Calculation of the selection of ball screw

1、 Model and parameter table of ball screw
The common specifications for the outer diameter of the screw include 12, 14, 16, 20, 25, 32, 40, 50, 63, 80, 100, and 120. However, please note that among these specifications, manufacturers generally only stock 16~50, which means that most other diameters are futures. The nominal diameter is basically proportional to the load, and the larger the diameter, the greater the load. Specific values can be found in the manufacturer's product samples.
Here, only two concepts are explained: dynamic rated load and static rated load. The former refers to the rated axial load in motion, while the latter refers to the rated axial load in static state. You can refer to the former when designing. It should be noted that the rated load is not the actual load, and the smaller the ratio of the actual load to the rated load, the higher the theoretical life of the screw. Recommendation: Choose a diameter of 16~80 as much as possible. Lead. Also known as pitch, it refers to the distance that the nut moves in a straight line for each rotation of the screw. Common lead sizes include 5, 6, 8, 10, 16, 20, 25, 32, and 40. Small and medium-sized lead sizes are generally only available in stock, while large lead sizes include 1616, 2020, 2525, etc. (the first two digits of the four digits are the diameter, and the last two digits are the lead). The lead is related to the linear velocity, and under a constant input speed, the larger the lead, the faster the speed.
2、 Selection and calculation of ball screw
1. Determine the positioning accuracy;
2. Determine the lead of the screw through the motor and the requirements for speed;
3. Check the nut size to determine the stroke and related screw shaft end data;
4. Determine the average axial force and rotational speed through load and speed distribution (acceleration and deceleration);
5. Determine the pre pressure through the average axial force;
6. Expected lifespan, axial load, and speed determine dynamic rated load;
7. The basic dynamic rated load, lead, critical speed, and DmN value limit determine the outer diameter of the screw and the form of the nut;
8. Outer diameter, nut, preloading, load determination rigidity (machine design);
9. The ambient temperature and the total length of the nut determine the thermal variation and cumulative lead;
10. The rigidity of the screw determines the pre tension force through thermal displacement;
11. The maximum speed of the machine tool, temperature rise time, and screw specifications determine the motor drive torque and specifications.
3、 Working principle of ball screw
1. According to the national standard GB/T17587.3-1998 and application examples, ball screws (which have basically replaced trapezoidal screws, commonly known as screws) are used to convert rotational motion into linear motion; Or an actuator that converts linear motion into rotational motion, with high transmission efficiency and accurate positioning.
2. When the ball screw serves as the active body, the nut will be converted into linear motion according to the corresponding specifications of the lead as the screw rotates. The passive workpiece can be connected to the nut seat and nut to achieve corresponding linear motion.