A new, CNC- based, re-engineering package from Holroyd is enabling existing users of the company's range of mechanical gear hobbing machines to update them and benefit from DIN 5 levels of accuracy in the production of worm wheels and sets, at a cost up to 60% less than that of an equivalent new machine. Holroyd has a long and successful history of producing gear hobbing machines - and of exporting them to all parts of the world. The company manufactured its machines for about 25 years until the late 1970's when the market became saturated and the requirement for new machine stock had started to decline.
At that time the machines produced by Holroyd were mechanically superb.
They were constructed using all cast components and manufactured to a degree of accuracy that compares favourably with the most accurate machines on the market today.
'The highly stable cast base and structure that we routinely provided on our range of gear hobbing machines provides the ideal platform for updating the machines to achieve the highest levels of accuracy at a fraction of the cost of buying new,' says Holroyd Director, Steve Whitehead.
'We have already proved both the effectiveness of the conversion - and the cost savings - by updating one of our own production machines in our own factory.
Previously the machine was referred to as Class B precision, producing product to DIN 7 levels of accuracy.
Following re-engineering, the hobber is now a class A machine, producing to DIN 5 accuracy, a figure that enables the machine to satisfy over 80% of the market for worm wheels.
With most retrofit packages, improved accuracy on its own would more than justify the equipment outlay.
We have gone a step further, however, realising major improvements in set-up times, down from 2 hours to 20mins on the re-engineered hobbing machines.' Holroyd's original production of gear hobbers ran to five sizes of machines with table dimensions of 12in, 24in, 48in, 60in and 72in.
All of these machines were designed using the mechanical, 'multiple differential principle', whereby a single motor drive gives all motion differentials which are coupled mechanically.
In the new re-engineering package this motion is now controlled electronically by a Fanuc 16i CNC machine controller, working in conjunction with four brushless servomotors.
The Fanuc controller was chosen because it offers users the time saving advantages of plain language shopfloor programming.
As an example of this, program features are laid out in simple table formats that allow parameters for the finished worm gear to entered simply and quickly.
Set-up times are much reduced, as a result, leading to real gains in productivity.
The Fanuc CNC co-ordinates the motion of the four machine axes: Hob Spindle, Table Drive, Cross Feed and Infeed, via servomotors equipped with high-resolution encoders; the unit on the Hob spindle being used a reference to synchronise all the remaining axes.
The operation of these servomotors is optimised by the replacement, on the machine's linear axes, of the original plain screws by precision ground ballscrews.
Further mechanical improvement is also realised by the use of precision ballscrew end bearings, which have been adapted to mount worm shafts.
The use of these modified bearings prevents axial 'end wind', or a figure of eight movement encountered as the worm shaft is driven under load.
The complete process of stripping the original Holroyd machine down to its basic structure and then re-engineering with the new CNC package takes on average 26 weeks - saving around 3 months on delivery compared to buying new, and costs approximately GBP 300,000.
'This represents excellent value for money, generally, and especially so when compared to purchasing a new machine,' says Steve Whitehead.
'The buyer who chooses the latter route could be paying anywhere between GBP 500,000 to GBP 750,000 to achieve equivalent levels of quality, and be waiting around 9 months for delivery into the bargain.' At the present time the re-engineering package is available only on the five sizes of hobbing machine produced by Holroyd.
However, the company is prepared to quote for performing similar work on other companies' machines.
Up-to-date system guards CNC gear hobber
Bespoke guarding system combines maximum operator flexibility with highest safeguarding protection on a rebuilt hobbing machine.
Nelsa have designed and manufactured a bespoke guarding system that provides ultimate ease of use and maximum safeguarding on a precision hobbing machine recently rebuilt by precision engineers Holroyd. The Nelsa guarding system is part of a re-engineering package that Holroyd has applied to update the mechanical hobbing machine. CNC based, the package enables DIN 5 levels of precision to be achieved at a cost up to 60% less than that of an equivalent new machine.
Holroyd, based in Rochdale, is a world leader in the design and manufacture of specialist milling and grinding machines for helical components.
The company also has a long and successful history of producing mechanical gear hobbing machines The company manufactured them for approximately 25 years, up until the late 1970's.
