GRINDER, METHOD FOR OPERATING IT, AND GRINDING DISK

Abstract

A grinder having a motor, wherein the grinder can be connected to a grinding disk. The grinder is configured to enable a wobbling movement, in addition to a grinding movement in a flat plane, of the grinding disk when the grinding disk is connected to the grinder. As a result, the grinder is able to perform a grinding movement, which constitutes a superimposition of a grinding movement in a flat plane and a wobbling movement of the grinding disk. This makes it possible to operate the grinder in two operating modes, the wobbling movement being able to be stopped by an arresting device. method for operating a grinder and a grinding disk for the grinder, the grinding disk having an unbalance for assisting the wobbling movement is also provided.

Description

The present invention relates to a grinder having a motor, wherein the grinder can be connected to a grinding disk. In other aspects, the invention relates to a method for operating a grinder and to a grinding disk for the grinder.

BACKGROUND OF THE INVENTION

The invention is situated in the technical field of grinders. In this field, three tool types are known, specifically angle grinders, orbital grinders and eccentric grinders. The intention of the present invention is to improve the grinding power of such a tool. What is common to all three tool types is that they have a grinding disk, the grinding disks of angular and eccentric grinders usually having a circular shape and those of orbital grinders being rectangular or square.

In conventional angle grinders as are known from the prior art, the preferably circular grinding disk performs a purely rotational movement. On its outer circle, the grinding disk has grinding elements which abrasively machine the underlying surface. For example, angle grinders can be used to abrasively remove concrete or to machine concrete surfaces. In this respect, the grinding movement is a rotation on a planar plane formed by the underlying surface to be machined. The grinding elements may for example comprise diamond grinding elements or diamonds, in order to increase the grinding power of the grinding disk.

In conventional orbital grinders, as are known from the prior art, a preferably rectangular grinding plate can be furnished with a grinding means, such as abrasive paper, with the grinding plate preferably moving circularly on a planar grinding plane. Here, the grinding element itself does not perform any rotational movement, and is consequently conjointly moved by the grinding plate.

In conventional eccentric grinders, as are known from the prior art, the grinding disk not only rotates but in addition performs eccentric movements in its center. The combination of eccentric and rotational movement in a planar grinding plane makes it possible to achieve very fine abrasive removal and a homogeneous grinding pattern. By means of eccentric grinders, it is possible to machine metal, plastic, wood, glass, painted and lacquered surfaces.

SUMMARY OF THE INVENTION

What is common to all three tool types is that their grinding disks or grinding elements always move in a planar plane. In this respect, the grinding contact pressure applied by the user of the grinder acts on the entire surface of the grinding element. A disadvantage of the grinders known from the prior art is the sometimes high vibrational loading for the user, which can result from the circular movements of the grinding disk.

An object on which the present invention is based is to overcome the above-described shortcomings and disadvantages of the prior art and to provide a grinder with which the grinding power can be further enhanced, without significantly increasing the vibrational loading for the user of the grinder in the process. In addition, it would be appreciated by those skilled in the art if no increased physical loading for the user of the grinder were to be associated with the improved grinding power and a homogeneous, uniform grinding pattern on the machined surface were to be produced. Another concern of the invention is to provide a grinding disk and an operating method for a grinder which make it possible to assist the improvement of the grinding power of the grinder.

According to the invention, what is provided is a grinder having a motor, wherein the grinder can be connected to a grinding disk. The grinder is configured to enable a wobbling movement, in addition to a grinding movement in a flat plane, of the grinding disk when the grinding disk is connected to the grinder. Within the meaning of the invention, it is very particularly preferred for the grinding movement in the flat plane and the wobbling movement of the grinding disk to be superimposed. The rotational grinding movement in a planar plane preferably superimposes an additional wobbling vibration of the grinding disk, wherein the wobbling movement is fixed at a vibration node within the grinder. The superimposed movement preferably corresponds to the movement of a pendulum body which is fixedly mounted at a suspension point and performs a circular movement in the region of the pendulum body. In this respect, the vibration node of the proposed grinder corresponds to the suspension point of such a pendulum, and the pendulum body preferably performing the circular movement corresponds to the grinding disk. By virtue of the superimposition of the rotational grinding movement and the wobbling movement, the grinding disk performs a preferably three-dimensional movement in the course of which only a respective part of the grinding disk is in direct contact with the object to be ground or the underlying surface to be machined. Within the meaning of the invention, the wobbling movement is preferably denoted as being “three-dimensional” because, while such a wobbling movement is being performed, the grinding disk is not only substantially parallel to an underlying surface to be machined, but because, in the course of the wobbling movement, the grinding disk is at least partially not in contact with the underlying surface and “lifts off” from it. Possible positions of the grinding disk are depicted in FIG. 2. By contrast, the grinding movement known from the prior art of a grinding disk in a planar plane is preferably denoted as being “two-dimensional” within the meaning of the invention.

