Ultirx / THE BEST high speed multipurpose vertical machining centre

ULTRIX

The workpiece : Tyre moulds
Manufacturing moulds for producing tyre sidewalls is a complex process which includes intense grinding as well as precise finishing operations.

Who drives a vehicle is very familiar with tyres or at least should be. Tyres are in fact a crucial element when talking about vehicle safety. The correct type of tyre, the right pressure and moderate wear in tread ensure that the vehicle maintains ideal road holding performance in whatever gear.
Today’s tyres consist of two main parts: a rubber covering with tread which comes into contact with the road surface and a shoulder/sidewall forming the side of the tyre. This part extends from the road surface to the rim and in modern tyres it has another important feature as it acts as an air seal with the rim.
The sidewall is that part of the tyre visible to drivers, in fact tyre specifications are moulded into this part and include a unified code for identifying the type of tyre (for example to be mounted on a car or on a truck), tread width in millimetres, the ratio between height and width, the carcass, radial or cross-ply, rim diameter, speed and maximum allowable weights. The tyre manufacturer name is also moulded into the sidewall as well as other logos, trademarks or wording which vary from tyre to tyre.

The workpiece
Tyres consist of specific polymer rubber mixes which are specifically developed for moulding processes. In this article we are going to look at the mould used for producing tyre sidewalls.
The mould itself is manufactured from a piece of steel which is machined and milled to obtain a high-quality surface finish respecting product tolerance margins and surface texture.
At this point the mould is engraved - in negative - with all the required wording, logos, trademarks which are then visible on the tyre when mounted to the vehicle.

The machine
The machine utilised to obtain this mould is an Ultrix 800 RT designed and developed by Breton located in Treviso, Italy. The Ultrix machine is part of a range of machining and milling centres this Italian company offers. Machines designed and developed considering the specific requirements of today’s mould manufacturing industry.
The Ultrix 800 RT is a multipurpose machining and milling centre with a vertical spindle and five continuous axes, a tilting turntable, moving cross beam and gantry structure.
The table rotates around axis C and reaches up to 50 rpm when milling and 1,000 rpm when turning. Tilting axis A can reach up to 100 rpm. The linear axes operate at a speed of 60 m/min.
Ultrix is a multipurpose machine offering different machining options turning, milling, boring and grinding and without having to reposition the workpiece on another tool machine.
The vertical design of the Breton work centre is ideal for machining large diameter pieces such as moulds for producing tyre sidewalls.
Ultrix can turn the piece in vertical or horizontal and with axis A tilting. Thanks to a turning bar on the side of the ram the machine acquires an additional 150 mm in vertical travel allowing this machining centre to turn the outer face of workpieces which have heights greater than vertical travel of the machine. This feature allows the user to fit shorter tools resulting in a reduction in overhang and in the use of vibration damper bars except for intense machining operations and when very hard and resistant materials are being machined.
Ultrix can be fitted with a lathe / milling spindle allowing the lathe tool to be moved into different positions, this centre can machine the workpiece vertically and then horizontally optimising machining operations and tools, and when operating in diagonal can machine workpieces up to 1,000 mm regardless of the maximum diameter of the machine which is 800 mm.
Ultrix 800 RT is fitted with a tool magazine which can hold 30-60-150 tools. A numerous choice of lathe and milling spindles are available. Milling spindles S6/S1 40/40 kW (M100/18) S1 torque 100 Nm with a speed of 18,000 rpm or 28/20 kW (M38/28) S1 torque 38 Nm with a speed of 28,000 rpm or 55/40 Kw (M16/40) S1 torque 16 Nm and with a speed of 40,000 rpm.
The lathe spindle M1000/08 in S1 has a power of 30 kW and 1,000 Nm torque and a speed of up to 1000 rpm.
The PC architecture which adopts a windows user interface for the numerical control of the Breton machining centre allows the operator to interface the machine with the company intranet system and with a remote network. Regarding numerical control both the machining programs developed in CAM as well as the information concerning the tools to use defined by Tool Room, can be uploaded to the machine and thanks to the possibility of interfacing with the company’s intranet system and with a remote network, it is possible to run machine checks, adjustments etc. in real time through the remote diagnosis feature maximising machine efficiency and performance. Machining operations can be run in automatic ensuring milling quality thanks to specific check cycles which control workpiece dimensions during operations. In fact the machine detects the true dimension and the workpiece is finished to the required tolerances satisfying specifications. This feature enhances the capacity and efficiency of the Ultrix multipurpose milling centre transforming it also into a measuring centre.
In addition to the 800 RT model this range also includes the 800 4-axis model, Ultrix 1000, 1000 RT and 1000 RT HD all of which with a lathe diameter of 1,000 mm with 4 or 5 axes.

