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Anti Backlash Machine Screw Jacks

Model: Anti Backlash Machine Screw Jacks
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Place of Origin: Made In China
Brand Name: JACTON
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Anti Backlash Machine Screw Jacks Descriptions
Machine Screw jacks are used for positioning loads in numerous applications, however when the load direction alternates between tension and compression within the operating cycle and a high position accuracy must be maintained then a specific type of screw jack is required. The Anti Backlash Machine Screw Jacks is recommended for such applications, as it is able to reduce the axial backlash between the lead screw and the trapezoidal screw thread in the gear to a practical minimum.

Axial backlash exists in standard screw jacks as the "gap" or "play" between the flanks of the lead screw thread and the internal thread on the worm gear nut. This gap or play is due not only to normal manufacturing tolerances, but to the fact that there must be some clearances to prevent binding and galling when the screw jack is operating under load. In most applications either the load direction is constant so axial backlash does not occur or the position error caused by the axial backlash is considered negligible for the application. However some applications require minimal or regulated axial backlash for accurate and repeatable positioning. Such an application is for positioning the rollers in steel straightening machines for tube, bar or sheet steel production.

Anti-backlash mechanism on machine screw jacks can be used to reduce axial-backlash to a practical minimum or a regulated value. Reduction in axial backlash below this minimum is not normally recommended as it can cause binding and excessive wear. As the screw jack is operated over time the axial backlash will increase as the lead screw thread on the gear wears due to normal operation. To compensate for this anti-backlash device can be adjusted to re-set for the required amount of regulated backlash. To help with the identification of wear machine screw jacks can also be fitted with a wear monitoring device for visual use or with electronic sensing for integration into a motion control system.


Anti Backlash Machine Screw Jacks Pictures


Anti Backlash Machine Screw Jacks Application Case 1

Above picture is special manufactured 450MM Stroke Inverted 2 Ton Anti Backlash Machine Screw Jacks following customers requirements. The assemblies can be adjusted in the future, to maintain the zero backlash, and precise location. Two flanges Anti Backlash Machine Screw Jacks, big flange for IEC90 motor, another small flange for geared potentiometer. Special devices like anti-backlash device, anti rotation keyed screw configurations, travel stroke controlled limit switches, lengthening threads end, anti rust and anti dust protection tube etc. 

Anti Backlash Machine Screw Jacks Application Case 2
10" Stroke Inverted 2 Ton Anti-Backlash Gearing Machine Screw Jacks application in precision Single-Point Adjustment (SPA) in roll forming tube and pipe, tube mill, pipe mills industries. The assemblies can be adjusted in the future, to maintain the zero backlash, and precise location. Non-Standard Lengthening Worm Shaft Anti-Backlash Gearing Machine Screw Jacks, mechanical digital position indicator / counter is mounted on Non-Standard Lengthening Worm Shaft. Manual operation two jacks system. Special devices like anti-backlash device, lengthening worm shaft, anti rust and anti dust protection tube, cast iron hand wheel etc. 


Anti Backlash Machine Screw Jacks FAQs
What are anti-backlash devices?
Anti-backlash devices are internal jack components used to minimize backlash (free movement between the lifting screw and nut) in machine screw jacks.

Why are anti-backlash devices needed?
Anti-backlash devices are typically used in reversing load applications where the lifting screw position is critical.

Where are anti-backlash devices used?
Anti-backlash devices are frequently used in steel mill applications where the screw jacks are used to set and maintain the position of the movable upper roll of a rolling mill. In operation, the initial weight of the roll pulls the lifting screw to one side of the nut. When steel passes through the rolls, the load reverses on the lifting screw and movement in the opposite direction is limited by the anti-backlash device. Other common applications include screw jacks used to position communication antennas and solar panels. In these applications, directional changes in the wind can buffet the panels thus affecting the position of the lifting screw. During these high wind conditions, anti-backlash devices minimize the lifting screw movement.

Will the anti-backlash device require adjustment?
When the internal nut threads begin to wear, lifting screw backlash increases. Subsequent adjustment of the anti-backlash device compensates for the nut wear and allows the user to limit the backlash to the recommended value. Adjustment frequency will vary depending on load, duty cycle, and temperature. The anti-backlash device should be replaced when no further adjustment is possible due to thread wear.

What effect do anti-backlash devices have on torque requirements?
Torque requirements for screw jack operation are affected by the clearance between the lifting screw and nut thread. Adjusting anti-backlash devices (within recommended values for each design) will not increase the torque to move a given load. If the backlash is set below the recommended values, torque values will increase significantly and thread wear will accelerate.

Can anti-backlash devices be used on ball screw jacks and bevel ball actuators?
No. Rather, the use of oversized ball bearings in ball nut assemblies is recommended to reduce endplay in ball screw jacks and bevel ball actuators.

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Jacton Industry Co.,Ltd.
Contact: Warren Lee
Skype: jactonjack
T: 86-769-81585810
F: 86-769-81585852
E: sales@screw-jack.com
W: www.screw-jack.com

Building C, No.3078, Garden Road, Xin An Community, Chang An, Dongguan 523880, Guangdong, China    Phone: 86-769-81585810 | Fax: 86-769-81585852
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