As practice shows, conventional gate systems in a modern design allow final shaping of the finished product with clear contours. In some cases, special designs are used when the metal undergoes a long and complex transformation. Such units are equipped with a circular collector that improves filling conditions.
Side modifications
The side gate systems are equipped with feeders that are located at right angles to the inlet gate. This type is often used in forms with one or more work sockets .
The feeder, when approaching the working cavity, has a reduced thickness, aggregates with the inlet element, the cross section of which affects the amount of metal passing through the mold cavity. In side-type feeders, the raw material moves along the plane of the connector with the subsequent filling of the lower part of the working chamber. In this case, the ventilation ducts are blocked, which makes it difficult to remove air. In this regard, the side gating systems are most effective in the manufacture of shallow workpieces.
If you move the cavity into the moving part of the unit, the metal coming under pressure will also prevent the removal of air bubbles from the depth. It is worth noting that when casting parts with large central rods located perpendicularly, a number of defects may occur.
Features of the side gate
Placing the side feeder in a tangent line allows you to level the frontal impact and turbulence. The casting has a wide element, which is installed perpendicular to the rod, and also large air connections are present. As a result, there is no air porosity and oncoming jets.
With tangent sprues, ring casting is most efficiently obtained, provided that the width of the part is commensurate with the same indicator of the working element. It is irrational to use a similar mechanism when casting annular blanks with stepped diameters and solid parts. This is due to the fact that when the metal rotates, it swirls, and this negatively affects the filling of the central part, forming spaces in it. To solve the problem, a gate with a wider diameter is used.
The calculation of the gate system requires taking into account the width of the intake manifold and its placement. These factors affect the quality of the casting. It is worth noting that when the gate is located near a wide part of the workpiece, the metal will flow in a wide stream , swirling and filling the ventilation slots prematurely. If the system is mounted on the narrow side of the part, the feed will flow along the walls without significant swirl.
Gating systems of the central type
Central variations are used for casting flat workpieces for which a free central field (frames, rings) is provided. They are also used to produce box and cylindrical parts with an open central cavity.
A similar design feature allows you to mount the running gate in the center of the axis from the front side. In this case, several feeders can be used. Central holes are used in the manufacture of parts with cavities, the bottom of which has a hole. A rod is passed through it, transforming into a divider. This element can pass strictly in the center or with an offset, which makes it possible to place the form in the cavity asymmetrically to the running element.
Among the advantages of central gating systems for injection molding, the following are noted:
- It is possible to fill the working cavity with several feeders without the formation of oncoming jets of metal.
- The design has the same temperature regime of all work surfaces, which ensures the exclusion of surface deformations.
- A significant reduction in the path of the metal without an additional jet from the compression chamber is guaranteed.
- An equal direction of metal intake and air extraction is ensured.
For the correct operation of the unit and the elimination of vortices, the jet should be directed parallel to the center rod and the walls of the mold.
Application of central sprues
The considered devices are used exclusively in forms with one working socket. The casting of thin-walled workpieces requires the installation of several feeders. To work with a thick-walled part and poor streamlining, one element will be enough. It is mounted tangentially with the inlet compartment, which allows for the intake of metal from one side to maximally remove air impurities.
The processing of large box-shaped and case-shaped blanks is carried out using several central-type feeders. This allows you to provide power to all remote areas of the working cavity, as well as to eliminate the occurrence of a continuous stream, causing delamination of raw materials. The total value of the feeders increases, and the advantages of the central injection mold appear if the cross section of the input element is exceeded so as to provide power to the working cavity without interruptions in the jet of liquid metal on each feeder.
Direct feeders
Central feeders without dividers are used for casting structures whose configuration does not allow the installation of side analogues. In this case, the elements of the gate system are mounted directly on the part and also serve as a feeder. It is reasonable to use direct modifications for casting thick-walled compact workpieces that are processed at low speeds by large section feeders.
Filling when working in such conditions does not present special difficulties. The main emphasis is on metal compaction with the resulting pressure. Optimum results in the process are obtained when the load on the raw materials is not removed before the opening period of the working form (extruded type chambers).
Circular manifold models
Such gating systems for steel castings are used when it is impossible to provide one feeder with sufficient filling of all remote parts of the working chamber . The main purpose of the unit is to synchronize the supply of metal to all peripheral compartments, after which the raw material enters the difficult to feed points with the help of several inlet elements .
This design is appropriate in the presence of remote parts from the gate, which do not fit into the standard overall dimensions . In addition, this configuration is suitable for casting lattice blanks, which in the manufacture meet obstacles due to the thin-walled design. This is especially important if rods are installed near the remote compartments. When the lattice ebbs , the meeting of two jets in narrow nests practically does not experience vortex obstacles, in contrast to a similar process in large cavities.
Exploitation
Circular collector casting systems are used for machining small gears with thin walls that have a wide pitch and tribock . Feeders with a small cross section and a thickness of about 0.5 mm are fed to each tooth from the collector.
The use of directional feeders makes it possible to displace air from the metal even in hard-to-reach and poorly ventilated places. They are optimally suited for the smelting of box-shaped and case-shaped workpieces. The design avoids the occurrence of frontal impacts and excessive turbulence.
Press form
This element of foundry is a complex device for producing metal, polymer and rubber products of various shapes. The unit serves for molding a variety of products under pressure from injection molding machines. The mold can be of several types:
- Mechanical type.
- Semi-automatic or automatic.
- Fixed and removable mounting.
- With horizontal and vertical planes of the connector .
The node includes a fixed matrix and an active part. The forming cavities of these parts are designed in the opposite way, which allows to provide the desired imprint of the workpiece. Raw materials are supplied through the sprue system, and the temperature is regulated using water circulating in the cooling circuit.