Archive for the ‘CNC Grinding’ Category

Process improves grinding wheels

Monday, July 20th, 2009

Norton BCG Vortex centerless grinding wheels by Saint-Gobain Abrasives incorporate a technology that improves porous structure and abrasive spacing.

Unlike other porous vitrified-wheel technologies, the one used for the Vortex wheels did not involve artificial pore inducers (chemicals), which results in cool wheels for heat-sensitive applications, good metal removal rates, extended life for reduced cycle times, and improved part quality.

http://www.americanmachinist.com/304/Issue/Article/False/11870/Issue

Mill-turning up to 3m long

Thursday, July 16th, 2009

Mill-turning up to 3m long

Preston-based subcontractor Autoy has acquired new premises that will double its working space and allow further investment in CNC machine tools. The first of these is a large 5-axis mill-turning machining centre that can take parts up to 920mm diameter and 3m long.

The new Mazak Integrex at Autoy can mill-turn up to 920mm diameter and 3m long

The new Mazak Integrex E650-H II has a 5 tonnes capacity and a 1025mm (X) by 650mm (Y) by 3122 (Z) working envelope. 70Bar high pressure coolant system allows gun drilling in 5-axes and high speed machining, while a built-in automatic tool stocker allows the use of multiple large boring bars up to 1 metre deep.

Preston-based subcontractor Autoy has acquired new premises that will double its working space and allow further investment in CNC machine tools. The first of these is a large 5-axis mill-turning machining centre that can take parts up to 920mm diameter and 3m long.

The new Mazak Integrex E650-H II has a 5 tonnes capacity and a 1025mm (X) by 650mm (Y) by 3122 (Z) working envelope. 70Bar high pressure coolant system allows gun drilling in 5-axes and high speed machining, while a built-in automatic tool stocker allows the use of multiple large boring bars up to 1 metre deep

Says Alex Catterall of Autoy: “The purchase of this new machine has increased our size limit for production and opened up new opportunities – including those in the oil and gas industries and nuclear,power generation, amongst many other sectors.”

She adds that the move to new premises will not only increase the available working space, it will also provide upgraded office and visitor facilities and allow the company to hold larger stocks of components for customers for call-off as required.

Says Ms Catterall: “We have a very wide customer base and have not suffered from the effects of the credit crunch. We have continued to do really well and our current limitations on space are holding us back. With the new premises we will be able to invest in more machines and take up the opportunities open to us.”

Autoy offer a rapid high precision machining and manufacture service on both bespoke prototype components and large volume strategic production runs of standard components in any material. Its wide customer base ranges from the aerospace and automotive industries to food and drink, printing, textiles, medical, nuclear and subsea equipment.

http://www.engineeringcapacity.com/archive101/2009/july/industry_news/mill-turning_up_to_3m_long

CNC surface grinding machine exceeded all requirements for grinding a diverse range of cylindrical mould tooling

Sunday, May 24th, 2009

The Gates Corporation of Denver, Colorado in the united states was established in 1911.

CNC surface grinding machine exceeded all requirements for grinding a diverse range of cylindrical mould tooling from 292mm) to 711mm diameter to be used in timing belt technique manufacture.

Formally known as the Gates Rubber Company, they are now two of the largest high precision automotive timing belt manufacturers in the World.

Recently when needing to ramp up their production facilities in support of new business growth, they contacted Jones and Shipman and asked them to review a project they had on the table.

The challenge was to grind a diverse range of cylindrical mould tooling from 11in (292mm) to 28in (711mm) diameter.

It consisted of a specific and demanding set of criteria that had to be met in support of a new range of Gates high precision timing belts.

Jones and Shipman is not traditionally known as a manufacturer of large capacity production surface grinders.

Soon after an initial contact Jones and Shipman’s application engineers provided an in depth application assessment report confirming that a model in their ProGrind range was capable of not only achieving their requirements, but also exceeding them in all departments, accuracy and system time, and giving them the requested larger capacity.

However with the introduction of their award winning Dominator range, with its three dimensional grinding capabilities and more recently a high accuracy ProGrind range, most applications can now be fulfilled.

