EP2072183A1 - Surface grinding machine - Google Patents

Abstract

The machine (1) has a grinding plate (2) driven by an eccentric pin (21) that is aligned eccentrically to a drive shaft (16), where the drive shaft is connected with a drive motor (12). A leveling compound (31) is arranged on the eccentric pin or the drive shaft. The leveling compound is fastened to the eccentric pin or drive shaft in a drive direction of the eccentric pin about 60 degree to 90 degree opposite to an eccentricity (e) of the eccentric pin with respect to the drive shaft in an offset manner.

Description

The invention relates to a surface grinding machine with an oscillating drivable grinding plate, which is driven via an eccentric aligned with a drive shaft connected to a drive shaft eccentric and wherein on the eccentric and / or the drive shaft a balancing mass is arranged.

Such implements are known in a very large number of different configurations, which are offered under the names oscillating, eccentric, delta or multi-sander. By engaging in the grinding plate eccentric pin which is driven in different ways, in this case the grinding plate is placed in an oscillating motion, are caused by the particular in idle vibrations. In order to compensate for the imbalance caused by the eccentric, a compensating mass is often provided on the eccentric pin, which is arranged offset by 180 ° to the eccentricity of the eccentric pin. By this measure, the vibrations caused by the mass imbalance are damped.

In order nevertheless to prevent unavoidable vibrations on the handles of such surface grinding machines, which arise during grinding, largely, it is by the DE 10 2006 034 078 A1 known to connect the handle via a vibration decoupling element, which has an inherent elasticity and is to be flexible bending, with the housing of the grinding machine. The additional Construction cost for vibration damping is thus significant, but a relief for the operator of the grinding machine in their operation is not achieved.

From the WO 2007/000074 A1 an anti-vibration device for a surface grinder is shown. In the introduction to this document, the vibration problems occurring are addressed in detail and already explained various constructive solutions. Such vibrations of grinding machines have therefore long been known and it is trying to compensate for such vibrations by a variety of measures. From the WO 2007/000074 A1 can be seen that two grinding wheels are provided, which are stored in each other. The inner grinding wheel is thereby arranged eccentrically to the outer grinding wheel, so that the two grinding wheels produce grinding forces which are offset in their direction to each other.

A disadvantage of the surface grinding machine according to the WO 2007/000074 A1 It has been found that the two discs work in their grinding force by 180 ° against each other and thus although the vibrations occurring due to the contact force are mutually balanced, but this arrangement of the grinding wheels can cause considerable damage to the workpiece to be ground, as between the two grinding wheels an air gap is to be provided. The grinding wheels therefore do not form a uniform grinding surface, which can cause damage, for example, when placing the two grinding wheels on the surface of the workpiece, because the grinding wheels have two mutually projecting edges on those that can cause damage in a careless operation of the hand tool.

Furthermore, the structural design of this hand tool is extremely complicated and costly, because the two grinding wheels must be stored staggered. The abrasive paper to be attached to the grinding wheel must also be changed simultaneously on both grinding wheels. The grinding machine according to this prior art has a considerable weight. For all that, that the handling of the grinding machine after the WO 2007/000074 A1 difficult and awkward.

It is therefore an object of the invention to improve the surface grinding machines of the aforementioned type in such a way that without additional construction effort an effective damping caused by the grinding force vibrations during the operation is almost automatically accomplished without undermining the grinding result to be achieved with the grinding machine is.

The damping should be reduced in this case depending on the contact pressure of the grinding plate, so that the optimum contact pressure with the help of the attenuation by the operator to easily determine and thus an optimal work result can be achieved by means of the achievable damping of the grinding machine.

According to the invention, this is achieved in a surface grinding machine of the type mentioned above in that the balancing mass is offset in the drive direction of the eccentric pin by about 90 ° relative to the eccentricity of the eccentric pin with respect to the drive shaft on this or the drive shaft.

According to another embodiment, it is also possible to fix the balancing mass in the drive direction of the eccentric pin by more than 90 ° and less than 180 ° relative to the eccentricity of the eccentric pin with respect to the drive shaft offset on this or the drive shaft.

It is particularly advantageous if the center of gravity of the balancing mass is rotatable about the axis of rotation of the drive shaft and / or spaced linearly movable and if the balancing mass on the drive shaft or on the eccentric pin in an adjustable angular position and / or at a predeterminable distance from the axis of rotation can be locked, because this allows each user individually arrange the balancing mass such that through this for the corresponding operation with the necessary contact pressure Vibration damping is achieved. Due to these adjustment possibilities, the vibration of the grinding wheel can be damped to almost zero.

