Explanation
Indicates the time or occasion when something happens; 'when', 'at the time of'.
Formation
Verb-dictionary form + 折に, Verb-た形 + 折に, Noun + の折に
Detailed explanation
The ～折に grammar point is used in a somewhat formal register to express that one event or action takes place on the occasion of another. It essentially means 'when' or 'at the time of'.
Examples
父が病気の折に、私は留学していました。
Chichi ga byouki no ori ni, watashi wa ryuugaku shite imashita.
When my father was ill, I was studying abroad.
日本へ行く折に、お土産を買ってきてください。
Nihon e iku ori ni, omiyage o katte kite kudasai.
When you go to Japan, please buy souvenirs.
子供が寝ている折に、静かにしてください。
Kodomo ga nete iru ori ni, shizuka ni shite kudasai.
Please be quiet when the child is sleeping.
彼に会う折に、この手紙を渡してください。
Kare ni au ori ni, kono tegami o watashite kudasai.
Please give him this letter when you see him.
Practice
Grammar content sourced from hanabira.org.