Tubular saw using torsional vibration damping

Abstract

The present invention relates to a sawing machine with a saw shaft (2) on which a saw blade (3) is mounted, which provides torsional vibration damping using a vibration damper (7), characterized in that the vibration damper (7) is arranged on the saw shaft (2) beside the saw blade (3) and completely surrounds the saw shaft (2) in cross section, the vibration damper (7) is separated from the saw shaft (2) by a gap (11) and is arranged with clearance on the saw shaft (2), and the gap (11) between the vibration damper (7) and the saw shaft (2) is filled with a fluid.

Description

Technical Field

[0007]

[0001] The present invention relates to a sawing machine with a saw shaft on which a saw blade is mounted.

Background Art

[0002] Sawing machines are known in the prior art. For example, a pipe sawing machine capable of cutting a section of a pipe into a certain length is known from German Patent Invention No. 102004053732. Pipe sawing machines are often part of an integrated sawing plant, which not only cuts the pipe into a certain length, but also washes, chamfers, or otherwise processes the pipe.

[0003] High-precision requirements for pipe sections cut to a certain length and the service life of the saw blade are still problematic. For example, metal pipes should be cut to a certain length with an accuracy of 0.01 mm, and this accuracy should be maintained with a probability of 99.99%.

[0004] Torsional vibrations have been found to be a particular problem, which is caused by the fact that the load acting on the saw blade is not constant but is subject to periodic variations due to the entry and exit of the saw teeth into the pipe material. This results in undesirable torsional vibrations being introduced into the saw shaft and the saw blade.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] Therefore, an object of the present invention is to provide a sawing machine that reduces the above-mentioned disadvantages.

[0007] The objective is satisfied by the sawing machine described, beginning with the features of claim 1. The sawing machine according to the present invention has a saw shaft on which a saw blade is mounted. According to the present invention, in torsional vibration damping, a damping body is provided positioned on the saw shaft next to the saw blade, completely enclosing the saw shaft in cross-section, the damping body being separated from the saw shaft by a gap and having clearance on the saw shaft, the gap between the damping body and the saw shaft being filled with fluid.

[0008] The damping element preferably extends completely around the saw shaft, along the section of the saw shaft within each cross-section. The damping element is preferably installed on the saw shaft with clearance in each cross-sectional direction. Preferably, the clearance has the same numerical size, with the gap having a width of 0.01 mm ± 0.005 mm. However, other numerical ranges are also possible.

[0009] Since the damping element is fitted on the sawtooth shaft with clearance, and the gap is preferably filled with a viscous fluid, the damping element produces a damping effect on the sawtooth shaft; that is, the damping element counteracts changes in the angular velocity of the sawtooth shaft. If the angular velocity of the sawtooth shaft increases slightly, the damping element follows the change slightly, and the fluid brakes the sawtooth shaft. Conversely, when the angular velocity of the sawtooth shaft decreases, the advancing damping element accelerates the sawtooth shaft.

[0010] Preferably, the saw blade is mounted on one end of the saw shaft, and a drive gear, which is fixed to the saw shaft so as to be rotatable along the saw shaft and connected to the saw shaft, is positioned between the vibration damper and the saw blade.

[0011] The saw shaft, and consequently the saw blade, is driven via a drive gear. The saw blade is used to cut profiles to a certain length, or similar materials, preferably metal pipes, or metal profiles.

[0012] In a favorable embodiment of the present invention, the surface of the sawshaft is cylindrical along the longitudinal section where the damping body is arranged, and the inner wall of the bore of the damping body is also cylindrical. This means that the outer wall of the sawshaft and the inner wall of the damping body are formed as two cylinders arranged concentrically toward each other. The gap is formed by a circumferential ring that can be filled with fluid. The damping effect in this case is produced by Newtonian friction. The damping body is preferably fully rotatable around the sawshaft.