A particularly advantageous structural attachment of the balancing mass can be achieved if the balancing mass is arranged in the immediate vicinity of the grinding plate, preferably between this and the drive shaft or in a recess provided in the grinding plate on the eccentric pin.

It is also expedient to select the size of the leveling compound in such a way that, given a contact pressure acting on the grinding plate, the vibrations of the surface grinding machine are completely or nearly equalized.

If a surface grinding machine according to the invention is formed, in which the compensating mass is offset relative to the eccentricity of the eccentric pin by about 90 ° on the eccentric pin or the drive shaft, it is easily possible to control the vibrations occurring during operations and this for optimal use of the device. The balancing mass in fact leads the eccentric in the drive direction, so that the force component which is caused by the frictional force between the grinding plate and the workpiece to be machined is compensated and the surface grinding machine is subjected to only slight oscillations as a function of the contact pressure. In contrast to the known embodiments, in which especially the resulting idle vibrations are damped, thus the unwanted vibrations are compensated, resulting from the contact of the grinding plate with the workpiece to be machined. The operator of the surface grinding machine can be displayed here or this feels this when the grinding plate is pressed with the optimum force, since in this operating state, the lowest vibrations occur.

An additional construction effort to achieve this significant improvement in the performance of the surface grinding machine, is not required, only the leveling compound is compared to the previous installation position by 90 ° offset. It is also advantageous that the damage occurring, for example, on bearings and fatigue fractures of housing parts, be significantly reduced by reducing the vibrations, especially during operations. Also, the health damage that can occur due to the vibrations acting on the hands and arms of the operator largely diminishes. And since the energy supplied to the grinding plate is almost completely utilized and is no longer dissipated in part via unwanted vibrations, the grinding efficiency is also improved. With the same power can therefore be built according to the proposal trained surface grinding machine smaller than a device of conventional design. With a measure that requires no additional construction costs, the functionality of surface grinding machines are thus changed in a manner favorable to the operator.

When the balancing mass is arranged in a frame and when the frame is pivotally supported on the drive shaft or the eccentric pin, the center of gravity of the balancing mass relative to the eccentricity of the eccentric pin with respect to the drive shaft in an angular range of 60 ° to 180 ° about the axis of rotation of Drive shaft moves and locked in this angular range, so that the user can easily arrange the balancing mass in a predetermined angular position and conveniently spaced from the axis of rotation, in which this has the optimal damping characteristic for the respective operation.

In order to adjust the distance between the balancing mass and the axis of rotation of the drive shaft, it is advantageous if the balancing weight is held in a frame by means supported in the frame spindle and if by turning the spindle, the distance of the center of gravity with respect to the axis of rotation of Drive shaft can be changed.

Figur 1a

ein erstes Ausführungsbeispiel einer Flächenschleifmaschine zur Betätigung einer Schleifscheibe mit versetzter an einem Exzenterzapfen angebrachter Ausgleichsmasse, die benachbart zu der Schleifscheibe angeordnet ist teilweise im Schnitt und in schematischer Darstellung, in einer ersten Schleifposition,

Figur 1 b

die Flächenschleifmaschine nach Figur 1a in einer zweiten Schleifposition,

Figur 2a

einen Schnitt nach der Line IIa - IIa in der Figur 1a,

Figur 2b

einen Schnitt nach der Linie IIb - IIb in der Figur 1b,

Figur 3

ein zweites Ausführungsbeispiel einer Flächenschleifmaschine zur Betätigung einer Schleifscheibe mit versetzter an einem Exzenterzapfen der Flächenschleifmaschine angebrachter Ausgleichsmasse, die in der Schleifebene einer Schleifscheibe verläuft, im Schnitt,

Figur 4

in einem Diagramm die Gegenüberstellung der bei der Flächenschleifmaschine nach Figur 1a auftretenden Schwingungen in Abhängigkeit von der jeweiligen Anpresskraft zu dem Schwingungsverlauf bei einem herkömmlichen Schleifgerät,

Figur 5

ein drittes Ausführungsbeispiel einer Flächenschleifmaschine zur Betätigung einer Schleifscheibe mit einem versetzten Exzenterzapfen und mit einer Antriebswelle, an der eine Ausgleichsmasse angebracht ist, im Schnitt,

Figur 6

ein viertes Ausführungsbeispiel einer Flächenschleifmaschine zur Betätigung einer Schleifscheibe mit einer wahlweise linear ausrichtbaren und an einem Exzenterzapfen drehbar angebrachten Ausgleichsmasse, in Draufsicht, und

Figur 7

in einem Diagramm die Gegenüberstellung der bei der Flächenschleifmaschine nach Figur 6 auftretenden Schwingungen in Abhängigkeit von der jeweiligen Anpresskraft zu dem Schwingungsverlauf bei einem herkömmlichen Schleifgerät.

