DE3040829A1 - METHOD FOR DAMPING THE VIBRATIONS OF AN EXTENSIVE, BENDABLE TOOL, AND A MACHINE PROVIDED WITH A TOOL VIBRATION DAMPING DEVICE - Google Patents

Description

Registration number.

^Aklenz - ^: IJ & JjSoZ Zl κö lν, the 29 ο 10 ο 1980

please specify he / ka

Note ₀ : Amada Company, Limited

200, Ishida, Isehara-shi, Kanagawa-ken (Japan)

Title: Method for damping the vibrations of an elongated, flexible tool and with a tool vibration damping device equipped machine

The invention relates to a method for damping the vibrations of an elongated, flexible tool and a machine tool, in particular a band saw machine comprising an elongated, flexible band saw blade, which revolves around several Sägebandrollen _β More specifically, the invention provides methods and devices has for an object with which vibrations and Noises from an elongated, flexible tool, such as a band saw blade, can be avoided when operating machine tools, especially band saw machines.

Since the present invention has been made with the aim of improving band saw machines, general problems arise explained using the example of band saw machines, although the present invention is not applied to band saw machines is limited, but can also be used in other machine tools.

As is known, a band saw machine with a flexible, endless saw belt and a plurality of, usually provided two Sägebandrollen or wheels to which rotates the saw blade "The rollers for the saw band are substantially mutually parallel axes rotatably supported ₉ wherein one of the driven Sägebandrollen and the saw band by rubbing

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bungsSchluß with one of its flat sides drives _β In order to properly tension the saw band, one of the saw band rollers with its axis or shaft is pressed in the radial direction from the other saw band roller or pulled away from it. One of the strands of the saw band is slidably guided between the saw band rollers and is held by two guide devices in such a way that its flat sides are perpendicular to the workpieces to be joined so that it can be used as a cutting strand during the cutting operations a main saw or saw unit, which can be lowered onto the workpieces when cutting so that the saw band can cut into the workpieces. In the case of vertical band sawing machines, the saw band rollers leading the saw band are at a vertical distance from each other and keep the cutting side of the saw band so vertical that the workpieces to be cut can be pushed horizontally against the saw band »

One of the most surprising problems with the known band saw machines consists in the fact that the saw band starts to vibrate and the vibration causes it to pierce and screech Generates noise when it performs the cutting operations. That piercing and screeching sound of the The saw band is of course very damaging to the hearing and is also harmful to the health of the operators of the band saw machines. In addition, this noise can be the starting point for considerable noise pollution, especially since band saw machines are also widespread in small factories and workshops that are not located in industrial areas »

The vibration of the saw band that causes the piercing and screeching noise is primarily due to that the saw band, due to its flexibility when cutting, not only laterally, but also in the direction of its flange or vertical natural vibrations »This one first

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resulting vibration of the saw band has a tendency to enlarge or rock due to the fact that a greater tensile stress in the part of the band of the saw band through which the workpieces to be cut have been cut prevails than in the part that is only about to cut into the workpieces because the saw band is driven and is pulled by the driving saw band roll under high tension. Although this is undesirable Vibration of the saw band is reduced by the saw band guides, which slide the saw band, lie the Things so that the vibration is too strong to be reduced to a desirable extent by just the saw band guides To be able to do this, undesirably, the saw band still vibrates considerably while it rotates around the saw band rollers.

What is even worse is that the vibration of the saw band not only creates a piercing, screeching noise, but also has a bad influence on the sonic accuracy and speed of the saw band and its service life, and also lets the sonic oil spray around. For example, the vibration of the saw band leads to one rough cut surface with a material to be cut workpiece and has the result that the first part of the cutting gap is wider "than the later resultant normal cutting width Therefore, a precisely straight cut could not be achieved _o Since the saw blade come into swimming and can extend decreases the cutting speed drops very far and the saw blade also has a tendency to wear out uselessly without making a cut. Furthermore, since the vibrating saw band sprays the cutting oil into a mist, this lubricant is lost from the band saw machine without being recovered, it stains the operators and the surroundings of the band saw machine, _etc.

