PIPE SAW HAVING TORSIONAL VIBRATION DAMPING MEANS

Abstract

The invention relates to a sawing machine with a saw shaft (2) on which a saw blade (3) is mounted, characterised by torsional vibration damping with a damping mass (7) which is arranged next to the saw blade (3) on the saw shaft (2) and completely surrounds the saw shaft (2) in a cross-section, and the damping mass (7) is separated from the saw shaft (2) by a gap (11) and arranged with a clearance on the saw shaft (2), and the gap (11) between the damping mass (7) and the saw shaft (2) is filled with a fluid.

Claims

1. Sawing machine with a saw shaft (2) on which a saw blade (3) is mounted, characterised by torsional vibration damping with a damping mass (7) which is arranged next to the saw blade (3) on the saw shaft (2) and completely surrounds the saw shaft (2) in a cross-section, and the damping mass (7) is separated from the saw shaft (2) by a gap (11) and arranged with a clearance on the saw shaft (2), and the gap (11) between the damping mass (7) and the saw shaft (2) is filled with a fluid.

2. Sawing machine according to claim 1, characterised in that the damping mass (7) is arranged with a clearance of 0.01 mm?0.005 mm in each cross-sectional direction on the saw shaft (2).

3. Sawing machine according to claim 1, characterised in that the saw blade (3) is mounted on one end of the saw shaft (2) and a drive gear wheel (6), which is connected to the saw shaft (2) in a rotationally fixed manner, is arranged between the damping mass (7) and the saw blade (3).

4. Sawing machine according to claim 1, characterised in that a surface of the saw shaft (2) in a longitudinal portion in which the damping mass (7) is arranged is cylindrical and an inner wall of a bore of the damping mass (7) is also cylindrical.

5. Sawing machine according to claim 1, characterised in that the surface of the saw shaft (2) has a profile in a longitudinal section in which the damping mass (7) is arranged, and an inner wall of a bore of the damping mass (7) has a corresponding profile.

6. Sawing machine according to claim 5, characterised in that the profile is a meander profile and the corresponding profile is a corresponding meander profile.

7. Sawing machine according to claim 1, characterised in that the damping mass (7) has radial bores for filling the gap (11) with the fluid.

Description

[0014] The invention is described by means of two embodiment examples in four figures:

[0015] FIG. 1a longitudinal section of a part of a first embodiment of a damping mass of a sawing machine according to the invention

[0016] FIG. 2a graphical representation of the dependence of an angular velocity on time with and without damping

[0017] FIG. 3a cross-section of a second embodiment of a damping mass according to the invention

[0018] FIG. 4a cross-section of a second embodiment of the damping mass in operation

[0019] FIG. 1 shows a section of the sawing machine 1 according to the invention with a saw shaft 2, on one end of which a saw blade 3 of circular cross-section with a saw clamping cover 4 is mounted on a saw bearing 5. The saw shaft 2 is driven by a drive gear wheel 6 which is connected to the saw shaft 2 in a rotationally fixed manner. The drive of the drive gear wheel 6 itself is not shown. In addition to the drive gear wheel 6, a damping mass 7 is provided on the saw shaft 2. The damping mass 7 completely surrounds the saw shaft 2 along a section in cross-section. The drive gear wheel 6 is arranged between the damping mass 7 and the saw blade 3. A housing 8 runs between the drive gear wheel 6 and the saw bearing 5. The saw shaft 2 is mounted in a sliding bearing 9 in the housing 8.

[0020] There is a circumferential gap 11 between the damping mass 7 and the saw shaft 2, so that the damping mass 7 is arranged on the saw shaft 2 with a clearance that is 0.01 mm and +/?0.005 mm. The gap 11 is filled with a fluid. The fluid can be oil. For filling the gap 11, channels can be provided through the damping mass 7, which allow the gap 11 to be filled from the outside.

