This news article was originally written in Spanish. It has been automatically translated for your convenience. Reasonable efforts have been made to provide an accurate translation, however, no automated translation is perfect nor is it intended to replace a human translator. The original article in Spanish can be viewed at De eslabón más débil a superestrella de mecanizado

Why the new connection of husillo maximiza the start of shaving?

Of link feebler to superestrella of mechanised

Mark Huston, vice-president, Global Solutions of Engineering; Doug Ewald, director, Global Gestión of Products, Systems of tools; and Ruy of Rubs of Souza, manager, Global Systems of Tools, Engineering of Product. Kennametal Inc., Latrobe, PA09/07/2012

The mechanised of difficult materials like the titanium is a challenge in himself same. The mechanised of hard alloys with the additional pressesure to attain greater productive performances involves maximizar the start of shaving in front of speeds of low cutting and strengths of significant cutting. The manufacturers of machines tool have answered with centres of milling and of special turning that present husillos of rigidity and amortiguación improved and with big structures of machine, all this to minimise the no wished vibrations, that deteriorate the quality of the pieces and the life of the tools.

In spite of what these advances have contributed to increase the productivity, the feeblest point often has been the own connection of the husillo.

In the majority of the cases, the connection tool-husillo determines the quantity of material that can start in a determinate operation. This is due to the fact that this interface has to bear high loads without losing his rigidity until the deformation of the tool was too big or begin to appear the vibration. With the continuous advances in the tools of cutting and machining centres, a connection of husillo that make possible the best utilisation of the available power is an important consideration to investigate from the starts of the planning of the production.

Several types of connection of the husillo have developed or optimised along the last decades. Because of a good relation cost/provision, the cone ISO 7/24 turned into one of the most popular systems of the market. It has been a success in a lot of applications, but the limitations of precision and high speed have prevented that it go further.

By means of the combination of strength of high subjection and levels of interference optimised, KM4X provides a robust connection, rigidity very high, and the capacity of load of flexión for a very improved performance in the mechanised of alloys of high resistance and other materials, what allows taxles very high of start of metal and a lot of more pieces finished by day.

The arrival of the contact of face represented an important step regarding the standard cone 7/24. The combination of the contact of face with the cone enterizo 7/24 provides big precision in the steering of the axis Z, but also presents some problems, to know loss of rigidity to greater speeds or high loads lateral. The majority of tools of the market are macizas and the husillos have a strength of subjection relatively low. The rigidity of the connection is limited since the radial interference has to keep minimum. The tolerances required to attain a contact of consistent face are, therefore very narrow, giving place to high costs of manufacture.

In 1985, Kennametal —signs commercialised in Spain by Kenci— and Krupp Widia initiated a conjoint program to develop a system of universal fast change, known like KM and recently standardised as ISO 26622. To principle of the 90, the system HSK began to employ in the machines of Europe and later turned into the norm DIN 69893, afterwards ISO 12164.

The system KM of fast change of tooling consists in two basic components: the unit of subjection and the cabezal of cutting. The unit of subjection mounts in the machine tool (a turret milling machines portaútiles or block of tools for fixed applications and a husillo rotatory to adapt to rotary presses applications) and is the receptacle of the unit of cut/tool holders interchangeable. When it is necessary a change of tool, an operario simply frees the system of fixation, replaces the unit of cut, and blocks it in his position. The time died of the machine is question of seconds.

The system of connection of the husillo KM4X of Kennametal has a configuration for able heavy work to work in conditions of high speed, under pair or low speed, high pair. Without KM4X, helicoidal milling cutters like this would surpass the limits of the moment of flexión enough before arriving to the limitation of the pair.

The KM4X of Kennametal represents the following generation of the KM. Some systems can be able to transmit considerable pairs, but the strengths of cutting also generate moments of flexión that exceed the limits of the interface before reaching the limits of pair. By means of the combination of high strength of tighten and levels of interference optimised, KM4X provides a robust connection, rigidity very high and the capacity of load of flexión for a very improved performance in the mechanised of alloys of high resistance and other materials, what allows taxles extremely high of start of metal and more pieces finished by day.

Resistance to the moment of flexión multiplied by 3

The connection of the husillo has to provide the pair and the capacity of load of flexión compatible with the specifications of the machine tool and the requirements for a greater productivity. It does evident in applications of milling, where the lengths of projection are typically greater, the factor limitador is the capacity of flexión of the interface of the husillo. To way of example, an interchangeable strawberry of helicoidal teeth, with 250 mm (9,84”) of projection from the face of the husillo and 80 mm (3,15”) of diameter, generates 4620 Nm (3407,5 ft•lb) for the moment of flexión and less than 900 Nm (663,8 ft•lb) of pair engine to start 360 cm³/min of You6To the4V with a depth of radial cutting (Radial Depth Of Cut, RDOC) of 12,7 mm and a depth of axial cutting (Axial Depth Of Cut, ADOC) of 63,5 mm.

The most critical parameters of a connection of husillo combined, cone with contact of face, are the strength of subjection and the radial interference. Maximizar The strength of subjection and select the appropriate values of interference can improve even more the rigidity of connection.

By means of the use of three surfaces of contact to improve the stability and optimise the distribution of the strength of subjection and the adjust with tighten (union to pressesure), the engineering of the KM4X gives like result a capacity of resistance to the flexión triple, compared with the one of other systems of tool.

The superficial contact and the strength of subjection combine to improve the adjust by tighten (union to pressesure) and reach thrice the resistance to the moment of flexión in comparison with other systems. The change of tool, fast and simple, reduces to the minimum the time died of the machine.

This means:

The workshops can improve machines tool of high provision, instrumented with KM4X to increase speeds and advances in the applications of mechanised difficult, obtaining like this the potential of complete productivity of the machine tool. - Often, a connection KM4X minor, like the KM4X100, will provide a performance of equal or better cutting that a greater connection.
The systems KM4X can apply in the machining centres, turning, multitarea and machines of transfer (transfer), in the manual modalities, semi-automatic or totally automatic.
By design, KM4X can llevar a wide range of operations, from the ones of low high/speed pair of torsion until the ones of high speed/under pair of torsion, what allows to the manufacturers take out the absolute maximum of his team of production.