Jack Pennuto Jr.Click image to enlargeby Jack Pennuto Jr.

Roll forming machines impact process quality

Roll forming machines, like most metalworking or forming equipment, are available in a range of sizes. A roll forming machine with more passes can produce a more complex shape, as each successive pass of the machine is able to form additional bends to produce the desired profile. In addition to the complexity of the profile, the overall size of profile that can be roll formed on a specific machine is dependent on several machine specifications.

The most straightforward is roll space. The roll space, or the area on each pass where the roll tooling is loaded, is the limiting factor for the width of the metal strip that can be roll formed. For example, a machine with 18 in. roll space cannot form a strip wider than 18 in. When the flat strip comes into the machine, that is the point where the greatest roll space is required. As the bends are progressively formed into the strip, the overall width requirement of the machine decreases.

The capability of any given machine with regard to height or depth of the section is measured mainly by the vertical distance available between spindles. This, together with the distance from the centreline of the bottom spindle to the top of the machine base and the horizontal centre distance between roll stands, establishes the maximum roll diameter.

Figure #1: Roll to Spindle RelationshipClick image to enlargeLet us look at the roll contour of the last roll stage for a simple channel as on Figure #1 and note its relation to the other parts of the machine. In addition to the restrictions just mentioned, there must be clearance between the outside diameter of the bottom roll flange and the top roll spacer, as well as clearance between the edge of the section and the top roll spacer. Note also the bottom roll flange diameter includes a lead-in or bell-mouthed contour to aid in threading from one pass to another.

Roll pitch diameter and gearing ratio
The roll “pitch” diameter is usually selected to engage a given profile at its widest and most nearly horizontal area. This area is important as it provides the most effective and balanced traction. The ratio between the pitch diameter of the top and bottom rolls must be the same as the ratio of the gearing connecting the top and bottom spindles.

Figure 2: Equal versus Unequal GearingClick image to enlargeSome manufacturers provide machines that are able to accommodate either equal ratio or unequal ratio rolls. On the left of Figure #2 is a cross-section through a stage of equal pitch diameter rolls. The drawing on the right shows the same roll stage in a machine fitted out for unequal ratio rolls. The pitch diameter in the latter is well below the mid-point between spindles and as you see, gains enough space to allow forming a much deeper section with the same vertical centres.

In machines where only equal ratio rolls can be applied, deep sections are formed by “floating the pitch line.” This is not a good procedure but can be applied in specific instances, particularly where light gauge and perhaps narrow shapes are concerned. In principle, it involves a different pitch diameter in successive roll passes which, as each bottom spindle is driven at the same rpm, can lead to “roll fight” between passes, excessive gear loads and excessive horsepower demands.

In summary, beyond the number of roll forming stations available, it is important to consider the available vertical distance between spindles, as well as the gear ratio. The combination of vertical spindle distance and gear ratio will define the maximum height of the finished profile that can be formed. If you are concerned about sizing the products to fit in your existing roll forming machine, or want help in sizing a new machine, contact your equipment supplier. SMT

Jack Pennuto Jr. is senior vice president of operations at Formtek Inc.


Fast track

by Kip Hanson

The Problem: Small shop, lack of skilled workers

The Solution: Build an automated beam processing facility

Alberta structural steel fabricator aims high with automation

An owner's guide to maintaining business continuity

Tax and managment consultant KPMG has released a guideline for maintaining business continuity throughout the continued lockdown and depressed business conditions stemming from the COVID 19 pandemic. 

Smarter Manufacturing

by Kristian Hulgard 

Intelligent end-of-arm tooling for better machining

Bystronic acquires Italian tube laser cutting firm TTM

Bystronic is expanding its metal fabricating reach with the acquisition of Italian tube laser cutting and laser welding equipment manufacturer TTM.

TRUMPF Laser Tech Center celebrates 20th year

TRUMPF Laser Technology Center celebrated its 20th anniversary during its annual open house in Plymouth Township, MI, on June 7.

The new normal

Automotive manufacturers shift from working harder to working smarter with bigger focus on innovation and technology

Selecting a Positioner

by Cliff White

Factors to consider to ensure you have the right one for your shop

Nd:YAG or fiber laser for micro welding?

Choosing the best option for your application

By Geoff Shannon, Amada Miyachi America

Four lasers can be used for micro welding: pulsed neodymium-doped yttrium aluminum garnet (Nd:YAG), continuous wave (CW) fiber, quasi continuous wave (QCW) fiber, and nanosecond fiber. Each laser type offers unique features that work best for specific applications. Here is a comparison of the pulsed Nd:YAG laser with the three fiber laser options, and a discussion of why and when one might be chosen over the other. In some cases, several options may work; in that case, cost of ownership and serviceability can tip the scales.

TRUMPF invests in laser marking production

TRUMPF has expanded its laser marking production facility in Grusch, Switzerland, to meet growing worldwide demand for its marking lasers.

Tripling tube and bar production output

Engine exhaust tube component maker triples production output-up to 11,000 parts per hour with zero rejects using a combination servo-controlled cold saw cut-to-length and brush deburring system

The power to pierce

by Kip Hanson

Fiber lasers make quick work of what was once an onerous task

Bernard bolsters consumables line

Welding products supplier Bernard’s AccuLock S Series consumables include additional diffuser and nozzle types and sizes, as well as new contact tip options.

Resistance projection welding

by Larry Koscielski

What to look out for in projection welding of fasteners

Bystronic adds 15kW fiber option

Bystronic’s new 15kW fiber for Bystar Fiber 3015 and 4020 improves speed, precision and flexibility for sheet metal processors.

Boosting skilled trades

Labour union training centres playing bigger role in apprentice training in fabricating, welding

by Mary Scianna

Apprenticeship programs in Canada have a long history.

Stay In Touch

twitter facebook linkedIn