Components of success

October 27 2009
A clever machine

Never before I met protection metallic fence around  machines. At OJSC “Izhorskie zavody”, in workshop No.34 around Aries 4 machine I found it first time. Power and rotation speed of spindle are so high, that chips fly away from the machine for few meters. In august horizontal boring machine Aries 4, made by Italian company Innse-Berardi (former Innocenti) was put into operation. Italy is strongly stays on third place in the world in field of machine tools building.

Swedish hardening and Italian temperament

Aries 4 is the horizontal milling and boring machine. Main operations, which it will provide and is already providing – drilling of holes and milling planes of large-sized details for nuclear power stations and for oil-chemistry industry. But this operations aren’t only, which Aries 4 can provide. It’s potential is much bigger, than other machines have.

But, if you want to reach maximal effect, you have to use at this machine only modern higly-productive metal cutting tools.

Starting from 2008  OJSC “Izhorskie zavody” is purchasing progressive tools from foreign manufacturers – mainly from Sandvik company (Sweden). Sandvik Coromant is the world leading manufacturer of metal cutting tools and inserts, made of carbide material. It proposes more than 25000 names of tools.

But machines, which OJSC “Izhorskie zavody” had till today, cannot expose all advantages of these tools. This connected with low speed of spindle rotation, which old machines have. For example, Skoda 2707 machine, situated in workshop No.34, after modernization provides only 700 rpm. All other machines, including Toshiba (Japan) – only 400 rpm. At the same time Aries 4 reaches 2000 rpm! For any machine there is a simple rule: if you have higher spindle speed, you have higher productivity.

This is first advantage of Aries 4 machine – absolute correspondence between machine’s and tools facilities.

Feel the difference

Second great thing in Aries 4 machine – tool cooling system. Machine’s design foresees special ducts, so coolant can be delivered trough tool. This is very important for drilling operations.

At machines, which have outside coolant deliver, coolant cannot reach drill, when it is in deep hole. And chips evacuation can be provided only manually. Operator has to take metal hook and take chips out of hole.

Drills, which can be used at Aries 4 machine, have inner channel for coolant supply. Chips are washing away from hole by coolant, which delivers with high pressure. Large diameter drill cuts stainless steel plate so easy, like hot knife cuts butter! Drilling speed is fantastic. And there are many holes to drill.

List of workpieces, foreseen by production program, is large. In first turn – plate of protection pipes block and cover of upper block of nuclear reactor. Then is planned to machine almost all inner devices of reactor: enclosure – drilling holes and milling edges, wellhole – drilling of big quantity of holes, then – protection pipes block. Speed of execution of these operations, which previously considered as very laborious, is increasing dozens of times! To compare productivity, two plates started to machine in the same time. First was installed to Aries 4 machine, second – to Shiess machine. Holes were almost equal size. So, while Shiess drilled one hole, Aries 4 drilled thirty!

Question is urgent ! in this case out of turn

Third advantage of new machine – it is completed with rotary table and floor plates 14 meters long. Load capacity of rotary table – 400 tons. This feature allows to install two workpieces in the same time. For example, first workpiece, which was installed – reactor cover. Period of its machining – almost one month. But suddenly appears necessity for machine plate of protection pipes block or steam generator. Aries 4 machine allows to stop machining of first workpiece and provide this urgent work, and after that to return to first workpiece.

At other machines is necessary to deinstall reactor cover and after machining of second workpiece, to install it back, align it, etc. But Aries’s long floor plates save this time. Machine’s column travels from first workpiece to second. By the way, traveling speed is fantastic – 15 m/min! Possibility to take some additional work without additional time expenditures – another one advantage of Aries 4 machine.

Human element

First work, which was performed at Aries 4 machine – trying of new technology of threading in reactor’s casing. This is one of the final and most difficult operations in all cycle of vessel manufacturing. It always was performed only by high-class operators with huge experience. By this thread connection reactor’s casing and cover must be assembled together. 54 threaded rods must hold 16.7 MPa pressure inside vessel.

Previously threading operation was provided by thread chasers. This is long and not-perfect method. If chaser was broken inside hole, it must be replaced to new one. This caused change of thread profile, it must be adjusted manually after machining. Destiny of multi-million order depended from skill of one-two man. For many years this operation was performed by high-class operator Albert Adjubalis. His skill compensated imperfection of  machine and tools. An there was no other technology…

Aries 4 machine allows to use principally other method - whirling thread cutting. This is threading by special thread mills.

There are many advantages. First of all – these mills have long life period. Threads in all 54 holes are absolutely equal, because made by same tool.

Second – quality of thread is much better because of milling method. Roughness of thread even lower, than drawing requirements.

Third – total absence of any adjustment works after machining.

During training for use new method, operators checked cutting parameters at two holes. Then provided finishing in third hole and made full machining of another three holes. All threads were identical. Now operators are ready to provide threading of reactor casing using new technology.

Clever machine

Measuring equipment, supplied by Renishaw, corresponds to leading world standards. Renishaw’s  specialization – devices and tools for control of cutting tools and workpieces at CNC machines. Besides contact devices, Renishaw also produces contactless systems, using laser technology.

Aries 4 machine equipped with Renishaw measuring system. Results of measuring stored in machine’s memory. As result, alignment of the workpiece before machining becomes much easier. Milling plane is determining automatically. For metal cutting equipment this is non-standard and important option.

There is another useful function. Machine equipped with special attachment head with independent motor. This head transforms Aries 4 machine to 5-axis machining center. Practical using of this facility is now examining by our technologists.

There is difficult task for programmers – to make slot for sealing in reactor’s casing, using milling method. This operation can replace machining at vertical lathe Shiess.

The problem is that finishing machining must be provided at independent block before reactor’s assembling, welding and heat treatment. After assembling reactor cannot be installed to vertical lathe.

If program will be made and technology will be changed, we will have double effect. First – milling is more productive method, than turning. Second – finished surface won’t be subject of heat treatment.

Adjusting of CNC system of Aries 4 machine was provided by Siemens company.

Chief technologist of OJSC “Izhorskie zavody” Anton Lebedev: “German specialists are very sociable. They were ready to teach our operators, how to use CNC system. Operators asked a lot of questions about using control panel, programming.

At such machine, as Aries 4, many things depend from operator. He must well know programming. Control panel allows to provide programming of 80% of machine’s functions. This can be done also by operator. For this purpose he must have necessary knowledge. I am glad, that people, who works at Aries 4 machine, are mostly young and interested in new technologies.”

Aleksey Smirnov

Translation from “OMZ-Mechanical engineering Cases magazine” N° 10(131) page 1,3 27.10.09