1. What is a hot runner?
One of the main functions of the hot runner is to keep the plastic melt in the hot runner at the correct processing temperature throughout the injection cycle, holding and cooling of the molding cycle. Thereby achieving no cold water outlet, reducing secondary processing, shortening the injection cycle, improving product consistency, achieving mass production and reducing production costs. This is followed by a relatively gentle transport of the plastic melt to minimize the pressure and shear stress applied to it. Thereby, the stress in the production, the injection pressure and the deformation of the product can be reduced, and the machining ability can be improved. The above advantages can be fully automated, improve user productivity, production profit and competitiveness.
Second, hot sputum, hot runner mold precautions
Appropriate hot nozzles should be selected according to the size of the rubber parts and different rubber compounds. Suppliers generally give the maximum amount of shots for each hot nozzle relative to a different flow compound. Because of the different materials, their fluidity is different. In addition, attention should be paid to the size of the nozzle opening of the hot nozzle, which not only affects the amount of shot, but also has other effects. If the nozzle opening is too small, the molding cycle will be extended; if the nozzle opening is too large, the nozzle opening is not easy to be closed, and it is easy to flow or draw.
2. Temperature control
The temperature of the hot nozzle and the hot runner plate is directly related to whether the mold can operate normally, and the temperature is generally controlled separately. Regardless of the internal heating or external heating method, the temperature in the hot nozzle and the hot runner plate should be kept uniform to prevent local overcooling and overheating. In addition, the power of the heater should be such that the hot nozzle and the hot runner plate can be raised from the normal temperature to the required working temperature within 0.5 to 1 h, and the heating time of the hot nozzle can be shorter.
3. Thermal insulation
The hot runner and the hot runner plate should have better insulation with other parts such as the mold panel and the A plate. The heat insulating medium can be used as a asbestos board or air. Except for the parts that need to be contacted, such as positioning, support, and sealing, the thickness of the insulating air gap of the hot nozzle is usually about 3 mm; the thickness of the insulating air gap of the hot runner board is not less than 8 mm.
The support between the hot runner plate and the mold panel and the A plate is a heat insulating block having a heat insulating property, and the heat insulating block is made of a material having a low heat transfer rate. The panels of the hot runners and hot runner molds should generally be covered with 6~10mm asbestos sheets or bakelite as insulation. The thickness of the insulation mat is generally 10 mm. In the above figure, in order to ensure good thermal insulation effect, the following requirements should be met: D1 â‰¥ 3mm; D2 is determined by the size of the hot sluice step; D3 â‰¥ 8mm, depending on the thickness of the central insulation block; D4 â‰¥ 8mm .
4. Insulation pad
The thermal insulation block between the hot runner plate and other parts of the mold not only acts as a heat insulator, but also supports the hot runner plate, the support point should be as small as possible, and the force is balanced to prevent deformation of the hot runner plate. For this reason, the insulation block should minimize the contact area with other parts of the mold.
In order to prevent the rotation and overall offset of the hot runner plate and satisfy the thermal expansion of the hot runner plate, the hot runner plate is usually positioned by a combination of center positioning and groove positioning.
6. Thermal expansion
Since the hot runner and the hot runner plate are thermally expanded, the mold should be designed with a budget expansion amount, and the design size should be corrected so that the expanded hot nozzle and hot runner meet the design requirements. In addition, a certain gap should be reserved in the mold, and there should be no structure that restricts expansion. The hot boring nozzle mainly considers the axial thermal expansion amount, and the radial thermal expansion amount is corrected by the gap of the fitting portion; the hot runner plate mainly considers the length and width directions, and the thickness direction is adjusted by the gap between the heat insulating block and the stencil.
Heavy-Duty Powder-actuated Fastening Tool is designed for hard base concrete which is between C40 and C55.
A powder- Actuated Tool (often generically called a Hilti gun or a Ramset gun after their manufacturing companies) is a type of nail gun used in construction and manufacturing to join materials to hard substrates such as steel and concrete. Known as Direct Fastening , this technology relies on a controlled explosion created by a small chemical propellant charge, similar to the process that discharges a firearm.
Powder-actuated tools come in high-velocity and low-velocity types. In high-velocity tools, the propellant charge acts directly on the fastener in a process similar to a firearm. Low-velocity tools introduce a piston into the chamber. The propellant acts on the piston, which then drives the fastener into the substrate. (The piston is analogous to the bolt of a captive bolt pistol.) A tool is considered low velocity if the average test velocity of the fastener is not in excess of 100 m/s (330 ft/s) with no single test having a velocity of over 108 m/s (350 ft/s). High-velocity tools may not be made or sold in the United States ; however, some made decades ago are still in use in the shipbuilding and steel industries. The main manufacturers of Powder Actuated Tools are Ramset, Hilti, Powers/DeWalt, Tomarco and Simpson Strong Tie.
Powder-actuated Fasteners are made of special heat-treated steel. Common nails are not used for powder-actuated fastenings. There are many specialized fasteners designed for specific applications in the construction and manufacturing industries.
Powder-actuated technology was developed for commercial use during the Second World War, when high-velocity fastening systems were used to temporarily repair damage to ships. In the case of hull breaches, these tools fastened steel plates over damaged areas. These tools were developed by Mine Safety Appliances, for the United States Navy. Powder-actuated tools were investigated and used prior to this development; they were used in submarine hunting during the First World War and were the subject of a 1921 United States patent (US Patent No. 1365869)
Heavy-Duty Powder-Actuated Fastening Tool
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Yibin Heheng Technology Co.,Ltd , https://www.chinadirectfastening.com