At that time the hobbers produced were mechanically superb, they were constructed using all cast components and were manufactured to a degree of accuracy that compares favourably with the most accurate machines currently on the market.
Today, the highly stable cast base and structure that was routinely provided on the mechanical hobbers provides the ideal platform for updating the machines to achieve the highest levels of accuracy at a fraction of the cost of buying new.
Holroyd is exploiting this potential with a re-engineering package that includes servomotors, ball screws and CNC.
Also included, as part of the package is a specially designed machine guarding system from Nelsa, part of EJA.
Nelsa designed the bespoke system, following in-depth discussions both with senior development engineers on the project and also with the machine operators.
As a result, it is easy to use, ensuring minimal disruption to the operator while, at the same time, providing maximum safeguarding against entrapment by moving cutters, chippings, swarf and even coolant.
The guarding system is also interlocked to inhibit machine operation when the operator is setting up or needs to enter the hazardous machining area for any reason.
The increasing complexity and automation of machines means that Nelsa is always being called upon to provide bespoke guarding arrangements which, like the Holroyd system, provide maximum operator protection, without, at the same time, hindering the production process.
These features are essential because experience shows that they are the best possible way to guarantee that when a guard is fitted, it stays fitted.
As evidence of this, the removal of awkward safety guards has been shown to be one of the most common pre-conditions for an industrial accident.
Nelsa have designed and manufactured a bespoke guarding system that provides ultimate ease of use and maximum safeguarding on a precision hobbing machine recently rebuilt by precision engineers Holroyd. The Nelsa guarding system is part of a re-engineering package that Holroyd has applied to update the mechanical hobbing machine. CNC based, the package enables DIN 5 levels of precision to be achieved at a cost up to 60% less than that of an equivalent new machine.
Holroyd, based in Rochdale, is a world leader in the design and manufacture of specialist milling and grinding machines for helical components.
The company also has a long and successful history of producing mechanical gear hobbing machines The company manufactured them for approximately 25 years, up until the late 1970's.
At that time the hobbers produced were mechanically superb, they were constructed using all cast components and were manufactured to a degree of accuracy that compares favourably with the most accurate machines currently on the market.
Today, the highly stable cast base and structure that was routinely provided on the mechanical hobbers provides the ideal platform for updating the machines to achieve the highest levels of accuracy at a fraction of the cost of buying new.
Holroyd is exploiting this potential with a re-engineering package that includes servomotors, ball screws and CNC.
Also included, as part of the package is a specially designed machine guarding system from Nelsa, part of EJA.
Nelsa designed the bespoke system, following in-depth discussions both with senior development engineers on the project and also with the machine operators.
As a result, it is easy to use, ensuring minimal disruption to the operator while, at the same time, providing maximum safeguarding against entrapment by moving cutters, chippings, swarf and even coolant.
The guarding system is also interlocked to inhibit machine operation when the operator is setting up or needs to enter the hazardous machining area for any reason.
The increasing complexity and automation of machines means that Nelsa is always being called upon to provide bespoke guarding arrangements which, like the Holroyd system, provide maximum operator protection, without, at the same time, hindering the production process.
These features are essential because experience shows that they are the best possible way to guarantee that when a guard is fitted, it stays fitted.
As evidence of this, the removal of awkward safety guards has been shown to be one of the most common pre-conditions for an industrial accident.
Gear grinder is easier to set up
Gear grinding machine is equipped with a mobile operator panel that makes machine set-up easier and includes dialogue software based on MS Windows operating systems for dressing cycles.
The new S 250 G gear grinding machine completes the Samputensili range of gear grinding machines for economical mass production. Particular attention has been paid to the choice of components used on this machine which have all been thoroughly tried and tested on Samputensili hobbing machines, grinding machines and in automation systems, guaranteeing high performance and reliable results. The cast iron machine bed ensures excellent vibration damping even when large amounts of stock are removed and it was in fact designed for our new S 150 - S 400 series of hobbing machines.
This rigid structure enhances the performance of the direct-drive motors both of which power the tool spindle (rotation speed of 0 - 10.000 rpm) and the workpiece table (rotation speed 0 - 1000 rpm).
