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We have compiled some general basic educational information regarding plate rolls and their use. It is our hope
that this information will assist you in selecting and properly sizing a machine to fit a particular application. For
further in-depth information and application engineering please contact Carell Corp. directly.
Plate or Sheet Bending Rolls are built in 2 main categories, single and double pinch and may have different
geometries or styles. Matching the most appropriate machine style to the application is important. General
machine styles are: 3 Roll Initial Pinch, 3 Roll Double Pinch, 4 Roll Double Pinch, 3 Roll Variable Translating, 3
Roll Pyramid and 2 Roll Systems. Plate rolls are also built in a vertical format for special applications.
Machine capacity is of equal or greater importance to style. Steel mills are producing materials with increasingly
higher yields. Plate roll manufacturers commonly rate machines according to a baseline material yield strength
between 36 to 38,000 psi. When choosing a machine you must refer to your mill certificates to verify the common
yields of the plates being delivered. It is not uncommon to find that the material you are actually rolling will have
yields in the 48,000 to 58,000 psi range if it is ‘mild steel’. Machine capacity must match your material type. Most
manufacturers can provide detailed tables or graphs that allow you to match capacity to yields.
You will often see ratings for pre-bending and rolling given for any one size Plate Roll. Pre-bending is performed
on the plate roll at the leading and trailing edge of the sheet (eventually the seam). Sheets cannot physically be
bent completely to the edge and thus will leave what is referred to as the ‘un-bent flat’. The minimum you could
expect for flat length is 1.5 x material thickness and often it will be from 2.5 to 3.5 times material thickness for
heavier plate. It is the pre-bending operation attempting to reduce the unbent flat to the minimum possible that
takes the most power. This is why pre-bending ratings are lower than rolling capacities for any given machine.
You must be mindful when reviewing machine ratings since the maximum total rolling capacity is generally
expressed with the intrinsic requirement of multiple rolling passes and very long un-bent flats. Un-bent flat lengths
for any given sheet are a function of thickness, width, cylinder diameter, machine type, yield, top roll size, operator
proficiency among other factors. NC and CNC Controls are ever more common in the workplace. Most all NC/CNC
machines are 4 roll types. Automated controls are recommended for high volume cylinder or shell production or to
roll complex shapes that are not easily reproduced by using manual machine controls. Multiple bends, variable
radius bends, ovals and the like are some examples.
Three Roll Initial Pinch or Single Initial Pinch Plate Rolls are generally for lighter capacity applications and may be
electro-mechanical or hydraulic. They work by "pinching" the flat sheet between two counter-opposed rolls while
the third offset roll or ‘bending roll’ moves upward to contact and then bend the sheet. When rotation of the rollers
is activated, the sheet exits at a given radius. With the sheet cut to the developed length and the bending roll
properly positioned; the part is rolled into a cylindrical form, where it can then be welded at the seam to produce a
cylinder. The upper roll is in a fixed position; the lower pinch roll can move up/down to pinch the material. The third
roll (the forming roll) is also adjustable. To remove a rolled cylinder, it must be extracted from off of the top roll.
Machines are generally equipped with some type of release mechanism on the top roll to allow extraction of the
cylinder. Typical methods are either a forward tilting or releasing top roll or a removable end yoke. In most
applications, these machines require removal and re-insertion of the sheet in order to pre-bend both ends. They
are cost effective but in contrast may be more labor intensive in a production setting. There were many large
mechanical initial pinch machines built during the 1930’s, 40’s & 50’s and can be found on the used market. All
have cast frames as modern alloys and welding techniques had yet to be invented.
Double Pinch Plate Rolls are available from light to extremely heavy capacities and may have three or four rolls.
The terminology can be confusing as these units may also be referred to as ‘double pinch pyramid plate rolls’ or
‘double initial pinch plate rolls’. Both three and four roll styles have fixed position top rolls and two offset rollers or
‘lateral rolls’, one on each sides. The 4 Roll styles have an additional roller underneath the top roll, which
constantly pinches the plate during rolling. Double Pinch Rolls can pre-bend both ends of the plate without
removal as is required with single pinch rolls. Three Roll machines generally require pre-bending the leading
end, running the sheet through the machine to pre-bend the trailing end then switching roll rotation direction to roll
the cylinder body. Four Roll Plate Rolls have a slight advantage in cycle time since the permit pre-bending of the
leading edge, rolling the cylinder body and finishing off the trailing pre-bend all while rolling in the same direction.
