Reducing the Lead Time Between Hot Folling and Inspection by Installing the Water Cooling Machine

oleh Suguru Ishikawa

Penerbit - Shi Aichi Corporation, Tokai, Japan

Kategori - Novel Am

In our company, we produce about 80000 ton of hot roll steel bars for automobile component applications such as crankshaft, ring gear, and etc. In order to prevent a car accident due to defects caused by the steel material, a total inspection of the materials is a standard practice in Japan; all our products will be inspected by surface flaw inspection (MLFT) & internal defect inspection (UT). Inspection of the as hot rolled material is a challenging matter to the delivery process since inspection operation is not possible at high temperature. If inspection is done directly from as hot rolled condition we can’t get the correct data from the UT and also it causes a crash of the MLFT censor, hence, generally steel bars has to be air cooled below 60 degrees C. When implementing air cooling we have to wait for 12 hours to drop the steel temperature to below 60 degrees C, and this has two disadvantages with respect to production. 1. Large storage is required. 2. The long lead-time disables early feedback to rolling process. Therefore, to solve this problem, we set up a water-cooling device immediately after rolling to continuously cool by water shower. However, we apprehend repetition of quality problems such as bar bending and deviation from the standard value in microstructural transformation. Therefore, we analyze the mechanism of these problems in advance by using CCT curve, computer simulation and make a pre-study on optimal water cooling condition & method in order to confirm the average level to air cooling.As a result, by installation of water-cooling device the microstructure transformation and bend level obtained was the same as the air-cooling and this help us to achieved reduction of the lead time. In this paper, we present the concept, cooling method, advance simulation and quality evaluation of water cooling unit.

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