Cutting – With randomly actuated stopping means – Responsive to tool detector or work-feed-means detector
Reexamination Certificate
2000-01-28
2001-12-18
Rachuba, M. (Department: 3724)
Cutting
With randomly actuated stopping means
Responsive to tool detector or work-feed-means detector
C083S076000, C083S074000
Reexamination Certificate
active
06330848
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a circular saw cutting machine and particularly relates to a circuit saw cutting machine for preventing chatter vibration generated by cutting a metallic work material.
BACKGROUND ART
A circular saw cutting machine of this type reduces the rotation of an electric motor through a pulley and a gear mechanism provided in a gear box and transmits the reduced rotation to a main shaft, has a circular saw attached to one end of the main shaft which end protrudes from the gear box, rotates the main shaft at a low speed with a high torque and thereby cuts a metallic work material. Since the circular saw cutting machine uses gears in a rotation transmission section as stated above, the backlash of gears occurs. Due to this, at the start region and end region of cutting a work material for every cutting operation with the circular saw, with the number of cutting related teeth Zi being in a range of 0 to 1.0, when the saw tooth is bit into and pulled out of the work material, the rotational variation corresponding to the backlash of the gears occurs. Also, with the number of cutting related teeth Zi being high, a regenerated chatter which is a self-excited vibration in the feed direction of a main body of the machine accompanied by the rotational variation of the gears often occurs. The rotational variation of the gears causes chatter vibration in the circular saw and deteriorates cutting accuracy. At the same time, the damage, failure and the like of a tip shortens the service life of the circular saw. Further, vibration and noise deteriorate working environment.
In a circular saw cutting device designed to prevent such rotational variation of the gears, as shown in, for example, Japanese Utility Model Examined Application Publication No. 62-28334, pressing pieces are provided on both sides of the circular saw, one of the pieces actuating a hydraulic cylinder to thereby apply a frictional force before the start of cutting operation. Thus, cutting operation is started while eliminating the backlash of a power system and the frictional force is removed by a timer during the operation. According to another circular saw cutting device, as shown in Japanese Utility Model Examined Application Publication No. 7-48339, a control shaft is directly coupled to a main shaft, to which a circular saw is attached, through a gear and a braking device is provided at the control shaft. According to this circular saw cutting device, from the start to the end of cutting operation by means of the circular saw, the backlash of the gears of a drive system is suppressed while a braking force is electrically controlled by a solenoid proportional valve, thereby eliminating the chatter vibration of the circular saw during the cutting operation.
The above-stated circular saw cutting device is, however, designed to apply a braking force to the driving system at the start and end of the cutting operation to thereby forcedly eliminate the backlash of the gears and to perform the cutting operation while reducing cutting power. Owing to this, the mechanical structure is complicated and an electric control structure is required, with the result that the machine disadvantageously becomes expensive and the maintenance of the machine requires more labor.
The present invention has been made to solve the above disadvantages. It is, therefore, an object of the present invention to provide a circular saw cutting machine capable of eliminating the chatter vibration of a circular saw during cutting operation to thereby enhance cutting accuracy, prolonging the service life of the circular saw and suppressing the occurrence of noise at low cost.
DISCLOSURE OF THE INVENTION
To obtain the above object, the characteristic in constitution of the first invention lies in a circular saw cutting machine for transmitting the rotation of an electric motor to a main shaft and for cutting a work material by using a circular saw attached to one end of the main shaft, characterized in that if an outside diameter of the circular saw is D (mm), the number of revolution is N (rpm) and a cutting force per tooth as a component of force in tangential direction is F (kgf), a moment of inertia I (kgf·m·sec
2
) of the main shaft is set at I≧F×(D/2)/[1000×250×(N/60)
2
].
Further, the characteristic in constitution of the second invention lies in a circular saw cutting machine for transmitting the rotation of an electric motor to a main shaft and for cutting a work material by using a circular saw attached to one end of the main shaft, characterized in that a flywheel is attached either directly to the shaft or to a shaft extended from the main shaft; and if an outside diameter of the circular saw is D (mm), the number of revolution is N (rpm) and a cutting force per tooth as a component of force in tangential direction is F (kgf), a moment of inertia I (kgf·m·sec
2
) of the overall main shaft including said flywheel is set at I≧F×(D/2)/[1000×250×(N/60)
2
].
Further, the characteristic in constitution of the third invention lies in a circular saw cutting machine for transmitting the rotation of an electric motor to a main shaft and for cutting a work material by using a circular saw attached to one end of the main shaft, characterized in that if an outside diameter of the circular saw is D (mm), the number of revolution is N (rpm) and a cutting force per tooth as a component of force in tangential direction is F (kgf), a sum J of moments of inertia (kgf·m·sec
2
) of main shaft conversion of respective shafts including the main shaft, the respective shafts cooperated with one another in a state in which a backlash is eliminated from the main shaft is set at J≧F×(D/2)/[1000×250×(N/60)
2
].
According to the first, second and third inventions constituted as stated above, power for rotating the main shaft is reduced by power transmission means (a reduction mechanism), such as a V-shaped belt, and transmitted from the pulley of the output shaft of the electric motor to the pulley of the main shaft to which the circular saw is attached. As for the main shaft-side pulley, by using a pulley of a large mass or by attaching a flywheel of a large mass concentric with the pulley, the moment of inertia I (kgf·m·sec
2
) of the main shaft can be made higher than F×(D/2)/[1000×250×(N/60)
2
]. The flywheel can be attached either directly to the main shaft or to the extended main shaft.
Further, not only the moment of inertia of the main shaft but also the sum J of the moments of inertia of main shaft conversion of the respective shafts including the main shaft cooperated with one another through the reduction mechanism in a state in which no backlash occurs between the main shaft and gears in a drive system may be set to be higher than F×(D/2)/[1000×250×(N/60)
2
]. Further, the smaller sum J of either the sum of the moments of inertia of the main shaft in the drive system or the sum of the moments of inertia of main shaft conversion of the respective shafts including the main shaft cooperated with one another through the acceleration/reduction mechanisms in a state in which no backlash occurs between the main shaft and the gears in the driven system may be set higher than F×(D/2)/[1000×250×(N/60)
2
].
As stated above, by setting the moment of inertia of the main shaft or the sum of the moments of inertia of main shaft conversion high, it is possible to suppress rotational variation in a region in which the number of cutting related teeth Zi at the initial cut positions arid the final cut positions of the work material is not more than 1.0, by using the circular saw cutting machine in which rotational variation tends to occur. Namely, by setting either the moment of inertia I of the main shaft or the sum J of the moments of inertia of main shaft conversion to be higher than F×(D/2)/[1000×250×(N/60)
2
] where F is a cutting f
Nishio Satoru
Ohno Kunio
Kanefusa Kabushiki Kaisha
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Rachuba M.
Tran Kim Ngoc
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