Stack several semi-finished products, weld their peripheries, and finally attach the front and rear seat rings to form the specified corrugated pipe. The main process involves the following steps: cutting and forming the corrugated sheets, cleaning, inner seam welding, outer seam welding, welding the front and rear seat rings, inspection, heat treatment, and inspection.

1. Blanking and forming

     The punching and forming of corrugated sheets can be completed in one step. The shape of the corrugated sheets has a significant impact on the performance of corrugated bones. Currently, there are two types of grinding tools: one is a metal grinding tool, and the other is a polyurethane rubber punching and forming mold. The former has a curved punching surface, which requires high precision, is difficult to manufacture, and has a large workload on the mold, making it difficult to correct the gap between the concave and convex punching edges. The latter has a simple structure and is easy to manufacture. During the punching and forming process, there is less misalignment between the concave and convex punches, which generally prevents scratching of the corrugated sheets

Second, cleaning

Cleaning of the wave plate is one of the important conditions for ensuring welding quality, especially for the cleaning of the weld seams on the inner and outer peripheries. The wave plate needs to be cleaned with detergent, pickled, neutralized, rinsed with clean water, and then soaked in acetone for scrubbing.

Third, welding

The welding of corrugated pipes is a precision welding process, thus the operation room must be equipped with comprehensive air conditioning and air filtration and conditioning systems to ensure constant temperature, humidity, and a dust-free environment.

The welding of corrugated tubes does not use welding rods, but instead employs fusion welding in an air environment (with Ar as the working gas and Ar+N2 as the shielding gas) to avoid the formation of welding slag at the welding site, which could affect the inherent properties of the corrugated tube material. To prevent surface stress during melting, the welding area is shaped into a semi-spherical form. For single-layer corrugated sheets, the weld bead is typically 2.2-3 times the thickness of the corrugated sheet, while for double-layer corrugated sheets, it is 4-5 times the thickness. The corrugation spacing should be uniform, and the weld bead shape should be symmetrical. The welding process often employs micro-plasma welding, which has been standardized and mass-produced in China, such as the LH-16 micro-plasma welding machine

IV. Quality inspection

In the manufacturing process of corrugated pipes, quality control is extremely strict. For example, the plates used to make corrugated pipes undergo metallographic microscopy to inspect the size and arrangement of grains, as well as microscopic examination of the plates to understand the depth of welding, the shape and symmetry of the weld. All welds undergo air tightness inspection, usually using a helium mass spectrometer leak detector, with a vacuum leak rate of 1*10mL/s. In addition, precise measurements are taken of the elasticity, expansion and contraction characteristics, relaxation and hysteresis of the corrugated pipes.

V. Heat treatment of corrugated tubes

As for the corrugated pipe made of AM-350 material, its heat treatment must be carried out in a vacuum furnace at 850 degrees Celsius, followed by a low-temperature treatment at -80 degrees Celsius (cooled to F12) to increase elasticity and stabilize dimensions.