold with a plurality of gates located adjacent a perimeter of the injection mold. The method further includes commingling a first material and a second material into a flow, the second material comprising a color that contrasts with a color of the first material and injecting the commingled flow into the plurality of gates to form a building product. Thereafter, the method includes removing the building product from the injection mold. The second material extends through an interior of the building product and appears as contrasting streaks on an exterior of the building product to form a variegated grain appearance. The method also includes notching a portion of the building product, such that the building product has a substantially linear grain in an exposed portion thereof.

In order to be capable of reliably supplying a prescribed amount of fiber materials into a heating cylinder for each cycle and continuously manufacturing a homogeneous composite material, a plasticizing unit is provided with a fiber supply device 3 that supplies prescribed amount of fiber materials A2 having a prescribed length into the heating cylinder 1. The fiber supply device 3 is provided with: a cutting section 12 that cuts off a long fiber material A1 pulled out from a reel 11 into a prescribed length; a pressure-feeding section 13 that presses the fiber materials A2 having the prescribed length cut off by the cutting section 12 into the heating cylinder 1; and a fiber transfer device 45 that forcibly transfers the fiber materials A2 accumulated in the cutting section 12 to the pressure-feeding section 13. The pressure-feeding section 13 is constituted by a press cylinder 41 and a press piston 42, and the fiber transfer device 45 is constituted by a vacuum device.

The interior of a heating cylinder (2) is divided into a first stage (5) and a second stage (7) due to the shape of a screw (3). A first compression zone in which a resin is compressed is formed in the first stage (5). A starvation zone (7a) in which an inert gas is injected and a second compression zone in which the resin is compressed are formed in the second stage (7). A barrier flight (13) that is obtained by combining a main flight (14) and a sub-flight (15) having a greater lead angle than the main flight is provided to a section of the screw (3), said section corresponding to the first compression zone. A multiple flight is provided to another section of the screw (3), said section corresponding to the second stage (7).

Provided are a two-color molding method, and a two-color molded article capable of suppressing deterioration of the appearance quality which is caused by resin shrinkage or resin deformation in the two-color molding. The two-color molding method includes: molding a first resin portion by a common die and a primary die; and molding a second resin portion integrally with the first resin portion by the common die and a secondary die. An abutting portion is molded on an edge of the first resin portion to protrude toward the secondary die when the first resin portion is molded, and a distal end surface of the abutting portion is maintained to be abutted on a cavity surface or a parting surface of the secondary die when the second resin portion is molded. The deformation of the abutting portion or the first resin portion is suppressed to suitably mold the second resin portion.

An injection molded product may include a corner shingle resembling a single course of tiles that differ in size. The corner shingle may be a semi-crystalline thermoplastic and having a wood grain direction. Streaks may be formed in the corner shingle that are substantially parallel to the wood grain direction. The streaks may extend through an interior of the corner shingle and appear as contrasting streaks on an exterior of the corner shingle to form a variegated wood grain appearance. In addition, an injection molded vestige may be formed in the corner shingle. The injection molded vestige may be located adjacent a perimeter of the corner shingle, and may comprise the location at which material entered an injection mold through a gate.

After the injection shaft moves backward and the gas is supplied into the injection chamber, it is desired to accurately control the gas supply amount in the injection device in which the injection shaft is moved forward to compress and dissolve the gas in the molding material in the injection chamber. An injection device of the disclosure supplies a gas into an injection chamber via a gas supply hole which passes through an injection shaft and is opened at a tip surface of the injection shaft. The injection device and a gas dissolution method thereof according to the disclosure perform backward and forward movement of the injection shaft for a plurality of cycles. The injection device of the disclosure has at least one seal ring and at least one piston ring aligned in an axial direction on an outer circumferential surface of the injection shaft.

An injection molding system, to produce fiber-reinforced plastics material parts, has an injection molding device with a housing and a housing bore formed therein. A screw shaft, which is rotatably drivable about a rotational axis and can be displaced along the rotational axis, is arranged in the housing bore to melt and introduce plastics material into a mold. For feeding fibers, the injection molding system furthermore has a feed device, which is configured in such a way that cut fibers can be fed through a feed opening directly into the housing bore. The injection molding system according to the invention allows simple and flexible production of fiber-reinforced plastics material parts.

After the injection shaft moves backward and the gas is supplied into the injection chamber, it is desired to accurately control the gas supply amount in the injection device in which the injection shaft is moved forward to compress and dissolve the gas in the molding material in the injection chamber. An injection device of the disclosure supplies a gas into an injection chamber via a gas supply hole which passes through an injection shaft and is opened at a tip surface of the injection shaft. The injection device of the disclosure has at least one seal ring and at least one piston ring aligned in an axial direction on an outer circumferential surface of the injection shaft.