I.Application
The seven roll straightener is used to straighten the bending of bar or tube created in the rolling process. It has obvious effect  in solving bar head or tail bending, eliminating slight ellipticity and removing oxide scale. The material of bar or tube includes Carbon tool steel, carbon structural steel, alloy tool steel, alloy structural steel, spring steel, stainless steel, bearing steel, titanium chromium nickel alloy etc..


II.Main Features Of Equipment
1.7 roll straightening machine adopts optimized hyperbolic and deep-shallow concave composite roll system, which absorbs the advantages of 2 roll and multiple oblique roll straightening machine, at the same time conquers the disadvantage of the two. The precision is high.
2.The principle of rolls against pressing with controllable loading turns the rigid frame is a flexible frame which ensure the necessary pressure imposed on the bar thus enlarge the Plastic range of bar, the result is better straightening precision and little damage to the machine.
3.Main drive adopts AC frequency conversion driving device with stepless speed regulation, constant torque output at base speed, and constant power output above base speed.
4.There is hydraulic station in the Hydraulic system which uses 
constant pressure pump as power source. The accumulator can be used for quick oil filling, and the overload unloading adopts a direct acting overflow valve which plays the role of pressure buffer.
 
III.Equipment Composition And Structure
This machine is composed of loading system, straightening main body, unloading or discharging table roller and discharging collective system, with corresponding electronic control, equipment lubrication and cooling system.

1.loading system:

1.1 loading rack
Function: It is used for material Stacking and spreading, making preparation of normal function and continuous and automatic processing of next step.
Structure: The frame body is a structural component. The material is carried and put on the loading rack by crane and paved in order by hand. The front end of the loading or feeding rack is provided with an adjustable material retaining or blocking device,Pneumatic kicking arm delivers the processing material in turn onto loading or feeding roller smoothly.
Main parameter:  The loading rack inclination angle is 7°.
Table size: （6000×1740×1300）in length*width*height

1.2 loading table roller
Function: It is used for material flipping and delivering to the main body of straightening machine for the next step processing.
Structure: It is a swing table roller with all rollers installed on the swinging frame. The frame is driven by the cylinder, making up and down motions. The bar material is flipped onto the table roller when rollers are lifted. Rollers are driven by motor and reducer. When table roller rises, the bar is delivered into straightening machine. During straightening process, the table roller makes downward swinging to avoid bar material banging. It gets protected by avoiding the bar end from whipping.
Main parameter:
Roller: φ80×120
Reduction ratio: 1:17
Table size: length * width * height (6000 x 400 x 1000)

2.main body of 7 roll straightening machine
Function: Then main part of 7 roll straightening machine adopts crossed and symmetric pressing straightening principle to acquire desirable work-piece by straightening process.
2.1 Structure: 7 roller machine is 2 beam 5 column, seven oblique roller (2221) structured. Two pairs of rollers are powered ones with upper roller equipped with powered pressing down mechanism. Both up and down roller are equipped with angle adjusting mechanism, and the middle bottom roll is installed with manual lifting adjustment mechanism.
2.2 straightening principle:
It adopts crossed and symmetric pressing straightening principle. Through the inclined arrangement of roller, the design of roller shape, distance between rollers, and the matches of guiding distance, the bar experiences multiple times of crossed symmetric pressing which makes each section of bar subjected to multiple elastic-plastic bending deformation, and eventually acquires higher straightening precision.
Main parameter: straightness after fine straightening: ≤1‰. 
2.3 main driving
Structure: 2 AC motors individually drive the upper and lower rollers through reducer and SWC type universal joint shaft. The reducer is 1 in and 2 out pattern. Two pairs of roller are self driven. The bar material rotates forward under the rolling of 3 pairs of rollers. Through the multiple rotary pressing of rollers and the assisted straightening of 7th roll, the processing bar gets required straightening effect.
Main parameter: 
main motor 45kw*2(AC frequency conversion)
Speed ratio 13.3942
2.4 roller:
Structure: The structure of seven roller is basically the same which is composed of bearing seat and straightening roller. The roller shape adopts equidistant hyperbolic style.
Main parameter: 
Roller:φ250×380
Roller surface hardness: HRC60~62
2.5 pressing downward and upward system:
Structure: It is driven by motor and reducer to make up and down movement. The lower roller of middle pair of rollers is also equipped with manual lifting device, driving through a pair of bevel gear. The connection of middle part thread enable the roller to make up and down motion within a certain range.
Pressing down stroke: 85mm
Motor power: 2.2kw
2.6 angle adjusting mechanism:
Structure: Angle is manually regulated.
Main parameter: adjusting range of 27°~31°
2.7 protective guiding sleeve:
There is protective guiding sleeve at the beginning of straightening machine, for the purpose of restricting bar end whipping in the straightening process, and helping to guiding the bar as well.

3.unloading or discharging table and collecting basket:
This part is main composed of guiding groove and soft collecting basket.
The function of collecting basket is for the collection of finished material to pile up smoothly and safely, and finally finishing the product processing and collection.
Structure: The skeleton is welded structured, and the collective basket is split type six arc structure receiving baskets.
Main parameter: 5 tons in storage.
Table size : Length * width * height (6000 * 900 * 1100mm)

4.electrical system:
Function: This system is used for the controlling of gas and electric of the whole line to guarantee the successful operation of equipment.
4.1 the controlling of the two AC inverter main motor .
4.2 the controlling of auxiliary machine: mainly refers to the control of pressing down motor, lubrication system.
4.3 equipped with electrical cabinet and operation table.

5.Lubrication:
Function: It is for the purpose of lubricating each moving section to ensure the normal function of equipment.
Dry oil lubrication adopts scattered point manual refueling, and the reducer adopts Oil sump lubrication.

6.Pneumatic system:
Function: It is for the purpose of realizing movement of each pneumatic component to ensure the running of equipment. Bar flipping system, feeding roller swinging, opening and closing of clamping roller, and material discharging all adopt pneumatic controlling.
Main parameter: 
0.4~0.8MPa in pressure, 20m³/h with 2 stage of oil water separator.