In belt conveyors, although idlers are small, they play a crucial role—they account for 35% of the equipment’s cost and 70% of the running resistance, and they directly affect the service life of the conveyor belt. However, in traditional manufacturing processes, issues such as elliptical errors and uneven wall thickness during the machining of the tube stop face make it difficult to meet the required standards for radial runout performance of the idlers. This article will explore in depth three innovative process solutions, providing enterprises with feasible pathways for technological upgrades.

I. Pain Points in Traditional Craftsmanship: A Chain Reaction from Cutting to Assembly and Welding

In current mainstream processes, the pipe-cutting stage suffers from a lack of front-end support, leading to horseshoe-shaped deformation at the pipe end face. This elliptical error is further amplified during subsequent flange-machining operations, resulting in wall-thickness variations. Even more critical is that the clearance fit between the pipe and the bearing housing relies on the operator’s experience; after welding, misalignment issues frequently occur, ultimately causing the roller’s radial runout to exceed tolerance limits.

II. Comparative Analysis of Three-Stage Process Schemes

Scheme 1: Stop-milling + Clearance Fit (Current Process)

Root cause of the problem: Cutting deformation leads to positioning errors, and the accuracy of clearance fits is affected by human factors.

Room for improvement: The support structure of the cutting equipment needs to be optimized, but the issue of welding deformation cannot be completely resolved.

方案 2: Dual-end welding equipment + dual-positioning fixture

Technical Highlight: By employing dual control—axial positioning and end-face clamping—this method achieves concentric rotational welding between the pipe and the bearing housing.

Limitations:

Fixture changes require frequent adjustments, which are time-consuming and rely on operational skills.

The equipment has high complexity, leading to a significant increase in maintenance costs.

Different pipe diameters require custom fixtures, resulting in insufficient versatility.

Scheme 3: Interference Fit + Cold Extrusion Assembly

Innovative Breakthrough: Eliminating the need for stop-machining and achieving a rigid connection between the bearing housing and the pipe through interference fit control.

Implementation Path:

Interference Fit Test: By conducting stepped press-fitting tests, determine the optimal interference fit range for materials of different pipe diameters.

Cold extrusion process: Hydraulic or mechanical pressing equipment is used to ensure uniform contact between the bearing housing and the inner wall of the tube.

Welding Optimization: After assembly and welding, minor deformations are corrected via laser inspection to ensure that the radial runout of the outer circle is ≤0.3 mm.

III. The Practical Value of Scheme 3

Quality Improvement: Interference fit eliminates gaps, reducing welding deformation by more than 40%.

Cost optimization: By eliminating the edge-finishing process, the manufacturing cost per unit is reduced by 15%-20%.

Efficiency breakthrough: The takt time for cold extrusion assembly has been reduced to one-third of that of conventional processes, making it suitable for large-scale production.

Technical threshold: Equipment investment is only 60% of that required for a dual-end welding solution, and frequent adjustments to fixtures are unnecessary.

IV. Prospects for Industry Applications

A leading conveyor equipment enterprise has piloted Scheme 3, achieving the following in the production of Φ89mm idlers:

The pass rate for radial runout has improved from 78% to 95%.

Annual savings on fixture maintenance costs exceed 500,000 yuan;

The product lifecycle has been extended by 30%, and the customer complaint rate has decreased by 65%.

Conclusion: Process innovation drives industrial upgrading.

It has become inevitable for idler manufacturing to shift from “experience-based” to “data-driven” approaches. Scheme 3, which integrates interference fit control with cold extrusion technology, offers the industry a solution that is both feasible and cost-effective. In the future, as intelligent inspection and adaptive press-fitting technologies become more widespread, the precision of idler manufacturing is expected to enter the micrometer-level era.