Seamless Rolled Rings
Seamless rolled rings are forgings formed from a single "donut"-shaped block of metal by the application of horizontal and vertical pressure. Seamless ring-rolling is a unique type of metal forging that produces seamless metal rings with great tensile strength and structural integrity. Seamless rings may be forged into a wide range of dimensions, from small bearing housings to wind turbine slewing rings.
The outside dimensions of seamless rolled rings can range from a few inches to 30 feet, height can reach from less than an inch to higher than 9 feet, and weight can be as much as 350,000 pounds. The shape of seamless rolled rings can be configured to be flatter, like a washer, or to have high walls like a hollow cylinder. Unlike other types of ring forming, this forging process creates a seamless ring with great integral strength, capable of resisting high degrees of internal or external pressure. This is why wheel hubs, bearing housings, pressure vessels, gears, jet engine bearings, engine turbines and wind turbines – all applications which apply significant force – are usually made from seamless forged rings. Seamless rolled rings are also utilized in nuclear reactors, off-road equipment, couplings, rotor spacers, sealed discs and cases, flanges, valve bodies and many other high stress applications.
A seamless rolled ring begins as a solid, circular block of metal that is heated to forging temperatures and then punched through the center to form a "donut" shape. This preform is then placed on a rolling rig with a roller touching the inside of the donut and a roller touching the outside of the donut. The two rollers begin to rotate in opposite directions, turning the ring, and at the same time the rollers slowly squeeze inwards, thinning the ring wall and causing the diameter of the ring to increase. Some ring-rolling machines also have a roller that presses down on top of the ring as it turns, governing the height of the ring wall. The process continues until the ring has been thinned, flattened or otherwise shaped to its desired dimensions, at which point it may receive secondary processing such as size fine-tuning or heat treatment. Rings
can be shaped at high forging temperatures for faster forging or, for rings that require the highest pressure resistance, such as aluminum car wheels, the rolling can be done at lower temperatures over a longer period. Lower forging temperatures and longer forging times result in greater tensile strength. The ring-rolling process can be modified in any number of ways to produce a wide range of precise contours both on the inner dimension and outer dimension. Seamless rolled rings are unequaled in tangential strength, ductility, and adaptability.
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Seamless Rolled Ring – Ferralloy Inc.
Seamless Rolled Rings – Ferralloy Inc.
With the right material selection, proven forging processes, and propertools, Weldaloy has all the ingredients to manufacture seamless rolled ringsin less time, with less material wastage, and with a more uniform grain thatensures the strength and reliability of your product.
The goal of this technical paper is to help you determine which forgingprocess is right for you in meeting your seamless rolled ring needs. Becausewhen you fully understand the differences between each forging process,you can improve your design and, ultimately, the quality and performanceof your product.
Weldaloy offers complete forging capabilities to a variety of industries suchas Aerospace, Power Generation, Electronics and others using copper,aluminum, and other non-ferrous forgings. We manufacture seamlessrolled rings using the open die forging process, closed die forging process,and rolled ring forging process.
Seamless Rolled Ring Forging Process
With our 40-ton ring rolling machine, Weldaloy has the capability to manufacture seamless rolledrings using most of the metals we offer. This process provides significant flexibility allowing forvarious sizes, and provides a more uniform product that is stronger, more reliable and made in lesstime and with less material waste than traditional forging processes.
The process starts with raw material (a blank) being cut to size,then rounded to a disk shape.
The blank is punched then pierced in the center, using the opendie forging process, to create a preform in the shape of a donut.
The donut shaped preform is then placed on the ring rolling millfor rolling.
The axial rollers control the height of the ring. The idler roller, ormandrel, applies pressure to the preform by pressing it against thedrive roller to decrease wall thickness and height and increase ringdiameter until the correct diameter is reached.
The seamless rolled ring forging process, when done properly, produces a superior ring containinga more uniform grain, more repeatable mechanical properties, and a truer/rounder shape, whichmakes more efficient use of materials (less waste) and produces rings in less time. After rolling,the product can be sent on for heat treatment and machining to achieve the tolerances andspecifications for the finished product.
Whether your order is 10 rings or 100 rings or more, the seamless rolled ring forging processminimizes the variation from ring-to-ring.
Forged rolled rings can be configured in various sizes as shown in the table below. Specialized orderscan be produced to manufacture seamless forged rolled rings in customized configurations.
Table 1: Rolled Ring Forging Process Capabilities
|Minimum Outside Diameter ||10”|
|Maximum Outside Diameter ||40”|
|Maximum Height ||8 1/4”|
|Maximum Weight ||500 lbs.|
|Tolerance Range ||± 1/8”|
Open Die Forging Process
In the open die forging process, a piece of metal is deformed by placing it between dies that donot completely enclose it. The dies hammer or deform the metal through a series of movements toachieve the desired shape and form. From here, the product can be sent on for heat treatment andmachining to achieve the tolerances and specifications for the finished product.
The open die forging process is used to produce forgings that are simple in shape and made insmaller quantities. This process works well for producing products that:
· Are too large to be produced using other manufacturing methods
· Require mechanical properties that cannot be achieved in other metal forming methods
· Have a small quantity requirement that would not justify tooling costs
· Have a short delivery requirement that will not allow time to make proper tooling
Rings that have special mechanical requirements or that may require warm work or cold work, or aretoo large to be produced on a ring rolling mill can be open die forged.
Table 2: Open Die Forging Process Capabilities
|Maximum Thickness ||20”|
|Maximum Weight ||4,500 lbs.|
|Maximum Diameter ||72”|
Closed Die Forging Process
The closed die forging process (also called impression die forging) uses pressure to force orcompress a piece of metal to fill an enclosed die impression of a predetermined shape and form.Depending on the product’s size, shape, or specifications, several impression dies can be used toform the finished product.
This process is best suited for producing rings that are smaller in size and in higher quantities and donot have difficult mechanical property requirements.
Table 3: Closed Die Forging Process Capabilities
|Minimum Inside Diameter ||5”|
|Maximum Outside Diameter ||10” to 19”|
|Maximum Thickness ||Contact Weldaloy to discuss|
The Weldaloy Advantage is Clear
Weldaloy’s vertical integration system provides significant advantages in meeting your seamlessrolled ring forging needs:
- Cost savings – No added transportation expenses from moving products between suppliers. Everythingdone under one roof.
- Consistent quality – Leads to higher profitability for our customers
- One supplier – Simplifies the whole process and keeps costs down
- No hidden fees or charges – We hold our prices to what was agreed upon
- Technical and engineering expertise – With 70 years of metal forging experience, Weldaloy has theknowledge and skills to help you achieve your metal forging goals
- Reliability – With a Quality Management System (QMS) that is AS9100C and ISO9001: 2008 certified
- Customer first approach – We work with you every step of the way to ensure your product exceedsyour expectations
- Flexibility and customization – Our vertical integration process means we have the equipment,knowledge and material to customize your product to your specifications.
Weldaloy has the equipment and forging processes to accommodate a wide range of sizes to meetyour ring needs. Below is a summary of each process. We also have the expertise to help you withcustom and/or unique product orders. More Seamless Rolled Rings Information
Table 4: Summary of Each Forging Process
OPEN DIE FORGING
CLOSED DIE FORGING
ROLLER RING FORGING
|Larger ring sizes ||Smaller ring sizes ||Smaller ring sizes|
|Lower quantities ||Higher quantities ||Higher quantities|
|Little or no tooling costs ||Cost savings/less raw material needed ||Little or no tooling costs|
|Can achieve mechanical propertiesother forging processes may not||Best on complex shapes with closerdimensional tolerances ||Consistency in parts produced|