Carbide saw

However, attempts to cut ferrous material with carbide tips failed because the existing saws lacked the speed, rigidity, and innovation required to transfer high force with low vibration.

Also, the existing tooth geometry with positive cutting angles caused cracking of the carbide tips which were harder and consequently, more brittle than the high-speed steel (HSS) circular blades.

However, HSS blades use coolant and the cut surfaces don't get hot, thus called cold saws.

Between 1963 and 1969, professor Pahlitzsch and engineers Arno Willemeit and Horst Doepcke at the University of Braunschweig, developed new carbide tip geometry with a negative cutting angle and a pair of teeth which split the chip into three parts.

The machine was sold on the global market under the name Metalcut 12 and was exhibited at trade shows in Milan, Italy, and Chicago.

Chamberlain Manufacturing Corporation, contracted by Frankford Arsenal ([2]), has conducted an evaluation of the Goellner carbide billet saw.

Proclaimed advantages included faster cutting speeds, long blade life and improved quality of cutoff interfaces.

From 1972 to 1976 for his dissertation, Horst Doepcke, a scientific assistant at the Institute for Machine Tools and Manufacturing Engineering at the University of Braunschweig, developed a specific carbide cutting geometry for tubes which had every tooth splitting each chip into two.

In 1984, Speedcut Inc. of Rockford, Illinois developed another type of carbide tooth geometry by the name of, "Notch Grind".

In 1969, the first horizontal carbide billet saw was developed by AME and built for Metalcut Inc. For the first time, Hennig telescopic steel way covers and steel aprons were used to protect the vital components of the saw from high velocity flying chips that are difficult to control.

In 1974, the first carbide saw with a vertical slide was developed by Arno Willemeit, the co-inventor of the Braunschweig tooth geometry.

Framag, an Austrian company later took over the production of this type of machine and also built it as a layer saw.

In 1973, Metalcut developed the first high-efficiency carbide pivot saw for 75 mm (3 inches) bars, where the center of rotation of the gearbox was mounted to the floor plate.

The pivot is located above the machine bed and the saw blade enters vertically in an arch-shaped manner into the material, but does not have a closed force loop.

In 2011, AME of Rockford, IL, developed a high-efficiency carbide saw where the pivot axis of the gearbox is fixed on the lower end of the machine bed, for cutting 350 mm (14 inch) billets.

In 1973, Metalcut developed the first carbide rail saw which was later produced by other companies including Wagner.

In 1999, AME built a special model of a carbide saw for miter-cutting railroad rails for frogs and switches.

In 2008, AME developed a carbide hot saw which cuts off the ends on hot-forged axles for the railroad industry.

Carbide saws with ways (horizontal, vertical or tilted slide-arrangement) consist of a welded base made of solid steel plates which are sufficiently ribbed and often filled with vibration dampening material.

The feed system consists of either a hydraulic cylinder or a ball screw and gear reducer, which is powered by a servo motor.

The saw blade must be firmly mounted to the driveshaft in order to transmit the massive amount of torque without vibration.

From this experience a blade stabilizer was developed using two plastic coated ball bearings mounted on eccentric shafts and supported by a welded bracket to the gearbox.

Horst Doepcke, who saw this method during experiments carried out by Metalcut, also describes them in his dissertation “Sägen von Rohren mit hartmetallbestückten Kreissägeblättern”.

This stop can be accurately positioned by a ball screw servo mechanism and usually incorporates a shock absorber to dampen the impact.

This large amount of lost motion added to the torsional windup of the gear train, when a tooth enters the cut and relaxes when it exits, induces torsional vibration and must be reduced to a minimum by using anti-backlash mechanisms or by grinding the gear sets to an absolute minimum play.

The fluctuation of the load, when the tooth enters and exits the cut, induces vibrations and requires a very stiff gear box and machine.

Furthermore, the ball screw drive which forces the blade into the cut is bolted to the fixture frame which again is clamped to the billet and gives this arrangement additional rigidity.

Saws with horizontal or tilted slides have an open loop force flow (fig.2) and maintain any lost motion and compliance of the feed system.

The closed loop system reduces compliance and hence can be built lighter, while maintaining a high amount of stiffness.