First, how to enter the chiller In fact, a mold is a heat exchanger, the heat from the molten plastic into the mold, and then from the mold into the circulating cooling medium - ice water, only a small part of the air And injection molding machine press template. As we all know, plastic molding cycle, a considerable part for cooling, and sometimes can account for more than 80% of the plastic molding cycle, so to minimize the cooling time is absolutely necessary. For example, a pair of mold molding cycles typically lasts 20 seconds. For example, if the water in the original cooling tower is cooled by ice water produced by a chiller, it can be shortened to 16 seconds. Although the initial cost of selecting a chiller is higher, it can increase production by 20%, and it can make great profits in long-term production. So, how to choose ice water energy? From the above we can know that it is related to the specific heat capacity of the molding material, the temperature of the glue, the weight, and the temperature of the product when it is demolded.

The formula for the ice water energy needed for a mold is: q=w×c×? t × s Where: q is the required ice water energy kcal / h; w plastic raw material weight kg / h; c plastic raw material specific heat kcal / kg °C; t is the temperature difference between the melt temperature and the product when the product is demolded (see the attached table); s is the safety factor (generally 1.35-2.0), when the single machine is matched, the small value is generally selected, and when a chiller is used When the mold is matched, it takes a large value. If the air-cooled chiller is selected, the s should be properly selected.

For example: A pair of molds to produce pp products, about 50kg per hour, how much is the cooling requirement? How big a chiller should be? q=50×0.48×200×1.35=6480 (kcal/h); 6480kcal/h cooling per hour is required, ls203s chiller can be used.

In the actual selection of chillers, it is difficult to obtain relatively complete data. According to our past years of planning, supporting sales experience,? t = 200 °C, which is an average of many common products after years of statistics.

If a hot glue path is attached to the mold, the energy of the hot glue path should also be added to the calculation of the cooling capacity. The general hot glue path is in units of kw. When calculating, the unit should be converted to kcal/h, 1kw=860 kcal/h. If the water supply to the factory is sufficient, the temperature is lower, and the cost is lower, there is no need to use a chiller, which is generally not realistic unless the factory can be on the lakeside where the water temperature is relatively low; the other is to use Urban deep wells supply water to meet the needs of temperature and flow, but often the cost is too high. This method can be used for experimental devices, but it is not practical for factories.

Second, the temperature of the ice water mold cooling fluid (ice water) temperature is generally subject to the processing of materials and product shape and a greater change, such as polystyrene thin wall beaker, the mold requires ice water temperature below 0 °C; and other great In most cases, the temperature of the ice water required by the mold is above 5°C. The microcomputer full-function chiller provides ice water above 5°C, and the low-temperature intelligent temperature-controlled chiller can meet the requirements below 5°C and below 0°C. The temperature difference of ice water at the inlet and outlet of the mold is often set according to the requirements of the product. In many cases, the temperature difference is 3-5°C, but it is sometimes desirable to have a temperature difference of 1-2°C. The smaller the temperature difference, the greater the amount of ice water required to bring the same heat out, and vice versa. For example, when the temperature difference is 5°C, the flow rate needs 60l, and when the temperature difference is 2°C, the flow rate needs 150l.

Third, the flow of ice water required by a pair of molds is directly related to the temperature of the mold to take away and the temperature difference between the ice water and the mold. For example: To remove 6480 kcal/h of heat from the mold, if the temperature difference is 3°C, what is the minimum required flow rate? Ice water flow q=6480÷3÷60=36 (l/min).

Fourth, the ice water quality of the water, the softening of the water, in the process of using the chiller, is also a problem that can not be ignored, the ph value of the water also need to be constantly observed, the best ph value should be equal to 7, greater than 7 of the ph value It will produce a terrible corrosion phenomenon. If no measures are taken, it will produce dirt in the evaporator and mold, and it will play a role in heat insulation. When serious, the energy conversion effect will be reduced by 30%. Obviously this requires the consideration of the softening of hard water. The most effective method is to configure an electronic hard water softener in the system. Such a softener is designed based on the principle of exchange. According to the different flow rate can be configured with different specifications of the softener, directly connected to the circulating water pipeline, the general configuration of the water treatment softener costs will not be too high, can also be scheduled during the circulation system to add a certain proportion of detergent .

Fifth, ice machine flow, pressure injection molding mold cooling general, ice water pressure selection 0.1 ~ 0.2mpa, to meet the requirements, and microcomputer full-featured chiller function to meet this requirement, when the pressure requirement is higher than 0.2mpa, need to be separately Planning to facilitate the use of appropriate pressure from the pump to meet the needs of the system's water supply.

VI. Cooling of Hydraulic Oil and Barrel Feeding Section Normally the hydraulic oil and barrel feeding section uses cooling tower water to cool it, because this is not only the best method, it is also costly to produce, and it is also very economical unless There are specific requirements for its temperature, which can be cooled with ice water.

7. The insulated ice-water pipeline of the ice water pipeline must be insulated, because the pipeline insulation can not only prevent the serious loss of the cooling capacity, but also prevent the formation of dew condensation water on the outer wall of the pipeline. For example: ice water temperature 10 °C, ambient temperature 30 °C, a 25 meters long, surface area 25m? The heat radiation of metal pipes can reach 750kcal/h, which is almost 10% of the refrigeration capacity of 3hp compressors, and about 6% of the refrigeration capacity of 5hp compressors.

The connection between the chiller and the mold is usually reinforced with a hose connection because the hose itself has a thermal insulation function, but when the length is more than 5m, moderate heat insulation is also considered.