Mandrel dwell

Multiple passes of carriage necessary to cover mandrel. Programmed relationship between carriage motion and mandrel rotation necessary. Reversal of carriage must be timed precisely with mandrel rotation. Dwell at each end of... 

Mandrel must remain motionless during pass of carriage and thenxotate a precise amount near 180° while carriage dwells. Fibers must be held close to support shaft during mandrel motion or fibers will slip. 

The desired carriage position is relative to the measured mandrel s circumferential position and can be visualized with the aid of Figure 5. The count PU LS Eman continues to increment. This is expressed by the ordinate, in terms of units of the circumference. The first peiss, the first dwell and the second pass are shown schematically. The desired locus of the two relative positions result in the line segments represented in bold print. The reference condition for the mandrel position at the start of the pass is PULSEman ref- The actual mandrel s position after an increment of time is PULSEman- The desired carriage position is PULSEqarwant- The two previous conditions are represented by the darkened arrow on the sketch. 

Figure 5.16 shows the principal steps for isos-tatically molding a simple solid cylinder. The mold cavity is formed inside an elastomeric membrane shaped like a hollow cylinder. In this case, it does not include any mandrels and is completely filled with the powder. The elastomeric bag is closed, sealed and placed inside a pressure vessel. The vessel containing a fluid is sealed, pressurized and held for a dwell period during which the powder is compacted by the action of a pressurized fluid. At the end of the dwell time, the vessel is depressurized and the mold is removed and disassembled for the removal of the preform. 

Dwell In filament winding, the time that the transverse mechanism is stationary while the mandrel continues to rotate to the appropriate point for the traverse to begin a new pass. 

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