Adjustable indexing tensioning device used for testing machine

The invention relates to an adjustable indexing tensioning device used for a testing machine. The adjustable indexing tensioning device comprises a ball screw nut pair, an indexing plate, an elastic needle, a clamping groove, a rotary block, a rotary handle, a tensioning sliding sleeve, a tensioning support, a bottom plate, linear bearings, a fixing plate and steel wire ropes, wherein the tensioning sliding sleeve is arranged on the tensioning support, the ball screw nut pair is arranged in the tensioning sliding sleeve, the indexing plate is fixed to the sliding sleeve, the rotary block is mounted at an end of a ball screw to be matched with the ball screw, the rotary handle is mounted on the rotary block, the elastic needle is mounted in the handle and is controlled to lock the handle by a spring, the linear bearings are fixed to a bottom plate through bolts, and each linear bearing comprises a bearing support, a plain shaft and a sliding block. The adjustable indexing tensioning device can apply tensioning force on a sample piece of the testing machine, also solves the problems about indexing and self-locking, enables the tensioning force to be more accurate during application and is simple in structure and convenient to operate.