[0021] The gap 11 is annular in cross-section in the first embodiment shown in FIG. 1 perpendicular to a longitudinal direction L when the saw shaft 2 and damping mass 7 are positioned concentrically to each other. The gap 11 is formed along the entire extension in longitudinal direction L of the damping mass 7 surrounding the saw shaft 2. The damping mass 7 has a hollow cylindrical shape.

[0022] FIG. 1 shows the saw blade 3 cutting into a workpiece 12, for example a tube, which is to be cut to length.

[0023] FIG. 2 shows undamped oscillations of an angular velocity 13 and damped oscillations of an angular velocity 14 around a constant operating angular velocity ?0. The saw blade 2 has the operating angular velocity ?0 in operation. The torsional vibrations of the saw blade 3 are superimposed on the operating angular velocity ?0. The torsional vibrations are caused by the fact that tooth meshing and tooth exit alternate and the saw blade is thus periodically slowed down and accelerated slightly.

[0024] The damped oscillation of the angular velocity 14 in FIG. 2 shows the effect of the damping mass 7, which causes the amplitudes of the torsional oscillations to be significantly reduced compared to the undamped oscillation of the angular velocity 13. The damping mass 7 is arranged on the saw shaft 2 so that it can move in the circumferential direction. In FIG. 1 Newtonian friction between the damping mass 7 and the saw shaft 2 in accordance with

[00001]$F_r=A.Math.?.Math.\left(\mathrm{dv}:\mathrm{dy}\right)$

takes place when the angular velocity of the saw shaft 2 increases or decreases. Here A means the gap area, and n means the viscosity of the fluid, in this case the oil, and (dv:dy) means the change in velocity in the direction of rotation.

[0025] The inertia of the damping mass 7 leads to the fact that when the angular velocity ? of the saw shaft 2 decreases, the damping mass 7 runs forward and generates an additional force against the decreasing angular velocity ?, whereas in the case of increasing the angular velocity ? of the saw shaft 2 the exactly opposite effect occurs.

[0026] FIG. 3 shows in a cross-section a second embodiment of the gap 11 according to the invention between the damping mass 7 and the saw shaft 2. The gap 11 has a meandering shape in a cross-section. Whereas in the first embodiment there is Newtonian friction between the damping mass 7 and the saw shaft 2, in the case of the second embodiment the damping occurs because the damping mass 7, due to its inertia, runs behind the change in angular velocity and the torsional vibrations displace or suck the fluid out of sections of the gap 11. The cross-sectional shape in FIG. 3 is referred to here as a meander shape. Other cross-sectional shapes are also conceivable.

[0027] FIG. 4 shows the effect of the gap 11 in meander form in detail. The angular velocity ? of the saw shaft 2 is variable. The angular velocity ? decreases when a tooth enters and increases when a tooth exits the workpiece 12. The change in the angular velocity ? of the saw shaft 2 is ??.

[0028] If a slight change in angular velocity ?? occurs, in which case the saw blade 3 and thus the saw shaft 2 are slowed down slightly by a tooth entry, the damping mass 7 runs forward in the direction of rotation, in FIG. 4 counterclockwise, and shifts clockwise relative to the saw shaft 2. Gap enlargements 16 and gap reductions 17 are produced. The gap enlargements 16 exert a suction effect on the fluid, and the gap reductions 17 displace the fluid. This gives the saw shaft 2 a small additional propulsion and the torsional vibration is damped.

LIST OF REFERENCE SIGNS

[0029] 1 Sawing machine [0030] 2 Saw shaft [0031] 3 Saw blade [0032] 4 Saw clamping cover [0033] 5 Saw bearing [0034] 6 Drive gear wheel [0035] 7 Damping mass [0036] 8 Housing [0037] 9 Sliding bearing [0038] 12 Workpiece [0039] 13 Undamped oscillation of the angular velocity [0040] 14 Damped oscillation of the angular velocity [0041] 16 Gap enlargement [0042] 17 Gap reduction [0043] L Longitudinal direction [0044] ? Angular velocity [0045] ?0 Operating angular velocity [0046] ?? Change in angular velocity