Although the foregoing has various known problems only have been explained using the example of band saw machines

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Of course, other machine tools also have more or less the same difficulties caused by vibrations and noises that are to be overcome, _etc.

In band saw machines, another fundamental problem is that the saw band on the saw band rollers slips when it runs over the saw band rollers while cutting When cutting, the band saw blade is always flooded with cutting oil or runs through a bath of lubricating fluid and that this is the case Lubricant is carried from the saw band onto the peripheral surfaces of the saw band rollers and between the saw band and these peripheral surfaces of the saw band rollers form a lubricant film. The end of the saw band on the saw band rollers leads to the fact that the saw band is more or less damaged because it slips against the workpiece to be cut is advanced without cutting, Even if the slippage of the saw band to some extent by increasing the tension of the saw band between the saw band rollers can be overcome, but too high a tension has premature wear or Breakage of the band saw blade «,

The object of the invention is to create a method and a device with which the vibrations and noises of a elongated, flexible tool in machine tools, such as a saw band in a band saw machine, can be avoided or reduced and with which it is possible at the same time, the tendency to slip between tool and machine »

This object is achieved with the invention in that the formation of a standing wave or interference wave is prevented from a superposition of a traveling wave with a reflected wave of a longitudinal wave oscillation arises, which is the main cause of the noise development during the operation of conveyor belts

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Sawing machines and other machine tools was recognized. According to the invention, the formation of a standing wave from a longitudinal wave oscillation is prevented by periodic destruction of the reflected wave by _{periodically changing the length or the tension of the elongated, flexible tool, such as a saw band 9} between its support elements, such as saw band rollers during operation of which the elongate tool is held.

This invention has the advantage that by changing the length and tension of the elongate tool, such as a saw band, the noise and vibrations when operating machine tools, such as Band saw machines, avoided or reduced to a minimum ο

Another advantage is that the machining accuracy, the working speed and the service life of the tool of the machine tool increase and that the tool, in particular the saw band on a band saw machine on which saw band reels no longer slipped

Further features and advantages of the invention emerge from the following description and the drawings, in which a preferred embodiment of the invention using an example is explained in more detail «It shows:

Figo 1 is the front view of a horizontal band saw machine, in which the principles of the present Invention can be realized,

Fig. 2a,

2b and 2c diagrams ₉ which show the changes in the development of noise at different speeds of the saw band in a horizontal band saw machine,

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Fig. 3a

and FIG. 3b is a graph showing the changes in noise development with changes in distance or in the distance between the guide means for the saw band in a horizontal band saw machine represent,

FIG. 4 shows the front view of a band saw roll for a band saw machine shown in FIG. 1, at which embodies the principles of the present invention,

Fig. 5, the Sägebandrolle of FIG _e 4 in an end view and

Fig. 6 is a schematic diagram showing the changes in the length of a band saw blade while a sawing operation in a band saw machine, having a Sägebandrolle of the type shown in Figure 4 and 5 _{o β}

In Fig. 1, a horizontal band saw is shown, which is designated in its entirety with 1 “However, it is to point out already here i: that the invention does not apply to the use in this special type of a band saw machine limited, but can be used with every known type of band saw machine and other machine tools is, e.g. in rope cutting machines for sawing stone blocks or the like

The horizontal band saw machine 1 consists of an elongated, box-like machine bed 3 on which a workpiece table 5 and a clamping device 7 for holding a workpiece W to be cut are mounted, and of a saw unit or main saw 9, which has two housing parts 11 and 13 arranged at a distance from one another and relative to the machine bed 3 movable up and down is the _e

