It is easier to cut iron sheets with scissors
Principle of operation
The hydraulic shear system is similar in principle to variations of the manual or electric type. The difference is characterized by the way the force is applied to the separating element. Instead of a gearbox or manual mechanism, a hydraulic cylinder or pump plays this role. There are many advantages to this design.
- The high efficiency of the conversion of efforts allows the development of a force for the blade equal to several tons. At the same time, the own weight of the tool varies from 1 to 4 kg.
- The mobility and autonomy of the device is higher in comparison with manual or electrical devices.
- The cut quality is better as the cut is longer.
- The hydraulic drive is safer than other options.
- The guillotine type of knives is considered an improved option compared to lever tools.
- The blade moves at a low speed, so the work process is easier to control.
These are the main advantages of a hydraulic tool. Fast and accurate work is essential when cutting sheet metal. This factor is especially relevant for detailed cutting of thick sheets.
Hydraulic shears: description, types and subtleties of use
- Features of the
- Principle of operation
- Varieties
- Selection recommendations
- User’s manual
Special equipment is required for any construction or dismantling of buildings and structures. If there are iron elements in the structure, then hydraulic shears are an indispensable device. The specificity of this type of equipment is different and depends on many characteristic features.
Features of the
Hydraulic shears are successful in cutting rebar, which is needed for concrete structures. Steel products will also not become an obstacle for this type of equipment. The technical structure of the hydraulic shear seems to be complicated, but in reality it is simple. The tool is popular not only in construction work, but also in industrial production.
The device has individual settings that suit the purpose of use. There are types equipped with automatic equipment for feeding the processed material.
The hydraulic cylinders are responsible for this setting. Because of them, automatic systems are usually very large. The length of the cutting edge of such types reaches eight or more meters.
If a large device is not necessary, you can choose the option with manual control parameters. The scope of use of such equipment is already, but scissors can be used, for example, for cutting a cable. The force is transmitted to the object by the pressure generated by the internal pump.
This built-in hydraulic system delivers a powerful enough force to make cutting even thicker cables much easier.
At the same time, manual devices are characterized by compact dimensions and increased mobility.
In the production of various materials, handheld shears with an external pump are used. The tool is suitable for cutting products with particularly large dimensions. The pressure is supplied to the tool through a long flexible tube. This distinctive feature allows you to place the separating part at absolutely any angle. Labor is also simplified thanks to the ability to connect any pumping device.
Both hand pumps and large stationary stations are combined with the scissors.
Working with metal is possible without a special separating device. One-time undercuts or cutting of thin rods are also allowed with an angle grinder. An electric jigsaw and conventional metal cutters are also suitable. We will talk about the scope of application of hydraulic shears and the principles of operation of the device further.
Selection recommendations
The performance and specifications of most hydraulic variations are versatile. When machining workpieces, it is important to consider the thickness of the material. The shape of the working part of the product is selected based on the scope of its use. When choosing, special attention must be paid to the dimensions and weight of the scissors themselves.
Hydraulic tools have basic operational parameters that you can rely on when choosing tools for cutting metal, rubber, concrete, tires:
- the maximum possible indicator of the cutting force, calculated in kN or tons;
- the gap between the cutting blades in mm;
- unclamping force, calculated in kN;
- tractive effort in kN;
- thrust travel parameter in mm.
Combined scissors designed for opening structures are equipped with an additional pedal. It relieves the pressure in the working pump. If the tool has been idle for a long time, this part may not work properly.
Working with this type of instrument should begin with a mandatory check of the pedal equipment.
Classic hydraulic shears can cut a profile with a cross section of about 100 mm. The tool is suitable not only for rolled metal, but can also be used as attachments to an excavator. There are firefighters or cable hydraulic shears, they are used by the corresponding services. A tool with knives, working like a guillotine, is needed to cut rebar, wire or cable. The cuts made with such products are of good quality, even if the cables are thick enough. These device options differ in the way the blades are closed.
Industrial scissors can handle materials up to 60 cm in length and 35 cm in height.The tool is connected to a platform, which is driven by an electric motor with a power of 5 kW or more.
To choose scissors for your home, you need to consider:
- location of cutting edges;
- the shape of the blades;
- cutting feature of the tool;
- model power;
- convenience for use in a specific situation;
- presence of basic defense.
For a single cut, it is not at all necessary to spend money on an expensive model.
