Press

The specialist for sheet metal joining, TOX PRESSOTECHNIK, enlarges its program of pressure joining processes and clinch technologies by the future-oriented solid punch riveting process

The irresistible tendency toward the weight- and resource-saving light construction of vehicles, requires the use of alternative of completely new materials as well as new production and joining techniques for them. While the problems of joining hybrid materials e.g. aluminium with steel or high-strength steel sheets with more simple carrier sheets are dealt with already now, future materials and material combinations pose additional challenges for production techniques. The technology enterprise TOX PRESSOTECHNIK GmbH & Co. KG, 88250 Weingarten, has already taken up these subjects some time ago and developed a corresponding supply and performance program for the joining of sheet metals. Besides the „original process“, i.e. the TOX-Round-Point, they offer the Flat Joint, the Vario Joint, the SKB system and the ClinchRivet. At present, such sheet joining processes are used in modern vehicle construction in more than 200 different applications. The application range covers also crash-relevant component parts and assembly groups. In addition, the mentioned processes are, according to requirements, also used in combination with glue coatings or laser welding. The advantage has to be seen in the fact that with all TOX processes, additional mechanic preparing work and costly production facilities are no longer needed, whereas, for example, with conventional rivet joining, a preparing work is indispensable. Yes, of course, there exists the alternative of semi-hollow rivets, but still there are certain restrictions.

Process-safe solid punch instead of semi-hollow punch rivet techniques

This is the reason why TOX PRESSOTECHNIK has developed further the innovative process of solid punch riveting for an automobile manufacturer. TOX is here responsible for the industrial and process-safe placement and machining technology and the equipment. A direct comparison of the semi-hollow rivet with solid punch rivets shows at first sight that the semi-hollow rivet creates an elevation on the die side, whereas the solid punch rivet shows a flush image on punch and die side and a level surface. Moreover, almost no distorsion of the piecepart takes place with the solid punch rivet. And again, the semi-hollow rivet allows a maximum of three sheet layers to be joined, whereas the solid punch rivet allows four layers. The solid punch rivets are, in addition, appropriate for joining high-strength and ultra-high-strength materials (tensile strengths higher than Rm = 1600 MPA), whereas semi-hollow rivets can only be used for joining sheets up to Rm = 800 MPA. For the semi-hollow rivet there arise also difficulties with the joining of cast material because of dimensional restrictions and the need of a special die in any case. With the solid punch rivet it is possible to join all usual cast materials. With regard to joining directions, they are also limited for the semi-hollow rivet, and also the joining strategies „thin into thick and hard into soft“ must be observed. In case of the solid punch rivet there is only a restriction with regard to ultra-high-strength materials saying that the brittle-hard material must be put on the punch side. For the use in the crash zone of automobiles, the solid punch rivet in connection with glue additive has already been released.

Solid punch riveting is a distinct advantage with regard to construction and production techniques

Solid punch rivet - complete solutions as whole package deal

For each rivet diameter and rivet length the corresponding placement heads are available which may then be used for the whole family of this diameter saving thus retooling cost and down-times of the plant. The modular concept for the construction of complete solutions fascinates by its standardization but nevertheless allows individual solutions as e.g. the installation of storage bins, feed- and singulator stations at distances up to 25 m from the robot. Due to the universal rivet placement head mentioned above, also with multi rivet applications, only minimized contours have to be taken into consideration. The robot is also able to use the joining tongs overhead. At present, joining solutions with the solid punch rivet are offered for aluminium and all usual automobile steels. Now that the development of solutions with the solid punch rivet for press-hardened steels is also speeding up, its production stage will not take long.