5 FAQs for Kiln Car Construction in Fired Brick Plants (Dedicated to Construction Phase)

Q1: After welding of the kiln car frame is completed, the main beam deforms and welds crack shortly after service. What construction problems cause this?

Answer: Three core causes during the construction phase: (1) Undersized steel sections for main and secondary beams, insufficient plate thickness, and inadequate load-bearing margin; (2) Lack of layered full welding and omission of stress relief procedures, leading to stress concentration and weld cracking under thermal cycling; (3) The frame was not fully leveled and aligned, resulting in excessive parallelism and height deviations among the four wheel sets, causing eccentric loading during operation.

Construction standard solution: Select national standard thickened I-beams for main beams, and thicken/widen the towing plates; after welding, perform overall tempering for stress relief; align the four wheels coaxially with a diagonal height error ≤2 mm.

Q2: After lining brick masonry is completed and the kiln car is put into operation, deck heat leakage and excessive bottom temperature damage bearings. What went wrong during construction?

Answer: Non-standard layered construction of the insulating lining: (1) The insulation layer thickness was reduced to less than 10 cm, whereas the standard three-layer structure should be lightweight insulation layer + insulating cotton + load-bearing high-alumina bricks; (2) Continuous vertical joints were used in lining bricks, allowing hot air to pass straight through to the frame; (3) Expansion joints were not reserved, causing high-temperature brick expansion to squeeze and arch, thereby damaging the insulation layer.

Construction requirement: Total insulation lining thickness ≥18 cm, staggered joints between layers, reserve 15–20 mm expansion joints in both directions, and fill with refractory fiber cotton for sealing.

Q3: After construction of the side sand seal plates, the kiln car experiences friction jamming and air leakage when entering the kiln. How should construction be rectified?

Answer: Common construction defects: the sand seal plates are directly fully welded to the main beam, causing thermal expansion deformation and warping that scrapes against the sand seal trough; the plates are too thin and prone to distortion, and large gaps between splices allow cold and hot air leakage.

Optimized construction process: Use bolted detachable connections with slotted holes instead of full welding; select steel plates ≥8 mm thick, fill joints with high-temperature resistant sealing cotton, reserve lateral expansion allowance, and pre-adjust clearances before factory delivery.

Q4: What common material selection and machining pitfalls should be avoided during assembly of wheels and axles?

Answer: Common mistakes: (1) Using ordinary pig iron or low-quality cast steel for wheels without heat treatment, resulting in rapid tread wear and rim cracking; (2) Using A3 ordinary carbon steel for axles, which bends under load; (3) Excessive assembly clearance in bearing housings and lack of high-temperature lubrication channels.

Construction specification: Wheel material ZG340‑640 cast steel, surface hardened 3–5 mm; axles uniformly use 45# quenched and tempered steel; bearing housings shall have high-temperature lubrication passages, and coaxiality shall be strictly aligned during assembly.

Q5: When building multiple kiln cars in batches, large gaps between cars cause air cross-flow that affects firing quality. What are the key construction control points?

Answer: Non-standardized dimensional and end-sealing structures: (1) Tolerances on individual car lengths exceed standards, resulting in uneven lengths across the batch; (2) The front and rear end lining bricks do not adopt a tongue-and-groove interlocking sealing structure, only flat butt joints; (3) The towing steel plate at the frame end is too thin, deforms under pushing pressure, enlarging sealing gaps.

Construction standard: Control total length tolerance of each car to ±3 mm; design front/rear lining bricks with tongue-and-groove interlocking ends; use thickened steel plates for towing ends; after batch completion, perform trial coupling in pairs and fill gaps with refractory fiber sealing strips.