Mandrel centering

Pipe and Tubing. A typical die for extmding tubular products is shown in Figure 4. It is an in-line design, ie, the center of the extmded pipe is concentric with the extmder barrel. The extmdate is formed into a tube by the male and female die parts. The male die part is supported in the center by a spider mandrel. Melt flows around legs of the mandrel and meets on the downstream side. The position of the female die part can be adjusted with bolts adjustment is requited to obtain a tube with a uniform wall thickness. 

Fig. 4. Pipe or tubing die for in-line extmsion A, die body B, mandrel, pin, and male die part C, die, die bushing, and female part D, die-retaining ring E, die-retaining bolt F, die-centered bolt G, spider leg H, air hole I, seat for breaker plate J, ring for attachment to extmder and K, die land (15).

A numerically controlled filament winder has been designed and constructed. The distance between the head-stock and tail-stock is six feet. Clearance between the centers emd the body of the winder is adjustable, but a specimen several feet in diameter could presently be fabricated. The mandrel and carriage are each driven by one horsepower, direct current motors with a maximum 2000 revolutions per minute. Three phase, 480 volt alternating current is transformed to a 90 volt, direct current power supply. A gear... 

Fig. 14.23 Typical blow molding die A, choke adjusting nut B, mandrel adjustment C, feed throat D, choke screw E, die head F, plastic melt G, die barrel H, heater band /, choke ring J, centering screw K, clamp ring L, die heater M, die N, mandrel. [Reprinted by permission from J. D. Frankland, A High Speed Blow Molding Process, Trans. Soc. Rheol., 19, 371 (1975).]...

Mandrel (Torpedo) suspended in the center of the circular passage in the die body with metal bridges called spiders (typically three are used). One spider allows for passage of air into the center of the torpedo, is streamlined to avoid flow stagnation, and supports the die pin. 

Fig. 2. Configuration for spirally wound rechargeable lithium cell. A, Cap B, cathode tab C, insulating disk (2) D, mandrel E, can F, ball G, safety vent H, glass-to-metal seal (with center pin) I, anode tab J, cathode K, separator L, anode. Courtesy of Moli Energy Ltd.

Preforms are made in a cylinder equipped with a mandrel and a pusher. The mandrel is positioned in the center of the cylinder and the resin is charged in the annular space. The diameter of the preform and the center hole are designed to the following guidelines ... 

The ram extruder for this process is a special unit and can be either horizontally or vertically oriented, which refers to the direction of the ram movement. The extmder consists of a heated barrel where the preform is loaded, and a hydraulic or screw-driven ram. The conductor is drawn by a power system through a hollow mandrel located at the center of the barrel. The mandrel terminates in a wire guide tube. 

The blown-film technique is widely used in the manufacture of polyethylene and other plastic films [14,15]. A typical setup is shown in Figure 2.23. In this case the molten polymer from the extruder head enters the die, where it flows round a mandrel and emerges through a ring-shaped opening in the form of a tube. The tube is expanded into a bubble of the required diameter by the pressure of internal air admitted through the center of the mandrel. The air contained in the bubble carmot escape because it is sealed by the die at one end and by the nip (or pinch) rolls at the other, so it acts like a permanent shaping mandrel once it has been injected. An even pressure of air is maintained to ensure urufoim thickness of the film bubble. 

Figure 9.12 is an example for an S-shaped design that is formed by wrapping the foils around two mandrels. These honeycombs are more robust toward thermal expansion, deformation and, in particular toward telescoping, the latter describing the axial displacement, that is, pushing out, of foil layers in the center of the honeycomb. 

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