Inert Gas Protection Classifier for 3D Printing Material Alloy Powder

I. System Overview

1Working Principle

This airflow classifier is specifically designed and developed for materials that are flammable, explosive, or prone to oxidation. It is based on conventional airflow classifiers and vertical turbine high-precision classifiers, with improvements such as altering the airflow composition, modifying the air intake and exhaust piping, and enhancing the sealing process of the equipment. The entire system uses inert gas as the fluid working medium. The complete equipment set consists of an inert gas source, an oxygen content tester, an intake piping system, a closed-loop feeding system, a vertical turbine classifier, an induced draft fan, a sealed replacement discharge valve, an anti-static pulse jet dust collector, an inert gas replenishment device, and a cooler. The outlet of the induced draft fan is connected to the air intake of the classifier, forming a closed-loop inert gas circulation system.

2Performance Features

The entire production line operates in a fully enclosed negative pressure circulation system, controlled by PLC programming to minimize manual operation and control factors. The control cabinet can be placed in a separate control room at a distance. Automatic packaging machines are used for packaging and discharging, while monitoring probes are employed for on-site observation, enabling fully unmanned operation.

2.1Automation control

(1). Start/Stop Control

All control points of the complete system adopt PLC intelligent control, utilizing controllers, modules, and a touchscreen to enable one-key start and stop for the entire machine. Additionally, the start and stop intervals between each control point and the next are time-set and adjustable. The parameters of each control point (such as motor current and detector data) are displayed on the screen, allowing the operational status of any part of the equipment to be observed directly from the display.

(2) Control of Inert Gas Compensation

Before startup and production, the inert gas system automatically purges the air inside the classification system, creating an inert gas environment throughout the system. An oxygen content detector is in place, and when the oxygen level falls below the set value, the compensation system automatically stops. Once the inert gas environment within the system meets the specified requirements, the system can automatically begin feeding materials for production. During production, if the inert gas purity drops below the set value, the compensation system valve automatically opens to reduce the oxygen content in the system. When the oxygen level meets the set value, the compensation valve automatically closes.

（3）Automatic alarm control

The operating parameters of each control point of the equipment are set with upper and lower limits, such as the current and voltage of the motor, the readings of the oxygen content detector, the purity of inert gas, and the pressure displayed by the pressure gauge. When any of these parameters exceeds or falls below the set values, the system will automatically trigger an alarm or restore itself.

2.2, grading accuracy

(1) This machine features strong dispersion and dissociation performance, with a unique gas-solid flow field system that effectively disperses and dissociates powders, thereby improving classification efficiency.

(2) The graded blades are made of stainless steel and formed in a single process. Through dynamic balancing, the balance accuracy reaches 0.3g (general dynamic balance accuracy ranges from 2-5g).

(3) The classifier rotor blades adopt a large-angle auxiliary blade design, strictly controlling the leakage of large particles.

(4) The fit between the classification wheel and the machine head adopts a double labyrinth groove with a fitting clearance of 0.02mm, further controlling the leakage of large particles.

(5) The high-pressure gas seal strip in the double labyrinth groove shows a pressure of (0.3-0.4 MPa) on the pressure gauge.

(6) Through the triple sealing of auxiliary blades, double labyrinth grooves, and high-pressure gas seals, it ensures that no large particles leak out.

(7) A unique secondary air supply device is installed between the classification zone and the collection bin, allowing the classified coarse material to be returned to the classification zone for repeated washing. This process removes fine powders from the material, achieving a fine powder extraction rate of over 95%, which is at an international level.

II. Application Fields

Currently, this series of machines is primarily used in **research institutes, metal powder processing, pharmaceutical ultrafine powder, and other fields**. The series operates with stability, safety, and reliability. Typical materials include: aluminum powder, cobalt powder, tungsten powder, iron powder, nickel powder, aluminum-iron-boron, carbonyl iron powder, selenium powder, and various other powder metallurgy materials.