Types of Cold Bending Roll Forming Machines

Overview of Cold Bending Roll Forming Machines

Cold bending roll forming machines are used to bend and form metal sheets into customized profiles through an incremental and continuous rolling process. They are ideal for mass production of parts like roofing panels, steel studs, gutters, door panels etc. Key features include:

  • Bends sheets up to 3 mm thickness from various materials like steel, aluminum, brass, copper etc.
  • Forms complex and accurate profiles through a series of arranged rollers
  • Continuous process with adjustable speed for high output
  • Computer controlled for automatic precision forming
  • Compact footprint suitable for factory integration
  • Lower tooling costs than press brakes or other fabrication methods

Types of Cold Roll Forming Machines

There are several types of cold roll forming machines that provide different levels of flexibility, automation and output capacities:

Table 1: Cold Roll Forming Machine Types

TypeDescription
Standard Roll FormerBasic machine with fixed forming rollers for continuous runs of one profile. Manual material feeding and part cutoff.
CNC Roll FormerComputer numerically controlled with servo motors for automatic roller adjustment. Allows quick changeovers between different pre-set profiles.
Production LineHigh output roll formers integrated with decoilers, straighteners, shears and other in-line processes for automated mass production.
Custom Roll FormerCustomized machine with specialty forming rollers for proprietary profiles. Requires engineering of roll dies and tooling.
Portable Roll FormerCompact and movable cold bending roll forming machine for on-site or workshop use. Limited profile capability.
cold bending roll forming machine
Types of Cold Bending Roll Forming Machines 3

Key Components of a Cold Roll Forming Machine

The main components of a typical cold roll forming machine include:

Table 2: Cold Roll Forming Machine Components

ComponentDescription
DecoilerHolds coil of sheet metal to be fed into the roll former continuously
FeederFeeds sheet into rolls at a controlled speed and tension
Forming RollersSpecial roll dies that progressively bend sheet into desired profile
CutterCuts formed profiles at set lengths for individual parts
Control PanelControls roller position, material feed, cut-off etc.
PLC/Computer ControlFor programming recipes and automating process parameters
FrameRigid frame that houses components under tension loads

Design and Working Principle

Cold roll forming works by continuously feeding a flat strip of sheet metal through a series of roller dies to incrementally form the material into a designed profile. As the material passes through each roller pair, it is gradually shaped until the final profile is achieved.

The rollers are arranged along the progressive forming stations in a sequence that allows material bending without overstressing. The roller design and position is engineered specifically for the profile that needs to be formed. Typically around 12-16 roller pairs may be used depending on part complexity.

Lubricants are applied to the sheet metal to reduce friction as it passes through the rollers at high speeds. The lubricant also helps maintain smooth surface finishes. Chemical coatings may be applied for corrosion resistance or UV protection after forming.

Applications and Profiles Produced

Cold bending roll forming can produce a wide range of formed metal components. Typical applications include:

Table 3: Cold Roll Forming Applications

IndustryCommon Profiles Produced
ConstructionRoofing panels, decking, purlins, wall studs, floor joists, doors, railings
AutomotiveBody panels, shells, chassis parts, brackets
AppliancesPanels, housings, enclosures, shells
FurnitureLegs, frames, desks, wireways
PackagingRacks, pallets, boxes, shelves, tubs
SolarMounting rails, clamps, channels

Nearly any open profile shape can be formed, from simple arcs, ribs and bends to complex geometries with punchouts and embosses. Hollow closed sections may require specialized rollers. Common profiles include:

  • C-channels
  • Zeds
  • Angles
  • Hat sections
  • Box tubing
  • Formed tubes
  • Custom ribs, beads

Specifications

Cold roll forming machines are available in a wide range of sizes and specifications to produce small parts to large panels up to 3m wide. Main parameters include:

Table 4: Cold Roll Forming Machine Specifications

ParameterTypical Range
Forming Length1 – 10 m
Forming WidthUp to 3 m
Material Thickness0.3 – 3 mm
Forming Speed10 – 80 m/min
Forming Stations10 – 20
Roller Diameter100 – 250 mm
Roller MaterialAlloy steel or iron
Drive Motor5 – 15 kW
ControlPLC, CNC
Power Supply380V, 3-phase
Machine Weight2000 – 10000 kg

Larger and more powerful machines are available for specialized high-volume continuous production lines. Customized machines can be engineered for proprietary profiles and specifications.

Roll Tooling Design and Manufacture

The key to successful roll forming is the precision engineering of the roller dies. The roll tooling is designed based on the required profile specifications and the plastic deformation properties of the material.

Roll tooling design must take into account parameters like metal thickness, width, yield strength, bending radius, springback etc. to calculate optimal roller positioning and geometries. 3D CAD and FEA tools are used to simulate material flow and stresses for validating tool paths.

