METAL HOT-CUTTING CIRCULAR SAW BLADE Manual

newstime: 2017-02-10

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This manual, which includes the latest products information up to printing date, is for CNC-control TCT profiling circular saw blades produced by TANGSAW. TANGSAW is fully responsible for the modification rights. If needed, please contact us at anytime and we will response at the soonest time.
Tel.: 0086-315-2052139
Fax: 0086-315-2053342
Email: i-sales@tangsaw.com.cn; ken@tangsaw.com.cn 
 
1. Products Applications……………………...…….………………………………………………………1
 
2. Products Structure, Teeth Profile and Standard Specifications……………..………………… ……2
 
3. Products Parameters…………………………………………..…………………………………………5
 
4. Technical Requirements…………………………………………………………………………………6

1. Products Applications
Metal hot-cutting circular saw blades are mainly applied for rolling mills. It can be equipped with different sawing machines to cut steel pipes, sections, rounds, etc. made of normal carbon steel, alloy steel, bearing steel, high-speed tool steel, etc. The cutting temperature is usually above 750°C, while 800°C for high alloy steel.
2. Products Structure, Teeth Profiles and Standard Specifications
2-1 Structure diagram: structure diagrams can be divided into 3 types according to saw blade structures.
2-1-1 Flat structure: it is the most common type which can be used for hot cutting of steel pipes, sections, etc.
 
 
2-1-2 Taper structure: it can be applied to cut medium-large steel products which can reduce the cutting resistance and save power consumption. It is usually with small-medium diameters.
 
 
2-1-3 Hollow structure: it can be applied to cut medium-large steel products which can reduce the cutting resistance and save power consumption. It is usually with small-medium diameters.
 
D: diameter
d: bore
b: body thickness
d1: pinhole diameter
D1: PCD of pinholes
d2: lifthole diameter
D2: PCD of lifthole
T: teeth distance
α: teeth angle

2-2 Teeth Profiles: teeth profiles are different from workpiece. There are four kinds of common teeth profiles which are as follows. (from left to right/top to bottom: rat teeth, triangle teeth, wolf teeth, curve teeth)

Rat teeth is sharp and easy re-grinding, so it is one of the most common teeth profiles used for all kinds of workpiece; triangle teeth is strong, wearable and easy re-grinding, so it is more suitable for workpiece with high strength and low cutting temperature; wolf teeth and curve teeth are similar, they are strong and wearable, but different to re-grind, so it is not widely used.
Teeth distance for metal hot-cutting circular saw blade is usually 12-22mm based on workpiece sizes. Generally speaking, the smaller the thickness and diameters of workpiece are, the smaller teeth distance will be, vice versa. Small teeth distance is recommended under good cooling system without sticky teeth problem, because it could reduce the cutting resistance and improve the cutting quality.
2-3 Saw Blade Specifications: the diameters can be from 800mm to 2500mm and the standard sizes are as follows. Customers can choose the following sizes in priority or we can also make based on customers’ requirement.
TABLE 1 STANDARD SAW BLADE SIZES
3. Products Parameters
3-1 Material: 65Mn or 45Mn2V (45MnV)
3-2 Heat Treatment:
   Body hardness: HRC 27-35 (maybe decreased when thickness is over 12mm);
   Teeth hardness: HRC56-63 (65Mn), HRC48-56 (45Mn2V/45MnV)
   Teeth hardness depth: 3mm or 1/3 teeth height
3-3 Dimensions, shapes, accuracy, balancing and tension will conform to Circular Saw Blade for Hot Metal Cutting (YB/T5223-2005) issued by The people's Republic of China Ferrous Metallurgical Industry Standard.

4. Technical Requirements
4-1 Requirements on Sawing Machine
4-1-1 Main driving motor: sawing machine should be equipped with main motor with enough power which could offer enough cutting force and milling speed.
4-1-2 Over-all properties: sawing machine should be with certain structure rigidity and mechanical accuracy. The feeding speed should be stable and can be adjusted between 0-300mm/s.
4-1-3 Flange: it should keep good accuracy and rigidity, and could fix the saw blades evenly and tightly. The side run-out and radial run-out should conform to the followings:
TABLE 2 FLANGE SIDE RUN-OUT AND RADIAL RUN-OUT