In the drawing, four embodiments of a surface grinding machine according to the invention are shown, which are explained in more detail below. Hereby shows:

FIG. 1a

a first embodiment of a surface grinding machine for operating a grinding wheel with offset on an eccentric pin mounted balancing mass, which is arranged adjacent to the grinding wheel is partially in section and in a schematic representation, in a first grinding position,

Figure 1 b

the surface grinder after FIG. 1a in a second grinding position,

FIG. 2a

a section after the line IIa - IIa in the FIG. 1a .

FIG. 2b

a section along the line IIb - IIb in the FIG. 1b .

FIG. 3

A second embodiment of a surface grinding machine for operating a grinding wheel with offset on an eccentric pin of the surface grinder attached balancing mass, which runs in the grinding plane of a grinding wheel, in section,

FIG. 4

in a diagram the comparison of the surface grinding machine FIG. 1a occurring vibrations as a function of the respective contact force to the vibration profile in a conventional grinding device,

FIG. 5

A third embodiment of a surface grinding machine for operating a grinding wheel with a staggered eccentric and with a drive shaft, on which a balancing weight is mounted, in section,

FIG. 6

A fourth embodiment of a surface grinding machine for actuating a grinding wheel with an optionally linearly alignable and rotatably mounted on an eccentric pin balancing mass, in plan view, and

FIG. 7

in a diagram the comparison of the surface grinding machine FIG. 6 occurring vibrations as a function of the respective contact force to the waveform in a conventional grinder.

The in the FIGS. 1a and 1b illustrated and designated 1 surface grinding machine is used for machining workpieces by grinding with the aid of an oscillating drivable sanding plate 2, to which 4 staples sandpaper 3 is attached. The grinding plate 2 is in this case driven by a motor 12 used in a housing 11 only partially shown, the output shaft 13 is connected via bevel gears 14 and 15 with a supported by means of bearings 17 in the housing 11 drive shaft 16 is drivingly connected.

The drive shaft 16 accordingly has an axis of rotation 18, which is subsequently used as a reference point for the attachment and alignment of a balancing mass 31.

The drive shaft 16, which can be driven in different ways, is provided with an attached eccentric pin 21, which is rotatably mounted via rolling bearings 22 in a recess 5 incorporated in the grinding plate 2. Furthermore, the balancing mass 31 is arranged on the eccentric pin 21 in order to compensate for the oscillations caused by the oscillating movements of the sanding plate 2. Upon rotation of the drive shaft 16, 21 oscillations a are triggered namely by the offset with respect to this with an eccentricity e oscillations, according to FIG. 4 depending on the force exerted on the grinding plate 2 Pressing force P in a conventional grinder according to the dashed line curve I increase.

In order to reduce the vibrations acting on the operator and to keep it as low as possible, especially in grinding operations, the balancing mass 31 is offset in the drive direction D of the eccentric pin 21 by exactly 90 ° relative to the eccentricity e. The centrifugal force F of the balancing mass 31 thus acts, as shown in the FIGS. 2a and 2 B is drawn by an arrow, parallel to the grinding force S in the direction of movement S of the grinding plate 2, so that in the idle range, although higher vibrations than manual devices without the balancing mass 31 arise because the centrifugal force F of the balancing mass 31 increases the vibration of the disc in idle mode. In the in FIG. 4 drawn working area A, in which the grinding plate 2 is pressed against the workpiece to be machined with the contact pressure P, the vibration load for the operator but, as can be seen from the curve II, reduced to a considerable extent, since the centrifugal force F of the balancing mass 31st now counteracts those force components that are responsible for the vibration. These force components are composed of the grinding force F running in the direction of movement D and the contact pressure P applied by the operator. This resultant R is in the FIGS. 2a and 2 B drawn and engages in the axis of rotation 18 formed by the drive shaft 16 and extends substantially in the plane formed by the grinding wheel 2. The centrifugal force F generated by the balancing mass 31 should be of the same magnitude as the resulting element R. The direction of the centrifugal force F should be rotated by 180 ° in the direction of the resultant R, so that the force component R of the centrifugal force F in the direction and is fully compensated in the amount. This then leads in the operating state of the surface grinding machine 1 to a vibration-reduced application that is produced with a single grinding wheel 2, so that no transition regions of the existing grinding surface of the grinding wheel 2 are necessary and also ensures extremely easy interchangeability of the sandpaper 4 and the handling of the surface grinding machine 1 is.