Tests have shown that, by virtue of this only partial contact between the underlying surface and the grinding disk, the grinding power or grinding efficiency of the grinder can be considerably improved, without increasing the vibrational loading for the user of the proposed grinder. It was moreover possible to show that a surprisingly homogeneous grinding pattern is produced without it being necessary for the user to increase the contact pressure. Consequently, by means of the present invention, the grinding power and the grinding pattern can be increased without adversely affecting the operating comfort for the user or subjecting the user to higher loading. The invention differs from the prior art by superimposing a preferably three-dimensional wobbling movement on a rotational movement of the grinding disk in a flat plane, in that usually only the rotational grinding movement is carried out in a planar, i.e. two-dimensional plane. Within the context of the invention, it is preferred for the wobbling movement of the grinding disk to be enabled by a wobbling movement of the grinding shaft, which will be explained in the next paragraph. Within the context of the invention, it is preferred for the terms “flat” and “planar” to be used preferably synonymously within the meaning of the invention.

Within the context of the invention, it is preferred for the grinding disk to be connected to a grinding shaft on the grinder, wherein the grinding shaft has a rigid portion and a wobbling portion. The transition between the rigid portion and the wobbling portion of the grinding shaft is preferably formed by the vibration node of the wobbling movement of the grinding disk, wherein this vibration node is preferably also denoted “fixed point”. Within the context of the invention, it is preferred for the grinding shaft to have such a fixed point, wherein the fixed point divides the grinding shaft into the rigid portion and the wobbling portion. There is preferably a fixed or stationary mounting of the grinding shaft at this fixed point. The region above the fixed point preferably constitutes the rigid portion of the grinding shaft, whereas the region below the fixed point constitutes the wobbling portion of the grinding shaft. Within the context of the invention, it is preferred for the grinder to have a fixed mounting for the grinding shaft in a transition region between the wobbling portion of the grinding shaft and the rigid portion of the grinding shaft.

Within the context of the invention, it is preferred for the wobbling movement of the grinding shaft to correspond to the movement of a thread pendulum, which is fixedly mounted at its suspension point and performs a circular movement in the region of the pendulum body. In this respect, the suspension point of the thread pendulum preferably corresponds to the fixed point or the vibration node of the grinding shaft of the proposed grinder. The configuration and mounting of the grinding shaft advantageously enables a superimposition of a wobbling movement on a grinding movement of the grinding disk in a flat plane, wherein this superimposition advantageously has the result that only a part of the grinding disk is in contact with the underlying surface to be machined. This makes it possible to enable improved grinding power by means of the proposed grinder, without it being necessary for the user of the grinder to increase the contact pressure on the negative pressure. Consequently, the invention, in particular the provision of a wobbling movement of the grinding disk, makes it possible to considerably improve the work efficiency of the grinder without the work performed with the grinder becoming more strenuous or difficult for the user.

Within the context of the invention, it is preferred for the grinder to have a flexible mounting, which enables the wobbling movement, for the grinding shaft in a region of the wobbling portion of the grinding shaft. Within the context of the invention, this preferably means that a flexible mounting, which enables the wobbling movement of the grinding disk or of the grinding shaft, of the grinding shaft is provided at the height of the wobbling region of the grinding shaft. The flexible mounting is preferably provided at the height of the lower portion of the grinding shaft, that is to say below the fixed point of the grinding shaft or below the vibration node of the grinding shaft.

Within the context of the invention, it is preferred for the flexible mounting of the grinding shaft to have an elastic element, which enables the wobbling movement of the grinding disk. The flexible mounting may be realized by a preferably resiliently shaped bearing seat or particularly preferably by the use of a bearing seat, wherein the bearing seat comprises a flexible material or flexible elastomers, such as rubber or silicon, for example.

