In connection with many types of manufacturing processes, it is desirable, and sometimes required to join two sheets of material, by forming clinch joints therebetween. Clinch joints obviate the need for welding or special fasteners, are highly effective in holding two sheets of material together and can be formed using relatively simple apparatus. Clinch joints may be of the so-called pierce type in which one or both sheets of material are pierced in order to form an interlocking joint, or may be of the so-called waterproof type in which an interlocking joint is formed without piercing either sheet.
Apparatus for forming clinch joints, of both the pierced and non-pierced types, are well-known in the art. Such apparatus normally includes a punch for forming a cup in the two sheets of material, a die which cooperates with the punch to form the cup, and an anvil which cooperates with the punch to complete the deformation process. Previous types of known apparatus employ cams and/or various types of camming mechanisms to move the die, anvil and/or punch in synchronism with each other. Such types of apparatus are not only relatively difficult to manufacture, because in part they require trip levers to trip the cams, but also require frequent adjustment, especially under high production conditions, since cam wear results in deterioration of the quality of the clinch joint.
The present invention is intended to overcome the foregoing problems.