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The Complete Guide to Shear Cutting Process and Equipment

Last updated:
May 10, 2024
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Table Of Contents

I. Cutting Process Parameters

Calculation and selection of cutting process parameters are shown in Table 1; the T/R ratio for some materials is shown in Table 2; preheating temperature for heated shearing is shown in 3; shearing conditions for different grades and specifications of materials are shown in Table 4; reasonable clearance for shearing blades is shown in Table 5.

Table 1 Calculation and Selection of Cutting Process Parameters

Serial NumberParametersCalculation and Selection
1Shear ForceWhen precisely selecting shearing equipment, verify the size of the shear force to ensure it is less than the tonnage of the equipment. Shear force can be calculated using the following formula
F=KAτb

where:
– F is the shear force (N)
– A is the shearing area (mm 2 )
– K is a coefficient considering factors such as blade bluntness, typically K=1.2~1.7
– τb is the material’s shear strength (10MPa), typically 0.7~0.8 times the tensile strength, i.e., τ=(0.7~0.8)R m , or refer to Table 2 for calculation
2Shearing TemperatureFor materials with higher strength (hardness) and larger cross-sectional sizes, preheat the material before shearing. The heating temperature should be: 350~550℃, see Table 3 for details. Refer to Table 4 to choose the shearing condition and decide if preheating is necessary
3Shear gapTo ensure the quality of shearing, there should be a reasonable gap value between the upper and lower blades (see Table 5). A larger value should be used when the material hardness is high or the cross-sectional size of the sheared section is large, and a smaller value should be used otherwise. A smaller value should also be used when shearing heated.

Table 2 Ratio of τb to Rm for some materials

Materialτb/MPaRm/MPaτ/RmA (%)Note
Q1952903360.86Annealing
375Cold work hardening
Q235341.74230.82Annealing
410Cold work hardening
Steel 152803600.7432
Steel 303564540.79Annealing
Steel 354205400.78Annealing
Steel grades 40, 45, 50460Annealing
Steel 7561010000.6110.8
30CrMnSiA75012000.6213.5Tempering
Pure copper1602000.8
H682003000.66
HPb59-12604200.62
Zinc1501870.91
2A121302300.5615Annealing
2A11220~240380~42015~20After hot extrusion
6A02701300.5422Annealing

Table 3 Preheat temperature for heating shear

Material hardness HBW269241229207
Preheat temperature/℃550400380350

Note: The preheat temperature is the temperature to which the material itself is preheated.

Table 4 Shear state of materials of different grades and specifications

Material gradeBlank diameter or side length/mmHardness HBWShear state
35 Steel≤75Cold Shear
80~85≥187Hot Shear
<187Cold Shear
>85Hot Shear
45 Steel≤60Cold Shear
65-75≥207Hot Shear
<207Cold Shear
>75Hot Shear
40Cr≤50Cold shear
55-60≥241Hot shear
<241Cold shear
>60Hot shear
45Cr
18CrMnTi
12Cr2NiA
≤35Cold shear
40~48≥255Hot shear
≥255Cold shear
>48Hot shear

Table 5 Reasonable clearance for shear blades (unit: mm)

Bar diameterBelow 2020~3030~4040~6060~90
Blade gap0.2~10.5~1.50.8~21.5~2.52.0~3.0
Bar diameter90~100100~120120~150150~180180~200
Blade gap2.5~3.53~43.5~54.5~87~12

II. Shear bed cutting blade

1. Blade type

The blades of the shear bed consist of two pieces, one fixed on the lower die seat and the other mounted on the upper template, driven by the slider to move up and down to achieve shearing. The types of blades seen in production are varied. The characteristics of single and multi-slot blades are shown in Table 6, and the characteristics of single and double-edged blades are shown in Table 7.