The grinding wheel head has been thoroughly tested on the Samputensili S 400 GT grinding machine and is well-managed thanks to the safe tool clamping system.
The tool work area is spaciously designed and the cooling liquid release system is PLC-controlled so that the jet of oil is aimed directly at the tool and workpiece contact zone.
This system also keeps the whole work area much cleaner.
The radial, axial and tangential movements of the axes are performed with the aid of backlash-free, pre-loaded re-circulating ball screws together with a synchronous servo-motor on roller guide ways.
Ceramic worm wheels can be dressed by the diamond dressing roller.
The fully automated system loads and unloads the dressing tool depositing it and collecting it from a specific on-machine tool storage area.
CBN grinding wheels should be used as form wheels.
In terms of automation, the machine is equipped with a fast, innovative, 3-axes CN telescopic loader.
It moves along the longitudinal axis and passes through the machine counter-column so that the loader is always outside the work area during the actual grinding phase.
The control system is the Siemens 840 D with linear and circular interpolation of up to 5 axes and high-performance geometric programming for easy profile and helix generation and relative congruity testing.
The machine is also equipped with a mobile operator panel which makes machine set-up easier as well as dialogue software based on MS Windows operating systems to facilitate the management of data, grinding and dressing cycles and data storage without the need for an external PC.
Other notable safety features of this machine are the interpolated tool withdrawal system in the event of power failure or emergencies which prevents tools from being damaged and the automatic fire extinguishing system which combats the risk of damage to the machine and its surroundings in the event of fire.
The new S 250 G gear grinding machine completes the Samputensili range of gear grinding machines for economical mass production. Particular attention has been paid to the choice of components used on this machine which have all been thoroughly tried and tested on Samputensili hobbing machines, grinding machines and in automation systems, guaranteeing high performance and reliable results. The cast iron machine bed ensures excellent vibration damping even when large amounts of stock are removed and it was in fact designed for our new S 150 - S 400 series of hobbing machines.
This rigid structure enhances the performance of the direct-drive motors both of which power the tool spindle (rotation speed of 0 - 10.000 rpm) and the workpiece table (rotation speed 0 - 1000 rpm).
The grinding wheel head has been thoroughly tested on the Samputensili S 400 GT grinding machine and is well-managed thanks to the safe tool clamping system.
The tool work area is spaciously designed and the cooling liquid release system is PLC-controlled so that the jet of oil is aimed directly at the tool and workpiece contact zone.
This system also keeps the whole work area much cleaner.
The radial, axial and tangential movements of the axes are performed with the aid of backlash-free, pre-loaded re-circulating ball screws together with a synchronous servo-motor on roller guide ways.
Ceramic worm wheels can be dressed by the diamond dressing roller.
The fully automated system loads and unloads the dressing tool depositing it and collecting it from a specific on-machine tool storage area.
CBN grinding wheels should be used as form wheels.
In terms of automation, the machine is equipped with a fast, innovative, 3-axes CN telescopic loader.
It moves along the longitudinal axis and passes through the machine counter-column so that the loader is always outside the work area during the actual grinding phase.
The control system is the Siemens 840 D with linear and circular interpolation of up to 5 axes and high-performance geometric programming for easy profile and helix generation and relative congruity testing.
The machine is also equipped with a mobile operator panel which makes machine set-up easier as well as dialogue software based on MS Windows operating systems to facilitate the management of data, grinding and dressing cycles and data storage without the need for an external PC.
Other notable safety features of this machine are the interpolated tool withdrawal system in the event of power failure or emergencies which prevents tools from being damaged and the automatic fire extinguishing system which combats the risk of damage to the machine and its surroundings in the event of fire.
Range of hobs suits SME batch gear production
Delivery ranges of hobs for small to medium batch production have been especially studied to meet the needs of small to medium sized batch and prototype gear manufacturers.
Samputensili X2 and X4 delivery ranges of hobs have been especially studied to meet the needs of small to medium sized batch and prototype gear manufacturers. Samputensili comprehends the present day need for increasingly rapid delivery of your purchase orders and thanks to our modern and sophisticated manufacturing cells, we now pre-machine hob blanks and finish them to your specifications, including coating, in just two weeks. All manufacturing phases of standard hob production are carried out in house so we are not reliant on sub suppliers.
