Welded Metal Bellows
What Is Welded Metal Bellows?
Welded metal bellows are mechanical devices designed to provide a flexible, leak-tight seal for various engineering applications. These bellows feature only the end edges of metal diaphragms being welded together in an alternating pattern, thus producing a hermetic seal between each individual plate. This design allows for minimal resistance while enabling high flexibility and elasticity. In comparison with other types of bellows, welded metal bellows offer better performance by providing high sensitivity to axial, angular, and lateral deflections, and by maintaining excellent vacuum or pressure containment capacities without compromising on movement capability.
High precision: The welded metal bellows has the effect of tension spring and is a combination of countless tension springs, so it solves the problem of general tension spring deformation due to centrifugal force, rotates at an appropriate height, and the sealing surface is pressed evenly.
Good oscillation resistance and flexibility: The bellows has high flexibility and good absorption effect on oscillation, so it has high habit ability of radial runout, axial clearance, oscillation and swing to avoid leakage.
Simple structure: Simple structure and easy assembly. Unlike the tension spring seal, which is composed of many parts, the use is complex.
Adapt to a variety of temperature conditions: The welded metal bellows has a small coefficient of thermal expansion and can be used at low or high temperature. And there is no o - ring disjoint temperature limit, the design is more comfortable.
Adapt to high pressure: Due to the balance effect of the bellows itself, the sealing surface area can be adjusted to offset the fluid pressure, reduce the friction of the sealing surface, and then reduce the amount of heating and wear. It can be applied to high pressure.
To protect the machine: The welded metal bellows has no o-ring, so the wear of shaft or sleeve caused by the abrasion of o-ring will not occur. It has the effect of protecting the shaft, so there is no need to install the shaft sleeve.
Habitual corrosive fluid: The welded metal bellows is made of highly corrosive hastelloy 276 and other materials to avoid the corrosion of tension spring and o-ring, so the sealing is completed.
No suspension: Using the general push ring mechanical seal, a small amount of leaked fluid solidifies and deposits in the air to prevent the movement of the moving ring o-ring. Therefore, the adhesion force of the sealing end face becomes weak or disappears, and then leads to leakage. The mechanical seals of welded metal bellows has no o-ring, which will not be affected even if there is solidified material. It can rotate safely and extend its service life.
Screw pumping effect: The bellows itself has screw pumping effect, which can effectively correspond to the fluid containing solid particles and help flush.
Single face
Balanced type
Arbitrary rotation
According with EN12756 (DIN24960) standard
KBF series is widely used, the dynamic ring "O" ring can not compensate for the role, so bellows movement without damping.
Single face
Balanced type
Arbitrary rotation
According with EN12756 (DIN24960) standard
KBWT80 series is widely used, suitable for high temperature, high viscosity medium, so bellows movement without damping.
KBWT80 series (mounting dimensions do not meet DIN24960 standards)
Comply with DIN24960 and GB6556
Metal bellows
"O" type sealing ring
Easy installation, easy adjustment
Corrosion resistant seal
K604 type: High temperature general purpose metal bellows, used for large shaft diameter and high speed condition and the sealed cavity is not standard big diameter.
K609 type: High temperature rotating bellows, its narrow cross-section design makes installation easier.
K606 type: High temperature rotating bellows, relying on the bellows under the fork drive, applied to the viscosity and easy crystallization conditions.
Balanced type
Arbitrary rotation
According with EN12756 (DIN24960) standard
KBF series is widely used, the dynamic ring "O" ring can not compensate for the role, so bellows movement without damping.
Design characteristics of corrugated pipe by using 45 wave of advanced, medium pressure on the inner hole weld mushroom stress decreases to a minimum, the auxiliary seal ring is made of flexible graphite materials, applied to more complex variety or mixed media conditions, suitable for single face or a series of integrated design for different type of pump can be assembled design of standard material combination for high temperature conditions for the users of the standard, can have a double blade design, may provide for the design of higher pressure conditions.
Design characteristics of corrugated pipe by using 45 wave of advanced, medium pressure on the inner hole weld mushroom stress decreases to a minimum, the auxiliary seal ring is made of flexible graphite materials, applied to more complex variety or mixed media conditions, suitable for single face or a series of integrated design for different type of pump can be assembled design of standard material combination for high temperature conditions for the users of the standard, can have a double blade design, may provide for the design of higher pressure conditions.
Our factory
Gaodao Sealing Technology (Suzhou) Co., Ltd. was established in 2021 with a registered capital of 12 million yuan. It is a member unit of the China General Machinery Industry Association and has been successfully selected as one of the first batch of innovative and entrepreneurial leading talent enterprises in Gusu in 2022.
