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The new Spiracon® roller screw line is a unique,
patented system consisting of a multi-start screw with an involute thread form
and a number of planetary rollers with annular grooves engaging the screw. Spiracon®
is designed for high precision, repeatable positioning and offers continuous
duty, high efficiency, and up to 20x the life of a ball screw for loads
up to 130 tons and speeds up to 98 ft/minute.
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| Spiracon® is a
planetary roller screw, which converts rotary motion to linear movement. It is
a unique concept, invented and patented by Illinois Tool Works, and available
in North America exclusively through Duff-Norton. |
Main features
of Spiracon® roller screws
• High dynamic load capacity
• High efficiency
• Positional accuracy
• Long life and low maintenance
• Same nut fits both right and left handed screws
• Hardened and ground rolling elements
• Clean operation
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Principle of operation
The Spiracon® system consists of a multi-start screw
with an involute thread form and a number of planetary rollers with annular
grooves which engage with the screw. These rollers also engage with a grooved
load bearing element which transmits the load through roller thrust bearings to
the nut housing. The rolling action results in a high efficiency mechanism,
while the line contact and hardened and ground construction achieves a high
dynamic load carrying capacity with almost no axial backlash or wear. |
Working Applications
Marine shipping
Application: Anti-sway mechanism on
ship-to-shore container crane.
Product: Four Spiracon® roller screws (two
right-hand, two left-hand), with associated bevel gearboxes and couplings. |
Steel roll clamping
Application: Positioning of clamping
machine for reclamation of steel rolls.
Product: Spiracon® roller screw operating
on a vertical clamp. |
Steel sheet shearing
Application: Positioning of flying shear
for cutting pre-formed steel sheets.
Product: Spiracon® roller screw operating
on a continuous reversal basis. |
Bridge inspection
Application: Raising and lowering of 16.5
ton (147 kN) bridge inspection and maintenance platforms.
Product: Spiracon® roller screws fitted
with disk brakes and mechanical stops. |
| There are 10 standard
Spiracon® roller screw models, available with diameters from 15mm to 120mm
(0.6-4.75 inches) and a choice of three lead variations per model size. Dynamic
load capacities of over 1,200 kN (130 tons) and linear speeds of over 30 m/min
(1100 inches/min) are possible. Where the standard range does not meet the
application specification, special roller screws can be designed to meet
customers’ specific requirements. (see Specials section on page 11) |
Efficiency
The Spiracon® roller screw has an efficiency of 85% -minimizing power
consumption and screw system size. Such high efficiency means that the screw is
not selfsustaining and a braking system is needed to prevent back driving. |
Tolerance
Highly accurate machining and assembly of each roller
screw achieves total axial play of less than 0.01mm (0.0004 inches). The
cumulative pitch error in the screw is typically less than 5 microns per 300mm.
(0.00019 inches per ft.). Combined with a high stiffness, this means that
accurate and repeatable positioning is possible. The screw straightness is
within 0.1mm:1,000 mm (0.004 inches:36 inches). |
Operating life
Operating life is dependent upon the dynamic load.
The maximum dynamic loads shown in the technical chart on page 14 are
equivalent to 1,000,000 revolutions of the screw. To determine actual operating
life, please refer to How to select a Spiracon® roller screw on pages 12 and
13. Where severe operating conditions exist, please consult our product
engineers. |
However, our products have
been proven in temperatures
as low as -30°C (-22°F) (Arctic),
and as high as +70°C (+158°F)
(steelworks). Wiper seals
prevent the entry of large
particles into the nut
mechanism, and bellows can
be provided to protect the screw.
Please contact our factory to
discuss hostile or hazardous
operating environments.
Lubrication and
maintenance
Spiracon® roller screws require only a minimum of maintenance during the
normal operating life.
Depending upon the duty,
periodic lubrication should be carried out through the nipple using Rocol MTS
1000 grease or equivalent. |
Mounting
The Spiracon® nut can be mounted using the standard mounting holes and
location diameter. Screw end machining to suit thrust bearings is standard
unless the customer requests custom machining. Mounting for operation in any
orientation is possible. |
Guiding the load
Loads must be guided to remove any possible sideload from the Spiracon® nut.
The guide system will resist the torque developed by the roller screw
mechanism. |
Screw length
The screw length is determined by the load and speed conditions (please refer
to step 2 of How to select a Spiracon® roller screw on page 12 and 13).
For total screw lengths greater than shown in the table at the bottom of this
page, please consult our product engineers. |
Operating environment
All units are designed for industrial operating conditions. Normal operating
temperatures are from - 10°C (+26°F) to +50°C (+122°F). |
Specials
Spiracon® can be offered to suit applications requiring:
• Special screw diameters or
leads
• Left hand screw threads
• Very high dynamic load
(over 1,200kN/130 tons)
• Special materials such as
stainless steel
• Extreme temperatures and
hazardous environments
• Special screw end
machining or nut
mounting |
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