Time is money and reducing your delivery time reduces your manufacturing costs.
Try out the advantages of this range yourselves and fill out one of our order forms.
You will be amazed by the speed with which your finished tools arrive.
Samputensili X2 and X4 delivery ranges of hobs have been especially studied to meet the needs of small to medium sized batch and prototype gear manufacturers. Samputensili comprehends the present day need for increasingly rapid delivery of your purchase orders and thanks to our modern and sophisticated manufacturing cells, we now pre-machine hob blanks and finish them to your specifications, including coating, in just two weeks. All manufacturing phases of standard hob production are carried out in house so we are not reliant on sub suppliers.
Time is money and reducing your delivery time reduces your manufacturing costs.
Try out the advantages of this range yourselves and fill out one of our order forms.
You will be amazed by the speed with which your finished tools arrive.
Consortium investigates face gear grinding
An Estonian-led consortium with partners from Italy and the Czech Republic is performing research into the development af a cost-effective technology for face gear grinding.
A consortium led by Feanor, including partners from Italy and the Czech Republic is performing a research for the development af a cost-effective technology for face gear grinding. Face gears have been known and studied for many years, but since they were used for low power and low speed, the requirement for a constant speed ratio was not very important. With the advent of high power and speed requirements, face gears have been driven out by conventional bevel gears, which are easier to be manufactured.
Face gears have important applications in helicopter transmission systems.
They proved to be effective also with insufficient lubrication, thus increasing the reliability of the aircraft, and they work also with bad alignment between pinion and the rotor gear.
Helicopters using transmission systems based on face gears have a higher safety and survivability.
The target of the Facegear project is to study a cost-effective method for the manufacturing of face gears, thus increasing their application in the helicopter industry.
Face gears have some other natural advantages, compared to bevel gears, such as: 1.
the pinion is a normal spur gear which axial position has no influence on the meshing zone provided its face is adequate (see point 2 of the proposal summary).
2.
assembly time is reduced because only the axial position of the face gears needs to be set.
3.
Lapping is not necessary because all gears irrespective of their tooth numbers or shaft angles may be interchangeably meshed with the common pinion upon which the particular generating hob geometry is based.
4.
There is no axial load on a pinion with straight spur teeth.
5.
The meshing is smoother due to oblique contact lines and high contact ratio.
6.
Face gears provide high transmission ratios in one stage.
7.
Cost effective manufacture on conventional CNC gear hobbing machines straddle mounted pinions, provided that the calculation is correct.
8.
Zero backlash transmission for positioning or measuring machines can be easily obtained.
9.
Face gears have high strength teeth and good contact geometry, which give high torque capability.
Objectives of the proposed EU project are a calculation software for face gear geometry, a cost-effective gear cutting technology for face gears and a measuring system for the geometry of face gears.
A consortium led by Feanor, including partners from Italy and the Czech Republic is performing a research for the development af a cost-effective technology for face gear grinding. Face gears have been known and studied for many years, but since they were used for low power and low speed, the requirement for a constant speed ratio was not very important. With the advent of high power and speed requirements, face gears have been driven out by conventional bevel gears, which are easier to be manufactured.
Face gears have important applications in helicopter transmission systems.
They proved to be effective also with insufficient lubrication, thus increasing the reliability of the aircraft, and they work also with bad alignment between pinion and the rotor gear.
Helicopters using transmission systems based on face gears have a higher safety and survivability.
The target of the Facegear project is to study a cost-effective method for the manufacturing of face gears, thus increasing their application in the helicopter industry.
Face gears have some other natural advantages, compared to bevel gears, such as: 1.
the pinion is a normal spur gear which axial position has no influence on the meshing zone provided its face is adequate (see point 2 of the proposal summary).
2.
assembly time is reduced because only the axial position of the face gears needs to be set.
3.
Lapping is not necessary because all gears irrespective of their tooth numbers or shaft angles may be interchangeably meshed with the common pinion upon which the particular generating hob geometry is based.
4.
There is no axial load on a pinion with straight spur teeth.
5.
The meshing is smoother due to oblique contact lines and high contact ratio.