The roll dies are CNC machined from alloy steel. One-piece rolls are used for common shapes like arcs and ribs. Multi-part split rolls allow forming of more complex profiles. Quick-change systems using spacers and shims allow flexibility for different profiles.

Process Design Considerations

Some key process factors to consider during cold roll forming:

Table 5: Cold Roll Forming Process Considerorsations

FactorDetails
MaterialDuctility, strength, thickness, coatings, width, microstructure. Yield strength important for calculating bending forces
ToolingRoller design, size, materials, surface finish. Precision machining for accurate profiles.
LubricationReduces friction between sheet and rollers. Allows higher forming speeds. Consider temperature stability.
Feed SpeedHigh speeds increase output but can cause defects. Optimal speed depends on material and profile.
Bending RadiiLarger radii distribute strain and reduce thinning. Minimize radii for strength.
SpringbackElastic recovery once part leaves rollers. Compensate by overbending. Depends on material.
DirectionFor sheet, bend perpendicular to rolling direction which has higher strength.
Section LengthLonger sections require support rollers to prevent sagging.
Wall ThicknessThicker materials need higher roll forces. Can cause webs to deform.

Careful design and trials are necessary to fine-tune the interacting parameters for a robust process. Defects like buckling, wrinkling, curling and tearing can occur if not properly controlled.

Manufacturers and Suppliers

Some of the major manufacturers supplying cold roll forming equipment include:

Table 6: Cold Roll Forming Equipment Manufacturers

CompanyLocation
FormtekUSA
Samco MachineryCanada
Bradbury GroupUK
GaspariniItaly
Shanghai SlitterChina
T&H LemontUSA
Innovative Produktionssysteme GmbH (IPS)Germany

In addition to large international suppliers, many regional manufacturers also offer cold roll forming machines. When selecting a supplier, factors like build quality, engineering support, cost, lead time, and maintenance services must be evaluated.

Cost Considerations

Cold roll forming equipment represents a major capital investment, but can pay back through operational efficiencies and reduced labor for high production volumes. Key cost factors:

Table 7: Cold Roll Forming Machine Cost Factors

ParameterTypical Cost Range
Standard Roll Former$50,000 – $500,000
CNC Roll Former$80,000 – $800,000
Production Line>$500,000
Custom Roll Former>$200,000
Portable Roll Former$15,000 – $100,000
Roll Tooling$2000 upwards per profile
Installation10-20% of machine cost
Freight & Taxes5-10% of machine cost

Larger production lines with decoilers, cut-offs, straighteners etc. can cost over a million dollars. Operating costs include maintenance, spare parts, consumables like lubricants and coatings, and electricity consumption.

Choosing the Right Supplier

Key factors when selecting a cold roll forming machine supplier:

Table 8: Choosing a Cold Roll Forming Machine Supplier

ConsiderationDetails
Technical ExpertiseExperience designing, building, installing similar equipment. Qualified engineers.
Build QualityUse of precision components from reputable brands. Robust structural design.
FlexibilityAbility to handle future custom profiles. Quick changeover systems.
Production CapacitySize and power ratings adequate for output volumes.
ControlsType of automation, ease of programming new profiles.
ServicesInstallation support. Local service for maintenance. Operator training.
Roll ToolingIn-house tooling design and manufacturing capability.
Lead TimesSchedule for design, manufacture, shipment, installation.
ReferencesTrack record executing similar projects successfully. Strong testimonials.
CostPricing in line with market and capabilities. Attractive payment terms.
ComplianceMeet all applicable safety, electrical, building codes.

Reputable manufacturers should be willing to provide referrals to previous buyers. Site visits to existing installations are highly recommended during qualification.

cold bending roll forming machine
Types of Cold Bending Roll Forming Machines 4

Installation and Operation

Proper installation and operation procedures are necessary for safe, efficient and quality roll forming:

Table 9: Cold Roll Forming Machine Installation & Operation

ActivityProcedure
InstallationLevel machine on vibration-isolation foundation
Connect electric power, pneumatic lines, lubrication
Test run without load to confirm clearances
SafetyEnclose pinch points, provide guards
Ensure operators wear gloves, goggles, non-slip shoes
Mark safety zones, provide interlocks
SetupInstall correctly designed roll tooling
Position guide rolls, support and straightening rolls
Thread sheet through rollers and align
Set feed speed, cut-off length
OperationMaintain steady, even feed of sheet
Monitor lubrication levels and flow
Inspect profile dimensions continuously
MaintenanceClean rollers and framing regularly
Lubricate bearings and sliding parts
Check roll alignment and wear
Replace damaged rollers immediately
TroubleshootingAdjust roller alignment if profile distorted
Increase/decrease bend increment to correct springback
Slow speed for wrinkling; increase for tearing
Check roll design, material orientation

Only properly trained personnel should operate the machine after full safety procedures are established. Proper maintenance is crucial for preventing unplanned downtime and defects.

