PHPExcel dynamic sheet naming

There was a problem with naming sheets. I unload categories from the database, I want each category to have a separate sheet, I create it without problems, but as soon as it comes to assigning a name to the sheet, there are already problems, first I decided that the maximum length of the name is 30 characters, well, I cut the string to 30 characters , it still does not work, it is worth cutting the line to 10 characters, displays, but the names contain only 5 characters, who faced this problem, how to solve it?

Таблица категорий 7 Смесители на раковину 8 Смесители для ванны и душа 9 Душевые системы 10 Комплектующие для душа 11 Смесители для кухни 12 Сифоны и донные клапаны 13 Смесители для гигиенического душа 14 Аксессуары 15 Полотенцесушители 16 Смесители на борт ванны 17 Смеситель для биде 

Code itself

 $r=$this->get_typ(); $is=0; foreach ($r as $res){ if ($is!=0){ $objPHPExcel->createSheet(); $objPHPExcel->setActiveSheetIndex($is); $active_sheet = $objPHPExcel->getActiveSheet(); } $is++; $str=substr($res['nazv'], 0, 10); $active_sheet->setTitle($str);