CN1899765B - Devices with at least two counterweights, eccentric tools and hand-held power tools - Google Patents

Abstract

The invention relates to a device with at least two balancing weights (10, 12, 44) for balancing an eccentric tool (14) of a hand-held power tool (16), in particular of a superfinishing machine Grinding disc. The invention proposes that the first balance weight (10) is connected to the shaft (22) of the eccentric tool (14) and that the second balance weight (12) is integrated in the eccentric tool (14).

Description

Devices with at least two counterweights, eccentric tools and hand-held power tools

technical field

The invention relates to a device with at least two balancing weights. the

The invention also relates to a grinding disc, which is provided for detachable fastening on a fine grinding machine. the

The invention also relates to a hand-held power tool, in particular a superfinishing machine, with at least one replaceable eccentric tool and with at least two balancing weights. the

Background technique

It has already been proposed to equip a fine grinding machine with two or more balancing weights for balancing the grinding disc. This prevents the eccentric vibrating movement of the grinding disc from causing uncomfortable vibrations of the housing during operation of the superfinishing grinding machine. The dynamic tilting moments to which the shaft of the hand-held power tool is subjected during operation can additionally be reduced by means of two counterweights arranged in different planes and arranged opposite one another. the

Contents of the invention

The invention relates to a device having at least two balancing weights for balancing an eccentric tool of a hand-held power tool, in particular a grinding disc of a fine grinding machine. the

The invention proposes that a first balancing weight is connected to the shaft of the eccentric tool and that a second balancing weight is integrated in the eccentric tool. It can thus be achieved that the mass and position of the counterweight are precisely adapted to the distribution of the eccentric tool and its mass; remain largely vibration-free. the

An eccentric tool here can be any tool that is considered appropriate by the technician, which is provided for being guided on an eccentric track during operation of the hand-held power tool. the

The solution according to the invention can be used particularly advantageously on grinding discs of superfinishing machines, since such grinding discs perform an oscillating movement at a relatively high frequency, which can cause Uncomfortable vibrations. Finally, this vibration can also shorten the service life of the superfinishing grinding machine. the

In principle, the second balancing weight can be fixedly connected to the eccentric tool or can be designed to be adjustable. In particular on superfinishing machines in which the grinding discs can be equipped with grinding layers of different weights, the device can be balanced by means of adjustable counterweights. the

The counterweight can be designed, for example, in such a way that the mass distribution of the parts connected to the drive shaft, in particular the parts of the eccentric tool, and the counterweight is free of imbalance, so that the eccentric tool is not in contact with the hand-held power tool when it is running freely. When in contact with the workpiece, the housing of the hand-held power tool remains at least substantially vibration-free. However, configurations of the invention are also conceivable in which the oscillating forces transmitted by the eccentric tool from the workpiece to the hand-held power tool housing are at least partially compensated by the distribution of the counterweight. the

In one refinement of the invention it is provided that the eccentric tool is provided for being driven eccentrically. The eccentric tool is provided, in particular, for being driven eccentrically, if a shaft bearing unit is provided for connection to the eccentrically moving drive shaft. In this context, any periodic and quasi-periodic motions, for example elliptical, cycloidal, or motions resulting from the superposition of two circular motions of different frequencies are referred to as eccentric motions. Here, "setting" can also be understood as "design" and "equipment". the

Furthermore, it is proposed that the eccentric tool is provided for detachable fastening on the hand-held power tool. Especially when the eccentric tool is replaceable and detachable, a counterweight adapted to a type or a weight of the eccentric tool is necessary for comfortable working of the hand-held power tool. By means of the solution according to the invention, a balancing process associated with changing the eccentric tool can be avoided, and largely vibration-free operation of the electric power tool can be achieved with the aid of several eccentric tools with different centers of gravity and/or weights. the

If the eccentric tool is designed as a grinding disc of a superfinishing machine, the inertial weight of the grinding disc must also be adapted to the grit size of the grinding discs used or the sanding paper used. In this case, the advantages of the solution according to the invention can be used in particular in combination with superfinishing machines with exchangeable grinding discs. the

A particularly stable structural configuration with an advantageously shielded balancing weight can be achieved if the second balancing weight is arranged between a shaft bearing unit and a grinding layer holding surface of the grinding disc. . the

When the second balance weight is connected to the shaft through the shaft bearing unit in a non-rotatable manner, a reliable and detachable connection between the balance weight and the shaft can be obtained, so that the shaft bearing unit can transfer the torque from The shaft is transferred to the balance weight. In this case, the part of the shaft bearing unit that is rotatably supported on the eccentric tool acts as a connecting part, for example the inner bearing ring of the shaft bearing unit, which can be used particularly advantageously as a sliding bearing, a ball bearing bearings or rolling bearings. the