6.
Face gears provide high transmission ratios in one stage.
7.
Cost effective manufacture on conventional CNC gear hobbing machines straddle mounted pinions, provided that the calculation is correct.
8.
Zero backlash transmission for positioning or measuring machines can be easily obtained.
9.
Face gears have high strength teeth and good contact geometry, which give high torque capability.
Objectives of the proposed EU project are a calculation software for face gear geometry, a cost-effective gear cutting technology for face gears and a measuring system for the geometry of face gears.
Low cost centre grinds gears to better than DIN 2
Although easy to set and operate, a grinding centre uses a novel machining system to achieve better than DIN 2 accuracy for the form grinding of high precision helical, spur and worm gears.
Holroyd's new Smart GTG2 grinding centre employs a unique (patent applied for) machining system to achieve DIN 2 levels of accuracy - and beyond - in the form grinding of high precision helical, spur and worm gears. Designed with high levels of onboard intelligence, the GTG2 is extremely easy to set-up and operate. It also benefits users with onboard CMM and an automatic, in cycle wheel dressing feature that enables closed loop profile control to be achieved.
'Our design aim was to produce the lowest cost, highest accuracy grinding machine for helical and worm gears in the world, and I am sure that we have succeeded,' says Dr Tony Bannan, Holroyd's Engineering Director, who led the design and manufacturing team that produced the machine.
'Although the GTG2 is designed to provide DIN 2 levels of accuracy, generally, it has exceeded this level under optimum operating conditions, producing its 'best ground' performance with a tooth profile of DIN 1, considered by many to be pinnacle of grinding performance.' The GTG2 is an extremely versatile gear grinding centre, developed for one-off or batch production of high precision helical, spur and worm gears in sizes up to 350mm diameter and 160mm gear face width.
The machine's exceptional performance is the result of a design synergy that combines a 'patent- pending' machining method, with high levels of machine intelligence and onboard features such as automatic co-ordinate adjustment, in-cycle wheel dressing, integrated profile management and CMM.
Holroyd's patent-pending machining method has been developed to compensate for helical twist, an unwelcome condition that occurs when helical gears are 'lead crowned' to improve meshing and reduce noise and wear.
Lead crowning varies the amount of material removed from the flank of a tooth across the face width, by causing the tool motion to deviate from a true helix.
However, in form grinding this has the undesirable effect of causing the profile of the tooth flank to vary across the face.
In many applications this 'error' is not of concern, but in high precision and low noise applications it affects gear wheel performance by concentrating loads on particular areas of the teeth during meshing.
Correction of this problem is achieved on the CNC controlled GTG2 machine by calculating additional motions of the grinding wheel and by then controlling them during the grinding operation using bespoke software written by Holroyd engineers.
In the machining process, the workpiece is rotated about its axis and translated parallel to its axis relative to the tool, and the tool is also moved so as to vary continuously the angle of inclination of its axis relative to the axis of the workpiece.
In this way the generating errors (i.e the deviation of the groove surfaces actually produced from those desired and specified) are reduced along each line of instantaneous contact between the tool envelope and the groove surface being machined.
The resultant benefits are better tooth contact during meshing and improvements in torque transfer efficiency.
Although it performs a highly complex operation, the technology that underpins Holroyd's new machining method is not unwieldy for the user.
Neither does it mean that the machine is difficult to program and use.
On the contrary: the GTG2 is referred to as a 'Smart' machine because of its high levels of onboard intelligence, which make it easy to set-up and operate.
The machine is equipped with Holroyd's own HTG8, 8 axis CNC with facilities such as an Advanced Touch Screen Interface and Integrated Profile Management System.
The touch screen interface enables an operator to take a typical design drawing and enter the specification directly into the machine; leaving high levels of inbuilt intelligence do the rest.
What this means in practical terms is that the machine, by integrating facilities such as automatic co-ordinate adjustment, in-cycle wheel dressing, profile management and automatic programmable cycles, replaces the variable of operator skill in precision machine set-ups and operations with machine intelligence.
By distilling operator knowledge and experience into the GTG2's CNC controller, the machine is able to take data from its (optional) on-board probing system and predict the minute alterations to the profile of the grinding wheel required to achieve any desired profile and make these alterations 'on the fly'.
