Vibration is increasingly becoming a problem as machine speeds have increased and paper quality requirements have risen along with increased competition. Balance grade G1 is requested and more time is spent on balancing the rolls in the machine. However, by balancing, mills typically measure only the MD vibration, especially with rigid assembled rolls (suction rolls, deflection compensated ...
The author finishes the paper with two case histories where VFD drives played a major role in the vibration problems experienced by the rotating machinery. PREVIEW "Motor Controllers. Variable frequency drives (VFDs) used to control the speed of alternating current induction motors have become the preferred mechanism for controlling the speed of industrial equipment. These VFDs have replaced ...
Core crushing occurs where the impact energy is absorbed by the core, which distorts and folds, often being returned to its original shape but with greatly reduced compressive strength. Significance of Defects in Composites It is clear that in many ways, a composite can differ from the ideal either during manufacture or in service. The extent to which any of these deviations from ideal ...
High vibration levels can cause machinery failure, as well as objectionable noise levels. A common source of objectionable noise in buildings is the vibration of machines that are mounted on floors or walls. Obviously, the best place to mount a vibrating machine is on the ground floor. Unfortunately (but fortunately for noise control consultants), this is not always possible. A typical problem ...
PROBLEMS OBJECTIVES: After completing this module you will be able to: For turbine generatorrotorvibration. describe: a) =eways in which itcan damage the machine; ~Pages 34 b Its five major causes; ~Pages 48 c) Two general operating practices used to prevent its excessive ~Pages 910 levels; d) Three protective actions performed when the vibration is exces~ ~Pages 1011 sive. a ...
another vibrational impact on the structure [28]. In addition to this force, the differential pressure across the orifice plate causes swirling and back stream which are the main causes of vibration. The vibration affects both the orifice plate and the pipe wall in the neighbouring area of the orifice plate. The vibration itself is not always the main concern in damaging pipes, but, to a more ...
· The crushing resistance impactor apparatus (HANDY), as shown in Fig. 1, is composed of an impact part, a sieve part and a frame part (Additional file 1). The impact part includes a hopper, a cover, a shell, a centrifugal disc and a motor, and they are arranged concentrically from top to bottom. A material feeding plate is set under the hopper. The hopper is mounted on the feed port which is ...
· The problem of the accumulation of the dynamic response of a rock mass disturbed by mining activities has been studied in many papers ( Cai et al. 2015). In Poland, surface miningrelated vibrations have a significant impact on surface and underground structures.
than the natural frequency of vibration of the body. Since the hammers/blow bars are rotating at a very high speed, the time for which the particles come in contact with the hammers is very small, hence here impact loading is applied. The shaft is considered to be subjected to torsion and bending. The grinding screen is also designed for optimal output from the crusher A performance model is ...
Highenergy impact breaking hammer. The Fractum breaker is the largest hammer in the world. Its energy impact, at up to 400,000J per stroke, is 15 times higher than the energy released by the biggest hydraulic hammer on the market. Rock, concrete and steel breaking with lowered vibration. Fractum breakers are compatible with all popular earthmoving equipment. The hammer head is lifted to the ...
Select the right mounting methodology. As seen in our previous article, the settings of vibration measurement are crucial if you want to achieve the right detection and diagnostic, this is not the only thing to consider in order to achieve the desired objectives. For instance, the sensor mounting method to collect vibration data can greatly impact the quality of the time wave ...
The most common noise and vibration problem in condominiums is transmission through floor–ceilings and it falls into four egories: 1) airborne, 2) footfall, 3) structural deflection, and 4) floor squeak. Plumbing noise is also a factor particularly when plastic piping is used in waste stacks or when pipes are undersized and not vibrationally isolated from the structure. Airborne noise ...
Industrial environments frequently expose equipment to high degrees of shock and vibration. This can impact performance and damage the device itself. Here, we discuss the tradeoffs involved in choosing an encoder for a high shockandvibration environment and how to ensure appropriate lifetime and performance for the appliion. There are three key factors to consider when specifying for an ...
Dynamic crush characteristics of structural components are currently assessed in impact and crashworthiness laboratories by means of horizontal sledges or vertical drop hammers. Specimens in the form of thinwalled boxes are used. The deformation of these elements can be employed as an energy absorbing mechanism in the case of car collision in order to limit the damage to the passenger ...
Higher levels may also need to be allowed when highervibration sources are nearby. An example is a diesel engine driving a gearbox and a highspeed pump, all on the same common skid base. The gearbox and pump vibration may not meet their specified levels because of the thumping from the engine, but all three machines may be to operate as is.
Antivibration machinery mounting guide Issue 1 Top quality corkelastomer based products for: • Vibration attenuation • Machinery mounting levelling • Impact absorption • Pipe supports • Bearing supports. 2 For further details, please call your local contact shown on the back cover or listed at Introduction Objectives of this guide • Introduce the TICO ...
· The fourbearing system greatly reduces this problem. Why these screens are vibrated is to ensure that the ore comes into contact will the screen. By vibrating the screen the rock will be bounced around on top of it. This means, that by the time that the rock has traveled the length of the screen, it will have had the opportunity of hitting the screen mesh at just the right angle to be able to ...
Disproportionately high amplitude at a single frequency (the resonant frequency) in the direction in which the resonant frequency is being excited. A "mode shape" analysis shows the structure vibrating in a way that models resonance. Those models are covered on the next page. Neither of those characteristics confirms resonance as a problem. A ...
· A system such as this has high vibration sensitivity. Very small changes in the residual imbalance of the rotor cause very large responses in the vibration levels. When fans are mounted directly on structural steel platforms, the potential for a natural frequency excitation exists. A flexible fan mounting provides one solution to this problem. A flexible mounting consists of a rigid subbase ...
A high percentage of the pumps brought to us for repair are experiencing a vibration problem. There are six main causes of pump vibration problems and any one could take a pump out of service for unplanned and expensive repairs. Read on for tips to help you determine whether your pump's poor performance is due to one of these vibration problems.