The Jones and Shipman (J and S) ProGrind is designed to marry physical size with high precision, high productivity and incredible flatness.

Incorporating Jones and Shipman’s simple to use and quick to set ‘Easy’ program by a GE-Fanuc Touchscreen control as well as a.C.

Digital Servos with Heidenhain ‘Absolute’ Linear scale feedback, it proved to be the ideal machine for the Gates Corporation.

Having established from the initial feasibility study that a ProGrind 1267 was the grinder of choice, design and system optimisation commenced.

A Nikken CNC Rotary indexer and heavy-duty hydraulic tailstock was chosen to support and drive the mould tools, each of which would be held between centres.

The discs, accurately lapped with 0.004-5in (0.1-0.125mm) radii, where chosen to complement the mould tooth profile accuracy and mounted on a J and S custom disc dressing unit for easy of use.

With all mould blanks being produced from alloy steel and of a fixed length of 17in (450mm), J and S recommended twin high precision diamond discs as the optimum wheel dressing option.

The wheel form profile and the mould tooth profile being initially optically checked against master overlays.

After machine build in the UK, grinding trials commenced on sample mould blanks to prove out the form and optimal wheel dress frequency.

Having established the initial wheel dress frequency and grinding parameters, the machine was accepted following a ‘lights out’ run of a Gates mould and shipped to Gates Corporation’s, Denver, facility for onsite commissioning and final grinding acceptance trials.

Further verification of the form being obtained by a ground tooth form test piece on a CMM.

From this point training moved on a pace and the first test blank a 115-tooth profile mould, was set and run with a roughing cut.

Operator familiarisation and training with the Easy program quickly progressed through dressing and grinding flat forms on a test mould.

After inspection the wheel was redressed for a four-hour finishing cycle.

As the ProGrind is a 24/7-production grinder the machine ran unmanned for the next day.

A full inspection by CMM of all geometry including size and profile angularity confirmed that all features where well within tolerance.

The ProGrind was then set to grind a 100-tooth mould; this took a day to rough grind.

In fact the CEO of the mould customer who was visiting at the time remarked on how efficiently the ProGrind was operating.

Their existing machine, an Okamoto, which had started an 80-tooth mould one-hour after the ProGrind, was still grinding with three teeth left after a day as well as a half.

Since then the operators have succeeded in further optimising production times, the Gates Corporation has not only achieved their objectives but are exceeding them in all regards and the J and S ProGrind is well on the way to paying for itself.

Final acceptance was signed and the ProGrind passed over to the Gates Corporation in Mid July 2006.

CAM650 CNC is supplied with software for grinding various types of cam profiles by interpolation of the X and C axis

Tuesday, May 19th, 2009

The machine model CAM650 CNC is supplied with application for grinding various types of cam profiles by interpolation of the X & C axis.

SRB Machines from Ghaziabad near New Delhi, India, has fitted its CAM650 CNC camshaft grinding machine with an SBS (Schmitt Balance Systems) automatic wheel balancer from Schmitt Europe.

The SBS automatic grinding wheel balancer is a dynamic method, permanently installed on the grinding machine spindle through an adapter arrangement.

The machine can also be used for cylindrical grinding.

A vibration sensor picks up spindle vibration caused by wheel imbalance & feeds this information to the SB4500 Series electronic controller.

The controller drives four tungsten weights inside a balance head – fixed to & rotating with the spindle.

The four weights are moved to positions to counteract the wheel imbalance, reducing vibration on the spindle.

All this is completed automatically, eliminating the require for wheel pre-balance or balancing on knife-edges prior to mounting on the machine.

The SBS method can be installed on  any cylindrical, centreless, roll, creepfeed or surface grinder.

An unbalanced grinding wheel will increase machine vibration & decrease the life of spindle, bearings, grinding wheel & diamond dresser.

Poor surface finish, chatter marks, workpiece ‘ovality’ & grinder/surface burn can often be attributed to a badly balanced wheel.

SRB took advantage of the I/O capability of the SB4500 dynamic balancer & interfaced it with the Siemens Sinumerik CNC on the CAM650 machine.

Useful outputs, such as balance in & out of tolerance, spindle rev/min & critical vibration are also used.