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Main saw 5 can with the help of a pivot pin 15 on the machine bed 3 pivotally mounted and designed so that it can be with a suitable lifting device, for example a hydraulic motor 17 in the form of a hydraulic lifting cylinder, lifted from the machine bed 3 and swiveled down again onto this In the main saw 5 a flexible, endless saw band 19 runs around a driving saw band roller 21 and a revolving saw band roller 23 to, which with spaced apart, parallel shafts 25 and 27 in the Housing parts 11 and 13 are rotatably mounted «. The driving saw band roll 21 together with its shaft 25 has a Power drive and transmits the rotational movement to the saw band 19. The traveling saw band roller 23 is by a suitable tensioning device pulled or pushed away from the driving saw band roll 21 to the saw band 19 appropriately to tension »In the cutting zone of the horizontal band saw machine 1, the saw band 19 is supported by two saw band guides 29 and 31 with vertically downwardly directed cutting edge held or guided so that the cutting edge Trum is located between guides 29 and 31. The saw band guides 29 and 31, the gewöhnliii so designed are that they supply the saw band 19 with cutting oil are releasably attached to the lower ends of support arms 33 and 35 or consist of one piece with these, which are carried by a support 37 in the upper part of the saw head 9 is attached. Furthermore, at least one of the support arms 33 and 35 can be adjusted along the carrier 37 to the distance between the saw band guides 29 and 31 adjust the cross-sectional length of the cut to be made in the workpiece W. When the saw head 9 around the tenon 15 is pivoted down from its raised position, ii * d around the driving saw band roller 21 and the driven one Saw band roll 23 in the main saw band rotating saw band 19 advanced against the workpiece W to be cut, which in the clamping device 7 is clamped on the workpiece table 5 «

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The above-described horizontal band saw machine 1 has hitherto had the disadvantage that the saw band 19 vibrates and as a result of these vibrations produce a very piercing and screeching noise · In addition, tended it slips on the saw band rollers 21 and 23 when cutting. The vibration that makes the noise of the band saw blade 19 has a tendency to increase or multiply because of the tensile stress in the one between the workpiece ¥ and the drive band saw roller 21 lying strand of the band saw 19 is larger than in the part of the saw band strand located between the workpiece ¥ and the accompanying band saw roll 23. Although the saw band guides 29 and 31 contribute to a reduction in the vibration of the saw band 19, the vibration was too great to be completely eliminated only by the saw blade guides. The saw band 19 therefore vibrated considerably and produced the piercing and screeching sound.

However, it has not yet been recognized that the piercing and screeching sound is from the vibration of the saw band 19 arises during the cutting process in band saw machines ·. The inventor therefore first made various experiments to analyze the frequency of the vibration and the noise of the saw band 19 and in particular with regard to to investigate the type of vibration wave that caused the piercing and screeching noise. In these experiments, the inventor sawed a rod made of stainless steel (Japanese Industrial Standard (JIS) s SUS 300) of 200 mm in diameter with a constant cutting speed and a feed pressure of 13 kg / cm with a horizontal band saw (model HA-404 from Amada Co «, Ltd») and a saw band (GLB-3M from the same company).

In order to first find out the changes in noise as a function of the saw blade speed, the inventor made Cutting test with a distance between the saw band guides of approximately 200 mm and with different saw band

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overall speeds of 30 m / min., 40 m / min, and 60 m / min. The tests showed that the noise changes with the frequency changes shown in the graphs in FIGS. 2a, 2b, and 2c. It can be seen that the basic values at saw band speeds of 30 m / min. 1,400 Hz, at 40 m / min _e 1,425 Hz and at 60 m / min. 1,425 Hz were, as shown in FIGS _o 2a, 2b and 2c. As a result, the tests showed that the frequency of 1,400 Hz as the fundamental oscillation is not so closely related to the speed of the saw band. As a result, the results of the experiments seem to indicate that natural oscillation of the saw band and the machine frame or body of the horizontal band saw machine has an influence on the noise ",

In order to find out the changes in noise as a function of the changes in the distance between the saw band guides, the inventor made experiments with cuts at a saw band speed of 30 m / min «, whereby the distance between the saw band guides was alternately set to 200 mm and 300 mm the frequency of 1,400 Hz assumed as the fundamental did not change whether the distance between the guides is now was set to 200 mm or 300 mm, as can be seen from the graphs of Figs. 3a and 3b. From the experiments in this way, it was found that the noise is mainly due to the longitudinal wave harmonic of the saw band of the horizontal band saw machine

As a result of parts of the horizontal sawing machine made in wrought iron for experimental purposes found that the body or machine frame of the horizontal band saw machine including the saw head and The saw band guides show no signs of resonance with the saw band Saw band together with the driving and following sawing

