U-shaped molded silicone hose integrated vulcanization molding process and dimensional parameter description

1、 Supporting mold structure and pre-processing process

The U-shaped silicone hose is shaped using a combination of metal molds. The entire mold is divided into three parts: an inner support core mold, an outer wrapping molding mold, and two end limit stop molds. The mold drawings are processed by CNC milling based on the radius of the U-shaped arc, the length of the straight pipes at both ends, and the inner diameter of the pipeline. The inner cavity of the mold is reserved with space according to the total thickness of the multi-layer composite pipe wall of the pipe material. The inner and outer sides of the U-shaped arc are smoothly transitioned and chamfered to reduce the occurrence of uneven wall thickness and rubber material accumulation wrinkles at the corner position of the pipe wall after vulcanization is completed.

After the completion of mold processing, carry out mold clamping verification operations to check the curvature of the U-shaped arc, the inner diameter of the mold cavity, the depth of the pipe end limit, control the width of the mold splicing gap, reduce excess material output during the vulcanization stage, and reduce the workload of manual trimming in the later stage. Before the qualified mold is put into production, the mold release agent is evenly applied to the inner cavity, and after natural air drying, it enters the filling process. A single set of molds completes the overall shaping of a single U-shaped hose in one go, without segmented bonding or secondary heating shaping processes.

2、 Integrated vulcanization complete molding process

The entire molding process is divided into seven steps: silicone mixing and cutting, interlayer laying, mold filling and locking, constant temperature vulcanization, natural cooling, demolding and trimming, and size sampling. The operators lay the inner layer of silicone, polyester fiber woven interlayer, and outer layer of silicone in sequence according to the layering order of the pipe wall. The three layers of materials are aligned and wrapped around the surface of the inner core mold. The external molding mold is closed and the mold is locked and fixed.

The vulcanization equipment maintains a constant temperature range to complete the curing reaction of the rubber material, so that the silicone substrate and the intermediate woven interlayer are fused together to form a complete composite pipe wall. After the vulcanization cycle is over, the mold is left to cool naturally to room temperature. The mold is disassembled and the formed pipe is taken out. The excess material at the pipe mouth and U-shaped arc position is manually cleaned to ensure that the inner and outer surfaces of the pipe are smooth and even.

The entire process relies on molds to fix the overall contour of the U-shape, and the circular arc shape of the formed pipe will not be significantly deformed by external forces or environmental temperatures. The circular arc curvature, pipe diameter, and straight pipe length of the pipe fittings produced by the same batch of molds are all within a uniform tolerance range, which is suitable for batch matching production needs.

3、 Layered structure design of U-shaped hose

The pipe adopts a three-layer composite structure, with the inner layer of silicone directly in contact with cooling liquid, circulating airflow and other media. The inner wall is flat without protruding particles, reducing the obstruction of medium circulation; The middle fiber woven interlayer is arranged in a uniform interweaving of warp and weft, evenly distributed throughout the entire area of the pipe wall, to share the tensile force caused by pressure fluctuations inside the pipeline; The outer layer is wrapped in silicone to isolate the internal structure from contact with oil, water vapor, and air oxidation.

The U-shaped arc segment is the transition area for integrated molding of the mold. The thickness difference between the inner and outer sides of the arc and the thickness of the straight pipe segments at both ends is controlled within a limited range, and there are no local thin-walled defects. Reserve straight pipe sections at both ends of the pipe, with the length of the straight pipe matching the specifications of conventional pipe clamps in the market, to facilitate the locking and fixing of fasteners during the assembly stage. The internal circulation channel of the pipe is continuous throughout the entire process, without any structural defects such as shrinkage or protrusions that hinder the flow of the medium.

4、 Specification for General Dimensional Control Parameters

The document uniformly lists the conventional control dimensions of U-shaped molded silicone hoses in circulation on the market. The core testing parameters include the inner diameter of the pipe, the total thickness of the pipe wall, the length of the single-sided straight pipe section, the radius of the U-shaped arc, and the tolerance range of the overall molding dimensions.

Divide the inner diameter into multiple standard gears to match the reference dimensions of various vehicle and industrial equipment pipeline joints; The pipe wall is set with two specifications: conventional thickness and thickened composite, corresponding to different pipeline pressure usage scenarios; Multiple fixed values are set for the length of the straight pipe section to adapt to different installation distances in the equipment cabin; The U-shaped arc radius distinguishes multiple specifications and adapts to different wiring spaces inside the equipment.

All dimensional parameters are marked on the mold processing drawings and product packaging labels. During the quality inspection process, calipers, arc gauges, and angle gauges are used for actual measurement and comparison. Products with measured values exceeding the tolerance range are sorted separately and do not flow into the assembly and supply process.

5、 The complementary role of process and size control

The standardized integrated vulcanization molding process, combined with unified size control standards, can reduce the need for on-site assembly adjustments, shape U-shaped circular arc structures to adapt to closed loop pipeline routing points, and reduce frictional contact between pipelines and surrounding shells, wiring harnesses, and mechanical parts. The seamless integrated molding structure, combined with uniform pipe wall thickness, is suitable for operating environments such as heat dissipation, alternating cold and hot intake pipelines, and continuous vibration.

The production end relies on molds to fix the basic form of pipe fittings, completes factory screening based on standardized dimensions, stabilizes the structural form of each batch of finished products, adapts to the long-term assembly and use of fluid circulation pipelines for motor vehicles and industrial equipment, and provides standardized matching pipe fittings for equipment folding pipeline points.