Legal basis: The term "utility model" in the Patent Law of People's Republic of China (PRC) refers to a new practical technical scheme for the shape, structure or combination of products. The difference between utility model and invention lies in: first, utility model is limited to products with a certain shape, and it cannot be a method or a product without a fixed shape; Second, the utility model is not too creative, but it is very practical. For example, the shape of a product refers to a certain spatial shape that the product has and can be observed from the outside. The technical scheme proposed for product shape can be the technical scheme proposed for product three-dimensional shape, such as the improvement of cam shape and cutter shape; It can also be a technical scheme of two-dimensional shape of products, such as the improvement of sectional shape of profiles.