If the device comprises at least one first counterweight, which is connected to the shaft of the hand-held power tool, then a fixed counterweight - which matches an eccentric tool of standard type - can be advantageously fixedly Integrated in the hand tool machine, the counterweight integrated in the plug-in eccentric tool is thus a corrective counterweight which represents a counterbalance relative to the standard version and can therefore be easily and cost-effectively replaced constitute. It is particularly advantageous to select as standard the type of eccentric tool that is produced or used in the greatest number. In this case, the second balancing weight can advantageously be integrally formed on the blower wheel of the hand-held power tool in order to save components. the

Furthermore, the invention relates to a grinding disc, which is provided for detachable fastening on a fine grinding machine. the

The invention proposes that the grinding disc includes an integrated corrective balancing weight for compensating centrifugal forces. The grinding disc can thus be used in particular in connection with superfinishing grinding machines which have a fixed basic balancing weight which is adapted to another grinding disc model. A superfine grinding machine can advantageously be realized by refitting with the grinding disc according to the invention. the

Furthermore, the invention relates to a hand-held power tool, in particular a superfinishing machine, which has at least one replaceable eccentric tool and has at least two counterweights. the

The invention proposes that a first counterweight is connected to the shaft of the hand-held power tool and that a second counterweight is at least partially integrated in the eccentric tool. The advantages of the invention can be combined especially with hand-held tools comprising a complete series of eccentric cutters, if the various models of eccentric cutters each comprise balancing weights adapted to the specific mass distribution of the grinding disc used. related to the use of machine tools. the

Description of drawings

Further advantages emerge from the following description of the figures. Exemplary embodiments of the invention are shown in the drawings. The drawings, description and other application documents contain several features in combination. A person skilled in the art can expediently examine the individual features in detail and summarize them in further meaningful combinations. the

The accompanying drawings indicate:

Fig. 1: A superfinishing machine with nested tools,

Figure 2: Shaft of a superfinishing grinder with a fan impeller and a grinding disc with three balancing weights, and

Figure 3: A fragment of the shaft and the grinding disc in Figures 1 and 2. the

Detailed ways

FIG. 1 shows a hand-held power tool 16 designed as a superfinishing grinder, which has an eccentric tool designed as a replaceable grinding disc 14 . In addition, the hand-held power tool 16 has a dust collection container 24 , an on/off switch 26 arranged on a handle element, and a power supply cable 28 with a power supply plug (not shown here). Another handle element 30 allows the operator to comfortably apply pressure to a workpiece. the

In the housing of the hand-held power tool 16 there is an electric motor, not shown here, which starts to work when the mains plug is plugged in and the on/off switch 26 is switched on, and which has a motor shaft, which The motor shaft can form a direct functional connection with a shaft 22 ( FIG. 2 ) of the hand-held power tool 16. the

Grinding disc 14 has a flat basic shape and is provided for receiving an exchangeable grinding layer, for example corundum sandpaper, on its side opposite the housing of hand power tool 16 . However, inventive configurations are also conceivable in which the grinding disc 14 is equipped with a permanent grinding layer. the

FIG. 2 shows a fragment of an eccentric of a hand-held power tool 16 with a fan wheel 32 and a shaft 22 . The first balancing weight 10 is integrally formed with the third balancing weight 44 arranged on the opposite side of the first balancing weight 10 and is fixedly connected to the fan wheel 32 or integrated on the fan wheel 32 . The third counterweight 44 is displaced in the axial direction of the main body of the hand-held power tool 16 to compensate for dynamic tilting moments relative to the shaft 22 . the

The shaft 22 has a flattened portion on a free end, with which the shaft is inserted into an associated groove of a shaft bearing unit 18 connected to the grinding disc 14 during assembly, so as to form no relative rotation and A detachable connection in which the rotational position of the shaft 22 relative to the bearing ring 40 of the shaft bearing unit 18 is fixed by the flattened portion. the

During assembly, the grinding disc 14 is also connected to the main body of the hand-held power tool 16 via a detachable quick-clamp connection and by means of flexible pivot spring feet. The oscillating spring feet allow a limited degree of movement of the grinding disc 14 in all directions in a plane pressed against by the grinding disc 14, while forming a rigid connection in a direction extending perpendicularly to this plane. By means of the quick-clamp connection, the grinding disc 14 can be detached from the main body of the hand-held power tool 16 without tool constraints and with minimal manual effort. the

The shaft 22 is mounted rotatably about an axis of rotation 34 which is displaced parallel to an axis of symmetry 36 by an eccentric distance 38 ( FIG. 3 ). the

FIG. 3 shows a grinding disc 14 in the assembled state on the main body of the hand-held power tool 16 , in which state the shaft 22 has been fitted into the groove of the inner bearing ring 40 . the

The shaft bearing unit 18 is configured as a rolling bearing with an inner bearing ring 40 whose inner surface forms corresponding grooves, and an outer bearing ring 42 which is designed as a plastic pressure injection part with the grinding disc 14. The bodies are connected without relative rotation. The shaft bearing unit 18 is arranged offset relative to the center of gravity of the grinding wheel 14 . the