[0013] However, gaps with other cross-sectional shapes are also possible. Preferably, the surface of the sawshaft has a profile in the longitudinal section where the damper is placed, and the inner wall of the bore of the damper has a corresponding profile. For example, the profile may be a meandering profile, and the corresponding profile may be a corresponding meandering profile. As a result, the damper is not rotatably positioned on the sawshaft but still has play in each direction. In this case, the damping effect is less influenced by Newtonian friction and is strongly influenced by the fact that the fluid placed in the gap flows back and forth between the tooth surfaces of the meandering profile, resulting in an attractive or pressure effect on the teeth of the sawshaft that acts in opposition to the change in the angular velocity of the sawshaft.

[0014] Advantageously, the damper has a radial bore for filling the gap with fluid. The bore can be closed from the outside.

[0015] The present invention will be illustrated with two examples of embodiments shown in four figures. [Brief explanation of the drawing]

[0016] [Figure 1] This is a longitudinal section of a portion of the first embodiment of the vibration damping body for a sawing machine according to the present invention. [Figure 2] This is a graphical representation of the temporal dependence of angular velocity with and without damping. [Figure 3] This is a cross-section of a second embodiment of the vibration damping body according to the present invention. [Figure 4] This is a cross-section of a second embodiment of the vibration damping body in operation. [Modes for carrying out the invention]

[0017] Figure 1 shows a cross-section of a sawing machine 1 according to the present invention, with a saw shaft 2. A circular cross-section saw blade 3, with a saw clamping cover 4, is mounted on a saw bearing 5 at one end of the saw shaft 2. The saw shaft 2 is driven by a drive gear 6 that is rotatably fixed and connected to the saw shaft 2. The drive mechanism of the drive gear 6 itself is not shown. In addition to the drive gear 6, a vibration damper 7 is provided on the saw shaft 2. The vibration damper 7 completely encloses the saw shaft 2 along a section in the cross-section. The drive gear 6 is positioned between the vibration damper 7 and the saw blade 3. The housing 8 is located between the drive gear 6 and the saw bearing 5. The saw shaft 2 is mounted on a sliding bearing 9 within the housing 8.

[0018] A circumferential gap 11 exists between the vibration damper 7 and the sawtooth shaft 2, and as a result, the vibration damper 7 is positioned on the sawtooth shaft 2 with a clearance of 0.01 mm ± 0.005 mm. The gap 11 is filled with a fluid, which may be oil. To fill the gap 11, a channel can be provided that passes through the vibration damper 7, allowing the gap 11 to be filled from the outside.

[0019] The gap 11 is an annular cross-section perpendicular to the vertical direction L in the first embodiment shown in Figure 1, when the saw shaft 2 and the damping body 7 are positioned concentrically with respect to each other. The gap 11 is formed along the entire length of the damping body 7 in the vertical direction L that surrounds the saw shaft 2. The damping body 7 has a hollow cylindrical shape.

[0020] Figure 1 shows the state in which the saw blade 3 cuts the workpiece 12 to a certain length, for example, into a pipe.

[0021] Figure 2 shows the undamped vibration of angular velocity 13 and the damped vibration of angular velocity 14 per a certain operating angular velocity ω0. The saw blade 2 has the operating angular velocity ω0 during operation. The torsional vibration of the saw blade 3 overlaps with the operating angular velocity ω0. The torsional vibration is caused by the fact that the tooth profile meshes and the tooth profile exits are arranged alternately, resulting in the saw blade decelerating periodically and accelerating slightly.

[0022] The damped vibration of angular velocity 14 in Figure 2 shows the effect of the vibration damping body 7. Compared with the undamped vibration of angular velocity 13, the amplitude of the torsional vibration will be significantly reduced. The vibration damping body 7 is arranged on the saw shaft 2 so that it can move in the circumferential direction. In Figure 1, the Newton frictional force between the vibration damping body 7 and the saw shaft 2 is obtained by the following formula: Fr = Aη(dv:dy) It occurs when the angular velocity of the saw shaft 2 increases or decreases. Here, A means the gap area, η means the viscosity of the fluid, in this case, oil, and (dv:dy) means the change in the speed in the rotational direction. [[ID=IO]]

[0023] Due to the inertia of the vibration damping body 7, when the angular velocity ω of the saw shaft 2 decreases, the vibration damping body 7 moves forward and generates an additional force against the decreasing angular velocity ω. On the other hand, when the angular velocity ω of the saw shaft 2 increases, the opposite effect occurs.

