Holding, changing, storing,
handling and administrating tools is a critical link in the chain that supports
successful machining. However good the cutting edge, insert-clamping method,
tool holder or cutter-body, if the tool holding interface with machine spindle
and turret is un-satisfactory, performance, reliability and quality will not be
as good as it can be.
An important potential for
efficient production may not be utilized. More and more machine tools are being
built where the tooling system plays an increasingly important role –
CNC-lathes, turning centers, multi-task machines as well as machining centers,
vertical turning centers, boring mills, etc. In many of these machines, tool changing is manual and
down-times are directly related to how long it takes to release a tool, replace
it, clamp the new one and establish the right cutting edge position. In many
other machines, tools are changed mechanically with automatic tool changers (ATC)
from a magazine to tool spindle. For efficiency in both cases, the tooling
system is the key factor.
MANUAL TOOL
CHANGING
In machines where tools are
manually changed, the time taken for these stoppages have a profound effect on
machine tool utilization and the time taken for completing batches of
components. If by shortening the tool-changing time the time-share of actually
cutting chips is increased, making the machine more efficient. Instead of tool
changing and tool orientation for a new component set-up taking most of an hour
(as it often has), tool changing with a quick-change tooling system is reduced
to a fraction of an hour (minutes).Similarly, stoppages for changing one
or few worn tools during a batch is
reduced dramatically with quick-change tooling. The effect this has is that the
machining time is increased from typically around a third of the available
production time to around half.
AUTOMATIC TOOL CHANGING
In machine tools where tools are
changed automatically, tool changing time is not the decisive factor. Instead
factors such as tool stability and strength, accuracy, positioning, flexibility,
compatibility, storing and handling together provide the advantages that result
in production benefits. More competitive cutting data thanks to higher
stability, fewer and better-organized tools, interchangeability of tools
between adaptors and machines, equal suitability for stationary tools and
rotating tools and the ability to be an interface between tooling system and
tool-spindle and tool-magazine are examples of vital qualities. A modular
tooling system having all the right qualities can give wide-ranging advantages
in not only individual machine tools but whole machine shops. In both
tool-changing cases - manual and automatic - the tooling system being modular
with a state-of-the-art coupling is what makes the difference.
TOOL CHUCKS
Incorporated in tooling systems –
and critical for performance - are tool chucks. The ability to securely and
accurately clamp and present shank-tools for a machining operation is decisive,
not only for achieving the desired component quality and tool-life, but also
for performing roughing operations productively. In times when spindle speeds
are continually elevated towards high speed machining (HSM) and new machining
methods are being introduced as well as finish milling is expected to reach new
levels, the quality of clamping solid carbide milling cutter and drill as well
as indexable insert end mill will in many cases make the difference between
competitive and uncompetitive machining.
TOOL HOLDING DEVICES
For doing different variety of
operations on lathe machines many different types of tools are used. To hold these tools in the respective positions,
various types of tool holders are used. The following tool holders are used in
capstan and turret laths:
Straight cutter tool holder
This tool holder
can hold tool bits perpendicular to its shank
Adjustable angle cutter tool holder
This is similar
in construction to the straight tool holder. But this tool holder has an
angular slot. The tool is fixed into this slot by means if set screws
Multiple cutter holder
This can hold
two or more tools at a time. By this arrangement turning of two different work
pieces can be done simultaneously.
Sliding tool holder
This type of
tool holder is used for boring; recessing, grooving, facing etc. the holder has
a slide which may be adjusted up and down perpendicular to the lathe axis. This
vertical adjustment is done accurately by means of a hand wheel using
micrometer.
Offset cutter holder
In this type of
tool holder, the holder body is offset with the shank axis. By this off set,
large diameter works can be turned or bored.
Knee tool holder
A knee tool
holder is used for simultaneous turning and boring or turning and drilling
operations. This holder has got a knee with three holes. The lower hole
concides with the lathe axis. Its is used for holding boring bars, drills, ect.
The top hole acts as a guide bush for the pilot bar projecting from the head
stock. A turning tool holder is held in the central hole.
Flange tool holder
It has a flange
which is bolted directly to the turret face. Tins holder has a cylindercal
bore. It can hold a boring bar. By means of a socket, drills and reamers are
also held in the bore. Two set of screws are available for fixing the tools and
sockets in position.
Roller steady box tool holder
This is a very
useful tool holder. It is commonly used for turning bar stock. There are two
rollers giving support to the work. The tool is mounted on a slot by means of
set screws.
Combination tool holder
This holder is
also known as multiple head. In this holder, a number of turing tools and a
boring bar can be fitted together as a combination. All these tools take the
cuts simultaneously.
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