Gear wheel milling machine
Development of a gear wheel milling machine for milling gear wheels made from wood or plastic
As part of their third-year studies towards a Bachelor's degree in Mechanical Engineering: Design and Development, three students at Konstanz University of Applied Sciences in Germany were required to consolidate their design strengths and skills in a project in which design was the focus. Their task was to develop a gear wheel milling machine that could be used for teaching purposes and would be able to mill gear wheels made from wood or plastic with varying numbers of teeth.
|The documentation included a morphological box, a full hand-drawn schematic diagram of the machine, individual assembly drawings, all the individual component drawings and production drawings, plus the necessary force and stability calculations.|
The purpose of the machine is to illustrate to students how an involute tooth profile is formed. It is hoped that more than just a design for the machine will be produced, and that it will go on to be built as part of subsequent project work taking place next semester.
This is why it has been necessary to pay attention to costs and use standard components wherever possible throughout the project.
Structure and function of the gear wheel milling machine
|Round blanks are the semi-finished products that go on to form the gear wheel at a later stage: these are marked out on a wood or plastic panel using a multi-template, and can then be cut out using a keyhole saw. A hole is drilled through the middle of the blank, enabling it to be fitted onto a pivoting, vertical shaft. This is where it is milled to the exact outside diameter of the gear wheel using a circular saw blade. Following this, the circular saw blade is replaced with a profiling miller featuring a 20° reference edge. An eccentric drive mechanism produces vertical oscillations in the miller.|
As the machine is designed for teaching purposes, the rotating motion of the gear wheel to be milled must be mechanically coupled to the horizontal linear motion of the miller in order to provide students with a crystal-clear visualisation of this relationship. To accommodate this, the plans include a gear rack on the miller slide and a sample gear wheel on the shaft. The gear rack is mounted vertically, in a way that allows it to move, and can be decoupled from the gear wheel by means of a Bowden cable in order to perform various machine functions. The ability to handle varying numbers of teeth is being accommodated by a range of sample teeth in different sizes, plus a variable distance between the vertical shaft and the miller. As one of the key aims of the design process was to create plenty of opportunities for students to interact with one another, an additional axis was provided for moving the miller, allowing gear wheels to be produced with profile correction.
|The entire machine was designed and brought to life using standard components from norelem's portfolio of products. These include linear guides, an elastomer shaft coupling, a range of levers and pins, plus many other components besides.|
|Form D indexing plunger|
Form G indexing plunger without collar with extended indexing pin
DIN 6885 A parallel keys
Mushroom knobs with external thread
Plastic, 2-spoke handwheels with revolving grip
Clamping lever with protective cap and external thread
DIN 6340 steel or aluminium washers for clamping tools
DIN 471 circlips for shafts
Springs for clamps
Profile guide rails
Precision guide shafts
Aluminium vernier scale and zero marks, self adhesive or with boreholes
Steel spur gears, milled module 1 toothing, straight teeth, 20° pressure angle
Steel gear racks, milled toothing, straight teeth, 20° pressure angle
Elastomer dog couplings with radial clamping hub
Plastic thrust washers
Cylindrical plain bearing
Rod ends with plain bearing internal thread
Plastic tube clamp flange