Roll diameter

In this work, a microwave interferometric method and apparatus for vibration measurements is described. The principle of operation is based on measurement of the phase of reflected electromagnetic wave changing due to vibration. The most important features of the method are as follows simultaneous measurement of tlie magnitude and frequency of the rotating object high measurement accuracy weak influence of the roll diameter, shape and distance to the object under test. Besides, tlie reflecting surface can be either metallic or non-metallic. Some technical characteristics are given. 

D Roll diameter cm in St - Critical Stokes number representing ... 

Operating experience (Wuestner et al., loc. cit.) has shown that roll diameters about 1 m are preferred, as a compromise between production rate and stress on the equipment. The press must be operated choke fed, with a substantial depth of feed in the hopper otherwise it will act like an ordinary roll crusher. 

Hard rubber is one of the few combustible materials which is generally ground on heavy steam-heated rollers. The raw material passes to a series of rolls in closed circuit with screens and air classifiers. Farrel-Birmingham rolls are used extensively for this work. There is a differential in the roll diameters. The motor should be separated from the grinder by a fire wall. 

The roll loading L is related to the maximum developed pressure and roll diameter by... 

Small variations in feed properties can have a pronounced effect on maximum pressure P, and press performance. RoU presses are scaled on the basis of constant maximum pressure. The required roll loading increases approximately with the square root of increasing roll diameter or gap width. 

The torque required to drive the rolls increases with yield strength so hot-rolling (when CTy is low - see Chapter 17) takes less power than cold-rolling. It obviously increases with the reduction in section (t - t2). And it increases with roll diameter 2r this is one of the reasons why small-diameter rolls, often backed by two or more rolls of larger diameter (simply to stop them bending), are used. 

Generally, a variety of mechanical deformation processes cause the nonuniform deformation that results in the formation of residual stresses. This nonhomogeneous deformation in a material is produced by the material s parameters, largely its process parameters such as the tool geometry and frictional characteristics. For example, the rolling of a strip can be accomplished by using relatively cold squeeze rolls. In the rolling process, parameters with a small roll diameter and little reduction produce deformation penetration that is shallow and close to the surface, whereas the interior of the strip remains almost undeformed. After the removal of the deformation forces and a complete... 

Rolling bank in the nip is small compared with the roll diameter... 

In fact a parabolic surface of the rolls in the flow region is assumed, which is valid as long as the rolling bank diameter is small compared with the roll diameter. This is normally the case in a calendering process. 

RB, rotating bar roll diameter and width, TF Mini 100mm x 25mm TF 156 150mm x 44mm. 

There is little work of a fundamental nature done that helps towards a better understanding or control of calendering of rubber. Most theoretical studies were concerned with the pressure developed when a stock of thick viscous rubber sheet material is reduced to a thinner sheet by passage between rolls. Calenders with 3, 4 or more rolls might be assembled to quite different configurations. Calenders in L shaped, F shaped, I shaped or Z shaped configurations with roll diameters of 168 mm, 250 mm and 350 mm are available on the market. 

For example, with df = lin. and d0 = 0.25 in., the roll diameter is figured as 18 in. Table 12.8(b) lists 16 in. as the smallest size suitable for this service, which appears to be somewhat marginal in comparison with the calculated result. According to the formula, 1 in. lumps could be nipped by 16 in. rolls with a spacing of 0.34 in. It is not possible to state who is smarter, the formula or the manufacturer. 

Figure 6.28 Comparison of theoretical and experimental pressure profiles [15], The experiments were performed by Bergen and Scott [2] with roll diameters of 10 in, a gap in the nip region of 0.025 in and a speed U =5 in/s. The measured viscosity was 3.2 x 109 P (Poise, 1 P=0.1 Pa-s).

Alternatively the two-roll geometry can be conveniently represented by bipolar coordinates, as suggested by Finston (36). This approach, as well as the FEM, enables the analyses of both equal and unequal roll diameters and frequency of rotation, termed asymmetrical calendering. However, the FEM method provides the most flexibility in dealing with both Newtonian and non-Newtonian fluids and asymmetrical calendering. Chapter 15 covers this method in some detail. 

The Roll Pump Derive a mathematical model for the roll-pump [depicted in Fig. E6. la(c)] having a barrel inner diameter, D, and a roll diameter, Ds, relating the flow rate, Q, pressure rise, Pout — Pln, and roll speed, N, to the relevant geometrical variables. Neglect back flow over the channel blade clearance. 

Three common methods, which are commonly referred to as roll-crown, roll-crossing, and roll-bending, are employed to compensate for this deformation. Roll-crown indicates that the roll diameter at the center is slightly greater than at the edges. In principle, by applying an appropriate roll diameter and profile, roll deflection can be exactly... 

Fig. 15.3 Pressure profiles in the calender gap at various cylinder axial positions, with rigid PVC (Vestolit Z 1877) at equal roll speeds of 5cm/s and roll temperature of 185°C minimum gap, 0.6 mm roll diameter, 30 cm width, 50 cm. Note the drop in pressure in the cross-machine direction with distance from the centerline, which drops to zero at the end of the rolled web. [Reprinted by permission from W. Unkruer, Doctoral Thesis, KV, Technischen Hochschule, Aachen, 1970.]...

Fig. 15.10(a) represents schematically the roll deformation along the roll axes, z, caused by the flow of a K-BKZ fluid. Figure 15.10(b) plots the initial roll-diameter profile... 

Fig. 15.10 (a) Representation of the deformation between rolls 3 and 4 of a calender design used by Mewes at al. (41) not to scale (b) calculated gap uniformity, resulting from the initially imposed roll diameter and the roll deformation for rolls 3 and 4. [Reprinted by permission from D. Mewes, S. Luther, and K. Riest, Simultaneous Calculation of Roll Deformation and Polymer Flow in the Calendering Process, Int. Polym. Process., 17, 339-346 (2002).]... 

Roll tangential velocity (mm/s) = roll speed (RPM) x roll diameter (mm)... 

Recognizing that the roll diameter from Eq. (6.1) and roll width from Eq. (6.2) are noncontrollable process parameters for a given dry granulation process equipment, the remaining process parameters identified within these two equations, roll speed, ribbon thickness, and ribbon density, serve to define the dry granulation throughput. 

Roll diameter, D, is calculated from eqn. (1) where a and Ri are determined from Fig. 5.7 and 5.8 for the given 5, 0 and K. Usually the maximum pressure exerted by the press is set equal to the maximum required briquetting pressure, Pb, to provide a safety factor in the design. A lower applied pressure can be used in press operation, if desirable. Note in Fig. 5.8 a correction may be necessary to Rx if the dimensionless roll gap S/D is different from 0.01. Since D is unknown, an iterative procedure is necessary in its determination. 

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