New generation of transfer machines,
optimizing versatility
with high output for tomorrow's industries

The new BUFFOLI TRANS-N-CENTER is an indexing turret machine tool with absolutely innovative characteristics. Thanks to various innovations in technical solutions, this new generation of rotary machines is suitable for the machining of different families of products, optimizing versatility with high productivity.

TRANS-N-CENTER machines are designed with reference to specific production fields in order to offer the optimum mix of flexibility and productivity and the best results in terms of quality and control of the production process. With respect to normal Transfer Machines, TRANS-N-CENTER machines are able to cover a wider application field. Moreover, our quick changeover capability allows the machining of small batches, simplifying production management according to just-in-time criteria, and reducing in process and finished goods inventories.

TRANS-N-CENTER machines are simultaneously transfer machines, machining centers and turning centers. Basically, they are indexing turret transfer machines (therefore, the part machining is divided among different working stations) where some stations are equipped with mini-centers, with movement along three axes, capable of processing several operations in sequence. The difference with respect to a flexible machining cell (i.e., a multi-station machining center) is that the machine's productivity is not reduced by the use of the multi-tool centers. They are dedicated to small operations made in sequence within the same time that the main machining operations are carried out. All the main machining operations are made by CNC working units with static turning heads that, through axis interpolation controlled by CNC, carry out any turning, facing, contouring, or internal and external threading operation, without the use of taps or threading dies but only with single point insert style turning tools.

Recently, at the Pegler factory in United Kingdom, BUFFOLI has installed a very advanced TRANS-N-CENTER. It is capable of machining more than 400 different types of fluid interception and regulation devices (up to 4" if made of brass, bronze and cast iron, and up to 2" if made of steel) with maximum facing strokes of 30+30 mm. The machine is able to produce economically: Globe Valves, Horizontal Check Valves, 3-way Gland Cock Valves, Vee Reg Valves, Spr Rel Valves, RD Globe Valves, Globe Valves SS Seat Disc, Gate Valves, Lever Gate Valves, Plug Cock Valves, Gland Cock Valves, Y Stop Valves, D/Reg Valves, Commissioning Set Valves, D/Reg Variable Oriz Valves, Swing Check Valves, Angle Globe Valves, Transformer Valves, etc. This new machine replaced several traditional machines (also more than 20 conventional machines, such as lathes dedicated to the execution of final operations, e.g. facing of flange valves not workable completely on Transfer Machines). These machines, often obsolete and underutilized, carried high costs relevant to maintenance, personnel training, safety, and occupied valuable floor space, etc.

The main novelties in the working performances are the following:

· Possibility to produce, with one piece of equipment only, a wide variety of parts. The achieved productivity is 100% to 200% of comparable Machining Centers or Machining Cells.

· Possibility to machine parts in one single clamping including those requiring machining in 5 directions, including angular orientation of part features. Improved component quality results thanks to the elimination of re-clamping errors and damage as a result of extra part handling between machines.

· Possibility to machine simultaneously, different parts in the same turret rotation. (For example the machining of the body and wedge of gate valves is made in order to allow the immediate testing of these two mating parts).

· For the production of parts that, besides the machining of the main operations, need various other small operations (bleeders, connections, etc.), TRANS-N-CENTER machines are equipped with fast drilling and threading mini-centers able to make, in sequence, several operations in a large operating area. These mini-centers make all these small operations within the machining time of the longest main operation. In this way, the machine productivity is the one typical of CNC transfer machines (much higher than those achievable by means of working cells and all other flexible production means). Like on a transfer machine, the cycle time is determined by the longest operation, because all other operations occur within this "masked" time (assured by and thanks to complete machining in one single clamping - better alignment, concentricity and squareness among the machined part features).

Technical Solutions Adopted

The machine works with the characteristics presented in the previous paragraphs thanks to the combined use, on a single piece of production machinery, of:

1. Turning, facing, and single point threading units, controlled by CNC, able to make any turning or threading profile. These units are equipped with quick change devices allowing quick tooling changeover time (with quick recall of the machining parameters of each part from the supervisory PC);

2. Very compact CNC mini-centers carrying out, in sequence, a series of light operations in the time range in which the working units installed in the other stations make the operations taking longer times. All these light operations, in the common technology, are made by means of re-clamping machines (with consequent problems of dimensional deviation and problems of moving and stocking of partially-finished parts, with risks of damage, slow-down of the production flow, inventory costs, etc.);

3. Rotating clamping devices, equipped with part recognition systems for the execution of a different part program;

4. High precision systems for the inclination and translation of the working units for the execution of inclined machining. They are equipped with devices for high rigidity and high precision angular positioning.

