Band-saw

The band saw was first patented in England in 1808. After 26 years, a patent in France was obtained for a saw of the same design by a man named Etienne, and after another 2 years - by B. Baker in the USA.

However, band saws became widespread only at the end of the 19th century. The reason for this delay was that manufacturers could not achieve the exact connection of the ends of the band saw.

The best band saws in those days were made in France, which retained its leadership in the production of this product to this day ^[1] .

Band saws come in three types:

• gear saws
• toothless friction saws
• electric spark saws

Band saws with teeth differ in length from hacksaw blades and are usually made closed. In appearance, they are similar to hacksaw. Saws with teeth are widely used, for example, on band saws for wood or metal. They are also used for cutting meat, fish, mineral wool, foam concrete and many others. Wood band saws are used on band sawmills .

Friction band saws work on the same principle as circular friction saws. They also have teeth, but the purpose of these teeth, as in circular saws of friction, is somewhat different. The presence of teeth enhances the heat generation during the friction process, therefore, increases the performance of the saw. Friction band saws are usually made from 6 to 25 mm wide and from 0.6 to 1.6 mm thick.

Electrospark band saws work on the same principle as circular spark saws. They are used when cutting workpieces with a thickness exceeding 150 mm which cannot be cut with circular saws of electric spark action due to their significant runout due to the large diameter and pitch. Electrospark band saws provide free cutting of workpieces with a diameter of up to 300-400 mm.

There are carbon steel blades (mainly used for cutting wood), bimetallic blades and blades with carbide teeth (soldered to carbide teeth).

The most common bimetallic canvas. For cutting metals, the edges of the teeth teeth should be solid and the blade flexible, therefore the blades are bimetallic (of two metals). The basis is a strip of metal made of hard spring steel (due to this, the fabric is flexible), a wire of high-speed tool steel is welded to it by electron beam welding (due to this, the workpiece is cut), then the teeth are milled.

The manufacture of saws for specific machines includes cutting in size and welding into a ring with a welded joint. Welding of band saws is carried out on flash butt welding equipment. After stripping on a stripping machine, the seam is almost invisible, an endless band saw with teeth is obtained.

There are both universal sheets of wide application and special sheets recommended for specific types of steel. The scope of the blade is determined by the pitch of the teeth (their size), the hardness of the teeth, the geometry of the teeth, wiring.

1. The larger the workpiece, the larger the teeth should be on the selected saw. Large-sized solid metal is cut with large teeth. To reduce resonance phenomena and increase the range of cutting lengths with one saw, a variable tooth pitch is used (teeth of different sizes on one blade).

2. The hardness of the teeth. Usually, a cloth with the designation M42 is commonly used everywhere (hardness of the edge of the teeth according to Vickers is 950 units). For cutting tool steel, a blade with increased hardness of teeth M71 (maximum hardness of the edge of the teeth, according to Vickers 1000 units) or M51 is recommended.

3. Tooth geometry: tooth profile and sharpening angle. For example, for cutting pipes and profile materials (corner, channel and other designs), vibrations and impacts are characteristic, leading to chipping of the teeth of ordinary canvases, therefore a blade with reinforced tooth backs is recommended. For cutting stainless steel, characterized by viscosity (viscous material, viscous shavings), a blade with a sharp sharpening angle of 15% and a large interdental space is recommended.

4. Tooth setting: for cutting large sizes of solid metal, a blade is recommended with alternating wide and narrow set of teeth in order to avoid pinching effect.

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