[0024] Figure 3 shows a second embodiment of the gap 11 according to the present invention between the vibration damping body 7 and the saw shaft 2 in cross section. The gap 11 has a meandering cross section. In the first embodiment, there is a Newton frictional force between the vibration damping body 7 and the saw shaft 2. However, in the case of the second embodiment, since the vibration damping body 7 generates attenuation due to its inertia, it lags behind the change in angular velocity, and due to the torsional vibration, the fluid is displaced or sucked out from the section of the gap 11. The cross-sectional shape in Figure 3 is called a meandering shape here. Also, other cross-sectional shapes are conceivable.

[0025] Figure 4 shows in detail the effect of the gap 11 in a meandering configuration. The angular velocity ω of the saw shaft 2 is variable. The angular velocity ω decreases when the teeth enter the workpiece 12 and increases when the teeth exit the workpiece 12. The change in the angular velocity ω of the saw shaft 2 is Δω.

[0026] A slight change in angular velocity Δω occurs, and in this case, when the saw blade 3, and consequently the saw shaft 2, decelerates slightly due to the tooth's entry, the vibration damping body 7 moves forward in the rotational direction, counterclockwise in Figure 4, and shifts clockwise relative to the saw shaft 2. Gap expansion 16 and gap contraction 17 occur. Gap expansion 16 exerts an attractive effect on the fluid, and gap contraction 17 causes the fluid to displace. This generates a small additional thrust force on the saw shaft 2, and the torsional vibration is damped. [Explanation of Symbols]

[0027] 1 saw blade 2 saw shafts 3 saw blades 4. Saw clamp cover 5 saw-tooth bearings 6 Drive gear wheel 7. Vibration damper 8 Housing 9 Plain bearings 12 Processed products 13 Undamped oscillations of angular velocity 14 Damped Oscillations of Angular Velocity 16. Gap widens 17. Gap narrowing L (vertical direction) ω angular velocity ω0 Operating angular velocity Δω Change in angular velocity

Claims

1. A sawing machine having a saw shaft (2) on which a saw blade (3) is mounted, wherein torsional vibration damping is performed using a vibration damping body (7), wherein the vibration damping body (7) is arranged on the saw shaft (2) and is provided to surround the outer circumference in a direction perpendicular to the longitudinal axis of the saw shaft (2), the vibration damping body (7) is separated from the saw shaft (2) by a gap (11) and is arranged on the saw shaft (2) with a clearance, the gap (11) between the vibration damping body (7) and the saw shaft (2) is filled with fluid, the saw blade (3) is mounted on one end of the saw shaft (2), and a drive gear (6) that is rotatably fixed and connected to the saw shaft (2) is arranged between the vibration damping body (7) and the saw blade (3).

2. The sawing machine according to claim 1, characterized in that the vibration damping body (7) is arranged on the saw shaft (2) with a clearance of 0.01 mm ± 0.005 mm in each cross-sectional direction.

3. The sawing machine according to claim 1, characterized in that the surface of the saw shaft (2) in the vertical section where the vibration damping body (7) is arranged is cylindrical, and the inner wall of the bore of the vibration damping body (7) is also cylindrical.

4. The sawing machine according to claim 1, characterized in that the surface of the saw shaft (2) has a profile in the vertical portion where the vibration damping body (7) is arranged, and the inner wall of the bore of the vibration damping body (7) has a corresponding profile.

5. The sawing machine according to claim 4, characterized in that the profile is a meandering profile and the corresponding profile is a corresponding meandering profile.

6. The sawing machine according to claim 1, characterized in that the vibration damping body (7) has a radial bore for filling the gap (11) with the fluid.

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