Vicoda-Lisega anti-vibration bases
Spring anti-vibration bases are used to isolate mechanical vibration in power plants on equipment such as turbines, pumps, blowers, coal mills, etc., or from large machines such as presses, forging hammers, crushers and the like.
Lisega now offers these elements widely used in industry and construction. It is important to clarify that in mechanical vibrations there are two types of solutions, passive and active. Within the passive solutions, Vicoda offers three types of solutions, one is to isolate, another is to cushion and the most sophisticated is to absorb.
The isolation is a passive method of vibration control, it is based on cutting off the transmission of energy from the vibration source (exciter) to the oscillating system. Thanks to the reduction in energy transmission, the oscillating system will vibrate with a lower amplitude than the non-isolated system.
The damping is another passive method that consists of extracting, through a damping element, the energy of an oscillating system. Unlike isolation, this procedure begins by transferring energy from the exciter to the oscillating system. Part of this vibrational energy is transformed within the damping element into another form of energy.
Absorbing can be a passive or active method, which consists of having a second oscillating system that is coupled to the original system. If an absorber is chosen with the appropriate characteristics, that is, with the appropriate mass, damping parameter and elastic properties, it will be able to absorb oscillatory energy from the original system. The absorber will oscillate and the vibration of the original system will be significantly reduced.
Why Vicoda?
Springs are the essential elements of a Vicoda anti-vibration base, but the firm was currently acquired and incorporated into Lisega, a world leader in pipe support systems. This makes Vicoda benefit from more than 50 years of experience in the design and manufacture of variable and constant load supports based on springs.
The stiffness of conventional coil springs suffers over time, particularly if they are exposed to high loads and high temperatures (relaxation). To counteract the negative effects of this common phenomenon, Vicoda uses pre-relaxed springs, which guarantee constant functionality throughout the life of the anti-vibration base.
Spring bases; small vibration isolators
VICODA® spring bases are an excellent solution for isolating vibration induced by equipment or the source of the vibration. By isolating, it does not allow energy to be transmitted from the vibration source (exciter) to the oscillating system, which may be the floor or civil and/or mechanical structures connected to the system.
These bases cover low frequencies between 2.5 and 5 Hz. All spring anti-vibration bases can be additionally equipped with viscoelastic dampers to not only isolate but also dampen mechanical vibration.
VICODA® spring anti-vibration bases are designed as follows:
- Each series has the same installation height.
- Large load range between 90 and 72, 200N (9 and 7362 kgf).
- 2.5Hz frequencies.
- Pressure and form lock height adjustment (also available in optional stainless steel).
- High quality corrosion protection (CDP coated springs).
- CRD type cushioning using the same dimensions (optional).
- Structural noise dampening (optional).
- Lifting device (optional).
Fields of application
VICODA® Spring Anti-Vibration Bases are suitable for use in a variety of applications. They provide the best solution for structural noise and vibration isolation, for example in:
- Fans or ventilation systems.
- Air conditioning systems.
- Pumps or Pumping Systems.
- Electronic equipment.
- Measuring equipment.
- Small and medium power presses.
Available models
Information necessary for correct selection
To calculate the dimensions, number of anti-vibration bases and type, the following information is required:
- Type of system/equipment requiring vibration-isolated installation.
- Total weight of the system/equipment or individual weight of components in kN.
- Drawing of the equipment base.
- Center of gravity of the system/equipment or individual centers of gravity of the components. (If not available, we will assume a central center of gravity.)
- Excitation frequency or rotation speed in Hz or rotations / min.
- Desired insulation efficiency.
- Interior or exterior installation.
Applications
Spring anti-vibration bases for concrete foundations, insulators and/or shock absorbers
Spring anti-vibration bases are the products commonly used to decouple and isolate an oscillating system from the source of vibration. Mounted between the source and the system, they allow the transmission of energy from the source to the system to be minimized.
VICODA® spring anti-vibration bases are effectively used for vibration isolation of heavy machinery beds, such as presses or hammers, in power plants, coal mills, diesel power sets, turbine systems, feed water pumps, condensers, etc. They provide support for static loads and reduce the transmission of dynamic loads to the foundation.
VICODA® spring anti-vibration bases are generally composed of three main parts: an upper and lower housing, coil springs and a viscoelastic damper. The frequency covered by anti-vibration bases is between 2 and 7 Hz.
Design
VICODA® Spring Anti-Vibration Bases are effectively used to isolate vibration in concrete foundations supporting rotating equipment such as turbines, feedwater pumps, etc. They provide support for static loads and reduce the transmission of dynamic loads to the foundation.
An important feature of these anti-vibration bases is that they can be locked at a predetermined load (preload). The preloaded spring elements are installed in a closed location (so they would work as rigid supports); At the end of the installation, which may be the installation of heavy machinery, the spring elements will be activated by unlocking them. From that moment on, the devices act as vibration control elements.