Work Cycle
Creating a tyre sidewall mould combines all the features of a modern tool machine: the first stage is intense grinding and turning to remove residual metal on the steel workpiece. As intense machining is required at this stage in the process, the spindle has to deliver enough power and a torque of up to 1,000 Nm. After having removed the unwanted metal the next stage is to rough finish and then finish the workpiece leaving it with the required surface texture and dimensions. At this stage the bottom of the mould is accurately and precisely finished as it is this part of the mould which will create the external part of the sidewall. The possibility of turning whilst the table tilts - axis A is interpolated with linear axes X and Y - results in achieving the required quality minimising machining times. However, there is still more to the work cycle: at this point small sized tools are now fitted which are 2 mm diameter chisels that work at a speed of 40,000 rpm. These chisels are used for engraving at very high speeds wording, logos, trademarks etc. and remove material without leaving burrs or rough edges which could damage the surface finish of the workpiece.

Added value
Ultrix 800 RT is designed to machine small and variable batches of workpieces satisfying the demands of the mould manufacturing industry. Ultrix is the ideal solution for this type of production requirement.
The Breton work centre combines in one machine all the necessary machining operations for removing material: milling, turning, boring and when needed grinding.
The flexibility and versatility of Ultrix does not finish here: the selection of heads and spindles supplied with the machine are ideal for intense rough milling as well as for delicate and precise high-speed finishing operations.
The various functions Ultrix offers provide considerable reductions in processing times: an example is the work cycle described in this article. By combining lathe operations with table tilting, mould profiling is completed in one run without having to resort to other machining processes to ensure a quality finish.
The added value that Ultrix 800 RT offers the mould manufacturing industry for tyres is the possibility of dealing with a complex process consisting of various and different stages with just one machine and without having to reposition the workpiece achieving a complete finished piece without downtimes and errors due to repositioning operations on other machines.
To conclude manufacturing a mould has become, regardless of the complex processes, a “short” work cycle managed by one machining centre efficiently and economically.

The workpiece
The mould for producing tyre sidewalls is manufactured from a piece of steel which is machined and milled to obtain a high-quality surface finish ensuring product tolerance margins and surface texture.
At this point the mould is engraved - in negative - with all the required wording, logos, trademarks which are then visible on the tyre when mounted to the vehicle.


The machine
The Breton Ultrix 800 RT is a high-speed machining and milling centre designed and developed focused on the requirements of the die and mould manufacturing industry.
The Ultrix 800 RT is a vertical 5-axis machining and milling centre with a tilting turntable, moving cross beam and gantry structure.


interpolated axes 5
machining surface area
lathe table diameter mm 700
turning diameter mm 800
capacity of standard lathe table kg 700
Travel - Speed
travel axis X mm 800
travel axis Y mm 900
travel axis Z with standard table mm 600
travel Z lathe tool with standard table mm 600
rapid axis X travel m/min 60
rapid axis Y travel m/min 60
rapid axis Z travel m/min 40
rotation axis A -30° ÷ +110°
rotation axis C continuous
rapid axis A travel rpm 50
rapid axis C travel rpm 100

Ultrix 800 RT can also be palletised for two up to five pallets satisfying applications which require maximum production flexibility and efficiency.

Work Cycle
The first stage is intense grinding to remove residual metal on the steel workpiece. As intense machining is required at this stage in the process, the spindle has to deliver enough power and a torque of up to 1,000 Nm.
After having removed the unwanted metal the next stage is to rough finish and then finish the workpiece leaving it with the required surface texture. Ultrix for finishing operations combines turning with tilting. Axis A - rotation - is interpolated with linear axes X and Y to profile the mould ensuring maximum efficiency. However, there is still more to the work cycle: at this point small sized tools are now fitted which are 2 mm diameter chisels that work at a speed of 40,000 rpm. These chisels are used for engraving at very high speeds wording, logos, trademarks etc. and remove material without leaving burrs or rough edges which could damage the surface finish of the workpiece.

Turning D piece max Ap F N min T
mm mm mm/giro rpm min
Rough grinding 650 4 0,35 110 180
Rough finishing – Finishing 650 0,5 0,2 110 30
Finishing sidewall profile 650 0,2 0,1 110 45
Total Time 255

Milling D mill Ap N T
mm mm rpm min
Rough grinding throat 1,6 0,5 40.000 5
Finishing throat 0,8 0,01 40.000 10
Rough grinding trademark 2,4 0,8 40.000 25
Finishing trademark 1 0,2 40.000 45
Rough grinding wording 0,8 0,4 40.000 25
Finishing wording 0,5 0,1 40.000 50
Rough grinding lines 0,3 0,05 40.000 25
Finishing lines 0,1 0,01 40.000 50
Total Time 235

Added value
The added value that Ultrix 800 RT offers the mould manufacturing industry for tyres is the possibility of dealing with a complex process consisting of various and different stages with just one machine and without having to reposition the workpiece achieving a complete finished piece without downtimes and errors due to repositioning operations on other machines.
The various functions Ultrix offers provide considerable reductions in processing times: an example is the work cycle described in this article. By combining lathe operations with table tilting, mould profiling is completed in one operation without having to resort to other machining processes to ensure a quality finish.
Manufacturing a mould has become, regardless of the complex processes, a “short” work cycle managed by one machining centre efficiently and economically.