The 403 Series 4-roll double pinch plate bending machine is in a sense a 3-roll initial pinch plate bending machine with an extra bending roll on the front side of the pinch rolls. The advantage of this type of machine is that it enables the operator to roll the workpiece from the leading to the trailing edge with minimal and usually negligible flats. As a rule of thumb, the flats are less than 1 1/2 to 2 times the work piece thickness. This can be accomplished in a single pass without turning the workpiece. See forming procedure for details.


Rolls - The heart of the WDM 4-roll plate bending machine is the rolls themselves. These rolls are machined from 1045/50 steel bars or forgings. They are crowned to compensate for deflection and supported on sealed, self aligning, spherical bearings requiring minimal maintenance. These rolls are sized according to the load imposed during the rolling cycle, making the machine more compact and streamlined than before without affecting the capacity.

Roll support and adjustment - The bearings that hold the rolls are supported on a set of master
and slave hydraulic cylinders with very effective seals and
travel in a radial path (bending) and a straight path (pinch).

Restoring parallelism of rolls - Restoring parallelism of rolls is accomplished by a special
valve arrangement designed by WDM which is activated
when the roll is lowered to the bottom and held momentarily
until all movement ceases. Roll is then parallel with top roll.


Control of Rolls - The hydraulic circuit is fitted with a half-turn valve that allows all adjustable rolls to be angled for cone rolling, etc. The control also contains motor starting switch, function speed. Restoring parallel ism of rolls control, pinch roll pressure regulator, and indicator gauge.

Roll position indicators - These very practical and trouble free roll position indicators consist of an etched dial and pointer located on main housing facing operator's position. Various other indicators are available.

Roll drive - The top and bottom center rolls are driven by individual low speed, high torque type hydraulic motors with very high volumetric and overall efficiency. The motors are coupled to rolls with rigid couplings and planetary and/or spur gear type speed reducers. (4" & 5" roll machines do not have speed reducers.) Top and bottom roll speeds are hydraulically synchronized and equalized. This drive type provides highly efficient transfer of torque.


Control valves - The control valves are manual actuation type and mounted on main machine housing. This standard feature gives excellent feel and feathering capability to the operator's finger tips. Many other controls are available.

Hydraulic system - The hydraulic reservoir is an integral part of the machine frame which helps dissipate system heat. This and careful attention to efficiency of components keeps the hydraulic system cool. The
pump, valves, and other hydraulic components are sized and designed with maximum efficiency and function in mind.

Speed control - The speed of the entire system is controlled via a flow control knob located on the main housing near the operator's station. This knob controls the roll rotation and the adjustment speeds.
Individual speed control is available as an option on smaller Frame machines and standard on larger machines.


Frame - All this is housed in a compact, streamlined, fabricated, and machined steel frame composed of steel plates and robust structural sections.

Safety Cable - A safety cable on three sides of the machine allows anyone to stop the machine by tripping the wire. Its switch incorporates a feature which makes it impossible to start the machine unless the cable is installed with proper tension. (Light curtains and safety mats are available as optional accessories.)

Finish - Machine is finished with V.O.C. compliant haze gray epoxy and safety blue enamel.