The machine can start & stop automatic balancing by the inputs, as well as locking the keypad.

Proflex line of flexible CNC external and internal grinding machines

Tuesday, May 19th, 2009

NL Machine Tool Consulting has unveiled the Proflex line of flexible CNC external and internal grinding machines.

NL Machine Tool Consulting has unveiled the Proflex line of flexible CNC external and internal grinding machines.

Proflex is a grinding centre that can be customised on the basis of specific production needs and grinding applications.

Two, two or two conventional or high-speed CBN wheels can be mounted simultaneously on integrated motor-spindle assemblies and used in successive grinding operations.

Its flexibility is facilitated by a range of wheelhead configurations, which makes it possible to use multiple tools in different combinations.

Proflex can be readily customised for any grinding application, thanks to a range of modern, ultra-dependable accessories and optional equipment.

The machine has a range of accessories and custom features, and can be interfaced with a variety of automated workpiece-handling systems including gantries, integrated loaders and robots.

Also obtainable are steady-rests with open two-point or closed three-point configurations, with automatic engagement and self-centring diameter compensating capabilities.

A selection of workholding and clamping units for workhead and tailstock provides the right solution for all between-centres grinding processes – whether they involve live centres, dead centres or face drivers – and any kind of chucking operation.

Special workheads, including units with integrated motor-spindle assemblies, make it possible to grind non-round shapes such as regular polygons, cams and threads thanks to crossfeed C-axis design.

Wheel dressers featuring either single dresser centres or diamond dresser wheels may be incorporated in the workhead and tailstock, or installed on independent units that can be positioned on the stationary table.

Designing machines for operating flexibility also means guaranteeing fast retooling during type changes.

Thus, in-process gauging instruments such as axial positioners and diameter gauges are easy to reset during type changes, thanks to manually operated self-aligning devices or automatic supports with hydraulic positioning on pre-set stops.

Where ‘absolute’ diameter gauging is required along the entire grinding length, the Proflex range is designed for easy technique integration with units featuring additional CNC-controlled axes.

In addition, ‘active’ axial positioning probes can be installed on the wheelhead.

The Proflex line-up consists of two models – PROFLEX2, PROFLEX3 and PROFLEX4 – which differ according to the number of external and internal grinding wheels housed in the wheelhead structure.

Other modular design features include a choice of two CNC-controlled W-axis workpiece length compensation units providing different compensation strokes.

Each model is specially designed to use conventional external wheels with 508, 610 or 760mm diameter and peripheral speeds from 50 to 63m/s (C line), or high-speed CBN wheels with 400 or 500mm diameter and peripheral speeds from 120 to 140m/s (S line), in combination with several internal grinding units.

Different spindle designs are obtainable for each wheel type.

All spindle units feature extra-precise ceramic rolling bearings, coaxial integrated drive motors and wheel balancers incorporated in the spindle nose.

Extensive product engineering work made it possible to create a full range of machine sizes with different between-centres capacities.

The machine bed and stationary table are modular units with one-piece load-bearing structure, ribbed to guarantee thermal and dynamic stability.

Stationary table design with recirculating roller or hydrostatic Z-axis crossfeed and X-axis infeed minimises the machine’s footprint and rationalises liquid and electrical technique layout.

All setup, programming, grinding, cycle monitoring and diagnostics operations involved in normal machine use are elementary and ‘familiar’ to the operator thanks to a specially designed working environment.

User-friendly programming is ensured by Tacchella’s Tacchella Operator Package (TOP); interactive program that meets the challenge of combining flexibility with full technique capacity.

The most commonly used wheel profiles are stored in the package’s Standard Wheel Library.

Geometrical characteristics are specified basically by assigning the desired value in the table of variables appearing in the screen form for the selected wheel.

The selection of standard grinding cycles makes it possible to satisfy a range of needs, carrying out complete, complex grinding operations with ease.

The standard grinding cycles, which can be combined in any machine configuration, can be used for diameter, shoulder, groove radius, chamfer and taper grinding with or without interpolation, as well as for contouring and grinding threads, regular polygons, non-round shapes and cams with regular or special wheels, all in a single setup.

The TOP Tacchella program package is patented by Tacchella Macchine.