First, the full name of the blow molding machine in Eng […]
First, the full name of the blow molding machine in English is BLOW MOULDING MACHINE. It is referred to as BMM. Its basic working principle is: inflate the softened thermoplastic parison to make it close to the cooling surface of the closed mold, and the inflated parison is solidified. Form hollow plastic products.
Second, let’s start with the screw. The screw of the blow molding machine. There are single-screw twin-screw and multi-screw because of the different products they make, so let’s talk about single-screw. Most of the screws now are driven by motors. Hydraulic transmission>Use the frequency converter to control the screw speed. There is a heating coil on the outside of the screw barrel to melt the plastic. Because the melting point of each plastic is different, you should have three temperature function displays when designing the heating coil. <And in the electrical cabinet Each solid-state relay in the heating coil has a current transformer in the form of an ammeter to show it clearly and clearly> One is the set temperature such as 200 degrees. The other is the maximum allowable temperature such as 250 degrees. <The fluidity of the plastic is too high. Accelerate the impact on product quality> The screw will stop automatically when it reaches the maximum temperature, and an alarm will be displayed. Third, the minimum allowable temperature, such as 160<The temperature is too low, the fluidity of the plastic will be very low, not only will affect the product quality, but the shear force of the screw will be large. Great damage to the screw>The screw will stop automatically when the minimum temperature is exceeded, and an alarm will be displayed. The motor cannot start when the temperature of the screw is at the highest or lowest temperature!
Third, the die head. The die head is divided into continuous type and storage type. Let's say continuous type. The main function of the die head is to extrude a molten plastic uniformly in a hollow shape to facilitate blow molding. The second is The most important way to control the wall thickness of the parison is to control the wall thickness of the parison by hydraulic means. The main use is to use the servo proportional valve to move up and down to control the size of the die opening to control the wall thickness of the parison. So when you design the die control, I have the following A few comments. First, the screw motor cannot start when the die hydraulic pressure is not started. Second, the screw motor cannot start when the die is completely closed.
Fourth, molds are generally blow-molded in two halves. The parisons extruded from the die are combined and blow-molded during work. Its standard procedure is generally as follows: mold-moving-closing-locking Mold-pressurize-blow needle entry-blow-exhaust-release pressure-mold opening-mold transfer-enter the next cycle. So I see you when designing and controlling. You are required to do it. The mold is not in place and the mold is not closed. If the mold is not in place, do not lock the mold. If the mold is not in place, do not pressurize. If the pressure is not in place, the blowing needle does not enter. The blowing needle does not enter the position and does not blow. When the pressure is lower than the set pressure relief value during exhaust, the mold does not open Mold. Mold opening is not in place and does not move. The mold is not in place and the next cycle will stop working and give an alarm. Every action that is not in place can be alarmed and can be clearly displayed on the PLC or operation panel. Also, the cooling water temperature is normal. High or too low can be displayed. When too high or too low, it can alarm and display that it does not necessarily require shutdown.