Square Neck Bolts with Large Semi-circular Heads

Square neck bolts with large semi-circular heads, also known as carriage bolts, are a common type of mechanical connection parts.

Structural Features of Square Neck Bolts with Large Semi-circular Heads:

Head Shape: The head is in the shape of a large semi-circle, which is relatively smooth. The top is arc-shaped, and the edge has a slight curvature. This shape makes the contact area between the bolt head and the connected part relatively large. When tightening, it can evenly transmit the pressure. Moreover, it has a more beautiful appearance and is not easy to hook other objects.

Square Neck Design: There is a square neck section below the head, which is its key structure. The square neck matches the square hole on the connected part. When the bolt is inserted and the nut is tightened, the square neck can prevent the bolt from rotating along with the nut, facilitating installation and fixation. At the same time, it can also move parallelly within the groove.

Thread Part: The screw rod has external threads, usually using standard metric or imperial threads to cooperate with the corresponding nuts to achieve a firm connection. The precision of the threads has an important impact on the reliability and stability of the connection.

Relevant Standards of Square Neck Bolts with Large Semi-circular Heads:

National Standard: GB/T 14-1998 is the national standard for square neck bolts with large semi-circular heads, which stipulates their specification dimensions, technical requirements, marking methods, etc. It is applicable to square neck bolts with large semi-circular heads with thread specifications ranging from M6 to M24. It gives clear numerical ranges for the dimensions of each part of the bolt, such as the head diameter, thickness, square neck size, thread length, etc., to ensure the interchangeability and reliability of the products.

German Standard: DIN 603 is a commonly used German standard. It is also widely adopted internationally. It standardizes various parameters and performance requirements of square neck bolts with large semi-circular heads, which helps to promote international trade and the global application of products.

Materials and Properties of Square Neck Bolts with Large Semi-circular Heads:

Materials: They are usually made of materials such as carbon steel, alloy steel, or stainless steel. Carbon steel materials have a relatively low cost and a certain strength, which is suitable for general mechanical connection occasions. Alloy steel materials have higher strength and better toughness, and can withstand larger loads and impact forces, and are often used in equipment or structures with high requirements for connection strength. Stainless steel materials have excellent corrosion resistance and can maintain good performance in harsh environments such as humidity, acids, and alkalis, and are widely used in industries such as food processing, chemical engineering, and medical treatment.

Performance Characteristics: They have good fastening performance, and reliable connection force can be provided by tightening the nuts. Due to the anti-rotation function of the square neck, the position of the bolt can be kept stable during installation and use, and it is not easy to loosen. According to different materials and surface treatment methods, they also have good wear resistance, corrosion resistance, and fatigue resistance, and can meet the usage requirements under various working conditions.

Application Fields of Square Neck Bolts with Large Semi-circular Heads:

Connection of Wooden Structures: They are mostly used in trucks, barges, iron-wood looms, and other wooden structural parts. Because the supporting surface of their heads is large, it is not easy to sink into the wooden connected parts, and they can provide a reliable connection without causing excessive damage to the surface of the wood.

Connection Parts with Appearance Requirements: They are suitable for some occasions where the exposed parts of the bolts are required to be smooth, such as the legs and wall panels of agricultural machinery. They can make the appearance of the equipment neater and avoid potential safety hazards caused by the uneven surface of the bolt heads.

Connection Scenarios Requiring Anti-rotation: When the structure of the connected part is limited and it is not suitable to use hexagonal bolts, and the bolt needs to maintain a fixed position and prevent rotation during the installation process, square neck bolts with large semi-circular heads can play their unique role, such as in the connection of some parts with a groove-shaped structure.