Tension control

Increase Adhesion Tension Maximize Surface Tension Minimize Contact Angle Determine the critical surfactant concentration to maximize adhesion tension. Control impurity levels in particle formation... 

To show this, we will present and discuss some typical results readily available in the literature. Here we will select systems simulated in the constant-pressure constant-surface-tension ensemble, i.e. with a temperature, pressure and surface tension control. 

Adhesive remains unchanged until it is cured No multiroll coating needed No complex tension controls needed Adhesive bond established almost instantly Real-time quality control... 

PetrosiUo, G., Di Venosa, N., Ruggiero, F.M., Pistolese, M., D Agostino, D., Tiravanti, E., Fiore, T., and Paradies, G. 2005. Mitochondrial dysfunction associated with cardiac ischemia/reperfusion can be attenuated by oxygen tension control. Role of oxygen-free radicals and cardiolipin. Biochim. Biophys. Acta 1710 78-86. 

The wet end—where in an unwind stand the reel of paper is supported and fed under suitable tension controls into a bath of resin at controlled temperature. In many cases, instead of total immersion, the paper is wetted on one side only—to allow the resin to penetrate, force air out, and give a fully saturated sheet. To allow time enough for the required penetration a skying system of variable rollers is used, as shown in Figure 55 this transports the web upwards and then down again before a final immersion in the resin, followed by metering. 

Figure 18.3 is an extrusion line schematic drawing of tension control equipment for the unwinding substrate. The arrows indicate the motions of the driven tension control rolls and idlers as well as the substrate, and the direction of outward pressure-on the rolls. Figure 18.4 is what is called a flying splice on a double-station-unrolling stand where ... 

Figure 18.3 Examples of tension control rollers in a film, sheet, or coating line...

Tension Control Roil These type rolls provide the important function of material tension control. There is a proportional relationship between winding tension and lay-on-roll forces (eliminating areas were bumps, valleys, unwanted stretch, etc. develop). There are various tension control techniques available. The proper selection involves decisions on how to produce the tension, how to sense the tension, and how to control the tension. For instance, if the material has a very low tension requirement and if exact control is required, then perhaps, using a magnetic particle brake with an electrical transducer roll with appropriate electronic control is best. However, if the material is on large diameter rolls and moves at slow speed, then a roll follower system can be used effectively. 

Adjustable Roil The dancer rolls, canvas drag brakes, various pony brakes, and pneumatically operated brakes are manual adjustment systems. The most expensive would be the regenerative drive systems. The transducer rolls and dancer rolls would be a close second. These systems are usually required in high web speed applications where accurate tension control of expensive and/or sensitive material is paramount. With roll windup systems different roll or reel-change systems are used to keep the lines running at their constant high speeds. 

A more reliable extension tester is produced by Hepatex AG, Wattwil, Switzerland. This machine (the Dehnungspriifgerat DP-5) has hydraulic damping and constant tension controls to provide reproducible stretching forces to the fabric. Fabrics can be tested in the wet or dry states. The degree of elasticity, E, can be calculated by ... 

C.Beccari, G.Gasciola and L.Romani An interpolating 4-point C2 ternary non-stationary subdivision scheme with tension control. CAGD 23(4), pp210-219, 2007... 

L.Romani A circle-preserving C2 Hermite interpolatory subdivision scheme with tension control. CAGD 27(1), pp36-47, 2010 C.Deng and G.Wang Incenter subdivision scheme for curve interpolation. CAGD 27(1), pp48-59, 2010... 

Interfacial tension controls the ease of drop breakage. Low interfacial tension (cr < lOdyne/cm or 0.01 N/m) systems require lower power for dispersion than high interfacial tension (cr > 30dyne/cm or 0.03 N/m) systems. 

Figure 9-11. Driven system of the expanding zone. 1. Differential gear unit 2. Cloth tension control 3. Actual value 4. Nominal value.

Another possible method of hot mercerization consists of wet-in-wet impregnation of fabric immediately after washing at 95 C and a subsequent hot squeezing with high speed steam injected. The heated fabric is then impregnated with caustic solution at 30 C in the first step and 20 C in the second step. These offer the stabilisation. Sequence is normally carried out under tension controlled condition. 

Decomposition of copper(II) malonate Examination of fracture sections of cooled, solidified particles of partly reacted salt, by electron microscopy, revealed the intraparticular generation of a frothlike material composed of bubbles with rounded surfaces (30). This texture was ascribed to the evolution of gaseous products within a fluid matrix. The predominantly curved surfaces were ascribed to surface tension control, and no regularly aligned features or flat surfaces, characteristic of crystalline materials, were found. 

The message from Figure 8 is that static lamellae are stable to small disturbances until a critical capillary pressure is attained then coalescence is catastrophic. In porous media, the liquid saturation, absolute permeability, and surface tension control this critical capillary pressure through the Leverett J-function (75). Of course, static lamellae may coalesce at lower capillary pressures, if they are subjected to large disturbances. Figure 8 also reveals that static lamellae in equilibrium with the imposed capillary pressure are amazingly thin. 

The Sopares gradient system uses a similar device. A conducting chart on which the gradient curve 1s drawn with a compass point is displaced with a linear movement in front of an optoelectric device which follows the curve exactly. This gives two electric signals, which can control two tension-controlled pumps, A low-volume (less than 200 ul) mixing chamber is used. The response time of the system can be less than 1 sec. Two tapes drawn on the chart allow the control of various on-off devices. 

The main function of a winder is to guide the film evenly into the roll form. To accomplish this, it must provide tension control on the film to produce evenly wound rolls. A secondary nip, either as part of the winder or just prior to the film entering the winder, is used to provide this tension control. Tension must be sufficient that the roll will not telescope when handled, but must not be so much that it causes crushed cores or center-roll bagginess. Tensions on center drive winders are generally tapered from the core to the outer wraps to compensate for the change in diameter of the roll. On a surface winder, the compensation is automatic because of the drive mechanism. When tension is being adjusted on a winder, it must be kept at or below 0.5% of the secant modulus of the film to avoid excessive stress in the film. One reason for this low value of recommended tension is that the film is not totally at equilibrium at the time it is wound into the roll. Dimensional changes occur as the film crystallizes or cools, and induce stress. 

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