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tape rolls form an independent vibration system while the frame of the horizontal band saw represents a different, independent vibration system,

As explained above, it was found from the experiments that the noise in the horizontal band saw machine mainly originates from the longitudinal wave oscillation, which is independent of the machine frame of the horizontal band saw machine «, This test result is through the mathematical calculation of the natural oscillation of the horizontal band saw, which was used in the experiments became"

The differential equation of a longitudinal wave of a flexible part is as follows:

where: C = *

ρ a density
E = modulus of elasticity

With regard to the saw band, equation (1) can be transformed as follows:

ί ¹ J ^ e - - ^E

where: u = deflection of the "saw band

t »time

χ »Coordinates

A »Cross-sectional area of the saw band

Ij «mass moment of inertia of the moving Saw band roll

r = radius of the driving and the moving saw band rollers

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When a longitudinal vibration wave on a saw band occurs in the band saw machine, the boundary conditions between the saw band and the driving and driven ones Band saw roll expressed as follows:

- ^E.

-E A r ² ^ (χ - O)

where: I _K - mass moment of inertia of
antßibenden saw band roll

However, the above equations are insufficient to solve equation (1), and the mass moments of inertia I _K and Ij of the driving and following saw band rollers are very large. Assuming that both ends of the strands of the saw band stretched between the saw band rollers are fixed, the following equations can be obtained:

ua 0 if χ »L
(2)

u »0 if χ» 0

Equation (1) is then transformed as follows:

'uQ · Χ
(3) QA sin yt + B cos vt

X-C sin jx + D cos ^ Tx

where: y «natural vibrations frad / f-

LsJ

A, B, C, D s constants

By substituting the equations (2) into the equations (3), the natural vibrations can be expressed as follows;

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When using equation (4), the natural vibrations of the saw band in the SKgeversuohen can be obtained as follows will:

SOT ρΣΣΰξΣ ^ ΓΙ _27Γη . 1,891.2 ^

»Η · 1,891.2 Hz (η - 1, 2, 3, 4

where: L - 1,358 mm »135.8 cm

E »2.1 · 1 <Λ kg / mm ² - 2.1 · 10 ⁹ g / cm ²

f - 7.8 g / cm

g »s

cm

^ T

This result of the above equation is approximately equal to the fundamental oscillation of 1,400 Hz, from which it can be concluded that the attempts are sensible "

In general, longitudinal wave oscillation occurring in an elongated flexible member attached at both ends will progressively travel along or be transmitted along that elongated part to its attached end and then be reflected at that attached end and return as the reflected wave. In such a propagation of the longitudinal wave oscillation, the advancing wave and the reflected wave are out of phase with each other by half an oscillation, and the advancing wave and the reflected wave combine with each other to form a standing wave that generates the sound. It can also be seen that the standing wave of the longitudinal wave oscillation is prevented from being generated by periodic disturbance of the reflected wave _e

According to the invention, the standing wave is the longitudinal wave oscillation of an elongated, flexible part, such as a saw band, prevented from arising by periodic disturbance of the reflected wave,

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that the length or the tension of the elongate, flexible element is changed periodically.

4 and 5, a saw band roller 21 and 23 is shown, in the horizontal band saw machine shown in FIG. 1 as a driving shaft 21 and / or a rotating shaft 23 can be mounted so that the saw band 19 revolves around these rollers. The saw band roll shown in FIGS 21 or 23 is provided on its circumference with grooves 39 to the length or the tension of the saw band 19 during to change a cutting process. The grooves 39 are parallel on the circumferential surface of the saw band roll 21 and 23, respectively molded to the shafts 25 and 27 of the saw band rollers at suitable intervals, so that the length or tension of the saw band changes periodically and the reflected wave of the longitudinal wave oscillation is disturbed. Instead of Grooves 39 can of course also have elongated projections or webs on the circumference of the saw band roll 21 or 23 this molded in one piece or on the circumference of the saw band roll be attached to change the length or tension of the saw band when the saw band roll 21 or 23 turns "

If one of the two saw band rollers 21 and 23 is provided with grooves 39, the length L of the saw band 19 changes between the saw band rollers 21 and 23 periodically between