Smaller machines can be mechanical but most modern machines are hydraulic and include drop end yokes for
easy extraction of the work-piece.
Automatic NC or CNC Controls and Four Roll Plate Rolls: Automatic cycle systems are generally used only on four
roll plate rolls because there is minimal chance for slippage thanks to the constant pinching action of the forth roll.
Automatic controls use an encoder to track movement of the plate through the machine. If the plate slips, the
bending roll movements will be out of synch with the rolling movement.
Variable Geometry Three Roll Plate Rolls are not new but are gaining in popularity around the world. They are
built for medium, heavy to extremely thick plate applications. The top roll moves up/down and the lower two rolls
each move horizontally. This lower roll movement allows increasing the offset distance from the top roll and
commensurately increasing mechanical advantage in bending. A machine of this type works well over a wide
range of material thickness. By adjusting the geometry they can be used similar to single pinch, double pinch and
pyramid style machines and require minimal sheet movement during the pre-bend operations. In the past these
machines were commonly found in shipyards but now are being placed in general job shop and manufacturing
applications.
True Pyramid Machines are rarely used in modern business. They may be found on the used market and are
more common in third world or developing countries. The have three rolls, both lower rolls fixed in position and the
top roll moves up/down. In general they leave a very long un-bent flat and have several other disadvantages.
Two Roll Machines are designed for thin gauge material rolled to reasonably small diameters. They use a large
diameter urethane coated pinch roller which moves up with extreme pressure against a small diameter steel top
roller. A mandrel or drum, very close in OD to the desired ID of the part is fitted over the top roll. Two roll sheet rolls
are extremely fast and will roll a round part even if the blank has cutouts or holes. Since they require a mandrel for
each different part diameter and material thickness they are not as versatile as some other machines. For
dedicated high speed production however they are often the absolute best choice.
Optional Equipment can be found listed on most proposals for plate rolling machines: The most important
items to consider are hardened roll surfaces and cone rolling devices. With today’s harder materials and
laser/plasma cutting techniques it is ever more important to have very hard outer roll surfaces. Look for hardness
rating from 50 to 55 Rockwell C Scale. Hardness in this range will have a reasonable penetration depth and
provide long lasting protection against roll surface wear. Hardness exceeding 60 will have a shallow penetration
and result in cracking or crazing of the roll surface. Cone rolling devices permit the operator to roll a conical shape
and are standard on some machines. Lateral material supports and overhead supports are optional but less
frequently requested. Overhead supports prevent lighter materials from collapsing when rolled to large diameters.
A side support can also assist in this function to prevent light materials from re-curving toward the floor if the
radius is very large. Some machines have extended roll shafts that protrude through the machine frame and
section or pipe dies can be fitted on these ‘stub shafts’. It is not practical to roll angle iron on a plate roll since
angle tends to twist when rolled. Plate rolls do not have outboard adjustable lateral material guides to prevent this
twist. You should consider using a section rolling machine or angle roll. In general, section dies on plate rolls are
good for bending flat bar the hard way, rods or small pipe.
General Note: Roll Bending Machines are very dangerous if used carelessly. It is the responsibility of the owner to
ensure the installation and proper use of point of operation safety guards or devices.
that this information will assist you in selecting and properly sizing a machine to fit a particular application. For
further in-depth information and application engineering please contact Carell Corp. directly.
Plate or Sheet Bending Rolls are built in 2 main categories, single and double pinch and may have different
geometries or styles. Matching the most appropriate machine style to the application is important. General
machine styles are: 3 Roll Initial Pinch, 3 Roll Double Pinch, 4 Roll Double Pinch, 3 Roll Variable Translating, 3
Roll Pyramid and 2 Roll Systems. Plate rolls are also built in a vertical format for special applications.
Machine capacity is of equal or greater importance to style. Steel mills are producing materials with increasingly
higher yields. Plate roll manufacturers commonly rate machines according to a baseline material yield strength
between 36 to 38,000 psi. When choosing a machine you must refer to your mill certificates to verify the common
yields of the plates being delivered. It is not uncommon to find that the material you are actually rolling will have
yields in the 48,000 to 58,000 psi range if it is ‘mild steel’. Machine capacity must match your material type. Most
manufacturers can provide detailed tables or graphs that allow you to match capacity to yields.
