DE102008031105A1 - Automatic balancing device i.e. balancing element, for rotating machine part i.e. grinding disk, of angular grinder, has imbalance compensating disk comprising two semi shells made of fiber-reinforced plastic - Google Patents

Abstract

The device has an imbalance compensating disk (1) surrounding a rotation axle (17) of a rotating machine part. Freely movable balance masses e.g. balls (5), ball casters and cylindrical rollers, are arranged in circular hollow space (4), where the masses balance imbalance by receiving a counter position. The compensating disk comprises two semi shells (2, 3) made of fiber-reinforced plastic, where the circular hollow space is formed by a material-engagement connection between the semi shells. The material-engagement connection is formed by ultrasonic welding or sticking.

Description

Field of the invention

The The invention relates to a device for automatic balancing a rotating machine part, in which within a Rotation axis of the machine part surrounding imbalance compensation disc freely movable balancing masses in an annular cavity arranged, which is an existing imbalance by taking a counter compensate, wherein the balancing wheel from a first and a second half-shell, and the annular one Cavity is formed by the first and second half-shell.

Background of the invention

Yourself rotating machine parts are manufacturing-related and under certain circumstances also operationally more or less large imbalances on. With rotation of these machine parts, therefore, vibrations in the devices in which these machine parts are stored. For example, in washing machines in the spin cycle their Hop well known, mainly from an operational imbalance, namely the uneven Distribution of the laundry results. Thus caused On the one hand, vibrations are problematic for the bearings the rotating machine parts. So can wrong Design bearing damage occurs. On the other hand Vibrations of hand-picking machines, for example Hand grinders, in extreme cases even to physical Cause damage to the user.

It It is known to solve such imbalance problems by balancing masses. Such free on a circular path movable balancing masses arranged axially in the vicinity of an imbalance on a shaft. As the shaft rotates, the balancing masses automatically seek positions on, which are opposite to the imbalance. With that they form a force that balances the imbalance.

Such a balancing device is z. B. from the DE 10 2006 030 163 A1 or the EP 1 174 537 B1 known, wherein two half-shells, which form the cavity for the balancing masses, produced by machining or non-cutting production and z. T. are hardened. A disadvantage of balancing devices with metallic housing parts is that the total weight is relatively large, the items are expensive and expensive to manufacture and in operation a strong noise occurs.

Object of the invention

task The present invention is an apparatus for automatic Balancing the input described type to provide the opposite the known from the prior art solutions a low weight has and is easy and inexpensive to manufacture. In addition, the noise in the Operation be reduced.

Summary of the invention

According to the invention this object by a device for automatic Balancing a rotating machine part according to the features of the independent claim 1 solved. In the inventive Device are within a surrounding an axis of rotation of the machine part Unbalance compensation disc in an annular cavity freely movable balancing masses are arranged, which are an existing Balance the imbalance by taking a counter bearing, with the imbalance compensation disc consists of a first and a second half-shell, and the annular cavity through the first and the second half-shell is formed, wherein the first and / or the second half-shell made Plastic is or exist.

Of the Contact of the usually metallic balancing body with the now made of plastic half shell to a significant noise reduction. Farther can be achieved by the invention, the total weight of the device significantly reduce what is especially important when the machine part Part of a portable machine is. The plastic Half shell can also be made much easier and cheaper be, in particular, z. B. on a corrosion coating be waived. Especially the design as injection molded component achieves another with higher quantities Cost advantage. It is also advantageous that this half-shell cost can be colored according to customer requirements.

It is conceivable that both half shells form complete ring elements which completely surround the axis of rotation of the machine part, in particular with respect to this axis are rotationally symmetrical. The cavity is formed in this case by the joining of the two half-shells, wherein the half-shells are connected to each other with at least one axis of rotation of the machine part completely enclosing contact surface. It is also conceivable that both half shells each form a tubular half-ring element, wherein each half-ring element, the rotation axis only to z. B. 180 degrees encloses. Both half-ring elements composed form a complete ring element, which then completely encloses the axis of rotation of the machine part. In this case, the Cavity formed by the joining of the ends of the half-ring elements. Of course, more than two half-ring elements could be used to form the hollow body.

Around to further reduce the total weight and costs according to one embodiment, both half-shells made of plastic. These can be made by a cohesive Connection are connected, which is advantageous here, that by the cohesive connection simultaneously a sealing connection or a sealing joint arises. This will be according to one embodiment exploited to the effect that the annular cavity through a cohesive connection between the first and the second half-shell is formed. The annular cavity is thereby hermetically sealed and it prevents an optionally located in the cavity damping fluid can escape. Separate seals, as known in the art, are then no longer necessary, so that also reduces the number of components becomes. In particular, according to one embodiment, the cohesive connection by ultrasonic welding or sticking. A welded connection can with two half shells made of plastic relatively easy be, as opposed to a welded joint of two Metallic half shells require a lower processing temperature is.