 
Flange diameter is usually 40-50% of the saw blade diameter. Flange should be selected as larger as possible.
4-1-4 Protective cover: sawing machine should be equipped with suitable protective cover with the purpose to keep the safety cutting. Its thickness should be more than 10mm and cover 1/2-1/3 areas of the saw blades. Cross stud should be welded onto the cover surface in order to increase the bounce impact force.
4-1-5 Cooling system: cooling water with pressure more than 3MPa should be applied for the saw blade with diameter less than 1500mm; cooling water with pressure more than 5MPa should be applied for the saw blade with diameter more than 1500mm. During cutting, cooling water should continuously flush the teeth and cool down the saw blade which could improve the saw blade lifetime and avoid the problem with sticky teeth. High pressure cooling water like 8-10MPa will be much better, especially for large-diameter hot saw. Cooling water should spray at 180° angle from backside, and normal pressure water is spraying at sides while medium or high pressure water is spraying in the middle.
4-1-6 Fixing system: fixing on saw blade could keep the saw blade stability and improve the impact on saw blades. We suggest that vertical and horizontal fixing should be applied at the same time. As to reduce the resistance from workpiece against saw blades, draw-back system can be applied on workpiece.
4-1-7 Coordinated control: sawing machine should be equipped with complete coordinated control system which could prevent the saw blades from damages on side caused by workpiece impact.
4-2 Requirements on Workpiece: workpiece could be all kinds of squares, rounds, pipes, sections with temperature more than 750°C (800°C for high alloy steel). Workpiece material could be carbon steel, alloy steel, bearing steel, spring steel, high-speed tool steel, etc. Workpiece after rolling should be straight with minimum bending or deformation.
4-3 Requirements on saw Blades
4-3-1 Normal cutting parameters: besides the suitable sawing machine and saw blades, right cutting parameters, such as peripheral velocity should be 90-120m/s, feeding speed should be 50-200mm/s, should be also adopted to ensure the performance. High feeding speed can be applied when workpiece temperature is high, material is soft and fixing is stable. Otherwise, feeding speed should be low. Returning speed is usually 250-300mm/s. All customers should try and find out the most suitable cutting parameters at site based on their own sawing machines and workpiece.
4-3-2 Saw blades should be re-sharpened with following conditions.
① Wearing width is about 2.5mm on teeth top;
② Burrs on the cutting sections are over;
③ Cutting sparks come more or cutting noises come loudly;
④ Cutting is not straight;
⑤ Saw blades are with problems like cracks, teeth broken, bending or spalling.
4-3-3 Repair requirement on saw blade: in order to keep the best performance after repair, replaced saw blades must be inspected and selected, and then repaired base on the following process.
① Inspect the flatness and strength. If flatness and strength is bad, saw blades need to be sent back to producers for hammering;
② Inspect the cracks. Cracks can be welded when they are short, less, scattered, or redial. Cracks less than 20mm can be ignored. Cracks between 20-50mm can be solved by drilling Φ8-10mm stopholes at ends. Radial cracks between 50-80mm can be welded by experienced technicians based on certain welding process;
③ Inspect the teeth wearing and sticky problem. As for sticky teeth, chisel should be used to remove the mash and then professional teeth re-sharpening machine is used for re-grinding. Teeth profile and radial run-out should be kept the same as original design.
④ Re-harden the teeth with professional teeth re-hardening machine. Teeth hardness after re-hardening is above HRC56 (65Mn material) or HRC48 (45Mn2V material). Customers can test the hardness with steel file. If files can wear away the teeth tip, it means the hardness is low and such teeth should be re-hardened again. If possible, low-temperature tempering is required after each re-hardening.
4-3-4 Discard of saw blade: In the sake of safety, saw blades should be discarded with following conditions:
① Radial cracks with more than 80mm length;
② Circumferential cracks are developed;
③ Concentrate cracks are developed and getting closing;
④ Spalling is developed;
⑤ Bending is developed seriously;
⑥ Saw blade is re-sharpened in to small diameters which results in the decrease of linear speed or difficulty in cutting.
4-4 Notes during Saw Blade Application
4-4-1 Saw blades with right diameter, thickness, teeth number, etc. should be used based on cutting workpiece and production requirements. Saw blade diameter is usually confirmed by sawing machine producer while thickness can be chosen from TABLE 1. Generally speaking, the bigger or stranger the workpiece is, the larger and thicker the saw blade will be. Teeth number is usually described by means of teeth pitch. As for rounds, pitch should be large than 17mm. As for sections, pitch could be 12-17mm. Customers can also adjust the pitch based on the workpiece on site.
4-4-2 Sawing machine and saw blades should be ensured with good conditions before application. Saw blades and flanges should be clean before installation. And installation should be fixed in the sake of safety.
4-4-3 Sawing machine should be idling for 5 minutes to inspect the abnormal problems before application.
4-4-4 During cutting, all the employees should get away from the rotating direction. Blade shell should be fix and strong. Sawing machine should be stopped immediately for inspection when there are any problems. DO NOT APPLY THE SAWING MACHINE WITH PROBLEMS.
4-4-5 Operators should supervise the machine running all the time and adjust the cutting parameters, especially such as cooling water, workpiece clamp, etc. on the basis of workpiece. Collision or violent friction between saw blade and workpiece must be avoided during rotating, feeding or withdrawing.
4-4-6 Operations should be taken care in order to avoid impact or stuck of the saw blades when cut the ends or bent workpiece. 
4-4-7 DO NOT CUT THE DARK WORKPIECE (temperature decreased) or it will cause damages on sawing machines or saw blades as it is so dangerous.
4-4-8 DO NOT USE THE SAW BLADE AS GUARD TO STOP THE WORKPIECE. Rolling line must be stooped when saw blades are working in order to avoid the collision of saw blade and workpiece.
4-4-9 Saw blades should be inspected in time. Saw blades with large cracks must be replaced.
4-4-10 FAQ is listed as follows with TABLE 3.
TABLE 3 FAQ