tire
A tire is a circular object that surrounds the wheel so that it does not hurt. Natural rubber is the most used raw material, but synthetic rubber is also used. The raw material rubber is first kneaded with a machine or a roll, such as a stirrer, called a bombard mixer, mixed with other materials, and kneaded uniformly. Examples of the material added to the raw rubber include sulfur vulcanizing agents, vulcanizing accelerators, carbon black as a reinforcing agent, zinc nitrate, zinc white powder, magnesium carbonate, antioxidants and coloring agents, and stearic acid and paraffin for facilitating kneading and molding . Thus, the uniformly kneaded rubber raw material comes out as a sheet. In the case of a tire, a plurality of layers of a tire coat or a metal wire for reinforcement are attached to this sheet. Then, it is put into a vulcanizing kiln and heated to simultaneously perform molding and vulcanization. Thus, the tires are made one by one by putting the material into the vulcanizing kiln and molding and vulcanizing them.