加熱：利用射頻加熱Weld

　　當我們想到射頻的時候，我們中的大多數人都會聯想到無線電、數據鏈和通信的圖像，有一個射頻設計工程師的整個亞文化，其工作與通信無關。相反，這些工程師使用射頻加熱，焊接和密封金屬物體。我們可以熟悉的一個例子是感應爐頂部，加熱金屬鍋和鍋，而表面仍然涼爽。

　　電磁感應使用的感應線圈，與RF驅動，導致電阻加熱效應的渦流引起的金屬在靠近射頻場。金屬，稱為基座，吸收熱，熱傳導到一個更大的面積或體積（用于液體加熱），或導致融化，融合，或焊接非常有效。沒有爆炸性氣體，煙霧或化學物質，使這個過程的工廠和自動化機械線的理想選擇。

　　Figure 1： A 25 mm metal bar can be made red hot using 15 kW of RF energy at 450 kHz.

　　This article looks at inductive heating using RF energy and discusses design solutions and applications where this technology can be used. All parts， data sheets， tutorials， and development kits referenced here can be found online at Digi-Key’s website.

　　Not just for cooking

　　For decades， inductive heating has been used on factory floors for sealing and packaging of metal containers. Early patent drawings show how relatively few components can implement an effective solution （Figure 2）。 Comparatively speaking， it is only fairly recently that inductive heating for cooking has been offered on medium- to low-cost cooking surfaces. However， we all have used products that have been inductively heat sealed. We are all familiar with cans of food that require an opener to break the vacuum seal. If you look carefully at the tops of these cans， you will see that the lids are welded to the cans; dedicated machines use specially designed inductive heaters driven by high-power RF to fuse the lids to the cans quickly， reliably， and repeatedly.