An CNC automatic tool changer, or shortened to auto tool changer, is used in computerized numerical control machine tools to enhance the tool carrying capacity and production of the CNC machines. CNC automatic tool changers are able to perform rapid tool changing, which greatly improves the efficiency.
Generally speaking, the primary function of a CNC auto tool changer is to improve the capacity of the CNC machine, enabling it to work with a handful of tools. It can also be used to change out broken or worn out tools. CNC automatic tool changers are an integral part of a complete automation system.
A simple CNC machine typically works with only one tool, but if more tools are required (e.g., turrets), a CNC automatic tool change needs to be provided. These tools are normally stored on a magazine which enables the machines to work with multiple tools without any operators.
A CNC automatic tool changer is composed of a main base, tool holder, gripper arm, support arm and tool magazines. Although the adoption of CNC automatic tool changer can increase the speed, accuracy and reliability of machining, it is not flawless. In fact, it is sometimes more challenging to use compared with manual tool changing methods. For instance, the tooling used must be easy to center to allow easy grabbing by the changer. And it will require a simpler mean for the self-disengagement of the tooling. Tools used in automatic tool changer are typically secured in tool holders specifically designed for this function.
When you issue the tool change command with the computer control, the tool changer will assume the “tool change position”, which prompts the arm of the tool to pick up the designated tools as it swivels between the magazine and machine turret. The grippers, each of which is located on each of the two sides, rotate 90 degrees to deliver tools to the front face of the turret. One picks up the new tool from the magazine and the other picks up the older one from the machine turret. It then rotates 180 degrees so that the tools can be placed into the designated position.
Such a unique mechanism improves the productive time to a very significant extent. It essentially acts as a tool storage which accommodates the returning machine tools after they’ve carried out the required operations. This improves the flexibility of the machine tool, allowing it to change heavier and larger tools easier as well as renewing cutting edges automatically.
There are basically two types of CNC automatic tool changers, characterized by the distinct shape of the magazine: the drum type automatic tool changer and chain type automatic changers. The drum type CNC automatic changer when the number of tools used is below 30 during the machining process. As the name implies, the tools are kept in the periphery of the drum.
The chain type CNC automatic tool changer, on the other hand, is used when the number of tools used is beyond 30. This number tends to vary depending on the distinct design and manufacturer of the tool changer. The rule of thumb is that the number of tools for the chain type automatic tool changer will always be more than that of drum type. However, search speed of the tool will be lower with a chain type CNC automatic tool changer.
Automatic tool changers were primarily used for chip-removal machinery, namely mills and lathes. Sheet metal working machinery largely capitalizes on one of these tool changers as well for automatic rearrangement of tools. Panel bending machines also incorporate the CNC controlled changer to enable the movement of punches based on the size of the part. Generally speaking, a 6-axis industrial robot is sufficient in handling the sheet metal blanks, and is also responsible for changing dies and punches amongst different batches. In a nutshell, CNC automatic tool changers cover a very broad range of applications topping the ones mentioned above, from very small payloads to larger payload applications that require exceptionally large tooling capacity.
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