You will often see ratings for pre-bending and rolling given for any one size Plate Roll. Pre-bending is performed
on the plate roll at the leading and trailing edge of the sheet (eventually the seam). Sheets cannot physically be
bent completely to the edge and thus will leave what is referred to as the ‘un-bent flat’. The minimum you could
expect for flat length is 1.5 x material thickness and often it will be from 2.5 to 3.5 times material thickness for
heavier plate. It is the pre-bending operation attempting to reduce the unbent flat to the minimum possible that
takes the most power. This is why pre-bending ratings are lower than rolling capacities for any given machine.
You must be mindful when reviewing machine ratings since the maximum total rolling capacity is generally
expressed with the intrinsic requirement of multiple rolling passes and very long un-bent flats. Un-bent flat lengths
for any given sheet are a function of thickness, width, cylinder diameter, machine type, yield, top roll size, operator
proficiency among other factors. NC and CNC Controls are ever more common in the workplace. Most all NC/CNC
machines are 4 roll types. Automated controls are recommended for high volume cylinder or shell production or to
roll complex shapes that are not easily reproduced by using manual machine controls. Multiple bends, variable
radius bends, ovals and the like are some examples.
Three Roll Initial Pinch or Single Initial Pinch Plate Rolls are generally for lighter capacity applications and may be
electro-mechanical or hydraulic. They work by "pinching" the flat sheet between two counter-opposed rolls while
the third offset roll or ‘bending roll’ moves upward to contact and then bend the sheet. When rotation of the rollers
is activated, the sheet exits at a given radius. With the sheet cut to the developed length and the bending roll
properly positioned; the part is rolled into a cylindrical form, where it can then be welded at the seam to produce a
cylinder. The upper roll is in a fixed position; the lower pinch roll can move up/down to pinch the material. The third
roll (the forming roll) is also adjustable. To remove a rolled cylinder, it must be extracted from off of the top roll.
Machines are generally equipped with some type of release mechanism on the top roll to allow extraction of the
cylinder. Typical methods are either a forward tilting or releasing top roll or a removable end yoke. In most
applications, these machines require removal and re-insertion of the sheet in order to pre-bend both ends. They
are cost effective but in contrast may be more labor intensive in a production setting. There were many large
mechanical initial pinch machines built during the 1930’s, 40’s & 50’s and can be found on the used market. All
have cast frames as modern alloys and welding techniques had yet to be invented.
Double Pinch Plate Rolls are available from light to extremely heavy capacities and may have three or four rolls.
The terminology can be confusing as these units may also be referred to as ‘double pinch pyramid plate rolls’ or
‘double initial pinch plate rolls’. Both three and four roll styles have fixed position top rolls and two offset rollers or
‘lateral rolls’, one on each sides. The 4 Roll styles have an additional roller underneath the top roll, which
constantly pinches the plate during rolling. Double Pinch Rolls can pre-bend both ends of the plate without
removal as is required with single pinch rolls. Three Roll machines generally require pre-bending the leading
end, running the sheet through the machine to pre-bend the trailing end then switching roll rotation direction to roll
the cylinder body. Four Roll Plate Rolls have a slight advantage in cycle time since the permit pre-bending of the
leading edge, rolling the cylinder body and finishing off the trailing pre-bend all while rolling in the same direction.
Smaller machines can be mechanical but most modern machines are hydraulic and include drop end yokes for
easy extraction of the work-piece.
Automatic NC or CNC Controls and Four Roll Plate Rolls: Automatic cycle systems are generally used only on four
roll plate rolls because there is minimal chance for slippage thanks to the constant pinching action of the forth roll.
Automatic controls use an encoder to track movement of the plate through the machine. If the plate slips, the
bending roll movements will be out of synch with the rolling movement.
Variable Geometry Three Roll Plate Rolls are not new but are gaining in popularity around the world. They are
built for medium, heavy to extremely thick plate applications. The top roll moves up/down and the lower two rolls
each move horizontally. This lower roll movement allows increasing the offset distance from the top roll and
commensurately increasing mechanical advantage in bending. A machine of this type works well over a wide
range of material thickness. By adjusting the geometry they can be used similar to single pinch, double pinch and
pyramid style machines and require minimal sheet movement during the pre-bend operations. In the past these
machines were commonly found in shipyards but now are being placed in general job shop and manufacturing
applications.