Varieties
Regardless of the principle of work, the tools are divided into:
- knife;
- nibbling.
The first version of the product is equipped with two single-edged knives. Only the edges of the material to be cut can be cut with these scissors. The middle of the workpiece can be cut with punching (nibbling) shears.
The following types of hydraulic shears are known.
- Manual ones are used for ropes and fittings. The tool has been successfully used in rescue operations. Scissors are used when cutting large quantities of rods and wires. The system of manual hydraulic shears is different in the design of the sharp part. Professional tools are guillotine and edging. If the first option can easily cope with bundles of wire and cables, then the second is useful in processing sheet metal.
- Stationary hydraulic systems are connected to the pumping station. The tool can cut any metal products of different thicknesses. The tool is widely used in the automotive industry. Devices of this type (press-shears) differ in the most overall dimensions.
- Alligator or sorting shears are used at metallurgical complexes. In these variations, the split part rotates relative to the handles, which makes the tool very practical to work with. Varieties of these models differ in the way pressure is applied. There are options with plunger pumps, and there are products with an external compressor station.
User’s manual
Before using the product, you must follow a number of the following recommendations.
- Each instrument is supplied complete with accompanying documentation, which must be studied in advance.
- Newer models usually have a protective lubricant that needs to be removed from the blades.
- The cylinder must be checked for oil level, and the entire pneumatic structure must be correctly combined into a single system. If there is no oil in the pump, it should be topped up using only suitable technical grades. Recommendations for the choice of lubricant are contained in the manufacturer’s technical documentation.
If the lubricant is incorrectly selected, no one guarantees the performance of the tool. This can also result in a shorter lifespan of the hydraulic shears.
When using the product, you must adhere to the following rules:
- the standard characteristics of the tool must correspond to the thickness of the processed material or be more;
- replacement of lubricants in the pump should be done at least once a year;
- in the event of an emergency, cutting must be stopped immediately;
- most of the tools of hydraulic type are subject to repair, after which they can be reused.
To use conventional hydraulic shears, the worker does not need special training, he just needs to learn the specifics of the design.
It is also important to know the general safety rules. When using the tool, it is important to consider:
- the correct position of the tool, especially its working part;
- features of treatment with anti-corrosion compounds during long storage;
- mandatory cleaning of moving parts before starting work.
Model overview of hydraulic shears for metal see below.
Bennett’s test problems
If the left gear turns in the direction indicated by the arrow, which direction the right gear will turn in?
In direction of arrow A.
In the direction of arrow B.
Which track must move faster for the tractor to turn in the direction indicated by the arrow??
| 3. If the top wheel rotates in the direction of the arrow, in what direction does the lower wheel rotate? 1. In direction A. 2. In both directions. 3. Towards B. |
In which direction the gear will move if the handle on the left is moved up and down in the direction of the dotted arrows?
Back and forth along arrows A-B.
In direction of arrow A.
In the direction of arrow B.
Part I. Psychological diagnostics
If two identical forces 1 and 2 act simultaneously on the round disc shown in the figure, then in which direction the disc will move?
In the direction of arrow A.
In the direction of arrow B.
In direction of arrow C.
Are both chains shown in the figure needed to support the load, or is only one sufficient? What?
Chain A is enough.
Chain B is enough.
Both chains are needed.
Three turbines are installed in the river, where the water flows in the direction indicated by the arrow. Water falls from the pipes above them. Which turbine will rotate faster?
Which wheel, A or B, will rotate in the same direction as wheel X?
What chain is needed to support the load?
Chapter 5. Methods of psychodiagnostics of adolescents and young men
Which gear rotates in the same direction as the pinion? Or maybe none of the gears rotates in this direction.?
Not one rotates.
Which axis, A or B, rotates faster or both axes rotate at the same speed?
Axis A rotates faster.
The B-axis rotates faster.
Both axles rotate at the same speed.
If the bottom wheel rotates in the direction indicated by the arrow, then in which direction the X axis will rotate?
In direction of arrow A.
In the direction of arrow B.
In both directions.
Which of the cars with liquid in the barrel slows down?
In which direction will the spinner, adapted for irrigation, rotate if water is put into it under pressure?
Round trip.
In direction of arrow A.
In the direction of arrow B.
_._ Part I, Psychological Diagnostics
Which of the handles will keep under spring tension?