Product range
The VICODA® product portfolio covers most typical base insulation applications in power plants as well as for mounting capacitors. By combining a set of VICODA® spring anti-vibration bases in one application, an optimal configuration can be achieved.
VICODA® spring elements can come with or without additional damping elements. The capacity for bases without a damping element is 126 kN (12,848 kgf) up to 2096 kN (213,732 kgf) and with damping loads up to 1300 kN (132,563 kgf).
Fields of application
- Foundation of turbines / turbo groups.
- Coal mill foundation.
- Fan / blower foundation.
- Assembly of capacitors.
Parameters and construction
The basic parameters necessary for the definition of a base isolation solution with spring anti-vibration bases are:
- The load [kN], determined by the weight of the supported machine and the distribution of the load.
- Natural frequency of the foundation.
- The main excitation frequencies [Hz] of the vibrating source.
- Operating temperatures [°C] in case of damping elements.
- Installation dimensions [mm] and geometric limitations.
Installing vibration-isolated machines greatly reduces the transmission of dynamic loads between the machine and the base. Source isolation reduces vibrations from crushers and presses.
Spring elements generally have very limited damping qualities, based on the low natural damping of steel; Base performance can be improved by integrating viscoelastic cushioning elements into the bases.
Although the vibration source goes through different operating states, with variable excitation frequencies, for example, when starting a turbine, damping elements are needed to control the vibrations. From its rest state (0 Hz), the turbine is accelerated to its operating frequency. Since effective isolation, using spring anti-vibration bases, is designed in such a way that the oscillating system has its own frequency Fo, well below the permanent excitation frequency Fr, that is, the operating frequency, after starting the turbine it will necessarily cross this resonance zone; To prevent an increase in vibration in this area, the system must be equipped with safety damping elements.
Advantages
- Wide load range: 1 kN (224.81 lbf) to 2,700 kN (606,984.15 lbf).
- Operational stability in accordance with EC 3.
- Low natural frequency (1 Hz to 8 Hz) of the system and therefore, maximum isolation.
- Horizontal spring rates from 20% to 130% of the vertical spring rate.
- Can be preset and locked so a replacement is always available.
- Surface coatings for corrosion categories up to C5 in accordance with DIN EN ISO 12944.
- Individual damping factor with integrated shock absorbers as required.
Viscoelastic Shock Absorbers (Dampers)
Application areas
Viscoelastic dampers are equipment that reduces mechanical vibration, in all directions, produced by rotating equipment. They effectively reduce vibrations by converting kinetic energy into heat, dampening system movement. Their design allows them to be used in a wide range of applications, however, the required type of viscoelastic damper depends on the planned application.
They can be used in almost all industrial sectors to reduce resonant vibrations. Applications include power production, process engineering and damping of individual machines or complete piping systems. Dampers can be used to solve vibration problems as long as there is an external structure or floor that offers the greatest possible rigidity.
Ambient temperatures from -30 (-22 ° F) to + 110 ° C (230 ° F), as well as extremely demanding environmental conditions (e.g. chemicals, dust or salt-laden atmospheres) are not an obstacle here. Viscoelastic dampers solve vibration problems in sets of equipment, inindividual machines or complete piping systems. They can be mounted in demanding environmental conditions and when attached to a piping system that transfers high temperatures, the viscoelastic shock absorber can be equipped with special insulation.
All viscoelastic shock absorbers and cushioning parameters are tested and monitored by our internal laboratory test. If required, they can be certified in external testing laboratories, according to the KTA 3205 Safety Standard.
Design
Viscoelastic shock absorbers consist of a metal shell filled with a highly viscous liquid and a piston connected to the upper connecting plate, which can move freely in all directions within the medium. Either the upper or lower connecting plate of the shock absorber can be connected to the vibrating system, while the other plate is mounted on a fixed pillar.
The shock absorbers cannot withstand static loads and are protected against corrosion as standard according to ISO 12944 C3 (M).
Models
VD type Viscoelastic Shock Absorber.
Buffer fluid: High viscosity bitumen.
Suitable for applications up to 554 kNs/m and frequencies up to 5 Hz.
Operating temperatures from +20 °C to +80 °C.
VM type Viscoelastic Shock Absorber.
Buffer fluid: High viscosity polybutane.
Suitable for applications up to 438 kNs/m and frequencies up to 5 Hz.
Operating temperatures from -10 °C to +40 °C.
Type VI Viscoelastic Shock Absorber.
Shock absorber fluid: High viscosity Silicone Oil.
Suitable for low commitment applications.
Operating temperatures from -30 °C to +110 °C.
Applications