Table 6 Characteristics of single and multi-slot blades

BladeTypeSimplified DiagramCharacteristics
Single-slot bladeIntegral typeBoth the upper and lower blades of the shears are open type
The lower blade is a closed type blade, which prevents the bar from bending, used for cutting small bars, while the upper blade (moving blade) is still made open type
The blade has cutting edges on all four sides, improving the utilization rate of the blade
Insert typeCan save some tool steel, but requires an additional blade holder
Same advantages and disadvantages as above, additionally can be used on three sides
Combination typeCan avoid stress concentration at the corners of the integral blade, improving blade life, but also requires a blade holder
Multi-groove bladeSame shape and sizeCan cut two bars at once, improving productivity, used for large equipment to cut small materials
As above, can cut three pieces at once
Same shape, different sizesCan cut multiple blanks of different sizes at once
Different shapes and sizesCan cut multiple blanks of different shapes and sizes at once
Enclosed typeWithout changing the blade, it can cut steel of different shapes and sizes, used on an ironworker machine. In the diagram, 2 is the moving blade, 1 is the stationary blade

Table 7 Characteristics of single and double-edged blades

BladeSimplified DiagramCharacteristics
Single-edged bladeCan reduce the lever arm, but when cutting, the blade presses deeper into the bad material, affecting the end face quality, and can only be used on one side
Double-edged bladeCan be used on both sides, better end face quality

2. Blade design

When designing blades, the following two conditions are mainly considered: equipment process specifications, and the shape and size of the material being cut.

(1) Circular blade

Circular blade design is shown in Table 8.

Table 8 Circular blade design

Main dimensions
  • R—Edge radius
  • 1 — Lower blade height
  • 2 — Upper blade height
  • A— Distance from the bottom of the lower blade edge to the bottom of the blade
  • B— Distance from the top of the upper blade edge to the top end of the blade
No.ParametersCalculation and selection
1Edge radius RThe edge radius mainly depends on the diameter of the rod being cut; too large an R can overly flatten the cross-section of the rod, sometimes even causing cracks

If R is less than half the diameter of the rod being cut, the rod’s side will have indentations, affecting the blade’s lifespan

The radius of the blade edge can also refer to Table 9, which is found by the diameter of the rod being cut
2Lower blade size ATake empirical data from equipment process specifications

5000kN shearing machine, A=120~130mm

10000kN shearing machine, A=130~140mm
3Upper blade size BThe smaller the value of B, the better, under the condition of ensuring blade strength and multiple regrindings, it can be determined by the following formula

B=H-[S+A+(0.3~0.32)Dmin ]

Where H is the height of the shear bed blade opening (mm)

S is the stroke of the shear bed (mm)
4Height of upper and lower blades h 1 and h 2The blade edge height of the upper and lower blades should be equal. It can be determined by the following formula

1 =(H+A-B)/2 + (7~10)mm

2 =H-h 1 +(15~20)mm
5Blade external dimensionsBlade thickness C: Mainly considering the strength and stiffness of the blade, can be selected

C = (0.25 to 0.5)D

where D is the diameter of the rod being cut (mm)

Blade thickness C, blade width L, can also be selected according to the tonnage of the equipment, see Table 2-18

The inclination angle α at the blade opening can be taken as 10°
6Bolt holesBolt holes for fixing the blade, generally 4 holes, i.e., 2 holes for the moving blade, 2 holes for the fixed blade; in some cases, 6 holes. Hole diameters d and D, center distances l, l 1 , h 3 , and dowel pin slot radius r, all related to the tonnage of the equipment, see Table 10

Table 9 Blade edge radius (unit: mm)

Rod diameter D28~3234~3638~4245~5054~5660~65
Edge radius R171922.526.529.534.5
Bar diameter D70~7580~8590~95100110130
Edge radius R39.544.550535868

Table 10 Dimensions of round inserts (unit: mm)

Equipment tonnage/kNdDll1h3rcL
500036552302255560419
1000048722602760680479

(2) Square edge blades

Square steel is generally sheared along the diagonal, and the blades are divided into integral and combined types. See Table 11 for the design of integral square edge blades.