In the embodiment according to FIG. 3 the leveling compound 31 is inserted directly into the grinding plate 2. For this purpose, a recess 23 is incorporated in this, in which the balance mass 31 rotates. By a latched lid 24, the recess 22 is closed. The centrifugal force F of the balancing mass 31 thus acts directly on the grinding plate 2 without any major overturning moments occurring.

The FIGS. 1a . 1b . 2a and 2 B is common that the balancing mass 31 has a center of mass MS. This center of gravity MS represents in a mechanically known manner a reference point in which the centrifugal forces F, which arise during the rotation of the balancing mass 31, attack. In the embodiment shown the Figures 1a - 2b Therefore, the point of application of the centrifugal force F in the center of gravity MS is offset by 90 ° to a center axis 20. The center axis 20 is the axis of the center of the axis of rotation 18 and the center of an eccentric axis 19 which in the FIGS. 1a and 2a shown position, take. The angle a 1 of FIG. 2b refers to any rotational position of the balancing mass 31 relative to the starting position after the FIGS. 2a and 2 B ,

Out FIG. 5 It can be seen that the balancing mass 31 is attached directly to the drive shaft 16. The mode of action is identical to that in the FIGS. 1a to 3 explained operation of the surface grinding machine shown there 1. By this arrangement of the balancing mass 31, the height of the surface grinding machine 1 can be reduced, because now the length of the eccentric pin 21 can be reduced.

In the FIGS. 6 and 7 It is now shown which adjustment a user of the surface grinding machine 1 has when the balancing mass 31 can be adjusted both in its angular position and with respect to the distance to the axis of rotation 18 of the drive shaft 16. FIG. 6 shows the structural design of the attachment of the balancing mass 31 on the eccentric pin 21; optionally, the balancing mass 31 may also be attached directly to the drive shaft 16.

Accordingly, if the centrifugal force F, which acts on the center of mass MS of the balancing mass 31, in the in the FIGS. 1a to 3 shown angular position, that is aligned parallel to the grinding force S, which are in the FIG. 4 shown vibration damping in idle and in the operation of the surface grinding machine 1 a.

These adjustable to the individual needs of the user of the surface grinder 1 settings options are the FIG. 6 refer to. In this case, the balancing mass 31 is supported in a frame 32 by means of a spindle 33. Due to the fact that the balancing mass 31 and thus its center of gravity MS can be moved by turning the spindle 33 in the direction of the axis of rotation 18 of the drive shaft 16 or away from it, the centrifugal force F is influenced. Namely, when the balancing mass 31 is moved in the direction of the axis of rotation 18, the distance and thus the amount of centrifugal force F decreases and when the balancing mass 31 is moved away from the axis of rotation 18, the centrifugal force F increases, because the distance that the balancing mass 31st or whose center of mass MS occupies the axis of rotation 18 increases. This centrifugal force F is defined by the physical formula F = mw ² r. The angular or rotational speed W is quadratic and the distance or radius r and the weight of the balancing mass 31 are linear in the calculation.

In the illustrated basic position, the centrifugal force F is offset by 60 ° to the eccentricity e of the eccentric pin 21. The frame 32 is held by means of a screw 36 on the eccentric pin 21 pivotally. By loosening the screw 36 namely the contact pressure of the frame 32 is reduced in the circumferential direction on the eccentric pin 21, so that the frame 32 and thus the balancing mass 31 relative to the eccentric pin 21 or when the frame 32 is attached to the drive shaft 16 relative to this, twisted. Thus, the balancing mass 31 in its angular position be changed over the eccentricity e. The angular position of the balancing mass 31 with respect to its center of mass MS therefore extends in a freely selectable angular range between preferably 60 ° to 180 °. At the same time, the linear distance between the axis of rotation 18 and the center of gravity MS of the balancing mass 31 can be adjusted by turning the spindle 33, whereby the balancing mass 31 is movable radially and radially from the axis of rotation 18 and the eccentric axis 19 and selectively fixed.

