GB/T 12601-1990Basic terminology of harmonic gear drive (English PDF)

3.1 Transmission elements and components

3.1.1 Harmonic gear drive Harmonic gear drive is mainly composed of three basic components: wave generator, flexspline and circular spline. It is a drive that relies on wave generator to make flexspline produce controllable elastic deformation and mesh with circular spline to transmit motion and force.

3.1.2 Mechanism of the harmonic gear drive The main components in the mechanism of harmonic gear drive are: a. Wave generator; b. Flexspline; c. Circular spline; d. Input shaft connection;

3.1.8 Deflection Under the action of the wave generator, the amount of deformation (radial, tangential or axial) at any point on the neutral layer of the flexspline toothed ring. Synonym: displacement

3.1.8.1 Radial deflection Under the action of the wave generator, the amount of deformation in the radial direction at any point on the neutral layer of the flexspline toothed ring. Synonym: Radial displacement

3.1.8.2 Tangential deflection Under the action of the wave generator, the amount of deformation in the tangential direction at any point on the neutral layer of the flexspline toothed ring. Synonym: Tangential displacement

3.1.8.3 Axial deflection Under the action of the wave generator, the amount of deformation in the axial direction at any point on the neutral layer of the flexspline toothed ring. Synonym: Axial displacement

3.1.8.4 Maximum deflection Refers to the maximum value of deformation (radial, tangential, axial) at any point on the neutral layer of the flexspline toothed ring under the action of the wave generator. Synonym: Maximum displacement

3.1.8.5 Coefficient of maximum deflection The ratio of maximum deformation to modulus.

3.1.9 Distortion When the drive mechanism is overloaded, the actual profile of the neutral layer of the flexspline's toothed ring will deviate or twist from its original profile under no load.

3.1.10 Equidistant curve The lost motion caused by the backlash between the flexspline and the circular spline as well as the gaps in other components, which is called the lost motion caused by clearance.

3.2.5.2 Lost motion caused by elastic deflection Lost motion as caused by elastic deformation of components.

3.2.6 Moment of inertia The sum of the product of each mass or the mass of mass unit in the component and the square of the distance from the given axis, which is called the moment of inertia of the rigid component to the given axis.

3.2.7 Natural frequency The frequency determined by the mass (moment of inertia) and stiffness (torsional stiffness) of the system itself.

3.2.8 Resonance frequency The vibration when the excited frequency coincides with the natural frequency of the system, which is called resonance. The forced vibration frequency when resonance occurs is called the resonance frequency.

3.3 Gear characteristics and size parameters

3.3.1 Mating flank In a gear pair, two flanks that mesh with each other are called mating flank.

3.3.2 Working flank A flank on a gear tooth that meshes with the flank of a mating gear and transmits movement.

3.3.3 Non-working flank The opposite side of the working flank of the gear tooth.

3.3.4 Left flank When an observer looks at the end face of the gear selected as the reference The process from the point when the flexspline starts withdrawal from the maximum depth of engagement to the point when the flexspline's teeth is disengaged.

3.4.1.3 Total number of teeth in engagement The number of teeth meshed simultaneously between the flexspline and the circular spline.

3.4.1.4 Region of engagement Under the action of the wave generator, the region where there is engagement between the flexspline's teeth and the circular spline's teeth.

3.4.1.5 Engaging-in region The region passed by the engaging-in process.

3.4.1.6 Engaging-out region The region passed by the engaging-out process.

3.4.1.7 Circular arc angle of engagement The center angle corresponding to the region of engagement.

3.4.1.8 Normal engagement The contact point between the flexspline tooth and the circular spline tooth is located within the working section of the tooth profile.

3.4.1.9 Tip edge engagement The engagement where the tooth tip edge of the flexspline is in contact with the tooth profile of the circular spline, or the tooth tip edge of the circular spline is in contact with the tooth profile of the flexspline.

3.4.1.10 Maximum depth in engaging In the engagement state, the absolute value of the difference between the radius of the addendum circle on the long shaft's half shaft (or short shaft's half shaft) and the radius of addendum circle of the circular spline after the flexspline is deformed.

3.4.2 Interference The phenomena when the tooth profile of the matched gear overlaps due to improper selection of design parameters, or crosses the normal limit, or overcuts.

6.1 Types of flexsplines

6.1.1 Cylindrical tube-shape flexspline The flexspline whose basic shape is cylindrical.

6.1.2 Ring-shape flexspline The flexspline whose basic shape is ring.

6.1.3 Cup-shape flexspline The flexspline whose basic shape is a cylindrical cup.

6.1.4 Bell-shape flexspline The flexspline whose basic shape is an ancient bell.

6.1.5 Double bell-shape flexspline The flexspline whose basic shape is approximately the shape of a single leaf hyperboloid.

6.1.6 Flexspline's toothed ring The part on the flexspline with gear teeth.

6.1.7 Lining ring A thin-walled ring arranged between the wave generator and the inner surface of the flexspline's toothed ring.

6.2 Geometric elements

6.2.1 Neutral layer of flexspline's toothed ring The layer, which is set in the flexspline's toothed ring, bisect the curved surface where the distance from the tooth root to the inner wall of the flexspline is located.

6.2.2 Original curve of neutral layer of flexspline's toothed ring

7.1.2 External circular spline The external gear.

7.2 Geometric elements

7.2.1 Beginning circle of involute profile on external circular spline A circle with an involute profile on the external circular spline tooth profile close to the tooth root.

7.2.2 Terminal circle of involute profile on internal circular spline The circle that terminates the involute tooth profile on the tooth profile of the internal circular spline close to the tooth root.

8.1 Coupling of wave generator and input shaft

8.1.1 Elastic coupling Coupling form which is flexible.

8.1.2 Rigid coupling Coupling form which is rigid.

8.1.3 Oldham coupling The input shaft and the wave generator are connected by a cross Oldham.

8.2 Coupling of flexspline and output shaft

8.2.1 Integrated coupling The bottom of the flexspline is coupled to the output coupling plate by screw or welding.

8.2.2 Dynamic coupling The coupling method that the wall of the flexspline cylinder and the output coupling disc form synchronous meshing motion by the inner and outer toothed rings with the same number of teeth.