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First, the working principle
Circulating balls are installed between the screw and the nut to achieve rolling friction
The motor drives the screw to rotate → the nut moves in a straight line
Reverse can also be: push nut → screw rotation
II. Core features
High transmission efficiency: up to 90% to 96% efficiency, much higher than the ordinary trapezoidal screw
Low friction, low heat generation: not easy to wear, long life
High precision: high positioning accuracy, high repeated positioning accuracy, can achieve micron level
Smooth transmission: no crawling, no hysteresis, good high-speed response
Pretensionable: Eliminate axial clearance, improve rigidity and accuracy
Irreversibility: Some structures can be self-locked, and some need to be braked to prevent reversal
III. Main structural components
Screw shaft: precision threaded raceway
Nut: Matches with screw
Ball: for rolling transmission
Ball circulation system: domestic circulation, external circulation
End structure: bearing position, keyway, thread, flange, etc
Fourth, accuracy level (commonly used)
Normal grade: C7~ C10, for general automation equipment
Precision grade: C5~ C3, for numerical control lathes, milling machines
Ultra-high precision: C2~ C1, used in grinding machines, precision testing, semiconductor equipment
Common materials and heat treatment
Material: S45C, 40Cr, GCr15, SUJ2
Heat treatment: high frequency quenching, overall quenching, surface hardness HRC58~ 62
Machining: precision grinding, thread grinding to ensure accuracy
VI. Main categories
1.In a circular fashion
Domestic circulation: compact structure, small size, high speed performance
External circulation: larger load, stronger rigidity, suitable for heavy loads
2.By preloading
Double nut preload
Single nut displacement lead preloading
Ball offset preload
3.By purpose
Positioning ball screw: high-precision positioning
Transmission type ball screw: focusing on transmission efficiency
Advantages
Good high-speed operation performance
High transmission efficiency, power saving and energy saving
Good accuracy retention, stable accuracy for long-term use
Suitable for frequent reciprocating, high-speed feed
Simple maintenance and moderate lubrication requirements
Eight, shortcomings
The cost is higher than that of ordinary trapezoidal screws
Heavy-load impact capacity is not as good as trapezoidal screw
If used vertically, it will fall without braking.
High installation accuracy requirements
Typical application fields
Numerical control machine: machining center, numerical control car, grinding machine, milling machine Z axis/X axis/Y axis feed
Automation equipment: manipulator, truss, dispensing machine, soldering machine, cutting machine
Precision equipment: coordinate measuring instrument, laser equipment, testing instrument
Electronic equipment: semiconductor equipment, 3C assembly and testing equipment
Logistics equipment: heavy-duty telescopic fork, stacker lifting and positioning mechanism
Medical apparatus: operating table, testing equipment, imaging equipment transmission
Key points of selection
1.Load size: axial load, impact load
2.Lead size: Determines speed and accuracy
3.Running speed: high-speed selection of small lead, high DN value
4.Accuracy level: Select C1~ C10 according to equipment positioning requirements
5.Installation method: fixed-fixed, fixed-support, support-support
6.Lubrication and dust protection: grease lubrication/oil lubrication, with dust ring, scraper
7.Whether self-locking is required: It is recommended to add brakes or self-locking mechanism for vertical installation