An example highlighting the proficiency of this system is a workpiece that does not meet tolerance requirements after a first grinding pass.
Following on-machine measurement, the GTG2 calculates the necessary adjustments to grinding wheel form or axis position and then passes the data to a 2-axis CNC wheel dressing system to achieve on machine dressing of the grinding wheel.
All of these operations are achieved automatically and rarely does the machine need to make further corrections after the first pass.
Holroyd's integration of the in-cycle wheel dressing system into the GTG2 is not a one off, rather it is part of an overall design strategy that takes a number of functions crucial to precise and effective gear grinding and integrates them into the machine as Automatic Programmable Cycles.
The GTG2 offers users eight of these cycles to simplify and improve gear production.
In addition to automatic wheel dressing they include: * Gear Tooth Grinding, with Optional Probing and Form Measurement.
* Repeat Cycles with Nesting up to 99 Times.
* Fillet Radius or Trochoid Root Form.
* Gear Crowning Cycle for Modified Tooth Forms.
* Lead Crowning by Bob Crowning, or by Adjusting the Lead or Combination of Both.
* Programmable Constant Peripheral Grinding Wheel Speed, Based on Actual Wheel Diameter.
* Optional Programmable Component Taper Correction.
Optimising the performance of the GTG2 in all of its bespoke and automatic operating cycles is a highly effective measurement system, provided by an inbuilt CMM.
This is designed, manufactured and calibrated to the same specifications and tolerances as standalone CMM, and also uses the same high level 3D scanning probes.
The CMM function is used at the start of each scan cycle to provide a validated reference point for commencement of the grinding operation.
Importantly, the probing operation, which is integral to this process, takes place without any machining forces and is therefore dynamically and kinematically stable.
In addition, as the workpiece is held in the same fixture used for machining, there is no requirement for off- machine measurement, and no consequent loss of position for corrective rework.
As a result the measuring process, overall, is that much more accurate and reliable.
* GTG2 Technology recognised for Queens's Award for Innovation - even before its major market launch, the technology that underpins the GTG2 grinding centre has been recognised by the prestigious Queen's Award For Innovation 2004.
'This award is an early recognition and a validation of all that we were trying to achieve with our design,' said Bannan.
'We have produced a highly cost competitive machine with grinding technology that literally leads the world, demonstrating our continuing ability to produce winners in the increasingly competitive global market for high precision machine tools.
Holroyd's new Smart GTG2 grinding centre employs a unique (patent applied for) machining system to achieve DIN 2 levels of accuracy - and beyond - in the form grinding of high precision helical, spur and worm gears. Designed with high levels of onboard intelligence, the GTG2 is extremely easy to set-up and operate. It also benefits users with onboard CMM and an automatic, in cycle wheel dressing feature that enables closed loop profile control to be achieved.
'Our design aim was to produce the lowest cost, highest accuracy grinding machine for helical and worm gears in the world, and I am sure that we have succeeded,' says Dr Tony Bannan, Holroyd's Engineering Director, who led the design and manufacturing team that produced the machine.
'Although the GTG2 is designed to provide DIN 2 levels of accuracy, generally, it has exceeded this level under optimum operating conditions, producing its 'best ground' performance with a tooth profile of DIN 1, considered by many to be pinnacle of grinding performance.' The GTG2 is an extremely versatile gear grinding centre, developed for one-off or batch production of high precision helical, spur and worm gears in sizes up to 350mm diameter and 160mm gear face width.
The machine's exceptional performance is the result of a design synergy that combines a 'patent- pending' machining method, with high levels of machine intelligence and onboard features such as automatic co-ordinate adjustment, in-cycle wheel dressing, integrated profile management and CMM.
Holroyd's patent-pending machining method has been developed to compensate for helical twist, an unwelcome condition that occurs when helical gears are 'lead crowned' to improve meshing and reduce noise and wear.
Lead crowning varies the amount of material removed from the flank of a tooth across the face width, by causing the tool motion to deviate from a true helix.
However, in form grinding this has the undesirable effect of causing the profile of the tooth flank to vary across the face.