Table 11 Design of integral square edge blades

Main dimensions
No.ParametersCalculation and selection
1Lower Blade Size ATake empirical data according to the equipment

For 5000kN and 10000kN shears, 110~120mm can be taken
2Upper Blade Size BB = H – [s + A + 0.7a min ]

Where H—height of shear blade opening (mm), obtained from equipment process specifications

s—stroke of the shear (mm), refer to equipment process specifications

min —the minimum side length of the square material cut by the same blade (mm), the maximum allowable side length of the square material to be cut

Should be within the following range

max ≤ 1.25a min
3Lower blade height h 11 = (H + A – B) / 2 + (7 ~ 10) mm
4Upper blade height h 22 = H – h 1 + (15 ~ 20) mm
5Die slot fillet radius rTo prevent stress concentration and damage to the blade during shearing, a fillet must be used at right angles, see Table 12
6Blade profile dimensionsThe determination of the blade profile dimensions is the same as for circular edge blades
7Bolt holesThe design and related dimensions of bolt holes are as per the design of circular edge blades

Table 12 Die slot fillet radius r (unit: mm)

Square material side length a<5050~7075~9090~105110~125130~150
Fillet radius r7912151521

(3) Flat edge blade

The blades for cutting flat steel can be made with a flat edge, as shown in the attached figure in Table 13. Type I, both upper and lower blades have grooves, used for cutting thick materials; Type II, the upper blade does not have grooves, i.e., B equals h 2 , often used for cutting thinner materials. Both types cut along the wide edge of the flat material.

Table 13 Flat Edge Blade Design

Type I Blade DimensionsType II Blade Dimensions
Diagram
No.ParametersCalculation and Selection
1Lower Blade Size ATake empirical data based on equipment tonnage

5000kN shearing machine, A = 175mm

10000kN shearing machine, A = 190mm
Type II Blade and Type I

The only difference is the upper blade does not have a groove, that is B equals h 2 .

Regarding dimensions, determination as above
2Upper blade size BThe upper blade (moving blade) edge should be below the lower blade edge at the bottom dead center of the stroke, can be determined by the following formula

B = H – S – A + (5 to 10) mm
3Edge length CThe length of the edge is mainly determined by the size of the flat steel being cut, for convenience

During grinding, the material should be slightly wider than the measurement

C = bwidth + (20~30) mm

M = (L – C) / 2 mm
4Upper and lower blade heights h 2 and h 1 h1=(H+A-B)/2 + 10mm
h2=H-h1+20mm
5Blade dimensionsThe determination of the dimensions is the same as for circular blade edges
6Bolt holesThe design and relevant dimensions of bolt holes are shown in the circular blade edge design

3. Blade fasteners

Blade fasteners mainly include bolts, locating pins, and nuts, designed based on equipment tonnage, see Table 14 and Table 15.

Table 14 Bolt and locating pin dimensions

Shearing machine tonnageBoltBolt and locating pin size/mm
dLlhDKARd1
5000kNUpper boltM3320070205225174.59
Lower boltM3326070205225174.59
10000kNUpper boltM4227090287034265.511
Lower boltM4236090287034265.511

Table 15 Nut dimensions

Shearing machine tonnage/kNNut size/mm
dHsDD1
50001M33305057.847
100001M42357080.866

4. Blade material

During the cutting process, the blade suffers severe wear, so the material used to make the blade must have high wear resistance, and its hardness should be more than twice that of the material being cut. For hot shearing blades, a certain level of hot hardness is also required, meaning that the blade must retain the necessary hardness at the shearing temperature.

When specifically choosing, factors such as the size of the blade and the grade of the material being cut must also be considered. The hardness and applications of materials for cold and hot shearing blades are shown in Table 16 and Table 17.

