Ball screws are ideal products for converting rotary motion into linear motion, or converting linear motion into rotary motion.
Ball screw is the most commonly used transmission element in tool machinery and precision machinery. Its main function is to convert rotary motion into linear motion, or convert torque into axial repetitive force, with high precision, reversibility and high Efficiency characteristics. Due to its small frictional resistance, ball screws are widely used in various industrial equipment and precision instruments.
The ball screw consists of a screw, a nut, a steel ball, a pre-press, a reverser, and a dust filter. Its function is to convert rotary motion into linear motion, which is a further extension and development of Acme screw. The important significance of this development is to change the bearing from sliding action to rolling action.
Ball screw principle
1. According to the national standard GB/T17587.3-1998 and application examples, the ball screw (which has basically replaced the trapezoidal screw, commonly known as the screw) is used to convert rotary motion into linear motion; or convert linear motion into rotary motion actuator, and has high transmission efficiency, accurate positioning, etc.
2. When the ball screw is used as the active body, the nut will be converted into linear motion with the rotation angle of the screw according to the lead of the corresponding specification, and the passive workpiece can be connected by the nut seat and the nut to realize the corresponding linear motion.
Ball screw application
Ball screw bearings are available in a wide variety of standardized products for various applications. It is widely used in machine tools, and the circulation methods of balls include circulation conduit type, circulator type, and end cap type. The preloading methods include positioning preloading (double nut method, positional preloading method) and constant pressure preloading. An appropriate type can be selected according to the application. The screw has a precision ball screw with high-precision grinding (accuracy is divided into 6 grades from CO-C7) and a cold-rolled ball screw bearing formed by high-precision cold rolling (accuracy is divided into 3 grades from C7-C10) level). In addition, in order to cope with the urgent need for delivery by users, there are also finished products whose shaft ends have been processed, semi-finished products and cold-rolled ball screw bearings that can be freely processed on the shaft ends. As the peripheral parts of this bearing, the screw support unit, nut support, lock nut, etc. necessary for use have also been standardized and can be used by users.
Ball screw bearings are based on the product technology accumulated over the years. From materials, heat treatment, manufacturing, inspection to shipment, they are managed with a strict quality assurance system, so they have high reliability.
Ball Screw Applications
Ultra-high DN value ball screw: high-speed machine tool, high-speed comprehensive machining center
End Cap Ball Screws: Quick Handling Systems, General Industrial Machinery, Automation Machinery
High-speed ball screws: CNC machinery, precision machine tools, industrial machinery, electronic machinery, high-speed machinery
Precision grinding ball screw: CNC machinery, precision machine tools, industrial machinery, electronic machinery, conveying machinery, aerospace industry, actuators used in other antennas, valve switch devices, etc.
Nut Rotary (R1) Series Ball Screws: Semiconductor Machinery, Industrial Robots, Woodworking Machines, Laser Processing Machines, Transfer Devices, etc.
Rolled-grade ball screws: low-friction, smooth-running benefits with fast delivery and low price
Heavy-duty ball screws: All-electric injection molding machines, punching machines, semiconductor manufacturing equipment, heavy-duty brakes, industrial machinery, forging machinery
How to choose the right servo motor and stepper motor?
[2] 1. It mainly depends on the specific application. In short, it is necessary to determine: the nature of the load (such as horizontal or vertical load, etc.), torque, inertia, speed, accuracy, acceleration and deceleration requirements, this ball screw has been It is included in Kuaiyiyou, and the upper control requirements (such as the requirements for port interface and communication), the main control mode is position, torque or speed mode. Whether the power supply is DC or AC power, or battery powered, voltage range. Based on this, determine the model of the motor and the associated drive or controller.
2. How to use the stepper motor driver
According to the current of the motor, use a driver that is greater than or equal to this current. If low vibration or high precision is required, a subdivision driver can be used. For high-torque motors, use high-voltage drives as much as possible to obtain good high-speed performance.
What is the difference between 3, 2-phase and 5-phase stepper motors, and how to choose?
