A machine tool that is specifically designed for a particular component or process is referred to as a special machine tool. It is often a crucial piece of equipment in an automatic production line type manufacturing system.
The earliest combination machine tool
The first combination machine was invented in 1911 in the United States and was used to machine automotive parts.
Initially, each machine tool manufacturer had its own standard for common parts. In order to improve the compatibility of these parts across different manufacturers and make them easier to use and maintain, Ford Motor Company, General Motors, and American machine tool manufacturers agreed to standardize the size of contact between components in 1953. However, the structure of the components was not specified.
The general-purpose components can be classified into five categories based on function: power components, support components, conveying components, control components, and auxiliary components.
The power components provide the main and feed motion for the machine, including the power box, cutting head, and power slide.
The support components are used to mount the power slide, cutting head, or clamp with a feeding mechanism and include side bases, intermediate bases, brackets, adjustable brackets, columns, and column bases.
The conveying components are responsible for moving the workpiece or headstock to the processing station and include indexing rotary tables, circular indexing rotary tables, indexing drums, and reciprocating moving tables.
The control unit controls the machine’s automatic working cycle and consists of a hydraulic station, electrical cabinet, and console.
Auxiliary components include lubricating devices, cooling devices, and chip evacuation devices.
For small and medium batch production, group technology is often applied to the machine to concentrate parts with similar structure and process, improving the machine’s utilization.
There are two common types of combination machines: the spindle box and the turret combination machine.
In the future, combination machines will increasingly use transmission motors such as adjustable speed motors and ball screws to simplify the structure and shorten production cycles. They will also adopt digital control systems, spindle box and clamp automatic replacement systems, and be integrated into flexible manufacturing systems.
Special machine tools are designed for multi-axis, multi-tool, multi-process, multi-face, or multi-station simultaneous processing, resulting in a production efficiency that is several times to several tens higher than that of general-purpose machine tools.
The use of standardized and serialized common components allows for flexible configuration as needed, reducing the design and manufacturing cycle.
This results in the advantage of low cost and high efficiency, making special machine tools widely used in large batch and mass production and suitable for forming automatic production lines.
These tools are typically used to machine parts with unique shapes or boxes.
During machining, the workpiece remains stationary while the tool rotates and performs relative feed motion, allowing for operations such as drilling, reaming, counterboring, boring, milling, cutting internal and external threads, and machining outer circles and end faces.
Some combination machine tools feature a turning head to hold and rotate the workpiece, allowing the tool to perform feeding motion and process the outer circle and end surface of rotating parts such as flywheels and automobile rear axle half shafts.