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How Ball Joint Space Frame is Made

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Ball joint space frames are integral structures in many modern architectural and industrial applications. Their fabrication involves two main processes: the production of rod members and the manufacturing of bolt balls. Here’s a detailed look at each stage of these processes.

Importance of the Ball Joint Space Frame

The ball joint space frame structure has the advantages of novel structure, large span, flexible planar shape design, reasonable force, light weight, low steel consumption, simple construction and positioning, and various installation methods. Thanks to these advantages, ball joints are widely used in large stadium space frames, public stadium space frame, power plant bolt ball space frame, cement industry space frame, warehouse logistics space frame, as well as ball joint space frame for exhibition centers, terminal buildings, factory workshops, etc.

Ball joint space frame has a large processing capacity in its component factory, and it is easy to install on-site. The ball joint is suitable for the special structure with a high on-sight schedule, restricted construction conditions and electricity consumption, complicated frame shape, and difficult rod positioning. Ball joint space frame is especially suitable for large curvature space structure systems such as barrel shell structure, spherical shell structure, and various architectural shapes.

How to make Ball Joint Space Frame?

The steel pipe, sealing plate, cone head and sleeve of the bolt ball joint are made of 16Mn steel specified in the national standard “Technical Conditions for Low Alloy Structural Steel” GB1591-88, the steel ball is made of No. 45 steel specified in the national standard “High-quality Carbon Structural Steel Grades and General Technical Conditions” GB699-88, and the bolts, pins or screws are made of 40Cr steel specified in the national standard “Technical Conditions for Alloy Structural Steel” GB3077-88. 8.8s bolts are made of No. 45 steel. The product quality meets the industry standard “Steel Grid Frame Bolt Ball Joint” JGJ75.1-91.

Rod Member Production Process

1. Steel Pipe Cutting: The steel pipe is cut to the length according to the drawing. If the pipe wall thickness is ≤4mm, it is directly cut to the size L=±1; if the pipe wall thickness is >4mm, it is cut to L+3; the end face is guaranteed to be perpendicular to the axis, and there is no horseshoe-shaped cross-section in appearance; for pipes with a wall thickness >4mm, grooves are processed at both ends of the pipe.

2. Cone Head Blank Forging: The next step is forging the cone head blanks. This involves heating the metal and shaping it into the desired conical form, which will later connect to the rod members.

3. Cone Head Machining: Machining refines the forged cone heads, ensuring they meet the precise dimensions and surface finish required for assembly.

4. Cone Head End Plate Assembly and Welding: Assemble the assembled cone head or sealing plate assembly with the steel pipe on the pre-welded mold. After checking that the length is correct, pre-weld 3-4 points in the circumferential direction of the sealing plate and the steel pipe.

Rod Member Production Process

5. Cone Head and Pipe Assembly: The welded cone heads are assembled with the steel pipes. Proper alignment and fitting are crucial to ensure the final structure’s accuracy.

6. Rod Member Welding: The assembled components are then welded to form the complete rod member. This step is critical for ensuring the strength and stability of the frame.

7. Rod Member Measurement and Correction: After welding, the rod members are measured and corrected as necessary. Any deviations from the specified dimensions are adjusted to ensure precision.

8. Sandblasting and Coating: The rod members undergo sandblasting to remove any surface impurities, followed by coating to protect against corrosion and improve durability.

9. Rod Member Numbering and Identification: Each rod member is then numbered and marked for identification. This aids in the assembly process and ensures each piece is placed correctly.

10. Rod Member Protection and Shipping: Finally, ensure they arrive at the construction site in optimal condition.

Bolt Ball Production Process

1. Round Steel Cutting: The production of bolt balls starts with cutting round steel to the necessary sizes. This ensures that each piece is ready for the subsequent forming processes.

2. Initial Steel Ball Pressing: The cut steel pieces undergo an initial pressing to form rough spheres. This preliminary shaping sets the stage for more precise forging.

3. Ball Forging: The rough spheres are then forged into solid balls. This process involves heating and hammering the steel to achieve the desired density and strength.

4. Datum Surface Machining: Machining of the datum surfaces follows, ensuring that each ball has the correct geometry for further processing.

5. Datum Drilling: Holes are drilled into the balls to create reference points. These holes are essential for the alignment and assembly of the bolt balls. Face-to-center distance marked on the drawing, machine the bottom hole with a lathe, and chamfer the hole.

Bolt Ball Production Process

6. Bolt Hole Drilling: Additional holes are drilled for the bolts. These must be precisely placed to ensure a secure fit with the rod members.

7. Marking: Each bolt ball is then marked for identification. This ensures that each piece can be correctly matched and assembled. After all the ball processing is completed, and after the inspection is correct, mark the ball number with white paint according to the steel stamp number.

8. Rust Removal: Rust and other surface contaminants are removed from the bolt balls.

9. Painting: Finally, the bolt balls are painted.

How do we ensure the position and angle of the bolt ball are accurate?

  • Thread tolerance: The thread of the bolt ball should comply with the 6H grade accuracy requirements in the national standard “General thread tolerance and fit” GB197-81 or GB/T 197.
  • Size tolerance: The allowable deviation of the distance from the center of the bolt ball to the end face is ±0.20mm, and the allowable deviation of the bolt ball hole angle is ±0.2°.
  • Adopt advanced measurement technology: Utilize the coordinate measurement system based on attitude angle sensor and rotation distance meter, combined with total station, angle encoder laser distance sensor, etc., to build a non-contact combined measurement system to improve measurement accuracy and efficiency.

High quality ball joint space frame manufacturer - Yunjoin

In today’s practical applications, ball joint space frames are widely used in various occasions such as spacecraft, exhibition centers, and exhibition halls. For example, in the structure of a spacecraft, the space frame acts as a support platform, which can carry concentrated and asymmetric loads and cover large spans without intermediate supports. This structure is not only lightweight but also meets high-performance requirements. These advantages make the ball joint space frame occupy an increasingly important position in the construction industry.

High quality ball joint space frame manufacturer

Yunjoin focuses on the production of ball joint space frames, constantly tries better technologies, optimizes instruments and equipment, and provides high-quality ball joint space frame products and services to major construction companies.

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