According to one Embodiment is the annular cavity by a positive connection between the first and the second half shell formed. A seal can be done here either by separate sealing elements or by a corresponding contact surface be effected between the two half-shells. According to one Embodiment, the first and second half-shell by Snap or snap hooks are connected. The rest- or snap hooks can on one or both half shells be formed or formed by separate elements. The Snap-in or snap hooks engage in undercuts or openings one or both half shells.

According to one Embodiment has at least one half-shell means for non-rotatable connection with the machine part. Here can it is z. B. act around a hole whose inner diameter is slightly smaller than the outer diameter of the machine part, so that a rotationally fixed connection by an interference fit, ie non-positively, becomes possible. Advantageously, the means for However, rotationally fixed connect by one or more axial projections or depressions on one end face of the first and / or the second Half shell formed. These projections or depressions a half-shell act with one or more corresponding Projections or depressions of the machine part together. The rotatable connection is made possible form-fitting.

The Unbalance compensation disc according to the invention can pick up or support a tool. Preferably a half-shell formed to a tool axially and / or radially support. It may be in the supported For example, act tool to a grinding or cutting disc. According to one embodiment, a Half shell to one perpendicular to the axis of rotation of the machine part extending driving surface for contacting an axial end face of a tool. This driving surface is preferred formed rotationally symmetrical to the axis of rotation of the machine part and has a circular ring shape. It is z. B. by an axial end face a half shell formed. Through the driving surface can axially acting on the tool in the direction of the driving surface Forces in the device according to the invention be directed. To a radial support of the tool to ensure this half-shell preferably has a axially over the driving surface outstanding collar on, whose outer diameter is substantially the inner diameter corresponds to the annular tool. The tool can thus be postponed to this alliance. Preferably both the driving surface for the tool as well as the Means for non-rotatable connection with the machine part to one and formed the same half-shell. This has the advantage that only this half shell must be constructively designed such that to be transferred between the tool and the machine part Forces can be absorbed. The other half shell can be much simpler in this case, however, z. B. have a lid-shaped shape. Also will be in In this case, a power transmission via the joint avoided between the two half-shells.

In order to increase the strength of a half shell made of plastic, this may have radially extending ribs. According to one embodiment, a half-shell made of plastic is produced by injection molding, so that such a structure can be easily made possible. According to the invention, the plastic shells can basically consist of any plastic material that withstands the forces to be transmitted. In particular, it may be fiber reinforced plastic, z. B. glass fiber reinforced plastic. It is also conceivable to produce both half shells of different plastics, z. As fiber-reinforced plastic for the half-shell, which is responsible for the power transmission between the tool and machine part, and an unreinforced plastic for the lid-shaped Half-shell.

For the formation of the balancing masses, this applies preferably as large a mass in the available to form standing space. Therefore, the balancing masses are preferred made of metal, z. As steel or lead. Typically while using balls. To the ratio of mass to Space to increase further, can also be castors or cylindrical rollers are used.

A Increase in mass with constant axial space can also be achieved in that the cavity has a radial has inner and a radially outer subspace, wherein balancing masses are arranged in each subspace. Both subspaces are arranged concentrically to each other. Typically located a damping fluid in the cavity, which at least partially fills the cavity.

The Inventive device for automatic Balancing a rotating machine part can in principle in larger, stationary machines as well be used as in handheld devices. In particular, can the device according to the invention as a compensation element used with angle grinders.

Brief description of the figures

in the Below, embodiments of the invention are based on the attached figures, show it

1 a sectional view of an inventive device for automatic balancing according to a first embodiment,

2 a sectional view of an inventive device for automatic balancing according to a second embodiment, and

3 a three-dimensional view of a device according to the invention for automatic balancing according to the second embodiment.

Detailed description the figures

1 shows a first embodiment of an apparatus for automatically balancing a rotating machine part, such as a grinding wheel of a hand-held angle grinder. The imbalance compensation disc 1 has a first half shell 2 and a second half shell 3 on. Both half shells 2 . 3 are made of plastic, z. B. by injection molding. Through the two half shells 2 . 3 becomes an annular cavity 4 formed in which there are bullets 5 as freely movable balancing masses. The annular cavity 4 is rotationally symmetric about an axis of rotation 17 arranged a machine part, not shown. The balancing masses may be standard rolling elements or also specially manufactured elements, for. B. lead. During operation of the device, the balls are running 5 essentially on the boundary surface 6 of the cavity 4 off, the part of the first half shell 2 is.

