摘要
Abstract
Objective To establish a rapid method of distinguishing straight handle bolt cutter from hydraulic bolt cutter by the cut burglarproof grid at crime scenes. Methods One type of hydraulic bolt cutter and three different types of straight handle bolt cutter with respective length of 450, 600, 1050 mm were employed as experimental tools. Eight various types of burglarproof grids were simulated using steel bars on the ground. The distances between bars were 110, 100, 90, 80, 70, 60, 50 and 40mm, respectively. The tools were used to cut burglarproof grids under some limited conditions, and the cut created a plane on the top of the cutting surface of the steel bar. The angle between the top plane on the cutting surface and burglar-proof grid was measured and analyzed. Results On the burglarproof grids with eight different spacing distance, the angles created by straight handle bolt cutter were measured in a range of 30°~150°, meanwhile, the angles created by hydraulic bolt cutter ranged from 0° to 75° or 105° to 180°. Conclusions Except for the overlapped range of angle created, the rest has distinguishing characteristics which can be utilized to differentiate the two types of bolt cutters. According to the angle between the top plane on the cutting surface and burglarproof grid found at the crime scene, 75°~105° indicates the related tool as a straight handle bolt cutter, while 0°~30°or 150°~180° indicates a hydraulic one. Hence, the angle between the top plane on cutting surface and burglarproof grid can be an effective index to differentiate straight handle bolt cutter from the hydraulic one.关键词
工具痕迹/防盗网/直柄式断线钳/液压式断线钳/立顶Key words
toolmarks/burglarproof grid/straight handle bolt cutter/hydraulic bolt cutter/top plane on the cutting surface分类
社会科学
