Rail Screw Dowel
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What is rail screw dowl?
Rail screw dowel, also known as rail plastic sleeve, concrete sleeper insert, is a counter-party fastener for a sleeper screw or anchor bolt. It is pre-imbedded into the concrete or wooden sleeper tie. Jointed with screw spikes, guide plates and rail clips, the plastic screw dowel can fasten the steel rail.
Pre-inserted railway dowel is a kind of embedded plastic railway fastener. It is mainly installed and fixed in pre-made products (such as concrete sleepers, bridges, buildings, etc.). After the dowels are being tied with the pre-made products, it is then ulitized by bolts or screws for fixing and fastening with other objects.
Railway dowel material: nylon fiberglass (PA66+GF), plastic (HDPE), cast iron, etc.
The production process is: injection molding by injection molding machine, which is the same as the railway insulator. Cast iron parts are produced by ductile casting iron.
Below are two kinds of materials that used for manufacturing rail screw dowels: HDPE and PA66 Nylon with glass fiber.
PA66 material rail screw dowel (Nylon 66.69%, glass fiber 30%, other)
HDEP material rail screw dowel
Railway Dowel Features
Features: Made of high-quality nylon 66 and blended and granulated with modifiers. It has good mechanical strength, heat resistance, wear resistance, high rigidity and pull-out resistance. Purpose: Rail fastenings for railways.
Railway Dowel Functions
The nylon rail screw dowel is plastic fastener pre-inserted in rail sleepers, with good mechanical strength, heat resistance, wear resistance and high rigidity. It has the advantages of simple and convenient installation and long service life. It can improve the durability, insulation, environmental protection level and comprehensive technical and economic indicators of sleepers, and meet the requirements of rapid railway development.
Railway Dowel Material and Adaption
The nylon rail screw dowel is made of glass fiber reinforced nylon composite material through injection molding process, and has threads both inside and outside.
A: The internal thread matching the rail screw spike is a serrated single bevel thread. The bevel of the thread is a large bevel, which puts the plastic dowel in the best stress state, thus greatly extending the service life;
B: The external thread embedded in the concrete sleeper is a thread groove with the same pitch as the internal thread. According to different construction conditions, full thread or half thread can be selected. At the same time, a transverse boss is added to the upper and lower ends of the casing. There are insertion holes in the boss, which facilitates the insertion of steel bars during pre-embedding and improves the pull-out resistance of the dowel from the sleepers.
It can be widely used in concrete-related engineering projects, such as railways, highways, bridges, houses, etc. It is especially suitable for use on railway sleepers. Pre-embedded in concrete turnout sleepers can increase the speed of trains and increase the speed of turnouts.
Railway Dowel Installation and Technical Requirements
When transporting, loading, unloading, and stacking sleepers, the bolts should be screwed into the rail screw dowel. Or use the plastic plug to seal the dowel opening, in order to prevent debris from falling into the dowel.
Before assembling the fasteners, the surface of the concrete turnout should be cleaned. The dowel should be clean and free of debris, the bottom of the dowel should not be blocked by debris or mud, and grease should be applied inside the dowel to prevent the bolts from rusting.
When assembling fasteners, the inappropriate accessories must be polished and repaired. Hitting hard with a hammer which lead to damages to the fasteners and dowel is not allowed.
When assembling fasteners, the bolt torque should be controlled at 250~300N·m.
When assembling fasteners, do not use force rods and other tools to assemble, otherwise the acceleration force will exceed the maximum bearing capacity of the nylon rail screw dowel and damage the dowel. A torque wrench must be used for assembly.