Hold Down Devices

These are special attachments which can be added to riveting machines which are used to :-

§ Remove gaps between components

§ Hold components securely whilst riveting

The photgraph below shows a typical example of a simple hold down device – this device is called a Pressure Pad.

This type of hold down device is used with Orbital and Sprial forming machines. It is fixed to the machine and advances with the orbital head during the forming cycle. The nose of the pressure pad is positioned slightly ahead of the forming peen and it is the nose which first comes into contact with the components being riveted. The pressure pad does not rotate.

As the nose presses down on the components, it creates a compressive force which both removes gaps and holds the components tightly together. The pressure pad is mounted on springs which can be adjusted to give various amounts of compression. Therefore, when the components are pushed together fully the springs in the pressure pad begin to compress so as to allow the orbital head to continue to advance form the rivet head.

Hold down devices also offer other benefits. For example, they can be used to fully enclose the moving parts of the Orbital forming machine and therefore provide additional safety. In the same manner they will also help protect operators from swarf and metal chips which may be egenerated during the forming process. In certain applications, coolant or lubrication can be injected through the side wall of the pressure pad to create an controlled "atmosphere" in the immediate vacinity of the forming rivet.

Finally, these devices can also be specially manufactured for very specific applications. For example, they can be fitted with load measuring devices and limit switches which can be integrated with process intelligence such as Watchdawg and used to detect the presence of correct parts.

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