Table 16 Hardness and Application of Cold Shearing Blade Materials

MaterialHeat Treatment Hardness HRCApplication
Carbon tool steelT7, T858~62Used for small blades, and produced in small batches
T9, T1058~62
Alloy tool steelCr, 9SiCr58~62Used for large blades, mass production in batches
CrWMn60~62
7Cr3, 8Cr350~55
Cr12Mo, Cr12MoV58~62

Table 17 Hardness and Application of Hot Shearing Blade Materials

MaterialHeat Treatment Hardness HRCApplication
5CrMnMo42~45Used for batch mass production with cutting temperatures above 200℃
5CrNiMo45~47
3Cr2W8V45~48
5CrW2Si45~50
6CrW2Si45~50
T7, T8, T9, T1055~60Used for small blades and small batch production with cutting temperatures below 150℃

III. Specifications and Production Capacity of Shearing Equipment

Specifications of shearing equipment are shown in Table 18 and Table 19. Shearing production capacity is shown in Table 20 and Table 21.

Table 18 Specifications of Special Shearing Equipment

Equipment NameModelMaximum Shearing Capacity/mm
Diameter of Round SteelSquare steel side length
Ironworker machineQ34—10Φ3528
Q34—16Φ4540
Q34—16AΦ3835
Q34—25Φ6555
Bar shearing machine

(Crank shear bed)
Q42—250Φ90
Q42—500Φ132125
10000kNΦ190180
12500kNΦ210185
16000kNΦ250 220
Billet shearing machineQA95-100Φ50 (cold shear)50 (cold shear)
150 (hot shear)

Table 19 Q42 type bar shearing machine technical parameters

Technical parametersModel
Q42-250AQ42-500QA42-500QA42-500AQ42-1000A
Maximum Shearing Force/kN250050005000500010000
Maximum Shearing Diameter/mmΦ100 (When R m ≥450MPa)Φ132 (When R m ≥450MPa)Φ105 (When R m ≥700MPa)p115 (When R m ≥620MPa)Φ190(R m ≥450MPa when)
Number of Strokes/(times/min)3018383816
Stroke Height/mm801009090140
Material Stop Range/mm55 ~500110 ~100065~50065~500120 ~1000
Motor Power/kW1730403075

Note: The equipment listed in the table is produced by Shenyang Forging Machine Tool Factory.

Table 20 Shearing Production Capacity (I) (Unit: pcs/h)

Blank Diameter/mmDifferent billet lengths/mm
100200300400600800100012001400160018002000
Φ202100160014001250800720650590380340300270
Φ301900140013501150760680600540360320290260
Φ401500120011001000660600540490320290260230
Φ5013001000900800520470420380250220200180
Φ601050800720650430390350320210200170150
Φ70 900700630550360330300270180160140130
Φ80800600540480320290260240160140130120
Φ90650500450400260230210190130120110100
Φ10045035031028018016014013090807065
Φ11030037025016014013012080706560
p12025023021014013012011070605550
Φ130200180160110100908055504540
Φ1401501301208070605535302725
Φ15011090805045403525232120

Note: The data in the table should be reduced by 20% during hot shearing.

Table 21 Shearing Production Capacity (II) (Unit: kt/a)

Equipment NameAverage mass of billet/kg
0.25~0.60.6~1.01.0~1.61.6~2.52.5~4.04.0~6
Crank shear bedCold cut 1 piece simultaneously101215
Cold cut 2 pieces simultaneously151822
Hot cut 1 piece simultaneously81012
Hot cut 2 pieces simultaneously121518
Ironworker machine45.26.58.511
Crank press1.32.34
Sawing machine0.060.080.10.140.210.27
Equipment nameAverage mass of blank/kg
6 to 1010 to 1616 to 2525 to 4040 to 6060 to 100
Crank shearSimultaneous cold cutting of 1 piece182226313643
Simultaneous cold cutting of 2 pieces2733394554
Simultaneous hot cutting of 1 piece141821242934
Simultaneous hot cutting of 2 pieces2226313643
Ironworker machine14182327
Crank press
Sawing machine0.40.480.60.9
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