The wobbling movement of the grinding disk or of the grinding shaft is enabled in particular in that the grinding shaft is supported by two bearings, wherein a first, or upper, bearing has a fixed form and a second, or lower, bearing has a flexible form. In particular, a fixed mounting is provided at the vibration node or fixed point and a soft, flexible mounting is provided in the lower region of the grinding shaft. The combination of two different mountings for the grinding shaft makes a significant contribution to being able to provide a preferably three-dimensional wobbling movement of the grinding disk or of the grinding shaft.

Within the context of the invention, it is preferred for the grinder to comprise an arresting device for securing the flexible mounting. The arresting device makes it possible in particular to secure the flexible bearing of the grinding shaft, in order to “turn off” the wobbling movement of the grinding shaft or grinding disk, with the result that, when the arresting device is secured, the grinder reverts to a simple, preferably two-dimensional grinding movement in a planar plane. The wobbling movement of the grinding disk or of the grinding shaft can preferably be suppressed by the arresting device. When the flexible mounting is secured, the grinder preferably performs only the grinding movement in the flat plane, and not the wobbling movement. Consequently, providing the arresting device enables operation of the proposed grinder in two work modes. In a first work mode, the grinder can operate in the known work mode with a rotational grinding movement in a flat plane, whereas in a second work mode the grinder is configured to operate with superimposition of the rotational grinding movement in a flat plane and a wobbling movement, wherein this wobbling movement is enabled in particular by the provision of the flexible mounting of the grinding shaft. The arresting device is preferably in the region of the flexible mounting of the grinding shaft of the proposed grinder.

The arresting device may have a comparable form to a drill chuck. The arresting device may preferably be designed as substantially orthogonal with respect to an axis of rotation of the machine tool and/or be clamped onto the corresponding bearing. As an alternative, the arresting device may be formed by a cone that can be adjusted substantially parallel to the axis of rotation. For a person skilled in the art, the term “substantially” is not an unclear wording, since a person skilled in the art knows that the term “substantially” includes deviations of for example 1-5% from the mathematically correct orthogonality or parallelism. Such deviations can arise, for example, from the production.

Within the context of the invention, it is preferred for the grinder to have a drive coupling element for damping vibrations. The drive coupling element is preferably in the region of the fixed point or the vibration node of the grinding shaft of the proposed grinder.

In a second aspect, the invention relates to a grinding disk for a grinder. According to the invention, the grinding disk has an unbalance for assisting the wobbling movement. The terms, definitions and technical advantages introduced for the grinder preferably apply in an analogous manner to the grinding disk and the operating method for a grinder presented later on. Within the context of the invention, it is preferred for the unbalance to be able to be provided by virtue of the following measures:

• • a) asymmetrical arrangement of grinding elements on the grinding disk,
  • b) use of grinding elements of different sizes and/or
  • c) asymmetric configuration of a basic body of the grinding disk.

The wobbling movement of the grinding disk can preferably be supported by the use of a grinding disk with a specific unbalance. The unbalance of the grinding disk may be achieved by an unsymmetric arrangement of the grinding elements, a reduced or enlarged grinding element, and/or a corresponding configuration of the basic body of the grinding disk. The basic body is preferably configured to receive the grinding means or the grinding elements. Therefore, the basic body constitutes the connection between the grinding means and the proposed grinder.

In a further aspect, the invention relates to a method for operating a proposed grinder, wherein the method is characterized by the following method steps:

• • a) providing the grinder,
  • b) operating the grinder, wherein the grinder performs a grinding movement which constitutes a superimposition of a grinding movement in a flat plane and a wobbling movement of the grinding disk.

Within the context of the invention, it is preferred for the wobbling movement to be able to be stopped by actuating an arresting device. Within the context of the invention, it is preferred for the grinder to be able to be operated in two work modes, wherein in a first work mode the grinder performs a grinding movement in a flat plane and wherein in a second work mode the grinder performs a grinding movement which constitutes a superimposition of a grinding movement in a flat plane and a wobbling movement of the grinding disk. The provision of the arresting device makes it possible to use the grinder advantageously in two work modes, wherein the first work mode corresponds substantially to the capacity of a conventional grinder, in which a grinding movement is performed in a planar grinding plane. In this respect, this planar grinding plane is substantially parallel to the surface to be machined of an underlying surface or of a workpiece. In this first work mode, the grinding shaft is secured, so that it has a rigid form as a whole. With the arresting device, is it possible in particular to secure the flexible mounting of the grinding shaft, with the result that the wobbling movement enabled by the flexible mounting can be switched on or off by the arresting device. In the second work mode, the grinding disk of the grinder moves in a manner corresponding to a superimposed movement of a preferably three-dimensional wobbling movement and the conventional rotating grinding movement of the first work mode. By virtue of this superimposition, only a respective part of the grinding disk is in working contact with the underlying surface to be machined. Use tests have shown that this partial contact between the grinding disk and the underlying surface, when the grinder is operated in the second work mode, makes it possible to work with the grinder particularly efficiently and that a surprisingly homogeneous grinding pattern is obtained.