Both will not hold on.
Handle A will hold.
Handle B will hold.
In which direction the bed was last moved?
In direction of arrow A.
In the direction of arrow B.
The wheel and brake pad are made of the same material. Which will wear out faster: a wheel or a block?
The wheel will wear out faster.
The pad will wear out faster.
Both the wheel and the block will wear out the same.
Are the containers of the same density filled with liquids or one of the liquids is denser than the other (the balls are the same)?
Both liquids are of the same density.
Liquid A is denser.
Liquid B is denser.
In which direction the fan will rotate under the pressure of air?
In direction of arrow A.
In the direction of arrow B.
In both directions.
Chapter 5. Methods of psychodiagnostics of adolescents and young men
In which position the disc will stop after free movement on the specified mowing line?
In whatever.
In position A.
In position B.
Which scissors are easier to cut an iron sheet?
Which wheel of the wheelchair rotates faster when the wheelchair is moving?
Wheel A spins faster.
Both wheels rotate at the same speed.
Wheel B spins faster.
How the shape of a sealed thin-walled tin can will change if it is heated?
As shown in figure A.
As shown in figure B.
As shown in Figure C.
Which gear rotates faster?
Part I. Psychological diagnostics
Which ball will the X ball collide with if it hits an obstacle in the direction indicated by the solid arrow?
Let’s say the wheels you have drawn are made of rubber. In which direction you need to rotate the drive wheel (left) so that the X wheel rotates in the direction indicated by the dotted arrow?
In direction of arrow A.
In the direction of arrow B.
The direction doesn’t matter.
If the first gear rotates in the direction of the arrow, then in which direction the upper gear rotates?
In direction of arrow A.
In the direction of arrow B.
The weight of figures A, B and C is the same. Which one is more difficult to knock over?
What pieces of ice can you quickly cool a glass of water with??
Piece in picture A.
Pieces in picture B.
Piece in picture C.
_ Chapter 5. Methods of psychodiagnostics of adolescents and young men
Which picture is correct
depicts a bomb falling from an airplane?
1. In picture A.
»2. In the picture B.
Picture C.
In which direction will this car, moving in the direction of the arrow, take a turn?
In any direction.
There is ice in the container. How the water level will change compared to the level of ice after it melts?
The level will rise.
The level will go down.
The level will not change.
Which of the stones, Aili B, is easier to move?
Efforts must be the same
coy.
Which axis rotates slower? 1.Axis.
Whether the weight of both boxes is the same or is one of them lighter?
Boxes of the same weight.
Part I. Psychological diagnostics
Bars A and B have the same cross-section and are made of the same material. Which bar can support the most weight?
Both will carry the same load.
How high will the water rise from the hose if it is released from tanks A and B, filled to the top.
As shown in figure A.
As shown in figure B.
Up to the height of the tanks.
Which one of these solid metal objects will cool faster when exposed to hot air??
In what position will a wooden disc with a metal circle inserted into it stop if the disc is rolled?
In position A.
In position B.
In any position.
Where will the stick break if you press sharply on its end to the left?
Chapter 5. Methods of psychodiagnostics of adolescents and young men
On which container are the risks indicating equal volumes correctly applied??
Which of the drawings correctly depicts water pouring out of the openings of the vessel?
Which bag will melt the ice cream faster?
How the suspended load will move if the upper wheel rotates in the direction of the arrow?
Intermittently down.
Intermittently up.
Continuously up.
Which wheel made of the same material will spin longer if spun to the same speed?
Part I. Psychological diagnostics
What is the easiest way to carry a stone on a smooth road?
In what direction will the water move in the gear pump system if its gear rotates in the direction of the arrows?
Towards A. 2. Towards B. 3. Both sides.
Which gear is harder to climb uphill on a bike??
When transferring type A.
When transferring type B.
When transmitting type C.
There is sand at the bottom of the tank. On top of it are pebbles (pebbles). How will the level of filling in the container change if pebbles and sand are mixed?
The level will rise.
The level will go down.
The level will remain the same.
Rack X moves half a meter in the direction indicated by the arrow. How far will the center of the gear move??
Which of the gears, A or B, rotates more slowly, or they rotate at the same speed?
Gear A rotates slower.
Both gears rotate at the same speed.
Gear B rotates slower.
