To, co chciałbym, aby wszyscy wiedzieli o oryginalnej metodzie cięcia — cięcie ręczne

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Manual cutting is to make sheet metal, profiles, bars through specialized shear equipment or tools to make it a straight line or curve along the predetermined separated. So it results in a variety of straight lines and curve shape (and sometimes can get in shape) billet machining methods. It is suitable for hardened steel, hard brittle materials (such as cast iron, ceramics, glass, hard alloy, etc.) of various materials.

Operation of Manual Cutting

Manual cutting including blanking, spare material, etc., almost all shapes of sheet parts can be completed by manual shearing. Manual cutting is flexible, convenient, almost without any restrictions.

Hand Cutting Tools

It includes straight cut, elbow cut, pneumatic direct cut and pneumatic punch cut (see the picture).

The straight cut is a hand cutting with a straight cutting edge. It is used for cutting sheet material with a straight-line outline. It can cut 1.5mm thick aluminum plate and 1mm thick steel plate. The cutting edge of the elbow cut, which is for the sheet material parts with the profile of the curve. It can shear a 2mm thick aluminum plate and 0.8mm thick steel plate. A portable pneumatic cut is a semi-mechanized hand shear tool, the cutting thickness of the division up to 2.5mm.

Operation Method of Manual Cutting

1. Operation method of manual cutting:  In general manual cutting sheet material, used to the right hand holding the scissors, the left hand holding material. The following picture shows the correct way to hold the scissors. The cutting handle should not expose the palm too long. Otherwise, it is inconvenient to apply force to the cutting handle. But the end can not be held in the palm of the hand, otherwise, it is not convenient to hold the scissors in the right hand. When the left-hand holds the material, it is fed in the direction of cutting. And the upper cutting edge is aligned with the cutting line, on a straight line, or on the tangent line of the curve.

When cutting, the cutting edge should be used to tightly press the material, and the cutting mouth should be at an angle with the material (to save effort), as shown in the picture.

At the beginning of the cutting, only 3/4 of the total length of the cutting edge should be opened on the two cutting edges. At the end of the first cutting, the cutting edge should not be completely closed, but 1/4 of the length of the cutting edge should be left. That is to say, each time the scissors open and close, the cutting edge is only 1/4 to 3/4 of its cutting edge contact with the sheet material, then each cutting, the cutting length of the sheet material should be about 1/2 of the length of the cutting edge. The picture shows each opening and ending position of the cutting edge.

When the cutting edge is closed, the pressure line is continuously cut, the cutting mouth should keep the gap 0~0.2mm, and the thin material should be a small value, take the maximum value of thick material, as shown in the picture.

2. Operation method of cutting line: It is shown in pictures (a) and (b) respectively. The directions of correct and false operation when cutting straight lines are given. And it’s called the right direction because in the cutting process Because right holds the body of the scissors with your right foot at A and your left hand at B. As the cutting deepens, the left hand should be lifted up, so as to give a helping hand to the tearing at the cutting edge gap, and to give the lower cutting room a capacity body place, because B board is small, it can easily lift up, so it is the right direction. However, in picture (b), due to the large area and weight at B, the material cannot be lifted during shear, so it is difficult to cut deeply, so it is in the wrong direction.

3. Operation method of cutting concave corners and angle materials:  If the cutting line on the sheet material is concave to the shape of the workpiece, that is, the so-called concave angle, should be drilled at the intersection of the concave cutting line stop hole or leave a certain distance not cut open. The purpose of drilling stop hole is to let the shear line on both sides of the cutting edge in the cutting end of the position of the cutting edge fall on the top hole, leaving a certain distance is not to cut on both sides of the cutting edge of the final cutting edge position in the workpiece, the purpose is not to leave the cutting edge mark at the intersection of the workpiece, so as not to produce stress concentration source. Generally, it is used to leave a certain distance at the intersection of the shear line, but after cutting, it is used to break off the joint by hand, and then use a file to repair the cutting requirements. For the truncation of diagonal parts, the angle root can be cut first, and then cut along the line with scissors, as shown in the picture.

4. Operation method of cutting curve:  When the cutting line is a curve, the direction of the cutting edge along the curve is so that the cutting edge does not cover the cutting line, so that the operator can keep the cutting edge on the control consistent with the tangent direction of the curve when cutting, as shown in the picture.