PP
L + w and L - -κ , as shown in FIG. 6. More specifically, this means that the stretch of the saw band 19 stretched between the driving saw band roller 21 and the following saw band roller 23 is periodically changed in length between L + | · and L - ^, as shown in FIG. since the end of the saw band strand, which rests on the saw band roll 21 or 23, changed its position between the two edges of each groove 39

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In this context, it should be pointed out that the grooves 39 or the elongated webs or strips arranged on the circumference of the saw band roll 21 or 23 serve not only to prevent the vibration and the generation of noise, as described above, but also the object have the saw blade 19 or on a slip on the Sägebandrolle 21 ", 23 to prevent the cutting operation * can be seen that the saw blade 19 is prevented from slipping because the or to the circumferential surface of the Sägebandrolle 21 _o 23 from the saw blade 19 applied cutting oil is pressed into the grooves 39 and cannot form a coherent film between the saw band 19 and the peripheral surface of the saw band roll 21 or 23 Slippage is prevented because the pressure exerted on the saw band 19 to tension the saw band when cutting is localized on the webs or projections is sated.

In order to avoid the generation of noise from the saw band 19, the standing wave of the longitudinal wave oscillation ar their emergence can be prevented by periodically changing the tension, the modulus of elasticity or the specific Weight or the density of the saw band 19 changed wind. The length and tension of the saw band 19 can also thereby be changed periodically that either the driving saw band roller 21 or the following saw band roller 23 through suitable means, such as a hydraulic motor, on top of one another be moved towards and away from each other to prevent a standing wave from being created. “Besides, it is possible to change the tension of the saw band 19 by a tensioning roller between the driving saw band roller 21 and the entrained saw band roll 23 is arranged and periodically pressed against the band saw blade 19 wire.

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Although the invention has only been explained using the example of a horizontal band saw machine and a saw band, the person skilled in the art will recognize that the invention can also be used with other machine tools that work with an elongated, flexible tool and where it is important, the occurrence of vibrations and prevent noise. This is the case, for example, with grinding machines with a revolving grinding belt or with rope cutting machines in which stone blocks are cut with a revolving wire rope _{or the like}

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Claims (2)

Patent claims: 1.) Method for damping the vibrations of an elongated, flexible tool of machine tools, in particular the rotating saw band or the like. one Band saw machine, characterized in that the length and / or the tension of the tool is periodic is changed. 2. Machine tool, especially band saw machine, with an elongated, flexible, around at least two rollers or the like. around three tools, especially one Saw band, characterized in that at least one of the rollers (21 or «23) with transverse to the circumferential direction extending grooves, webs (39) or the like. provided is ο 3ο machine according to claim 2, characterized in that the grooves (39) or webs run parallel to the roller axis Machine according to claim 2 or 3, characterized in that the grooves (39) or webs are equidistant (P) from one another to have. 130021/0765 Aa 260 - Ji - 3rd Machine according to claim 2 or 3 »characterized in that the grooves (39) or webs have different spacings have from each other «, 6 «, machine according to the preamble of claim 2, thereby characterized in that the tool, in particular the saw band (19), has a periodically changing over its length Has modulus of elasticity " 7β machine according to the preamble of claim 2, characterized characterized in that the tool, in particular the saw band (19) # has a periodically changing over its length Has strength » 8 "Machine according to the preamble of claim 2, characterized characterized in that at least one of the rollers (21, 23) runs in the direction of travel of the tool, in particular of the saw band (19), is mounted so that it can be moved back and forth and is provided with a periodically effective tensioning drive, which the rollers (21, 23) periodically move towards one another and moved away from each other " 9β machine according to claim 8, characterized in that the tensioning drive is a hydraulic motor, in particular a hydraulic push piston cylinder. 10, machine according to the preamble of claim 2, characterized characterized in that next to the tool, in particular next to the saw band (19), between the rollers (21 and 23) at least one tensioning roller is arranged, which is mounted displaceably transversely to the tool and by a Adjusting drive is pressed periodically against the tool (19) «, 1§002ΐ / 07οΊ