Chapter 5. Methods of psychodiagnostics of adolescents and young men
Which of the horses should run faster on the corner so that it is not overtaken by another?
Both must run with one-
From which tap should the stream of water hit harder if they are opened at the same time??
Both are the same.
When is it easier to lift the same weight?
In both cases, the same.
These bodies are made of the same material. Which one has the least weight?
Body A. 2. Body B.
Both bodies are the same in weight.
At what point the ball moves faster?
At both points, A and B, the speed is the same.
At point A, the speed is greater.
At point B, the speed is greater.
Part I. Psychological diagnostics
Which of the two rails should be higher on the bend.
Both rails must be the same height.
How weight is distributed between hooks A and B?
The gravity on both hooks is the same.
On hook A, gravity is greater.
Hook By Gravity
Which pump valves are in the correct position?
Which axis rotates slower?
The material and sections of the cables A and B are the same. Which one will withstand the heavy load?
Both ropes will carry the same load.
_ Chapter 5. Methods of psychodiagnostics of adolescents and young men
Which of the tractors should move further in order for the boats to stop at the shore?
Both tractors must travel the same distance.
Which of the gates has a better support cable?
Both gates have a fixed
equally.
Better secured at wicket A.
■ 3. Better secured at gate B.
Which hoist is easier to lift a load?
Both hoists are the same.
On the X-axis there is a drive wheel that rotates the cones. Which one will spin faster?
Both cones will rotate the same.
If the small wheel rotates in the direction of the arrow, then how will the large?
In direction of arrow A
Round trip. 3. In the direction of arrow B.
_ Part I, Psychological Diagnostics_
Which of the cables holds the pole more reliably?
Which winch is more difficult to lift?
Both winches are the same.
If it is necessary to support a bridge built across the river with a steel cable, then how is it more expedient to fix the cable?
As shown in fig. AND.
As shown in fig. IN.
As shown in fig. FROM.
Which of the chains is less tense?
Both chains are tensioned the same.
For each problem solved correctly within 25 minutes, the subject receives 1 point. The total amount of points scored by him is compared with table 17 and it is concluded on which of the five possible levels his technical thinking is:
Chapter 5. Methods of psychodiagnostics of adolescents and young men
Table 17 Average indicators of the level of development of technical thinking among boys and girls. senior school students
Intellectual technical quiz “We and technology
Intellectual technical quiz “We and Technology”
An intellectual technical quiz is one of the most exciting forms of work with students of children’s associations of technical interests, which helps to increase children’s cognitive interest in classes at the Center for Technological Education and Children’s Technical Creativity.
This form of extracurricular activities is intended for students of self-modeling, aircraft-modeling and ship-modeling associations MBUDO TSTOiDTT at the age of 10-14 years, however, it can also be carried out with younger children.
The game promotes the activation and development of students’ cognitive processes (perception, attention, memory, thinking, etc.).
This development can be useful for methodologists, educators-organizers, teachers, both additional education, and employees of educational institutions for extracurricular activities.
Purpose: popularization of children’s technical creativity, expansion of the polytechnic horizons.
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“Intellectual technical quiz” We and Technology “”
Municipal budgetary institution of additional education
“Center for Technological Education and Children’s Technical Creativity”
Belgorod
INTELLIGENT TECHNICAL QUIZ
“We and technology”
Prepared by: teacher-organizer,
Volokushin Vadim Mikhailovich
Belgorod 2018
Intellectual technical quiz “We and Technology”
Abstract: An intellectual technical quiz is one of the most exciting forms of work with students of children’s associations of technical interests, which helps to increase children’s cognitive interest in classes at the Center for Technological Education and Children’s Technical Creativity.
This form of extracurricular activities is intended for students of self-modeling, aircraft-modeling and ship-modeling associations MBUDO TSTOiDTT at the age of 10-14 years, however, it can also be carried out with younger children.
Best Way to Cut Corrugated Sheet Metal or Trapezoidal Roofing | Trumpf N 160 Li-ion Nibbler
The game promotes the activation and development of students’ cognitive processes (perception, attention, memory, thinking, etc.).
This development can be useful for methodologists, educators-organizers, teachers, both additional education, and employees of educational institutions for extracurricular activities.
Purpose: popularization of children’s technical creativity, expansion of the polytechnic horizons.
Equipment: PC, projector, multimedia presentation, award certificates.