The method of cutting the inner hole is: first open a process hole in the sheet material, and then use the curved shear to gradually expand to the cutting line, cut the large inner hole, the better method is vibration shear cutting.

Common Defects of Cutting and Solutions

In the cutting operation of sheet metal, the operation faults or defects such as continuous cutting, size out of tolerance, discontinuous cutting line, cutting crack and burr often appear. The following is to analyze it and provide the corresponding solutions.

1. The sheet is cut constantly :  The main reasons for the continuous production of sheet cut are as follows:

• For the upper and lower blades, the gap is too large. This is because of the different blade clearance for different thickness of the sheet, too small a gap will lead to the upper and lower blade wear, increase the cutting force operation; Excessive gap will lead to sheet turning and cutting. At this point, the gap between the upper and lower edges should be adjusted appropriately. The picture shows the gap adjustment method. Picture (a) is the method to narrow the gap by striking the edge of the rivet head and applying pressure to the convex washer of the scissors to make part of the metal move downward so that the gap between the two cutting edges will be narrowed. Do not exert too much force during operation, and only two or three hammers around can achieve the effect. Picture (b) shows the method to enlarge the gap. A cutting edge and cutting handle are padded with fixed support (the closer it is to the rotating shaft, the better the effect is), and then another cutting mechanism is hit with a hammer(The closer the strike point is to the axis of rotation, the better.) If the convex washers have become flat washers (see picture c), then no matter how to hit any part of the rivet head, the gap can not be adjusted. At this time, the solution is to destroy the rivet, replace the rivet and the convex washers.

• The blade is too blunt, the solution is to sharpen the blade.

• The sheet material is too thick and beyond the range of manual cutting.

2. Cutting size is out of tolerance:  The main reason for the cutting size over tolerance is that the upper blade of the scissors is not aligned with the cutting line of the sheet material. When the cutting line is a straight line, the upper blade should be pressed to cut the straight line. When the cutting line is a curve, the cutting direction of the scissors should not cover the line shall prevail, and the blade presses the sheet material to maintain the same tangent direction as the line for cutting.

3. Discontinuous cutting line :  The reasons for the discontinuous cutting line are as follows:

• Due to the loosening between the scissors and the sheet material when the adjacent cutting is done before and after the cutting, this phenomenon can be avoided as long as the pressure line on the blade is continuously cut.

• The cutting edge becomes bent due to long-term use, forming convex or convex, the solution is to adjust the cutting edge straight or replace the scissors.

4. Cutting crack:  The main reasons for cutting crack defects are:

• In the concave corner of the workpiece is not drilled to stop the hole or because the cutting edge over the line and left the uncut cutting edge resulting in stress concentration source, due to a variety of reasons and expand into a variety of cracks. The only way is to drill to stop the hole or leave a margin as required.

• The upper and lower cutting edges are too small, so the cutting edges are all closed to bite the parts during cutting. The way to avoid this is to adjust the gap of the blade, do not close it completely when cutting, and leave 1/4 of the length of the blade for further cutting.

5. Many burrs: The main reasons for the burr are as follows:

• The upper and lower blade cutting gap is not suitable. The gap is too large or too small, which will produce larger burr.

• The cutting edge is too blunt. If the cutting edge is too blunt, it will produce too many burrs.

Precautions for Cutting operation

1. In the process of manual cutting of sheet material, the cutting surface where the two cutting edges are located must be kept perpendicular to the surface of the plate to be cut, so as to make the cutting edge in the most effective shear relative position; The cut surface is forbidden to incline to the plate surface, otherwise, it will lead to excessive burr of the workpiece cutting mouth, it is not perpendicular to the plate plane, or even the cutting or clamping of the workpiece between the rotation plane of the two scissors.

2. The cutting force exerted by the cutting edge on the workpiece. It should be continuous and smooth. So When cutting thicker plates, it is forbidden to hammer the back of the scissors in order to increase the cutting force. This is not only easy to damage the cutting edge but also due to impact cutting, the curve to be cut becomes a broken line, which affects the cutting quality. At this time, try to increase the length of the scissors handle to increase the cutting force on the workpiece, such as adding a sleeve of steel pipe.