Advanced equipment
Our company has domestically advanced production, manufacturing and testing equipment, as well as professional technical personnel.
High quality
The company adopts an ERP management system, using scientific methods and data analysis to provide customers with high-quality products and stable delivery cycles.
Production market
In 2023, our company's total marketing revenue was 39.5 million yuan, providing strong support for the needs of major host factories, equipment factories, and end users nationwide.
24H online service
We try and respond to all concerns within 24 hours and our teams are always at your disposal in case of any emergencies.
Application of Welded Metal Bellows
Aerospace and defense
In aerospace and defense industries, welded metal bellows are used for maintaining pressurization, responding to temperature changes, and providing reliability under extreme conditions. They can be found in satellite propulsion systems, radar waveguides, fuel tank meters, avionics equipment cooling systems, cryogenic couplings or connectors, vacuum sealing components for infrared detectors or sensors.
Semiconductor industry
The semiconductor industry often uses welded metal bellows to maintain a clean environment by controlling contaminants within process gas lines (etching machines) or vacuum chambers (physical vapor deposition). They support the requirements of ultraviolet light exposure during photolithography processes with minimal outgassing. Additionally, they provide critical transfer capability for wafers during manufacturing by enabling low-friction and wear-resistant rotary motions.
Medical devices
In medical devices such as heart-assist pumps or artificial hearts,welded metal bellows deliver precision-driven flow control for fluids including blood or medicine while ensuring high reliability even in minute vibrations. They also help in achieving hermetically sealed enclosures containing sensitive electronic components which require protection against aggressive media present inside the human body.
Automotive industry
Welded metal bellows find use in automotive applications such as exhaust gas recirculation valves, waste gate actuators for turbochargers and servomotors employed within anti-lock braking systems. These components contribute towards efficient fluid regulation and response management during vehicular operation.
Pressure gauges & sensors
Several pressure gauges and sensors rely on the small-scale movement experienced by welded metal bellows to accurately record changes in pressure or displacement. They facilitate highly precise and sensitive measurements which are extended towards hydraulic accumulators, flow control valves, pressure compensators and vacuum switches.
Bellows Diaphragms
The building blocks of welded metal bellows are thin-walled, deep-drawn, circular diaphragms. These diaphragms consist of flat, annular ring-shaped sections with convex and concave profiles. They function as pressure boundaries and enable flexibility.
Weld Joints
To create a complete bellow unit from the diaphragms, individual pairs are joined together at their inner diameter (ID) and outer diameter (OD). This is achieved using an advanced welding technique called "edge welding." Each weld joint ensures reliability and fatigue resistance while allowing for movement within the system.
Spring Rate
Within each bellow assembly, spring rate determines the force required to deflect the bellow a specific distance in its axial direction or angular motion, often measured in pounds per inch (lb/in) or Newtons per millimeter (N/mm). A bellow's spring rate varies depending on factors such as wall thickness, material types, number of convolutions (diaphragm pairs), convolution height, and others.
Connecting Flanges
Some welded metal bellows incorporate flanges that enable an easy connection with mating parts within a mechanical system or vacuum chamber setup. Sealing surfaces are also taken into consideration during flange design.
Protective Covers
In certain cases where harsh environments come into play or extra protection is needed for smoother operation, protective covers might be integrated to shield the bellows from physical damage like scratches or abrasion.
Process of Welded Metal Bellows
Welded metal bellows is to stamp metal sheets of certain width into wave washer type plates, and weld the inner circumferences of the two wave plates to make a V-shaped semi-finished product, and then overlap several semi-finished products before welding the outer circumference, and finally weld the front and rear ring seats to form the specified bellows. The main process is: punching and forming of wave plates → cleaning → inner seam welding → outer seam welding → welding front and rear seat rings → inspection → heat treatment → inspection.
The punching and forming of wave plates of welded metal bellows can be completed at one time. Shape of wave plates has a great influence on the performance of corrugated bone.There are currently two kinds of molds. One is a metal mold, and the other is a polyurethane rubber punching and forming mold.
Since the end face of the former die is a formed curved surface which is high precision accuracy, it is difficult to manufacture and rectify the gap between the concave and convex die blades.
The latter has a simpler structure which means easier manufacture. Besides,during punching and forming process, displacement between concave and convex dies is small, thus wave plates are generally not scratched.
Cleaning of wave plates of welded metal bellows is one important factor to ensure welding quality, especially cleaning of inner and outer weld seams. The wave plates need to be cleaned with detergent, pickled, neutralized, rinsed with clean water and dried , and then soaked and wiped with acetone.