Advantages of Cold Roll Forming

Key benefits of cold bending roll forming machines:

  • Highly productive continuous process for mass production
  • Consistent and repeatable quality of parts
  • Capability to form complex custom profiles
  • Low tooling costs compared to other fabrication methods
  • Scalable production by adding in-line processes
  • Adjustable parameters through CNC control
  • Minimal secondary operations required after forming
  • Suitable for a variety of materials from thin gauge to thick metals
  • Strength and aesthetic appeal of roll formed parts
  • Safer operation compared to manual metal bending techniques

Limitations and Challenges of Cold Roll Forming

Some drawbacks and difficulties include:

  • High initial capital cost of equipment and tooling
  • Long lead times for design and manufacturing of roll dies
  • Not economical for very low production volumes
  • Size limitations based on machine capacity
  • Skill required for proper roll tooling design to avoid defects
  • Potential for scratching of material surface during forming
  • Noise generation requiring noise reduction measures
  • Requirement of sheet in coil form at set widths

Cost Saving Analysis

Here is an example cost analysis for a sample high volume production scenario:

  • Monthly volume of 100,000 C-channel roofing parts required
  • 12 ft long C-channel with hemmed flanges
  • Material is 0.05″ thick 5052 aluminum

Table 10: Cost Comparison – Roll Forming vs. Manual Fabrication

MethodRoll FormingManual Fabrication
Equipment Cost$250,000$50,000
Tooling Cost$20,000$5000
Production Rate600 ft/min10 ft/min
Monthly Labor100 hrs670 hrs
Labor Rate$25/hr$25/hr
Monthly Labor Cost$2500$16,750
Total Monthly Cost$29,167$21,667
Payback Period5 months

This simple analysis shows that despite higher initial equipment investment, labor savings of roll forming make it economical for such mid to high production volume scenarios. Exact breakeven points can be calculated through more detailed cost modeling.

Cold Roll Forming vs Press Brake Bending

Cold roll forming and press brake bending are two common sheet metal fabrication processes. Here is a comparison between the two methods:

Table 11: Roll Forming vs Press Brake Comparison

ParameterRoll FormingPress Brake
OperationContinuousBatch
AutomationHighLow-Medium
Setup timeMediumHigh
Production rateHighLow-Medium
LaborLowHigh
Capital costHighLow-Medium
Tooling costLowHigh
Thickness0.5 – 2 mm0.5 – 4 mm
StrengthHighMedium
TolerancesHighMedium
Surface finishGoodFair
Secondary opsFewMany
ApplicationsStandard profiles, panelsCustom parts, enclosures

In summary, roll forming is better suited for continuous high volume production while press brakes allow more flexibility for lower quantities and custom components.

Frequently Asked Questions

Q: What sheet metal materials can be roll formed?

A: Most ductile metals including low carbon steel, stainless steel, aluminum, copper, and brass. Best results are achieved with materials in annealed condition. Very high strength alloys may need intermediate annealing.

Q: What thickness range can be cold roll formed?

A: Standard cold roll forming is typically used for metal thickness between 0.3 mm to 3 mm. Thicker materials require higher roll tonnage capacity machines. Thinner foils under 0.2 mm require special handling.

Q: How many forming stations are required for typical profiles?

A: Most common profiles like C and U channels, ribs, gutters require 10-16 stations. More complex or taller profiles may need 20+ stations. Deeper profiles can be formed through a sequence of double pass stations.

Q: What defects can occur during cold roll forming?

A: Defects like wrinkling, warping, flaring, splitting, and scratching can happen if process parameters and tool design are not optimized. FEA simulation and prototyping should be done.

Q: Is lubrication required during cold bending roll forming?

A: Yes, appropriate lubricant must be applied for reducing friction between sheet surface and tooling. It lowers rolling forces required and improves surface finish.

Q: How long does roll forming machine design and manufacture take?

A: For standard catalog machines, lead time can be 4-8 weeks. Custom machines with production lines involve more extensive engineering and estimates up to 6 months should be considered.

Q: What is the typical production rate of cold roll forming machines?

A: Production rate depends on profile complexity and length of formed part. Typical speeds are 10 – 100 ft/min. Very long parts may require slower speeds and support rollers.

Q: Is cold roll forming process suitable for medium production volumes?

A: Yes, machines with quick changeover can be economical for medium volumes of 5,000-10,000 pieces/month by alternating between profiles.

Q: What regular maintenance is required for cold bending roll formers?

A: Maintenance includes lubricating bearing and shafts, inspecting & replacing worn rollers, cleaning deposits on tooling, checking belt tension & alignment.

Conclusion

Cold roll forming provides an ideal process for continuous high volume production of metal profiles across many industries. Machinery has become highly advanced with controlled automation and quick changeover capabilities between profiles. Precision engineered roll dies capable of intricate shapes combined with television monitored processes ensure consistently high quality standards. With proper machine selection, tooling design and process control, cold bending roll forming offers and efficient fabrication solution for mass producing formed sheet metal components.

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