Experimental Measurements of Load Distributions on Friction Stir Weld Pin Tools
- PDF / 599,665 Bytes
- 9 Pages / 593.972 x 792 pts Page_size
- 105 Downloads / 172 Views
I.
INTRODUCTION
AS the application envelope for friction stir welding (FSW) continues to expand, there is a continual desire to move to materials with higher strengths, in thicker plates, with higher production rates. The net effect of all three of these changes is to increase the stress on the pin tool, which increases the probability of failure. In order to design appropriate pin tools, it is necessary to know the force distribution on the pin, not just the total load. For example, Figure 1 shows three possible force distributions along the pin, which would produce three different root stresses if the total pin force were identical in all cases. Yet there is no available data on force distributions in FSW tool pins. This article examines a method to experimentally measure the longitudinal force distribution on a friction stir weld pin tool while welding 6061-T6 aluminum. By understanding the force distribution on the tool pin while welding, stresses can be analyzed and tool designs modified to minimize cracks and fractures and to maximize tool longevity. II.
RELATED LITERATURE
Tool forces have long been recognized as being related to process parameters, but relatively little work on force as a function of tool geometry has been published. Johnson[1] has measured the total lateral loads, thrust loads, and torque for several tools that CARL D. SORENSEN, Associate Professor, is with the Department of Mechanical Engineering, Brigham Young University, Provo, UT 84604, USA. Contact e-mail: [email protected] AARON L. STAHL, formerly Research Assistant with the Department of Mechanical Engineering, Brigham Young University, is Production Engineer with Precision Castparts Corporation, Portland, OR 97239-4262, USA. Manuscript submitted July 29, 2005. Article published online May 3, 2007. METALLURGICAL AND MATERIALS TRANSACTIONS B
varied in shoulder diameter, pin diameter, and pin length while welding various aluminum alloys. The results showed that the use of a larger tool shoulder diameter caused higher welding torques, and that increasing the shoulder had a larger effect on torque than increasing the pin diameter. Ding[2] focused on characterizing axial forces by the pin independently of the shoulder, by varying the pin length with a retractable pin tool. Correlations were made between forces and the tool pin position in relation to the weld material backside. Data showed that the axial force increased with decreasing distance from pin to material backside. Much work has also been performed on the relationship between tool forces and tool geometries and weld parameters. Colligan et al.[3] examined the relationship between forces and certain tool features such as flats. They found that travel per flat per revolution plays a role in determining transverse force. However, no literature was found that explored force distributions on a pin tool.
III.
THEORY
To minimize the size of the welded zone, it is desirable to have FSP pin tools with small pin diameters. However, as the pin diameter decreases, the likelihood of pin fai
Data Loading...