In order to visualize the corresponding optimal settings for each user, a scale 35 is provided both on the drive shaft 16 or the eccentric pin 21 and on the frame 32. The scale associated with the drive shaft 16 indicates an angular range within which the balancing mass 31 can be aligned together with the frame 32 about the axis of rotation 18 of the drive shaft 16. In the embodiment shown by FIG. 6 the balancing mass 31 is deflected at an angle of 60 ° with respect to the direction of rotation D to the central point axis 20 formed by the centers of the axis of rotation 18 and the center axis of the eccentric pin 21. The deflection of the balancing mass 31 can therefore be set in any position as a function of the force to be applied and the constitution of the user of the surface grinding machine 1.

The provided on the frame 32 scale 35 is in linear relationship with the distance, the center of gravity MS of the balancing mass 31 based on the axis of rotation 18 of the drive shaft 16 occupies.

FIG. 7 the course of the vibration damping can be taken. The curve III shows the surface grinder 1 in that operating point when the adjustable balancing mass 31 extends as close as possible to the axis of rotation 18. The optimum operating point A III is thus achieved at low contact pressure P. The curve IV shows the surface grinder 1 at that operating point A when the adjustable balancing mass 31 as far as possible away from the axis of rotation 18 is arranged. The optimum operating point A-IV is thus achieved at high contact pressure P.

Claims (9)

Surface grinding machine (1) with an oscillating drivable grinding plate (2) which can be driven via an excentric pin (21) aligned eccentrically with respect to a drive shaft (16) connected to a drive motor (12) and wherein on the eccentric pin (21) or the drive shaft (16) a balancing mass (31) is arranged,
characterized,
in that the compensating mass (31) in the drive direction (D) of the eccentric pin (21) is offset by 60 ° to 90 ° with respect to the eccentricity (e) of the eccentric pin (21) with respect to the drive shaft (16) on this or the drive shaft (16). is attached. Surface grinding machine (1) with an oscillating drivable grinding plate (2) which can be driven via an excentric pin (21) aligned eccentrically with respect to a drive shaft (16) connected to a drive motor (12) and wherein on the eccentric pin (21) or the drive shaft (16) a balancing mass (31) is arranged,
characterized,
that the balancing mass (31) in the drive direction (D) of the eccentric pin (21) offset by more than 90 ° and less than 180 ° relative to the eccentricity (e) of the eccentric pin (21) with respect to the drive shaft (16) on this or the Drive shaft (16) is fixed. Surface grinding machine (1) with an oscillatingly drivable S chleifplatte (2), via an eccentric to a drive motor (12) connected to the drive shaft (16) aligned eccentric pin (21) drivable and wherein on the eccentric pin (21) or the drive shaft (16 ) a balancing mass (31) is arranged, which has a center of mass (MS),
characterized,
that the center of mass (MS) of the balancing mass (31) about the rotational axis (18) of the drive shaft (16) rotatable and / or is spaced radially movable by the latter and that the balancing mass (31) on the drive shaft (16) or on the eccentric pin ( 21) can be locked in an adjustable angular position and / or at a predeterminable distance from the axis of rotation (18). Surface grinding machine according to one of the claims 1, 2 or 3,
characterized,
in that the balancing mass (31) is arranged in the immediate vicinity of the sanding plate (2), preferably between it and the drive shaft (16). Surface grinding machine according to claim 1, 2 or 3,
characterized,
in that the compensating mass (31) is arranged on the eccentric pin (21) in a recess (23) provided in the grinding plate (2). Surface grinding machine according to claims 1 to 4,
characterized,
that the size and / or the specific weight and / or the position of the balancing mass (31) is selected such that at a predetermined contact pressure (P) acting on the sanding plate (2), the vibrations (a) of the surface grinding machine (1) are completely or partially offset are almost balanced. Surface grinding machine according to claim 3,
characterized,
that the center of mass (MS) of the balancing mass (31) in the driving direction (D) opposite to the eccentricity (e) of the eccentric pin (21) with respect to the drive shaft (16) in an angular range of 60 ° to 180 ° about the axis of rotation (18) the drive shaft (16) is movable and can be locked in this angular range. Surface grinding machine according to claim 3 or 7,
characterized,
in that the compensating mass is arranged in a frame (32) and in that the frame (32) is pivotably held on the drive shaft (16) or the eccentric pin (21). Surface grinding machine according to claim 8,
characterized,
in that the compensating mass (31) is held in the frame (32) by means of a spindle (33) supported in the frame (33), and by rotation of the spindle (33) the distance of the center of mass (MS) of the balancing mass (31) with respect to on the rotation axis (18) of the drive shaft (16) is variable.

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