Guangming Group will talk about D-hole helical gears today

D-hole helical gear=helical gear+D-shaped shaft hole, is a commonly used structure that combines "smooth helical gear transmission" and "D-hole anti-skid", and is very common in automation, small reducers, and motor matching.

1、 What is a D-shaped hole

The inner hole is not a complete circle, but a circular arc with a straight edge, with a cross-section resembling the letter D.

Milling a flat surface (D-axis) on the corresponding axis, it can be installed and fixed in the circumferential direction without slipping, without the need for keyways, top screws, or glue.

2、 What is a helical gear

The gear teeth form a helix angle (15 ° -45 °) with the axis and are not straight.

Features:

Mesh is a gradual process with low noise, smoothness, high overlap, and high load-bearing capacity.

Disadvantage: It will generate axial force, and the bearing needs to withstand both radial and axial forces.

3、 Advantages and disadvantages of D-hole helical gears

advantage

Non slip: D-hole+D-axis, reliable torque transmission, can be fixed even without keyway.

Easy installation: Simply press or tap into place without adjusting the top thread or applying glue.

Smooth transmission: Diagonal teeth have 5-10dB lower noise than straight teeth, suitable for high-speed/low-noise scenarios.

Compact structure: eliminating keyways and flanges, the wheel hub can be made smaller.

shortcoming

Axial force: Single helical gear operation will push the gear towards one end, and the bearing should be selected to withstand axial force.

Processing is slightly more expensive: both D-holes and helical teeth require specialized tools/processes, which are more expensive than straight tooth circular holes.

Cannot frequently change direction with high torque in both directions: When the impact is large, the straight edge of the D-hole is prone to crushing (plastic gears are more obvious).

4、 Common specifications and coordination

Modulus: 0.5, 0.8, 1.0, 1.25, 1.5, 2.0 (commonly used for small automation).

Pressure angle: 20 ° (standard).

D-hole size: 2mm, 3mm, 4mm, 5mm, 6mm, 8mm, 10mm (matching with motor shaft/output shaft).

Spiral angle: 15 ° -20 ° (balancing stability and axial force).

Rotation direction: Left/Right (one left and one right when paired).

5、 Typical applications

Small motor matching: Output gears for N20, N30, 28BYJ and other motors.

Filling machine/packaging machine: small conveying, bottle shifting, measuring and fine-tuning mechanism (low noise, stable).

Automation equipment: precision transmission, low torque, frequent start stop situations.

Robots/servos: joints, gimbal, fine tuning transmission.

6、 Difference from "herringbone gear" (easily confused)

D-hole helical gear: single helical teeth+D-hole; There is axial force; Simple structure, affordable, and commonly used.

Herringbone gear (double helical teeth): symmetrical helical teeth for left and right rotation; Axial force self offsetting, suitable for heavy load and high speed; Processing is complex, expensive, and bulky.

7、 Key selection points

D-hole size: It must be tightly matched with the D-shaped size of the shaft (interference fit 0.01-0.03mm).

Spiral angle and direction: selected based on speed, noise, and axial force; Pairing requires one left and one right.

Material

Light load: POM, nylon (cheap, noise reducing).

Medium load: 45 # steel, powder metallurgy.

Heavy load: 20CrMnTi carburizing and quenching.

Axial force treatment: Single helical teeth should be equipped with deep groove ball bearings (capable of withstanding a small amount of axial force) or angular contact bearings.

Powder metallurgy, metal injection molding, powder metallurgy gears

Guangming Group focuses on the research and development of metal forming technology and wear-resistant materials. Its main products include metal compression molding and injection molding powder metallurgy products.

The company has a team of high-quality talents, with the founding team originating from the Guangzhou Nonferrous Metals Research Institute, a directly affiliated national and ministerial level scientific research institution. It has rich industry experience and research and development capabilities, providing a continuous source of innovation power for the company's development. The company has successively obtained 5 invention patents and more than 30 utility model patents. It has passed the IATF16949 quality management system, ISO9001-2015 quality management system, ISO14001 environmental management system, intellectual property management system, and obtained international trademark certification. It is an innovative enterprise in Guangdong Province, a small giant enterprise in science and technology in Guangzhou, a member of the Guangdong Powder Metallurgy Industry Technology Innovation Alliance, and an initiator of the Guangzhou Advanced Powder Metallurgy Cluster Promotion Center.