Model making of shield tunneling machine

Case study on the production of shield machine display model
1、 Project Background and Production Objectives
The 1:20 shield tunneling equipment model produced this time is specifically designed for educational purposes. The model needs to fully present the overall structure, cutterhead details, and supporting equipment of the shield machine, with a focus on showcasing its industrial beauty and sense of power as a large-scale construction machinery. The production goal is to achieve a 90% restoration of appearance through reasonable material selection and manual craftsmanship, vividly showcasing this iconic equipment of modern tunnel engineering.

2、 Material selection and pretreatment
The main structure adopts a layered design: the core skeleton uses 5mm aviation plywood to ensure overall stability. The outer shell is made of corresponding materials based on the characteristics of different parts – the cutterhead and front shield are made of ABS board for easy shaping of complex surfaces, while the middle shield and tail shield are cast with high-strength polyurethane resin. The cutterhead and cutting tools are made of modified nylon material, which ensures strength and reduces weight. All boards undergo constant temperature treatment before processing to prevent deformation in the later stage.

3、 Production process flow
The production process adopts a scheme of “segmented production and overall assembly”. Firstly, cut the laminated board into a circular frame according to the drawing, and use mortise and tenon joints to assemble the main skeleton. The disc part adopts a combination of 3D printing and manual carving: first print the basic structure, and then manually repair the tool installation groove with a carving knife. The shield body is formed through vacuum forming technology, and a 2mm thick ABS plate is heated and softened before being adsorbed onto the mold to ensure a smooth and natural curved surface.
The pipeline system is a highlight of the process: using copper pipes of different diameters to simulate hydraulic pipelines, silicone hoses to represent cable routes, all arranged along pre-set channels inside the shield body. The propulsion system is implemented through micro cylinders, which can simulate the forward movement of the equipment. The assembled pipe segments are produced in batches through molds, with each ring consisting of six standard blocks and one sealing block, fully simulating the real tunnel support process.

4、 Painting and aging treatment
Surface finishing before painting: Use 400-1000 grit sandpaper to polish step by step and fill the joints. Firstly, apply a deep gray primer as a whole, and then carry out zone coating: the cutterhead adopts contrasting blue and yellow warning colors, the main body of the shield is medium gray, and the rear equipment area is dark gray. During painting, the technique of masking and spraying is used to ensure clear and sharp boundaries between color blocks.
Aging treatment enhances realism: dry sweep metal silver around the tool mounting seat to show wear marks, spray brown filter solution on the lower part of the shield to simulate soil residue, and spot dye copper at pipeline joints to show metallic texture. Finally, use powder paint to create a dust accumulation effect at the structural depression, and all identification text is accurately positioned using water sticker technology.