Welding of bellows is precision welding, so there must be a complete air conditioning and air filter system in the operating room to ensure a constant temperature, constant humidity, and dust-free environment.Welding of bellows does not require welding rods, but fusion welding carried out in a controlled environment (working gas is Ar, shielding gas is Ar+N2) to avoid welding slag at the weld seam and affect the inherent characteristics of the bellows.
In order not to produce surface stress during fusion, the needed part of the metal bellows should be welded into a semi-spherical shape.Thickness of welding mushroom of a single-layer wave plate is usually 2.2-3 times that of the wave plate. As for double-layer ones,4-5 times.
Distances between waves must be uniform and shape of the mushrooms should be symmetrical. One purpose of using spacers is to prevent heat generated during welding from being transferred to other parts of wave plates of welded metal bellows. The welding speed is 1-1.2m/mim.
In the manufacturing process of bellows, quality control is extremely strict. Such as the production of bellows, metallographic microscopic examination of size and arrangement of the crystal grains and the hardness of plate;critical solder joints and heat-affected areas should also be microscopically inspected. In order to get knowledge of the depth of welding, the shape and symmetry degree of the welding mushroom, all weld seams must be inspected for airtightness.Leak detection is usually done with a helium mass spectrometer leak detector. The vacuum leakage rate is 1*10-10mL/s. In addition, the elasticity, expansion characteristics, force relaxation and hysteresis of the bellows must be precisely measured.
The welding metal bellows material adopts AM-350, 0Cr17Ni17Ti, 0Cr15Ni17Mo2Al precipitation hardening stainless steel. After welding, the austenite must be transformed into martensite by thermal aging treatment, and metal compounds will be precipitated from the martensite, and the hardened phase will be precipitated to obtain the results of high strength, high plasticity and yield ratio.
What is the difference between formed and welded metal bellows
Manufacturing process
Formed bellows are cold-formed or hydroformed from a single piece of metal, while welded metal bellows are assembled from individually stamped diaphragms that are welded together.
Size and length limitations
Formed bellows are typically limited to smaller diameters and shorter lengths due to the forming process, while welded metal bellows can be produced in much larger sizes and lengths.
Material options
Formed bellows are usually made from high-elongation metals like brass or bronze, while welded metal bellows can be constructed from a wide variety of materials, including stainless steels, high-strength alloys, and exotic metals.
Flexibility and spring rates
Welded metal bellows, particularly edge welded metal bellows, offer greater flexibility and lower spring rates compared to formed bellows, making them suitable for applications requiring significant axial displacement or angular movement.
Pressure and vacuum capabilities
Welded metal bellows can withstand higher internal and external pressures, as well as deeper vacuum levels, compared to formed bellows due to their robust construction and leak-tight welds.
Cost and lead times
Formed bellows are generally less expensive and have shorter lead times than welded metal bellows, as the forming process is simpler and more automated. However, the cost difference narrows for larger quantities or custom designs.
In addition to spring rates and materials of construction, there are several other design elements that must be addressed when manufacturing a welded bellows assembly.
Additional factors include:
Diaphragm plate thickness: Welded bellows diaphragm thickness is measured in mils (thousandths of an inch.) the thinner the plates = the lower spring rates = lower face and unit loading, all of which minimize the generated heat at the faces, leading to longer seal life.
Diaphragm plate shape: Welded bellows convolutions can be manufactured in a variety of configurations. A nesting ripple configuration maximizes flexibility; all the plates are contoured to "nest" together when compressed, maximizing high cycle life.
Vibration dampeners: A dampener pad feature is often designed and built into a bellows assembly to help protect the seal from damage caused by excessive pump vibration during operation.
Our Factory
Gaodao Sealing Technology (Suzhou) Co., Ltd. was established in 2021 with a registered capital of 12 million yuan. It is a member unit of the China General Machinery Industry Association and has been successfully selected as one of the first batch of innovative and entrepreneurial leading talent enterprises in Gusu in 2022.
The company currently has nearly 70 employees, including 12 technical engineers and 5 university and industry consultants. The company adopts an ERP management system, using scientific methods and data analysis to provide customers with high-quality products and stable delivery cycles. Having advanced domestic production, manufacturing, testing equipment, and professional technical personnel.
FAQ
Hot Tags: welded metal bellows, China welded metal bellows manufacturers, suppliers, factory, metal bellows mechanical seal, Metal Mechanical Seal, special type mechanical seal, Bellow Type Mechanical Seal, Mechanical Seals For Pumps, Seal For Pump
You Might Also Like
Send Inquiry