On the edge of the inner bearing ring 40 facing away from the housing of the hand-held power tool 16, a second counterweight 12 is arranged, which is adapted to the weight of the grinding wheel 14 and which passes underneath the belt of the grinding wheel 14. The grinding layer-retaining surface 20 of the spongy rubber layer is rotatable relative to the main body of the grinding disk 14 together with the inner bearing ring 40 , isolated from the outside. The second balancing weight 12 is thus arranged between the shaft bearing unit 18 and the grinding layer holding surface 20 . The grinding disc 14 is designed as a double shell in order to form an intermediate space for receiving the rotating second counterweight 12 . The second balancing weight 12 is connected in a rotationally fixed manner to the shaft 22 via the shaft bearing unit 18 or via its inner bearing ring 40 . the

The grinding layer holding surface 20 is formed with a layer of sponge-like rubber about 2 mm thick. the

If the shaft 22 turns, the free end of the shaft 22 fitted in the inner bearing ring 40 moves the grinding disc 14 along a circular orbit extending in the plane of the grinding disc 14, the radius of which is 3 mm, exactly is given by the eccentric distance 38 of the shaft 22 . The eccentric tool, which is designed as a grinding disc 14 , can thus be driven eccentrically. the

The grinding disc 14 is part of a series of grinding discs 14 of different weight and size, each of which is provided with a second counterbalance adapted to the weight and size of the corresponding grinding disc 14 Counterweight 12. There is only one standard grinding disc in the series, not shown here, which is produced in maximum number of pieces, which is fully balanced by the first balancing weight 10 and the second balancing weight is omitted 12. The balance weights 12 of other types of grinding discs 14 are calibrated balancing weights, which are arranged to compensate for differences in unbalance between the standard grinding disc and the corresponding grinding disc 14 . the

Table of reference signs

10 balance counterweight

12 balance counterweight

14 eccentric tool

16 hand tool machine

18 shaft bearing unit

20 grinding layer retaining surface

22 axis

24 dust collection container

26 switches

28 power supply cable

30 handle elements

32 fan impeller

34 axis of rotation

36 axis of symmetry

38 eccentric distance

40 bearing ring

42 bearing ring

44 balance counterweight

Claims (10)

1. Device with an eccentric cutter (14) having at least two balancing weights (10, 12, 44) for balancing the eccentric cutter (14), said eccentric cutter being arranged for detachable fixed on a hand-held machine tool (16), wherein the first counterweight (10) is connected to a shaft (22) of the hand-held machine tool (16), wherein the eccentric tool (14) has a Shaft bearing unit (18) with an inner bearing ring (40), characterized in that the shaft (22) fits into a groove of the inner bearing ring (40) in the assembled state, wherein the second balancing weight ( 12) is provided on the inner bearing ring (40). 2. Device according to claim 1, characterized in that the eccentric knife (14) is provided for being driven eccentrically. 3. The device as claimed in claim 1 or 2, characterized in that the eccentric tool (14) is designed as a grinding disc of a fine grinding machine. 4. The device according to claim 3, characterized in that: said second balance weight (12) is arranged on a shaft bearing unit (18) and a grinding layer holding surface (20) of the grinding disc (14) between. 5. The device according to claim 1 or 2, characterized in that the second balancing weight (12) is non-rotatably connected to the shaft (22) via a shaft bearing unit (18). 6. Eccentric tool (14), which is provided for detachable fastening on a hand-held power tool (16), the eccentric tool has a shaft bearing unit (18) with an inner bearing ring (40), characterized in that a shaft (22) of the hand-held power tool (16) fits into a groove of the inner bearing ring (40) in the assembled state, wherein an integrated balancing weight (12 ) is arranged on the inner bearing ring (40) of the shaft bearing unit (18) for compensating centrifugal force. 7. A hand-held power tool (16) having a main body; at least one exchangeable eccentric tool (14), which is arranged to be detachably fastened to the main body, wherein the eccentric tool (14) There is a shaft bearing unit (18) with an inner bearing ring (40); there is a shaft (22); and there are at least two balance weights (10, 12), wherein the first balance weight (10) and The shaft (22) is connected, characterized in that the shaft (22) fits into a groove of the inner bearing ring (40) in the assembled state and the second balancing weight (12) is arranged in the inner bearing on the ring (40). 8. The hand-held power tool as recited in claim 7, characterized in that the hand-held power tool (16) is a fine grinding machine. 9. The hand-held power tool as recited in claim 7, characterized by a quick-release connection, by means of which the eccentric tool (14) can be detached from the main body without being restricted by a tool. 10. The hand-held power tool according to claim 7, characterized in that the eccentric tool (14) is designed to be driven eccentrically, wherein the shaft (22) moves eccentrically during operation and the eccentric tool (14) 14) Comprising a shaft bearing unit (18) into which said shaft (22) is inserted when assembling the eccentric tool (14).

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