Participants: presenter, 2 judges, students of MBUDO CTOiDTT, engaged in technical children’s associations at the age of 10-14 years.
Total duration: 45 minutes.
Organization of the quiz:
the attendance of teams is provided by teachers of additional education;
teams must come up with their team name, logo and uniform in advance.
General rules for the quiz:
1) Instructions are given on the rules of the quiz:
2) To participate in the quiz, teachers preliminarily form their teams of 5 people. 2-4 teams take part in the game.
3) Each team has a captain.
4) The quiz is a list of questions (22 questions). The moderator reads out the question, the teams are given 10 seconds to discuss it, after which, if the team is ready to give an answer, the captain raises his hand or raises a signal card.
5) Assessment of answers: for the correct answer, the team earns 10 points, if the answer is incorrect, then 0 points, and the right to answer is transferred to the other team. The team with the most points wins.
6) Judges evaluate the results, who register the correctness of the answers, as well as summarize the intermediate and final results.
7) At the end of the game, the jury calculates the results, determines and awards the winners.
Organizational moment: Music sounds, teams take seats, choose captains.
Greeting. The rules of the game are explained. Submitted by the jury.
Main part: Conducting a quiz using ICT. Quiz questions
What is the purpose of the pattern on the tires of car wheels?
B. For better traction (correct answer)
B. Protects the wheel rim from impact
Why does a racing car need wings?
A. For more speed
B. For a steady turn
B. In order to better press against the road (correct answer)
What is the role of the battery in the car?
A. For energy storage (correct answer)
B. For water supply
B. For oil reserve
Russian inventor of the world’s first steam engine?
A. Ivan Polzunov (correct answer)
B. brothers Cherepanov
A device that determines the number of revolutions of the engine?
B. Tachometer (correct answer)
Where the first electric tram line in Russia was built?
A. Kiev (1892) (correct answer)
Than instead of gasoline the very first car was refueled?
(Correct answer: By firewood)
What does the word car mean in Greek??
(Correct answer: Self-propelled)
What in Latin means “aviation”?
A. Bird (correct answer)
What kind of aircraft does not exist in terms of flight speed?
A. Gigozvukovykh (correct answer)
What military leader and inventor built an airplane in 1883 at his own expense?
A. Alexander Mozhaisky (correct answer)
B. Igor Sikorsky
V. Nikolay Teleshov
Who first invented a heavier-than-air aircraft?
A. Brothers Karamazov.
B. Wright Brothers (correct answer)
V. Tsiolkovsky Konstantin
What is the name of this aircraft?
A. Iron Zeppelin.
B. Fighter F-16 Falcon.
B. Aircraft Breguet-14. (correct answer)
What is the name of this aircraft?
A. Plasticine crow
B. Passenger aircraft “Tu-104”
B. F-117 “Stealth” (correct answer)
According to legend, the first aircraft was developed by the ancient Greek philosopher Archytus of Tarentum. What was it called?
B. Dove (correct answer)
What was the name of the first female pilot in the history of aviation?
A. Lydia Zvereva
V. Raymonda Desroches (correct answer)
The system of supports required for the takeoff run, landing run, as well as its movement and parking on the ground?
How to cut Steel straight or corrugated Iron straight. Roofing steel cutting procedure
(Correct answer: Chassis)
What is called the “calling card of the ship”?
(Correct answer: A ship’s boat. Its cleanliness and serviceability were once judged on the naval training of the crew.)
Where was the first shipbuilding center known in history on Earth?
A. about. Crete (in the mid-terrestrial sea. The remains of shipyards found there date back to the III millennium BC) (correct answer)
A vessel with two masts with straight sails?
B. Brig (a vessel with two masts with straight sails) (correct answer)
A vessel having at least two masts with oblique sails on all masts?
A. Schooner (correct answer)
British steamer of the White Star Line in 1912, the largest passenger liner in the world at the time of its construction. His maiden voyage was the last due to a collision with an iceberg?
(Correct answer: Titanic)
23.If the left gear turns in the direction of the arrow, which direction the right gear will turn?
In direction of arrow A.
In the direction of arrow B. (correct answer)
Which track must move faster for the tractor to turn in the direction indicated by the arrow??
Caterpillar B. (correct answer)
Which scissors are easier to cut an iron sheet?
Scissors V. (correct answer)
Which gear rotates faster?