The half-shells 2 . 3 are permanent and cohesive with each other through a joint 7 with axial contact surface and a joint 8th connected to both radial and axial contact surface. Due to the cohesive connection is the cavity 4 hermetically sealed, so that a damping fluid located therein can not escape to the outside.

The first half shell 2 has an axial driving surface 9 for contacting an axial end face of a tool, not shown. The driving surface 9 protrudes axially slightly from an axial boundary surface 10 the first half-shell and thus forms a defined, circular ring-shaped contact surface for the tool. The first half shell 2 also has an axial over the driving surface 9 outstanding covenant 15 on. This serves for the radial support of the tool. Finally, at the first half shell 2 also axial projections 11 , for non-rotatable connection with the machine part, not shown. The entire power flow from tool to machine part as well as the absorption of the resulting forces during operation of the balls 5 , thus becomes through the first half shell 2 directed. This therefore has a correspondingly massive construction. In particular, the first half shell 2 by ribs 12 strengthened.

The second half shell 3 In contrast, has a simple structure without reinforcing ribs and is mainly used to fall out of the balls 5 and to prevent leakage of the damping fluid. Next to the joints 7 . 8th the second half-shell is supported 3 also at its radially inner end 16 at the first half shell 2 from. However, this does not have to be a joint, let alone a cohesive connection. So must the extra cavity 13 between the two half-shells 2 . 3 not be hermetic. In contrast to the first half shell 2 has the second half shell 3 a rotationally symmetrical shape.

Both the first half shell 2 as well as the second half shell 3 have a hole 18 on, the rotationally symmetric about the axis of rotation 17 is formed of the machine part, not shown.

The second embodiment according to 2 differs from the according to 1 by the balancing masses used. In the embodiment according to 2 are ball rollers 14 in the annular cavity 4 , The available space is thereby better utilized, so it is possible to bring about 25% larger balancing mass with the same space.

In 3 is a three-dimensional view of the embodiment according to 2 seen in this illustration, the radially extending ribs 12 can be seen.

1

Balancing wheel

2

first half shell

3

second half shell

4

annular cavity

5

roll

6

boundary surface

7

joint

8th

joint

9

drive surface

10

axial boundary surface

11

head Start

12

ribs

13

additional cavity

14

ball rolling

15

Federation

16

radial inside end

17

axis of rotation

18

drilling

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• DE 102006030163 A1 [0004]
• - EP 1174537 B1 [0004]

Claims (16)

Device for automatic balancing of a rotating machine part, are arranged within which the axis of rotation of the machine part balancing disc in an annular cavity freely movable balancing masses, which compensate for the existing imbalance by taking a counter-position, the balancing disc from a first and from a second half-shell consists, and the annular cavity is formed by the first and the second half-shell, characterized in that the first and / or the second half-shell consists of plastic or consist. Device according to claim 1, characterized in that that both half shells are made of plastic. Device according to claim 2, characterized in that that the annular cavity by a cohesive Connection formed between the first and the second half-shell becomes. Device according to claim 3, characterized in that that the cohesive connection by ultrasonic welding or sticking is formed. Device according to Claim 1 or 2, characterized that the annular cavity by a positive Connection formed between the first and the second half-shell becomes. Device according to claim 5, characterized in that that the first and the second half-shell by latching or snap hook connected to each other. Device according to one of the preceding claims, characterized in that at least one half-shell means for having rotationally fixed connection with the machine part. Device according to claim 7, characterized in that that the means for non-rotatable connection through a bore and / or by one or more axial projections on one end face the first and / or the second half-shell are formed. Device according to one of the preceding claims, characterized in that a half-shell is perpendicular to the Rotation axis of the machine part extending driving surface for contacting an axial end face of a tool. Device according to one of the preceding claims, characterized in that the at least one of plastic existing half-shell has radially extending ribs. Device according to one of the preceding claims, characterized in that the at least one of plastic existing half-shell made of fiber-reinforced plastic. Device according to one of the preceding claims, characterized in that the at least one of plastic existing half shell is made by injection molding. Device according to one of the preceding claims, characterized in that the annular cavity a radially inner and a radially outer subspace has and in both sub-areas balancing masses available are. Device according to one of the preceding claims, characterized in that in the annular cavity a damping fluid is located. Device according to one of the preceding claims, characterized in that the balancing masses as balls, ball rollers or cylindrical rollers are formed. Device according to one of the preceding claims, characterized in that the device as a compensation element used with angle grinders.