Application of mold heating tube

The mold hole heating process is one of the common and long-standing molding methods for plastic materials, and it is also a process method often used to study material properties. It has the characteristics of simple molding device, small equipment investment, and simple mold structure. In today's highly developed mechanized and automated production, it is still one of the most popular production methods. However, what are the key skills in the design of mold hole heating tubes?

The heating, insulation, cooling and clamping structure of the mold are the most important part of the composite material mold design. The structural design directly affects the appearance and internal quality uniformity of the product, and also affects the molding efficiency of the product.
1. Design requirements for heating tubes

Stainless steel heating tubes are heating methods that must be used in almost all plastic molding mold designs. They can be designed in various forms such as one-way wiring and two-way wiring. The material can be seamed tubes and seamless tubes. The characteristics are small heat loss, high thermal efficiency, and simple wiring. It can be designed as 220V or 380V according to needs, and the wiring is flexible and diverse. However, due to the limitations of its materials and processing technology, its characteristics should be paid attention to in mold design.
(l) The heating tube usually has a long cold end at both ends, which cannot play a heating role.
(2) The power design of the heating section should not exceed the limit of 10 watts/cm. For example, for a 20 cm long heating tube, the power should not exceed 200 watts as much as possible. If the design power exceeds this limit, the surface load of the heating tube is high, and the steel tube is prone to oxidation and corrosion, causing a short circuit. Yancheng Feiyu uses imported imitations, and the power can be slightly larger than that of ordinary heating tubes.
(3) For mold designs with temperatures above 250℃, it is difficult to use heating tubes. I have used electric heating tubes to heat up to 420℃, but this molding temperature has high requirements for the quality of the heating tube, and it is necessary to frequently check whether the circuit is smooth and short-circuited. Because under this condition, the heating tube, terminal block, copper wire used for connection and other media are very easy to oxidize, resulting in a short circuit. Therefore, special treatment is required for the electrical transmission medium to avoid exposing the conductive wire to the air as much as possible to extend the service life of the wire.
In the design, * insurance, air switch and other insurance measures should be taken, and the operation site should be kept clean and tidy, well insulated, and electrical faults should be checked frequently during operation to prevent unnecessary dangers.
2. Installation and drilling of heating tubes
From the perspective of heat transfer, the installation of the heating tube should fit the mold surface as closely as possible to facilitate the heat of the heating tube to be transferred to the mold as soon as possible. For example, if the diameter of the mold hole is 18mm, it is more appropriate to set the diameter of the heating tube to 17.8mm. In fact, the heating tube and the mold do not have much contact area. The essence of heat transfer is radiation, and conduction is secondary.