The 2-phase motor has low cost, but the vibration is larger at low speed, and the torque drops quickly at high speed. The 5-phase motor has less vibration and good high-speed performance, which is 30~50% higher than the speed of the 2-phase motor, and can replace the servo motor in some occasions.
4. I want to control the servo motor directly through communication, is it possible?
Yes, and it is more convenient, but it is only a matter of speed, and it is used for applications that do not require very high response speed. If fast response to control parameters is required, it is best to use a servo motion control card, which generally has DSP and high-speed logic processing circuits to achieve high-speed and high-precision motion control. Such as S acceleration, multi-axis interpolation, etc.
Ball screw type
There are two commonly used circulation methods: outer circulation and inner circulation. The ball is sometimes out of contact with the screw during the circulation process is called the outer loop; the ball is always in contact with the screw is called the inner loop. Each closed loop of the ball is called a row, and the number of leads contained in the closed loop of each ball is called the number of turns. There are 2 rows, 3 rows, 4 rows, 5 rows, etc. for each nut of the inner circulation ball screw pair, and each row has only one circle; each column of the outer circulation has 1.5 circles, 2.5 circles and 3.5 circles, etc.
1) External circulation: The external circulation is that the balls return to the screw and nut through the spiral groove or cannula on the outer surface of the nut and re-enter the circulation after the end of the circulation process. The return methods of the external circulation ball screw nut pair according to the ball circulation mainly include end cap type, intubation type and spiral groove type. Commonly used external circulation methods are end cap type; intubation type; spiral groove type. For the end cap type, a longitudinal hole is machined on the nut as a return passage for the balls. The cover plates at both ends of the nut are provided with return openings for the balls, from which the balls enter the return pipe to form a circulation. Intubation type, which uses elbows as return pipes, this structure has good manufacturability, but because the pipes protrude from the outside of the nut, the radial size is large. Spiral groove type, it mills a spiral groove on the outer circle of the nut, and drills through holes at both ends of the groove and is tangent to the threaded raceway to form a return channel. This structure is smaller than the intubation structure in radial size, but Manufacturing is more complicated. The outer circulation ball screw has a simple structure and manufacturing process and is widely used. The disadvantage is that it is difficult to smooth the seam of the raceway, which affects the stability of the ball raceway.
2) Inner circulation: Inner circulation adopts reverser to realize ball circulation, and there are two types of reverser. Cylindrical convex key reverser, its cylindrical part is embedded in the nut, and a reverse groove 2 is opened at the end. The reverse groove is positioned by the cylindrical outer surface and the round key 1 on the upper end to ensure the alignment of the thread raceway direction. Oblate insert reverser, the reverser is a general round head flat key insert, the insert is embedded in the groove of the nut, and the end is provided with a reverse groove 3, which is positioned by the outer contour of the insert. Comparing the two reversers, the latter is smaller in size, thereby reducing the radial dimension of the nut and shortening the axial dimension. However, the dimensional accuracy of the outer contour of the reverser and the groove on the nut is relatively high.
Type selection
The nut of the ball screw can be divided into: elbow type, circulator type and end cap type according to the circulation mode of the steel ball. The characteristics of these three circulation methods.
Elbow
(SBN, BNF, BNT, BNFN, BIF and BTK models) these models are searchable.
Circulating guide type (HBN type)
These models are the most typical of nuts, using elbows to circulate the steel balls. After the steel ball is drawn from the groove of the screw shaft into the elbow, it returns to the groove and performs an infinite circular motion.
circulator
(DK, DKN, DIK, JPF and DIR types)
These models are the smallest nut, which change the travel direction of the steel ball through the circulator, and return to the original position beyond the outer diameter of the screw shaft, making an infinite circular motion.
end cap
(Types SBK, SDA, SBKH, WHF, BLK, WGF, BLW, WTF, CNF and BLR)
These models are the most suitable nuts for high-speed feed. The steel ball is taken from the groove of the screw shaft into the through hole of the nut by using the end cover, and returns to the groove through the through hole, making an infinite circular motion.
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