DMG gamma 2000 TC tool thermoclamping machine of a modern machine Concern “Nicmas”
Previously, we wrote about the modern DMG gamma 200 TC machine of the “Nicmas” Concern. Today we will talk about a device that was purchased at the same time as the DMG gamma 2000 TC machine and which is an integral part of the equipment for its reliable operation
How does a thermo-clamping machine work and why is it needed?
Relatively recently, a whole type of auxiliary tools (so-called thermal mandrels or thermo-cartridges) was developed for fastening the cutting tool using a smooth cylindrical connection with tension, while this method is based on the physical phenomenon of changes in metal dimensions under the influence of temperature.
The tension connection of the chuck-shank system is necessary to keep the tool firmly in place. How is it implemented? The diameter of the hole of the auxiliary tool is made several microns smaller than the outer diameter of the shank of the tool and in a cold state they do not fit into each other, but when the thermal cartridge is heated (in practice, this is mostly done with the help of high-frequency currents, in particular, such as thermal machines) , it expands and allows you to freely insert the cold shank of a cutting tool (mills, adapter, etc.). When the heat setting has hardened, the cutting tool is firmly and reliably clamped. During operation, such a tooling system reliably transmits torque and cutting power with minimal runout that does not exceed a few microns. For most practical machining tasks, this is quite sufficient. Alternative types of fastening give a larger error. And for finishing operations, where high demands are placed on the accuracy and rigidity of the “machine-fixture-tool-part” system, this method has a significant advantage compared to alternative methods of tool clamping.
For pressing, the reverse procedure is carried out – the thermal cartridge with the tool is placed in the thermal machine on the stand, the induction head is brought up, the part at the junction of the shank of the tool with the thermal cartridge is heated, and in seconds, while this place is hot, the tool is removed. The number of clamping-unclamping cycles can reach 1000 times (this is guaranteed by the manufacturer of auxiliary tools of this type).
To speed up the process of cooling the frames in the thermal machine, a set of special heads that are put on the thermal cartridge is provided. They are a hollow cylinder inside which the coolant circulates. The choice of one or another head is dictated by the outer diameter of the frame. This method is implemented for almost all tools in the tool shop of the machine. For example, in order to process the working part of a steam turbine blade, it is necessary to use at least six tools in sequence.
There is preliminary processing, and there is finishing processing. The tools (mostly milling cutters) have different shapes and differ slightly in size, number of teeth, shape of the replaceable cutting part (plates). As a rule, the design of the blades has smooth transitions between the tail and the working part, made with radii – so-called fillets – and they need to be processed with separate tools.
The same tools allow you to process blades of different configurations and sizes. When parts are changed, shavings are removed from the base surfaces of machine tools, in order to ensure correct and accurate installation of the part in the machine (basing), it is necessary that all contact surfaces – both tools and parts – are clean.
Most of the tools used here are fixed in frames precisely on the principle of a thermal clamp. To get a working system “auxiliary tool – cutting tool”, you need to connect them in one of the ways. There are various methods of fastening, the most advanced is the thermoclamp, because it is reliable and accurate, but only on the condition that the frames and cutters are branded and tested. In this case, long and reliable work, including the machine, and minimization of unacceptable deviations from the requirements of the technical documentation on the processed parts are guaranteed.
This is a technically difficult procedure for the reliable operation of the DMG gamma 2000 TC machine of the “Nicmas” Сoncern.