The Complete Guide to Shear Cutting Process and Equipment

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

Table 2 Ratio of τ_b to R_m for some materials

Table 3 Preheat temperature for heating shear

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

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

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

Blade	Type	Simplified Diagram	Characteristics
Single-slot blade	Integral type		Both 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 type		Can save some tool steel, but requires an additional blade holder
			Same advantages and disadvantages as above, additionally can be used on three sides
	Combination type		Can avoid stress concentration at the corners of the integral blade, improving blade life, but also requires a blade holder
Multi-groove blade	Same shape and size		Can 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 sizes		Can cut multiple blanks of different sizes at once
	Different shapes and sizes		Can cut multiple blanks of different shapes and sizes at once
	Enclosed type		Without 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

Blade	Simplified Diagram	Characteristics
Single-edged blade		Can 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 blade		Can 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

• R—Edge radius
• h ₁ — Lower blade height
• h 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

Table 9 Blade edge radius (unit: mm)

Table 10 Dimensions of round inserts (unit: mm)

(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

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

(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 Dimensions	Type II Blade Dimensions
Diagram
No.	Parameters	Calculation and Selection
1	Lower Blade Size A	Take 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
2	Upper blade size B	The 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
3	Edge length C	The 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
4	Upper and lower blade heights h 2 and h 1	h1＝（H＋A－B）/2 + 10mm h2＝H－h1＋20mm
5	Blade dimensions	The determination of the dimensions is the same as for circular blade edges
6	Bolt holes	The 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

Table 15 Nut dimensions

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

Table 17 Hardness and Application of Hot Shearing Blade Materials

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

Table 19 Q42 type bar shearing machine technical parameters

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

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

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

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