By virtue of the wobbling movement of the grinding disk, only a part of the grinding disk rests on the surface to be ground. Consequently, the grinding pressure applied by the user of the grinder is concentrated in this contact area between the grinding disk and the underlying surface. The wobbling movement, assisted by the unbalance of the grinding disk, of the grinding disk or of the grinding shaft advantageously applies additional abrasive-removal pressure to the surface to be ground. This is comparable with an additional hammering movement, which increases the abrasive removal during the grinding operation. The fixed mounting of the grinding shaft at the vibration node or at the fixed point makes it possible to minimize the vibrational loading from the wobbling movement for the user, as use tests with the invention have shown. The arresting device gives rise to two basic operating modes in one tool, this considerably increasing the flexibility of the grinder in terms of possible use cases and enabling the provision of a grinder with a wide range of uses.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages will become apparent from the following description of the figures. The figure, the description and the claims contain numerous features in combination. A person skilled in the art will expediently also consider the features individually and combine them to form useful further combinations.

Identical and similar components are denoted by the same reference signs in the figure, in which:

FIG. 1 shows a side view of a preferred configuration of the proposed grinder,

FIG. 2 shows a schematic depiction of the movement of the grinding disk and of the grinding shaft,

FIG. 3 shows a schematic depiction of a preferred configuration of the grinding disk with an unbalance.

DETAILED DESCRIPTION

FIG. 1 shows a preferred configuration of the proposed grinder 10. The grinder 10 has a grinding disk 12, which is driven by a motor M of the grinder 10. A grinding shaft 14, which transmits the movement of the motor M to the grinding disk 12, is present between the motor M and the grinding disk 12. The grinding shaft 14 has a rigid portion 16 and a wobbling portion 18, wherein the rigid portion 16 forms an upper region of the grinding shaft 14 and the wobbling portion 18 forms a lower region of the grinding shaft 14. The two regions 16, 18 are preferably separated from one another by a fixed point 20, wherein a rigid, fixed mounting for the grinding shaft 14 is provided in the fixed point 20. The fixed point 20 preferably constitutes a vibration node for a wobbling movement of the grinding shaft 14 or of the grinding disk 12. Furthermore, a drive coupling element 32 for vibration damping may be provided in the region of the fixed point 20. A flexible mounting 22 of the grinding shaft 14 is provided in the lower region of the grinding shaft 14, which constitutes the wobbling portion 18 of the grinding shaft 14. The flexible mounting 22 advantageously allows the wobbling movement of the grinding shaft 14 or of the grinding disk 12. The flexible mounting 22 preferably comprises an elastic element 24. Furthermore, an arresting device 26, which makes it possible to switch off the wobbling movement of the grinding disk 12 or of the grinding shaft 14, may be provided in the region of the flexible mounting 22. The flexible mounting 22 of the grinding shaft 14 can be secured by the arresting device 26, with the result that the wobbling movement of the grinding disk 12 or of the grinding shaft 14 can be suppressed by the securing.

FIG. 2 shows a schematic depiction of the movement of the grinding disk 12 and of the grinding shaft 14. The object to be machined, such as for example an underlying surface U, is depicted in the lower region of FIG. 2. The fixed point 20 or the vibration node 20 of the wobbling movement of the grinding disk 12 or of the grinding shaft 14 is depicted in the upper region of FIG. 2. Possible positions of the grinding disk 12 or of the grinding shaft 14, while the grinding disk 12 or the grinding shaft 14 carries out a wobbling movement, are depicted in the middle region of FIG. 2. It can clearly be seen that only a respective part or a partial portion of the grinding disk 12 is in contact with the underlying surface U, with the result that the contact pressure of the user acts on the underlying surface in particular in this contact region between the grinding disk 12 and the underlying surface U. This makes it possible to ensure a particularly high abrasive-removal power of the superimposed grinding movement. Surprisingly, with the invention it is also possible to obtain a particularly homogeneous grinding pattern. As can be seen in FIG. 2, the unit composed of the grinding shaft 14 and the grinding disk 12 imitates the circular movement of a thread pendulum, wherein the grinding disk 12 corresponds to the pendulum body and the fixed point 20 corresponds to the suspension point of the thread pendulum. The region of the grinding shaft 14 that is depicted in FIG. 2 preferably represents the lower, wobbling portion 18 of the grinding shaft 14.

