Prestressed Anchor Pad Clamping Fixture with Dual Extrusion Units

The problem

Prestressed anchor backing plates are critical components in construction, used to distribute tension forces in concrete structures. Before these parts are installed, they undergo rigorous quality detection to verify their geometry and integrity. However, the anchor pad body often has an irregular shape, tapering from a narrow mouth to a wide mouth. When placed on a standard flat surface or held by simple vices, the part can shift, tilt, or rotate slightly during the measurement process. This instability causes deviations in the reading, leading to inaccurate quality assessments and potential rejection of good parts or acceptance of faulty ones. Existing fixtures lack a mechanism to simultaneously stabilize both ends of this specific tapered geometry without interfering with the sensor paths.

The solution

The patented fixture addresses this by providing a dedicated clamping tool with two distinct extrusion units.

1. First Extrusion Unit: Located at the narrow-mouth end of the anchor backing plate body, this unit provides a stable base point.
2. Second Extrusion Unit: Located at the wide-mouth end, this is the core mechanical assembly. It consists of a horizontally movable platform that slides toward the workpiece.
3. Inclined Arm Mechanism: On the front and rear side walls of the moving platform, first inclined arms are rotatably mounted. These arms connect to right-angle outer support plates.
4. Contact Points: One face of the outer support plate contacts the end part of the anchor pad, while the perpendicular face inserts into the anchor pad body to contact its inner wall.
5. Locking System: Second inclined arms connect the outer support plates to sliding blocks within grooves on the moving platform. Leaf springs apply elastic force to keep the arms pressed against limit blocks, fixing the geometry once deployed.
6. Mobile Base: The entire second unit sits on a base table with rolling wheels that ride on conical anti-skid plates, allowing smooth transverse movement while maintaining alignment.

Who it is for

• Quality Control Labs in pre-stress technology firms that need repeatable fixtures for inspecting anchor pads.
• Construction Hardware Manufacturers producing custom anchor systems who require internal QC tools.
• Third-party Inspection Agencies serving the infrastructure sector, looking for specialized jigs for geometric verification.
• Tooling Engineers designing production lines where anchor pads must remain stationary during automated scanning.

How it works

The main parts

Operating steps

1. Placement: The anchor backing plate body is laid horizontally. Its narrow end rests against the First Extrusion Unit.
2. Engagement: The operator pushes the Moving Platform (part of the Second Extrusion Unit) transversely toward the wide mouth of the plate.
3. Deployment: As the platform moves, the geometry of the inclined arms rotates the Outer Support Plates. One face presses against the outer edge of the plate, while the other face inserts into the cavity to press against the inner wall.
4. Locking: The sliding blocks reach their position in the grooves. The leaf springs pull the inclined arms tight against the Limit Plates and Stopper Blocks. This freezes the angle of the arms, locking the support plates firmly against the workpiece.
5. Detection: With the part immobilized by dual-point contact and rigid arm linkage, sensors or calipers perform measurements without deviation.

Applications

Pre-stress anchor inspection

Used in factory settings to verify the diameter and concentricity of anchor pads before they are shipped to construction sites.

Concrete formwork quality checks

Helps inspectors check the mounting holes and sealing surfaces of the backing plates, which are critical for water-tightness in bridge decks.

R&D prototyping

Engineers developing new anchor geometries use this fixture to test how different shapes fit into standard inspection routines.

Automated assembly lines

Integrated into robotic cells where cameras scan the anchor pad; the fixture ensures the part doesn’t vibrate during image capture.

Where it is less suitable

• Non-standard geometries: Designed specifically for the tapered narrow-to-wide profile of standard anchor pads; may not clamp cylindrical or square blocks effectively.
• High-volume rapid sorting: The manual engagement of the moving platform may be slower than pneumatic chucks for very high-throughput lines.
• Heavy-duty machining: This is a light-to-medium duty clamping tool for inspection, not for holding parts under cutting forces.