TURNING, FACING AND SINGLE POINT THREADING UNITS CONTROLLED BY CNC, EQUIPPED WITH QUICK CHANGE DEVICES

In order to process parts using non-profiled tools, the machine is equipped with CNC working units with static turning heads that, through axis interpolation controlled by CNC, make contoured profiles and internal and external threading with single point insert tools. The new generation of BUFFOLI software allows ease of use and programming quickness. Even for complex single point threading operations, programming is particularly quick and simple and can be also made in "teach" mode. The programming ease of the new software is possible thanks to the use of the multi-processor CNC designed by BUFFOLI, instead of a commercial CNC. In order to simplify the machine use and to reduce the CNC programming time, BUFFOLI has implemented automatic functions allowing the user to program machining operations by recalling one command only (i.e., "THREADING") instead of a long sequence of ISO instructions, "G codes".

The recessing heads with radial stroke, able to cover a wide range of profiles, allow a fast changeover of the spindles (from spindles with recessing heads to spindles without recessing heads, from spindles with single point contouring tools to spindles with form tools). The heads can be disassembled from the spindles as simply as tool-holders, with a push-button release. The machine is equipped with CNC heads with working strokes of 30+30 mm, suitable for the execution of facing operations on flange diameters up to 200 mm. A software program assures a constant cutting speed during the facing operation.

THREE-TOOL CNC WORKING CENTER

Drilling and threading centers have been specifically designed to be extremely compact in order to be located side by side on slide supports in our transfer machines. The solution traditionally utilized, on transfer machines and working cells, is to use heads with tools arranged in a star configuration (usually called Revolver Turrets). Equipping spindles installed on two orthogonal cross slides causes a considerable increase of the machine size, resulting in a slower machine, with less productivity and difficult accessibility for tool changing and maintenance.

As for the programming of the Working Centers with BUFFOLI software, we have implemented automatic "menu" functions allowing for a very simple programming language. Not standard according to ISO or "G code" rules, this system allows easy programming by non-skilled "shop" personnel (with consequent quick programming times).

ORIENTED CLAMPING DEVICES

The machine is equipped with rotating devices for part clamping. Through the CNC software, it is possible to program, for each station, the angular position of the chuck, or, if necessary, to set a multiple rotation sequence in order to present up to 5 faces of the part to the working spindles.

Since, in some cases, the machine processes different parts simultaneously, the rough parts loaded alternately into the jaws are identified as "part A" or "part B", in order to control the machining process as programmed for one or the other part. The CNC recognizes, at any point in the working cycle, "jaw A" and "jaw B" thus controlling the proper spindles and machining program for the relevant part.

UNIT INCLINATION AND TRANSLATION SYSTEMS

The machine is also equipped with machining spindle translation and inclination systems. These systems, matched with rotating devices for part clamping, allow machining at various inclinations.

The devices for angular positioning are particularly rigid and accurate, (built for adjustments of a thousandth of a degree), necessary for the production of parts with very tight angular tolerances. As a matter of fact, for the production of gate valves, the machine has been designed with four facing units programmable for different angles. The two units designed for the left and right facing operation on the wedges are installed in the same station and can be precisely adjusted to the angle set by the operator on the supervisory PC. They work complimentary to the two facing units designed for the machining of the internal seat of the bodies. In order to achieve an optimum metal to metal seal between body and wedge, it is particularly important that the inclination of the units making the finish seat on the body and wedge can be regulated by the CNC computer to a precision of one thousandth of a degree.

Since the part is clamped in the jaws at a considerable distance from the translation and inclination slides (half the machine span plus the frame thickness); the accuracy of few thousandths of degree on the part is achieved by the precision of the unit positioning system's translation and inclination slides, around 0,01 mm.

Actually, the TRANS-N-CENTER is a machine much different from traditional transfer machines; conceptually innovative it addresses the quality of the finished product. In fact the machine assures the highest quality of final product seen as an "assembled valve" and not simply as a single component. BUFFOLI has directed its engineering to the solution of the "finished product quality" problem and suitability for the end use of the product, instead of limiting the solution only to meet the technical part tolerances laid down by the customer.