FIG. 3 shows a schematic depiction of a preferred configuration of the grinding disk 12 with an unbalance. The exemplary embodiment of the invention that is depicted in FIG. 3 shows a basic body 30 of a grinding disk 12 and a series of grinding elements 28. The grinding elements 28 preferably form the grinding means; for example, this may be diamond grinding elements or diamond segments. The grinding elements 28 are preferably on an outer edge of the basic body 30 of the grinding disk 12. The unbalance of the grinding disk 12 can act in different ways. In the example of the grinding disk 12 depicted in FIG. 3, the grinding element 28 on the bottom right on the grinding disk 12 or on the basic body 30 is only half as large as the other grinding elements 28. This results in asymmetry in the configuration of the grinding disk 12, which causes an unbalance of the grinding disk 12. As an alternative or in addition, the basic body 30 of the grinding disk 12 may have an unsymmetric form. Furthermore, there is the option of arranging the grinding elements 28 asymmetrically on the grinding disk 12 or on the basic body 30.

LIST OF REFERENCE SIGNS

• • 10 Grinder
  • 12 Grinding disk
  • 14 Grinding shaft
  • 16 Rigid portion of the grinding shaft
  • 18 Wobbling portion of the grinding shaft
  • 20 Fixed point or vibration node
  • 22 Flexible mounting
  • 24 Elastic element
  • 26 Arresting device
  • 28 Grinding elements
  • 30 Basic body of the grinding disk
  • 32 Drive coupling element
  • M Motor
  • U Underlying surface

Claims

1-15. (canceled)

16. A grinder comprising: a motor,the grinder connectable to a grinding disk and configured to enable a wobbling movement, in addition to a grinding movement in a flat plane, of the grinding disk when the grinding disk is connected to the grinder.

17. The grinder as recited in claim 16 wherein the grinding movement in the flat plane and the wobbling movement of the grinding disk are superimposed.

18. The grinder as recited in claim 16 wherein when the wobbling movement is being carried out, only a part of the grinding disk is in contact with an underlying surface to be machined.

19. The grinder as recited in claim 16 further comprising a grinding shaft connected to the grinding disk, wherein the grinding shaft has a rigid portion and a wobbling portion.

20. The grinder as recited in claim 19 wherein the wobbling movement of the grinding disk is enabled by a wobbling movement of the grinding shaft.

21. The grinder as recited in claim 19 wherein the grinding shaft has a fixed point dividing the grinding shaft into the rigid portion and the wobbling portion.

22. The grinder as recited in claim 19 further comprising a flexible mounting for the grinding shaft in a region of the wobbling portion of the grinding shaft, in order to enable the wobbling movement.

23. The grinder as recited in claim 22 wherein the flexible mounting of the grinding shaft has an elastic element, in order to enable the wobbling movement.

24. The grinder as recited in claim 22 further comprising an arrester for securing the flexible mounting.

25. The grinder as recited in claim 16 further comprising a drive coupling for damping vibrations.

26. A grinding disk for the grinder as recited in claim 16, wherein the grinding disk has an unbalance for assisting the wobbling movement.

27. The grinding disk as recited in claim 26 wherein the unbalance is provided by virtue of the following: a) an asymmetrical arrangement of grinding elements on the grinding disk;b) grinding elements of different sizes; orc) an asymmetric configuration of a basic body of the grinding disk.

28. A method for operating the grinder as recited in claim 16, the method comprising the following steps: a) providing the grinder; andb) operating the grinder, the grinder performing a grinding movement constituting a superimposition of a grinding movement in a flat plane and a wobbling movement of the grinding disk.

29. The method as recited in claim 28 wherein the wobbling movement can be switched off by actuating an arrester.

30. The method as recited in claim 28 wherein the grinder is operable in two work modes, wherein, in a first work mode, the grinder performs a grinding movement in the flat plane or a further flat plane, and whereinin a second work mode, the grinder performs a grinding movement constituting the superimposition of the grinding movement in the flat plane and the wobbling movement of the grinding disk.