True Pyramid Machines are rarely used in modern business. They may be found on the used market and are
more common in third world or developing countries. The have three rolls, both lower rolls fixed in position and the
top roll moves up/down. In general they leave a very long un-bent flat and have several other disadvantages.
Two Roll Machines are designed for thin gauge material rolled to reasonably small diameters. They use a large
diameter urethane coated pinch roller which moves up with extreme pressure against a small diameter steel top
roller. A mandrel or drum, very close in OD to the desired ID of the part is fitted over the top roll. Two roll sheet rolls
are extremely fast and will roll a round part even if the blank has cutouts or holes. Since they require a mandrel for
each different part diameter and material thickness they are not as versatile as some other machines. For
dedicated high speed production however they are often the absolute best choice.
Optional Equipment can be found listed on most proposals for plate rolling machines: The most important
items to consider are hardened roll surfaces and cone rolling devices. With today’s harder materials and
laser/plasma cutting techniques it is ever more important to have very hard outer roll surfaces. Look for hardness
rating from 50 to 55 Rockwell C Scale. Hardness in this range will have a reasonable penetration depth and
provide long lasting protection against roll surface wear. Hardness exceeding 60 will have a shallow penetration
and result in cracking or crazing of the roll surface. Cone rolling devices permit the operator to roll a conical shape
and are standard on some machines. Lateral material supports and overhead supports are optional but less
frequently requested. Overhead supports prevent lighter materials from collapsing when rolled to large diameters.
A side support can also assist in this function to prevent light materials from re-curving toward the floor if the
radius is very large. Some machines have extended roll shafts that protrude through the machine frame and
section or pipe dies can be fitted on these ‘stub shafts’. It is not practical to roll angle iron on a plate roll since
angle tends to twist when rolled. Plate rolls do not have outboard adjustable lateral material guides to prevent this
twist. You should consider using a section rolling machine or angle roll. In general, section dies on plate rolls are
good for bending flat bar the hard way, rods or small pipe.
General Note: Roll Bending Machines are very dangerous if used carelessly. It is the responsibility of the owner to
ensure the installation and proper use of point of operation safety guards or devices.
| Choosing The Right Plate or Sheet Rolling Machine Courtesy of Carell Corporation |
Carell Corporation offers more plate rolling
solutions to more fabricators than any other
plate roll supplier in North America!
solutions to more fabricators than any other
plate roll supplier in North America!
Gulf States saw & Machine Co., Inc. is the largest distributor of technologically advanced metal fabrication machinery in Alabama, Georgia, Kentucky, Mississippi, Tennessee and the pan handle of Florida. Gulf States Saw
& Machine Co., Inc. proudly represents well known metal fabrication machinery manufacturers such as Piranha, HE&M Saw, Peddinghaus, Ermaksan, FMB, Pat Mooney, Flow, Eagle bending Machines, Carell
Corporation, Nitto Khoki, Ellis, Dake, Scotchman, Jet, Nishijimax, Plasma Automation, Vicon and others. Gulf States Saw & Machine Co., Inc. distributes machinery for the metal fabrication and manufacturing industry in
the form of ironworkers, press brakes, shears, band saws, waterjets, plasma tables, laser cutting, mag drills, portable punches, beam lines, drill lines, angle lines, notchers, pipe notching, pipe bending, plate rolls, angle
rolls, cold saws, blades, tooling, horizontal band saws, vertical band saws, bandsaws, pressbrakes, plate shears, drill press, annular cutters, punch, air compressors and many other products.
& Machine Co., Inc. proudly represents well known metal fabrication machinery manufacturers such as Piranha, HE&M Saw, Peddinghaus, Ermaksan, FMB, Pat Mooney, Flow, Eagle bending Machines, Carell
Corporation, Nitto Khoki, Ellis, Dake, Scotchman, Jet, Nishijimax, Plasma Automation, Vicon and others. Gulf States Saw & Machine Co., Inc. distributes machinery for the metal fabrication and manufacturing industry in
the form of ironworkers, press brakes, shears, band saws, waterjets, plasma tables, laser cutting, mag drills, portable punches, beam lines, drill lines, angle lines, notchers, pipe notching, pipe bending, plate rolls, angle
rolls, cold saws, blades, tooling, horizontal band saws, vertical band saws, bandsaws, pressbrakes, plate shears, drill press, annular cutters, punch, air compressors and many other products.
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| ALABAMA GEORGIA KENTUCKY MISSISSIPPI TENNESSEE |
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