Preparation of Technical Documentation for a Combine Harvester Cylindrical Gear

Technical documentation refers to the geometric, design and strength requirements of the workpiece and serves as an important source of data needed for production in practice. The identified causes and findings regarding the damage to the cylindrical gear were then incorporated into the preparation of the technical documentation. With the aim of improving the properties of the cylindrical gear and the guideline that the newly manufactured cylindrical gear must better withstand various loads during operation over a longer period of time, he prescribed material 17CrNiMo6 for the production of the new cylindrical gear, which is considered to be of higher quality and more suitable for operation in more demanding operating conditions than material 16MnCr5, from which the damaged gear was made.

Solution and Method

Technical documentation refers to the geometric, design and strength requirements of the workpiece and serves as an important source of data needed for production in practice. The basic guideline during the creation of this diploma thesis was how to improve the properties of the cylindrical gear compared to the damaged gear that needed to be replaced. In this way, the occurrence of potential damage on the newly manufactured gear could be prevented due to operation in more demanding operating conditions, and the operational service life could be extended.

The quality of the cylindrical gear itself is influenced by several factors. The most important are the optimally selected type of gear material and professionally executed methods of mechanical processing, heat treatment and final product inspection. At the beginning, he carried out a detailed inspection of the damaged cylindrical gear, where he established that three types of mutually different damage had occurred, which prevented further operation of the cylindrical gear: – tooth fracture, – plastic deformation of the tooth, – pitting. He concluded that the damage of tooth fracture and plastic deformation occurred due to a certain sudden overload, which led to the occurrence of visible damage.

Due to insufficiently high-quality material, plastic deformation can occur under the influence of greater load, which causes a change in the tooth shape and leads to continued damage. The cause of the occurrence of pitting, which was already quite widespread, was sought in the fact that the pitting had spread to its current state due to prolonged operation under heavy loads to which the cylindrical gear was exposed.

Results

The identified causes and findings regarding the damage to the cylindrical gear were then incorporated into the preparation of the technical documentation. With the aim of improving the properties of the cylindrical gear and the guideline that the newly manufactured cylindrical gear must better withstand various loads during operation over a longer period of time, he prescribed material 17CrNiMo6 for the production of the new cylindrical gear, which is considered to be of higher quality and more suitable for operation in more demanding operating conditions than material 16MnCr5, from which the damaged gear was made.

With the selection of higher-quality material 17CrNiMo6 instead of 16MnCr5 and the specification of heat treatment suitable for this material, namely case hardening to a depth of 0.9–1 mm and hardening to 60 + 2 HRC, it can be concluded that the new cylindrical gear will better withstand operation under various loads than the previously installed one, on which damage occurred during operation, and will have a longer operational service life. To ensure the quality of the cylindrical gear, he also carried out a precise geometric calculation, the data of which he included, together with the prescribed material and heat treatment, in the construction drawing of the cylindrical gear installed in the combine harvester working machine. In the continuation of the diploma thesis, within the framework of technological documentation, he selected the procedures for mechanical and heat treatment as well as final inspection methods. Mechanical processing, in addition to cutting and preparing the material, included processing by the turning procedure on a universal lathe, production of gearing by the hobbing procedure, which is used for the production of gearing in high-quality manufactured cylindrical gears, and mechanical processing of cylindrical grinding and gear grinding, to ensure the required surface quality.

The quality of the cylindrical gear had to be verified after mechanical and heat treatment with a final inspection, where through the measurements carried out he established the compliance of the manufactured cylindrical gear with the requirements of the construction drawing, which he produced within the framework of the technical documentation. It can be concluded that the new cylindrical gear, made from material 17CrNiMo6, will operate smoothly in combination with its gear pair, which is represented by the still originally installed gear drive, made from material 16MnCr5, as such cases in practice, where only one gear is replaced in a cylindrical gear pair, work well together.

With the selection of higher-quality material for the newly manufactured gear, its operational service life is extended. In the production of the diploma thesis, in addition to professionally executed mechanical processing to ensure the final quality of the cylindrical gear, he also established the importance of selecting the appropriate type of material and suitable heat treatment for it. He arrived at important findings and insights that will also benefit the author in his further work in the field of mechanical engineering and gear drives.