Glass Blow Molding – Electronic Flow Control Valve Solution

Abstract: In glass blow molding process, there always exist problems such as poor consistency and low yield of finished products due to unstable air pressure of manual blowing and machine blowing. In order to solve these problems, this article focuses on a full-automatic control solution for blowing air pressure using high flow rate version of electronic flow control valve, so that the blowing air pressure can be quickly and precisely controlled according to the set curve, which can greatly improve production efficiency and product yield.

1. Question
Glass is an amorphous solid. Glass products need to be softened by heating and blow-molded during processing. However, the current glass blow-molding process has the following problems that need to be solved:

(1) In most of the current glass blow molding process in which air is blown into the interior of glass products by manual mouth blowing, it is necessary to rely on people to blow air with a pipe and then shape the molten glass. This method greatly increases the burden on producer, easily causes dizziness due to lack of oxygen in brain, and reduces work efficiency at the same time. The finished products produced by this process have poor consistency and low yield. At the same time, the production cycle of glass products is prolonged, which is not conducive to widespread promotion and popularization.

(2) In the glass blow molding process, since the wind has been acting on the bottom of glass bottle after it comes out of the blow molding tube. The blowing pressure is not uniform, which will lead to different thicknesses of the bottom of glass bottle after forming. In the process of blow molding, the plastic device will have unstable air pressure, and it does not have the function of automatic voltage stabilization, resulting in different quality levels of glass bottles.

By analyzing the glass blow molding process of existing glass products, it can be found that the entire blow molding process is a typical air pressure change process in a small closed space. If this air pressure change process can be precisely controlled and the air pressure change process can always be accurately repeated, then realize the automation and quality reliability of glass blow molding process of glass products, greatly improve the yield and shorten the production cycle.

2. Technical scheme
The basic principle of automatic control of blowing pressure in glass molding is to quickly control the air pressure in a closed chamber as required, and use this air pressure to replace the pressure change during manual blowing. The shchem of the entire control method is shown in Figure 1.

The automatic air blowing pressure control device mainly includes a chamber, an electronic flow control valve, a pressure sensor, a PID controller and a high-pressure air source. The precise control of pressure in chamber adopts the dynamic control method, that is, according to the pressure.

The measured value of the force sensor is compared with the set value, and the PID controller adjusts the intake flow and exhaust flow at the same time, so that the pressure in the cavity quickly reaches a dynamic balance and controls the pressure at the set value.

The set value can be a constant pressure point that does not change with time. It can also be a curve of pressure changing with time designed according to the requirements of glass molding blowing process, so as to meet different pressure requirements.

In a word, through this technical solution, the automatic and precise control of blowing pressure of glass molding can be reached, and the control accuracy and repeatability can be ensured, so as to ensure the product quality and stability.

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