Automatic Tool Changer

For three axis machines which perform a wide variety of operations tool changes a programmed into the tape for fully automatic selection and replacement.

The automatic tool change system may consist of following elements:

 Rotary tool storage magazine for numerous tools.

 Automatic tool changer to remove tool holders from the machine spindle and replace them with tape programmed tools.

 Basic tool holders adaptable to a multiplicity of cutting tool types and work specifications.

 Tool coding rings and system for selection of proper tools in accordance with tape signals. In operation, the automatic tool change is accomplished in four steps:

 By tape command (and from any location the magazine) the tool magazine rotates to proper position to bring the pre-selected tool into place for particular operation. One end of the tool change your arm then grasps the tool while the opposite end grasps the tool to be replaced in the spindle.

 The tool changer arm moves out away from the spindle removing one tool from the magazine and other tool from the spindle

AUTOMATIC TOOL CHANGER

An Automatic Tool Changer is equipment that reduces cycle times by automatically changing tools between cuts. Automatic tool changers are differentiated by tool-to-tool time and the number of tools they can hold. CNC tool changers allow a machine to perform more than one function without requiring an operator to change the tooling. A CNC tool changer can quickly change the end effectors without the requirement of multiple robots. Tool changers can be a manual tool changers or automatic tool changers. A CNC tool changer fulfills the requirement of multiple tooling for a wide variety of machine tools.

Why Tool Changer is needed?

Tool changer is equipment which is used in CNC machines to reduce the cycle time. The term applies to a wide variety of tooling, from indexable insert, single point tools to coded, preset tool holders for use in automatic tool changers. It includes power-actuated, cross-slide tooling and turret tool holders for single spindle chuckers, interchangeable-block boring tools. A number of basic types of tool holders are available that accommodate most face mills, end mills, drills, reamers, taps, boring tools, counterbores, countersinks, and spot facers. Arbor type cutters such as face mills and shell end mills are held in an arbor type tool holders. Shank type mills are held in positive lock holder. Drills, reamers and boring tools are held in a straight shank collet type holder. Taps are held in a tension and compression collet type holders.

Types of automatic tool changer

There are mainly three kinds of tool changers available in market according to the tool magazine arrangements provided.

1. Tool change system with gripper arm 2. Tool change system with chain magazine 3. Tool change system with disc magazine

1. Tool Change system with gripper Arm In this system, there are mainly two elements

 Disc with magazine

 Gripper arm

In this system, a disc is provided with magazine, in which different types of tools are loaded. It can hold maximum 32 tools. In magazines, all the tools which are required are fixed in the magazines. The tool which is programmed in controller according to the program will

be indexed in front of the gripper arm and then the gripper arm grips the tool and performs the operation. After completion of the operation by each tool, the gripper arm places the tool back

DYNAMIC Industries Ltd.

Description of the gripper arm

The tool changer gripper arm consists of a central aluminum structure with terminal tool grippers of hardened steel. Tool gripping and release are obtained by means of a spring-operated mechanism actuated by the rotation of the arm. The latter, in turning, engages or disengages the grippers from the tools when these are in exchange position.

2. Tool Change system with chain magazine

In this kind of system, a chain is provided with magazines for tool holding. This chain can hold numerous tools so it is used in heavy machineries. Starting from 32 it can hold more than 100 tools. These chain is indexed in front of the head stock directly as per the tool. In this kind of system there is no arrangement like gripper arm. The chain itself is indexed and the machining is done while keeping the tool in the chain only.

Fig: Tool Change system with chain magazine

3. Tool change system with Disc magazine

In this system, the tools are held in a big disc. This disc is not similar to the disc provided in gripper arm mechanism. In this disc, there are tool grippers provided separately for each magazine these grippers holds the tool and performs machining operation as well.

This system disc can hold 32 to maximum of 64 tools. These type of tool changers are used in medium capacity machineries.

Fig: Tool change with disc magazine

DYNAMIC Industries Ltd.

CONCLUSION:

After the successful implementation of the automatic tool changer along with tool a pre-setter, following will be some of the major advantages:

 It would save 6-8 seconds of time per cycle, on an average, which is very good in terms of time-reduction.

 It can perform multiple operations in a single set up.

 It can re-tool quickly in order to accommodate product designs that are changing in timely response to market demands

 It is able to replace quickly a worn out or broken part

 Reintjes, J. Francis (1991), Numerical Control: Making a New Technology, Oxford University Press.

 Design and Simulation of Microcontroller Based Automatic Tool Changing System in CNC Machine, La Pyae Lynn, Theingi and Win Khaing Moe.

 Malloy, Robert A. (1994). Plastic Part Design for Injection Molding. Munich Vienna New York.

 Hanser.Todd, Robert H.; Allen, Dell K.; Alting, Leo

(1994). Manufacturing Processes Reference Guide. Industrial Press, Inc.