Lancet needle is a typical medical treatment device. Its tip consists of two lancet planes and one bevel plane. When the lancet needle is inserted into soft organ tissue, the insertion force may influence the needle cutting direction and treatment effect and increase the pain. One of the main factors affecting this insertion force is the geometry of the needle tip. Based on the research on the shape and processing method of the conventional lancet needle, a new lancet needle tip geometry was obtained by adjusting the relative position of the grinding wheel to the needle. A mathematical model of this new lancet needle was established. The relationship between processing parameters and needle shape was analyzed, and the needle insertion force was predicted. Compared with the conventional lancet needle, the new lancet needle is sharper, and the insertion force on the cutting edge is smaller. However, this change in the grinding position of the needle lancet plane has a great influence on the shape of needle tip near the intersection of the bevel plane and the lancet plane. Some special second bevel angle and rotated angle will cause a large change in the specific force at the intersection place, which is not conducive to reducing the insertion force.
Keywords: Lancet needle; cutting edge geometry; grinding; insertion force; mathematical model.