GB/T 37718-2019Precision planetary cycloidal reducers for robot (English PDF)

3.1 Precision Planetary Cycloidal Reducers for Robot

A precision transmission device composed of an involute planetary gear reduction mechanism and a cycloidal pin gear reduction mechanism, as shown in Figure 1.

The difference in the output shaft angle at 3% and -3% of the rated torque when the input shaft is fixed, and the output shaft is rotated from forward to reverse.

3.11 Rated Life

The life of the reducer when operating at its rated output torque and rated output speed, meaning that after testing, the reducer maintains normal operation and the increase in backlash and lost motion is less than the nominal value.

3.12 Torsional Stiffness

The ratio of the difference between 1/2 and 1 time the rated output torque to the difference in output shaft angle, when the input shaft is fixed, and a torsional moment is applied to the output shaft.

3.13 Transmission Error

The difference between the actual and theoretical angles of the output shaft when the input shaft rotates in one direction.

3.14 Allowable Moment Load

The maximum value of the vector sum of the radial load and the moment of the eccentric axial load that the reducer can withstand.

3.15 Momentary Max Allowable Acceleration Torque

The maximum momentary torque value that the reducer is allowed to withstand.

4.1 Schematic Diagrams

The output configuration of the reducer can be divided into two types. housing-fixed flange output and flange-fixed housing output. Schematic diagrams are shown in Figure 1a) and Figure 1b).

5.1 Main Components

The main components of the reducer include the pin gear housing, planet carrier, planetary gears, cycloidal gears, crank shaft, and pin gears. Their performance and heat treatment quality shall comply with the provisions of Table 9, or other materials with equivalent or superior mechanical properties may be used.

5.2 Assembly

The assembled reducer must comply with the following provisions.

--- Before assembly, all components shall be cleaned thoroughly, free from burrs, rolled edges, rust, foreign matter, etc.;

--- Parts must not be bumped, scratched, or corroded during assembly;

--- All connecting and fastening parts must not be loose;

--- There shall be no oil leakage at the sealing surfaces of all joints;

--- Operation shall be smooth, without abnormal impact, vibration, or noise.

5.3 Performance Parameter Requirements for the Reducer

The performance parameters of the reducer shall comply with the provisions of Tables 10, 11, and 12.

If the backlash is greater than that specified in Tables 10, 11, and 12, it shall be indicated in the accuracy code according to 4.3.6.

5.10 Torsional Stiffness

The torsional stiffness value can be obtained from the hysteretic curve of the reducer, as shown in Figure 6. In the hysteretic curve, the ratio of the load torque to the corresponding elastic deformation angle, b/a, is the torsional stiffness. b = Rated torque/2.

The torsional stiffness value shall comply with the provisions of Tables 10, 11, and 12.

5.11 Transmission Error

The transmission error shall comply with the provisions of Tables 10, 11, and 12.

5.12 Moment Load

After applying the moment load conforming to Tables 10, 11, and 12, and operating for the specified rated lifespan of the main bearing, the main bearing of the reducer shall show no abnormalities.

5.13 Lubrication and Sealing

Before operation, the reducer shall be sealed and filled with the required lubricating grease according to the product manual. No grease leakage shall occur during operation.

5.14 Appearance

The appearance shall be smooth, free of burrs, scratches, rust, and process defects; the joints between the housing and other parts shall be flat.

5.15 Rated Life

The rated life shall be no less than 6 000 h.

6.1 Test Devices

The test devices are divided into rotary test devices and moment load test devices.

6.1.1 Rotary test device

The driving and loading methods of the test device are not restricted. During performance testing, the loading torque and speed shall be stable, and loading and unloading shall be possible during operation; during accuracy testing, all moving parts or components of the instrument shall move smoothly, flexibly, and sensitively, without any jamming, and the measurement accuracy, flange mounting surface flatness, and coaxiality of the test system shall be ensured.

Before installing the tested sample, lubricating grease conforming to the manual shall be added.

During installation, ensure that the tested sample is coaxial with the test device, and the installed test system shall operate smoothly. A schematic diagram of the test bench is shown in Figure 7. Description.

1 -- Motor;

2 -- Reducer;

3 -- Crossbeam;

4 -- Bearing;

5 -- Loader; L -- Force arm of the radial load; F -- Radial load provided by the loader.

6.2 No-load Test

Operate in both forward and reverse directions for 30 min each at the rated output speed.

6.3 Load Test

Under operating conditions that ensure the housing temperature does not exceed 60°C (preferably at the rated output speed), gradually apply 25%, 50%, 75%, and 100% of the rated load. The first three stages of operation lasted 20 min, followed by 2 hours of operation at 100% of the rated load. Repeat the same operation in the reverse direction.

6.4 Overload Test

The load is gradually applied to the output shaft to the momentary max allowable acceleration torque within 5 s, maintained for 5 s, and then gradually unloaded within 5 s. This is performed once in both the forward and reverse directions.

6.5 Transmission Efficiency

6.5.1 Test conditions

After the load test, the reducer is cooled to room temperature (23±5)°C and operated at the rated output speed and rated output torque. Test data is collected and processed to obtain the measured transmission efficiency.

6.5.2 Data acquisition

At the rated output speed and rated output torque, record the input/output shaft torque measured by each sensor. At least 5 sets of data shall be collected uniformly within one revolution of the output shaft. […]