Gear C. (correct answer)
Which picture correctly depicts a bomb falling from an airplane?
Picture A. (correct answer)
In picture B.
Picture C.
In which direction the bed was moved the last time?
In direction of arrow A.
Which gear rotates in the same direction as the pinion? Or maybe none of the gears rotates in this direction.?
Not one rotates. (correct answer)
In which direction will this car, moving in the direction of the arrow, be brought on a turn?
In any direction.
Towards B. (correct answer)
The final part: The jury sums up the results, the winners and prize-winners are announced, rewarding.
List of sources used
Gray I. Everything about everything: Great encyclopedia / I. Graeme, P. Steri. M.: OOO “Astrel Publishing House”, 2003.
New polytechnic dictionary / Otv. ed. A.Yu. Ishlinsky. M.: BRE, 2003.
Encyclopedia for children. T.14. Technique / Head. ed. M.D. Aksenov. M.: Avanta, 2003.
Pereosnastka.ru
Wood and metal processing
Scissors are used for both manual and machine cutting of metals. The angle of sharpening p at scissors ranges from 65 to 85 ° depending on the hardness of the metal being cut: for soft metals (copper, etc.) it is 65 °, for metals of medium hardness 70-75 °, for hard metals 80-85 °. To reduce the friction of the scissors knives when working on the blades, a clearance angle a equal to 1.5-3 ° is created. Scissors knives are made of U7 carbon steel; their cutting part is hardened.
Cutting with hand scissors. Manual metal shears are shown in fig. 1. The most common sizes of scissors are 250-320 mm (along the total length of the scissors).
The hand scissors are divided into right and left. On the right scissors, the bevel on the cutting part of each half is on the right side, and on the left scissors on the left side. When cutting the sheet with the right scissors, the risk on the cut metal is always visible. When working with left scissors, in order to see the risk, you have to bend the cut metal with your left hand, shifting it over your right hand, which is very inconvenient. Therefore, cutting the sheet metal in a straight line and in a curve (circle and rounding) without sharp turns is carried out with the right scissors.
Manual scissors can cut sheet steel up to 0.7 mm thick, roofing iron up to 1 mm thick, copper and brass sheets up to 1.5 mm thick.
When cutting metal, the scissors do not open completely, but only enough so that they can grab the sheet. When fully opened, the scissors do not cut, but eject the sheet. When cutting round discs with scissors, the discs are turned counterclockwise, while the scissors should not cover the mowing line of the cut.
Cutting with chair scissors. One of the halves of these scissors has a handle with a pointed end bent downward; with this end, the scissors are fixed in a wooden bar. The second half. with a straight handle. serves for hand operation.
The chair scissors are stable when cutting and give a lot of freedom to the hands of the worker. They cut sheets with a thickness of 2-3 mm.
Cutting with lever scissors. In fig. 3 shows lever hand-held shears, designed for cutting sheet metal, thin bars and shaped material, and lever hand-held shears, used for straight cuts of sheet metal up to 2 mm thick (for steel) into strips. One knife is installed on the table of the swing scissors, on the lever itself, the second. A balance weight is placed at the end of the arm.
The sheet metal is cut by one person using the fly shears. The sheet is laid on the table so that the cutting line (when cutting with markings) coincides with the blade of the lower knife. Pressing the sheet with the upper bar, the lever with the upper knife is lowered with a strong movement. Then the lever is “squeezed” until the required part of the sheet is cut.
When cutting without marking, the width of the strips is adjusted with a movable guide ruler.
Cutting with parallel scissors. These shears, sometimes called guillotine shears, are used to cut sheet metal (for steel) up to 4 mm thick or more. In parallel guides of the scissors, a slider with an upper knife obliquely attached to it walks up and down; the lower knife is fixed motionlessly in the bed. Raising and lowering the top-
its knives are carried out by a crank mechanism, receiving movement from the working shaft, which is driven into rotation by an electric motor through a transmission from the drive pulley.
Cutting with circular (round) shears. In fig. 5 shows circular (circular) shears used for cutting sheet metal with an unlimited cutting length, as well as for curved cutting. The cutting tool is knife discs, located one above the other and rotating in different directions when working. To cut straight strips, the knives-discs are placed in parallel; for cutting curved shapes (circles, holes), knives and their axes are positioned at an angle to each other. You do not need to feed the sheet into disks; rotating discs themselves tighten the sheet,