Filling Gun

Core Classifications and Specifications

By Regional Style:

There are Chinese, Japanese, German, and Korean types, each with different structural dimensions. For example, the German-style filling gun with an ejector is 24×300mm (outer diameter 24mm, inner diameter 20mm, small head length 21mm); Chinese-style guns include 30×150mm (threaded rod type) and 30×180mm (plain rod type); Korean-style guns commonly use the 30×200mm plain rod type.

By Function: Includes standard filling guns, 2-in-1 filling guns with ejectors, and quick-lock filling guns. Filling guns with ejectors can quickly clear nozzle blockages, suitable for high-volume production scenarios.

Main Structural Components

Basic Components: Includes the filling gun head, tee connector, pressure plate, threaded cap, cylinder core, and cylinder shell. The gun head is the key exit for particles entering the mold. Some gun heads are designed with multiple ports to achieve uniform particle distribution.

Control Components: A piston/inner rod (with spring) acts as a valve to control the particle flow rate. The pneumatic filling gun also features a pneumatically driven ejection mechanism to clean residual particles from the tube.

Connecting Components: Threaded connectors made of brass, bronze, or aluminum alloy are used to connect the particle supply line and the mold, ensuring sealing and durability.

Working Principle of EPS/EPP Filling Gun

Preliminary Preparation and Feed Start-up

The filling gun first establishes a sealed connection with the granule hopper, compressed air pipeline, and mold inlet via threaded joints and other components, ensuring a leak-free conveying channel. After production starts, the EPS/EPP granules in the hopper, under gravity, first enter the connection between the filling gun’s feed branch pipe and the conveying pipe, awaiting conveying instructions. At this time, the piston/inner rod of the filling gun is in the open state, leaving a channel for granule passage.

Particle Power Conveying and Precise Filling

The core power comes from compressed air. The air compressor supplies a stable air pressure of 0.4-0.6MPa to the filling gun, creating airflow thrust inside the conveying pipe. Driven by the airflow, the EPS/EPP granules move rapidly along the conveying pipe and are finally injected into the mold cavity through a customized gun head (such as an inclined gun head adapted for irregularly shaped products). For large molds with multiple feed inlets, multiple sets of filling guns can work together to ensure uniform distribution of granules within the cavity, avoiding localized insufficient filling or accumulation.

Flow Control and Sealing Pressure Holding

During the filling process, the feed flow rate of the granules can be precisely controlled by adjusting the opening and closing degree of the piston/inner rod to adapt to the needs of products with different thicknesses and sizes. When the mold cavity is filled to the preset amount, the piston/inner rod moves rapidly under spring or pneumatic drive, sealing the conveying channel and preventing subsequent steam backflow or granule reflux. Simultaneously, the sealing rings and gaskets of the filling gun function to ensure the sealing of the connection between the mold and the gun body, providing a sealed environment for subsequent steam heating and shaping.

Auxiliary Molding and Reset Cleaning

After granule filling is completed, steam is introduced into the mold for heating. Some filling guns have a cutting design at the nozzle, which guides the steam along a specific path into the cavity, accelerating granule expansion and fusion. After the product cools and sets, the pneumatic filling gun will activate the ejector to clean the nozzle and conveying pipe of any remaining granules; some filling guns with raw material back-blowing function will also blow excess granules back to the hopper for recycling. Finally, the piston/inner rod resets, opening the channel to prepare for the next round of filling.

Application Scenarios:

Packaging Industry: Used to produce EPS foam packaging boxes, cushioning pads, etc., providing protective packaging for electronic products and fragile items.

Construction Industry: Filling EPS particles into wall insulation molds to produce building materials such as insulation boards and soundproofing boards.

Gardening/Daily Necessities Industry: Feeding EPP particles into molds for EPP flower pots, foam decorative parts, etc., enabling mass production.