Pigtail round heads are formed through a combination of shaping, heat treatment, and surface finishing to ensure strength, durability, and precise geometry.

Pigtail Coil Spring End Manufacturing

The pigtail end of a coil spring is created after the main coiling process. The process begins with loading the coiled spring onto a forming machine, where the end is oriented by an operator. A forming jig, programmed for the specific pigtail shape, bends the spring end into a tight loop or pigtail configuration automatically when the start button is pressed. The jig may need to be changed depending on the number of turns or the diameter of the pigtail portion ( ). After forming, the spring is transferred to quenching or tempering stations to enhance mechanical properties. The machinery often includes:

• Lead angle servo motors to control the pigtail angle precisely.
• Coil spring fixing devices to hold the spring in place during forming.
• Vertical and lateral moving mechanisms to position the forming tool accurately ( ).

Pigtail Bolt Manufacturing

Pigtail bolts, commonly used in power line and construction applications, are typically made from carbon steel or stainless steel. The manufacturing steps include:

1. Shaping the Pigtail End: The metal rod is heated and bent into a loop or hook shape using hot working techniques. This forms the characteristic pigtail end that can hold or connect other components ( ).
2. Threading: The opposite end of the bolt is threaded to allow secure installation into wood, concrete, or metal structures.
3. Heat Treatment: Bolts undergo quenching and tempering to improve strength and durability, similar to coil spring treatment.
4. Surface Treatment: Many bolts are hot-dip galvanized to provide corrosion resistance, especially for outdoor applications ( ).
5. Quality Control: Each bolt is inspected for dimensional accuracy, thread integrity, and pigtail loop geometry to ensure reliable performance.

Round Head Formation

For applications requiring a round head, such as rivets or bolts, the process involves:

• Heading: The wire or rod end is struck under a heading machine to form a rounded head.
• Shank Shaping: Rolling or draw-benching ensures the shank has the correct diameter and length.
• Knurling: Optional diamond-pattern knurling improves grip.
• Heat Treatment: Quenching and tempering refine the metal's microstructure.
• Finishing: Protective coatings or platings are applied to prevent corrosion ( ).

Summary

The manufacturing of pigtail round heads combines mechanical forming, heat treatment, and surface finishing. For coil springs, specialized forming jigs and servo-controlled machines shape the pigtail ends. For bolts, hot working, threading, and galvanization ensure strength and corrosion resistance. Round head features are added through heading and finishing processes, making the components suitable for demanding industrial and utility applications.