In many applications this 'error' is not of concern, but in high precision and low noise applications it affects gear wheel performance by concentrating loads on particular areas of the teeth during meshing.
Correction of this problem is achieved on the CNC controlled GTG2 machine by calculating additional motions of the grinding wheel and by then controlling them during the grinding operation using bespoke software written by Holroyd engineers.
In the machining process, the workpiece is rotated about its axis and translated parallel to its axis relative to the tool, and the tool is also moved so as to vary continuously the angle of inclination of its axis relative to the axis of the workpiece.
In this way the generating errors (i.e the deviation of the groove surfaces actually produced from those desired and specified) are reduced along each line of instantaneous contact between the tool envelope and the groove surface being machined.
The resultant benefits are better tooth contact during meshing and improvements in torque transfer efficiency.
Although it performs a highly complex operation, the technology that underpins Holroyd's new machining method is not unwieldy for the user.
Neither does it mean that the machine is difficult to program and use.
On the contrary: the GTG2 is referred to as a 'Smart' machine because of its high levels of onboard intelligence, which make it easy to set-up and operate.
The machine is equipped with Holroyd's own HTG8, 8 axis CNC with facilities such as an Advanced Touch Screen Interface and Integrated Profile Management System.
The touch screen interface enables an operator to take a typical design drawing and enter the specification directly into the machine; leaving high levels of inbuilt intelligence do the rest.
What this means in practical terms is that the machine, by integrating facilities such as automatic co-ordinate adjustment, in-cycle wheel dressing, profile management and automatic programmable cycles, replaces the variable of operator skill in precision machine set-ups and operations with machine intelligence.
By distilling operator knowledge and experience into the GTG2's CNC controller, the machine is able to take data from its (optional) on-board probing system and predict the minute alterations to the profile of the grinding wheel required to achieve any desired profile and make these alterations 'on the fly'.
An example highlighting the proficiency of this system is a workpiece that does not meet tolerance requirements after a first grinding pass.
Following on-machine measurement, the GTG2 calculates the necessary adjustments to grinding wheel form or axis position and then passes the data to a 2-axis CNC wheel dressing system to achieve on machine dressing of the grinding wheel.
All of these operations are achieved automatically and rarely does the machine need to make further corrections after the first pass.
Holroyd's integration of the in-cycle wheel dressing system into the GTG2 is not a one off, rather it is part of an overall design strategy that takes a number of functions crucial to precise and effective gear grinding and integrates them into the machine as Automatic Programmable Cycles.
The GTG2 offers users eight of these cycles to simplify and improve gear production.
In addition to automatic wheel dressing they include: * Gear Tooth Grinding, with Optional Probing and Form Measurement.
* Repeat Cycles with Nesting up to 99 Times.
* Fillet Radius or Trochoid Root Form.
* Gear Crowning Cycle for Modified Tooth Forms.
* Lead Crowning by Bob Crowning, or by Adjusting the Lead or Combination of Both.
* Programmable Constant Peripheral Grinding Wheel Speed, Based on Actual Wheel Diameter.
* Optional Programmable Component Taper Correction.
Optimising the performance of the GTG2 in all of its bespoke and automatic operating cycles is a highly effective measurement system, provided by an inbuilt CMM.
This is designed, manufactured and calibrated to the same specifications and tolerances as standalone CMM, and also uses the same high level 3D scanning probes.
The CMM function is used at the start of each scan cycle to provide a validated reference point for commencement of the grinding operation.
Importantly, the probing operation, which is integral to this process, takes place without any machining forces and is therefore dynamically and kinematically stable.
In addition, as the workpiece is held in the same fixture used for machining, there is no requirement for off- machine measurement, and no consequent loss of position for corrective rework.
As a result the measuring process, overall, is that much more accurate and reliable.
* GTG2 Technology recognised for Queens's Award for Innovation - even before its major market launch, the technology that underpins the GTG2 grinding centre has been recognised by the prestigious Queen's Award For Innovation 2004.
'This award is an early recognition and a validation of all that we were trying to achieve with our design,' said Bannan.
'We have produced a highly cost competitive machine with grinding technology that literally leads the world, demonstrating our continuing ability to produce winners in the increasingly competitive global market for high precision machine tools.
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