Drive apparatus for a balancing machine and a balancing machine

A balancing machine drive apparatus for driving rotational movement of a workpiece rotatably mounted about a rotational axis by a looping belt includes a frame at least partially surrounding, transaxially to the rotational axis, a workpiece mounting position and having an opening closable by an arch and through which the mounting position is accessible, the drive apparatus including guide devices on the frame and/or arch to guide the belt such that, when the arch is closed, the belt winds at least partially around a workpiece in the mounting position on a cylindrical circumferential workpiece region, and a drive device for the belt. The arch is held on the frame so as to be movable between open and closed positions. A balancing machine for balancing a workpiece includes a mounting apparatus in order to rotatably mount the workpiece about a rotational axis in a mounting position, and the drive apparatus.

CROSS REFERENCE TO RELATED APPLICATIONS

Applicant claims priority under 35 U.S.C. § 119 of German Application No. 10 2017 007 328.7 filed Aug. 4, 2017, the disclosure of which is incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a drive apparatus for a balancing machine for driving rotational movement of a workpiece, which is rotatably mounted about an axis of rotation, by means of a looping belt, the drive apparatus comprising a frame which, transaxially to the axis of rotation, surrounds a mounting position for the workpiece at least in part, the frame having an opening which can be closed by means of an arch and through which the mounting position is accessible, the drive apparatus comprising guide devices arranged on the frame and/or the arch, in order to guide the belt such that, when the arch is closed, the belt winds around a workpiece in the mounting position on a cylindrical circumferential region of said workpiece at least in part, and the drive apparatus further comprising a drive device for the belt.

The invention also relates to a balancing machine for balancing a workpiece, comprising a mounting apparatus in order to rotatably mount the workpiece about an axis of rotation in a mounting position, and comprising a drive apparatus.

2. Description of the Related Art

A wide range of balancing machines for balancing workpieces are already known in the prior art. A balancing machine of the type in question is described in JP 2001-33339 A, for example. In general, the workpiece to be balanced, often also referred to as the rotor, is rotated by means of a suitable drive and examined for unbalanced mass using sensors. Various drive approaches are also known, e.g. driven shafts that are connected to the rotor, or looping belts that act on an outer circumference of the rotor.

In the case of “belt drives”, there are known systems in which the belt is guided tangentially to the rotor and accordingly rests against the rotor in a more or less selective manner, i.e. only over a very small angle range of the circumference of the rotor in question. In the case of another class of known belt drives, the belt winds around the rotor and accordingly rests against the rotor over a large range of the circumference of the rotor. The invention concerns only the latter class of belt drives.

In the case of drives having encircling belts, i.e. those of the type in question, the problem often arises that the belt winds around up to half of the circumference of the workpiece and gets in the way when the workpiece is changed. The prior art therefore discloses belt drives in which the belt can be placed around the workpiece and lifted from the workpiece by means of a pivotable arm.

It is generally desirable to balance as many workpieces as possible in the shortest time possible and to the highest possible degree of precision, it being strived at the same time to be able to use the same machine for the widest possible range of different workpieces. This places high demands on variance, stability, reproducibility of the adjustment options, handling and ergonomics, which requirements have not previously been adequately met by existing systems.

SUMMARY OF THE INVENTION

The object of the invention is to improve at least a few of these aspects in comparison with known solutions.

Said object is achieved according to the invention by a drive apparatus for a balancing machine for driving rotational movement of a workpiece, which is rotatably mounted about an axis of rotation, by means of a looping belt, the drive apparatus comprising a frame which, transaxially to the axis of rotation, surrounds a mounting position for the workpiece at least in part, the frame having an opening which can be closed by means of an arch and through which the mounting position is accessible, the drive apparatus comprising guide devices arranged on the frame and/or the arch, in order to guide the belt such that, when the arch is closed, the belt winds around a workpiece in the mounting position on a cylindrical circumferential region of said workpiece at least in part, and the drive apparatus further comprising a drive device for the belt, the drive apparatus according to the invention having been developed in that the arch is held on the frame so as to be movable between an open position and a closed position.

The belt can generally be removed for replacement purposes. The invention therefore also expressly relates, in addition to an operational drive apparatus, to a drive apparatus, according to the invention, of which the belt has been removed.

One advantage of the invention is that the movable arch according to the invention does not have to be lifted, in contrast with known pivoting or hinged arches. In particular, the invention also makes it easy to operate the arch, requires little effort and involves short operating distances. This considerably improves the ergonomics and the cycle time for changing the workpiece.

A preferred development of the invention is characterized in that the mass distribution of the arch and all the components of the drive apparatus that are movable together with the arch are balanced such that the gravitational torque acting on account of the mass distribution is not sufficient to overcome a frictional force acting counter to movement of the arch.

In this connection, friction or frictional force is understood in particular to refer to static friction when the arch is in any stationary position and/or sliding friction when the arch is moved.

This advantageously prevents the arch from moving unintentionally and/or uncontrollably and/or independently and increases operational safety. At the same time, this is also achieved without damping or braking elements that increase the effort required to move the arch, to the benefit of the ergonomics.

The guide devices are each designed, for example, as guide rollers for the belt. If the guide rollers also comprise retaining devices, e.g. guide plates, the belt is effectively prevented from jumping off the guide rollers, and the operation of the drive apparatus according to the invention is further simplified.

If a first of the guide devices is arranged on the arch, and a second of the guide devices is arranged on the frame, the belt used as intended in particular being guided over the workpiece, mounted as intended, between the first guide device and the second guide device when the arch is closed, the belt thus advantageously clears the mounting position for the component when the arch is opened, without further intervention, such that a component can be readily inserted in or removed from the mounting position. When the arch is closed, the belt is then placed around the component, without further intervention, such that the drive apparatus according to the invention is operational as soon as the arch is closed.

A locking device, for example, is provided for fixing the closed arch. A both particularly simply constructed and easy-to-handle locking device comprises an eccentric tension lever in order to releasably frictionally fix the closed arch on the frame.

For the purpose of adjustment to different rotor dimensions, a drive apparatus according to the invention advantageously comprises a tensioning device for the belt. As a result, a belt of a specified length can be used for a wide range of rotor dimensions such that the set-up time for changing the belt is no longer required when the workpiece is changed.

The tensioning device is preferably arranged on the frame so as to limit the mass on the arch, which mass would otherwise have to be moved together with the arch when it is opened and closed. This also improves the ergonomics and reduces cycle times.

For the quality of the balancing results, it has proven to be particularly advantageous for the belt to extend vertically from below over the workpiece and to run vertically back downwards from the workpiece on the other side. In order to make it possible to guide the belt in this manner for different workpiece diameters, the second guide device is advantageously arranged on the frame such that its position can be changed. The first guide device is arranged, for example, on the arch such that its position can be changed. Additionally or alternatively, the closed position of the arch is particularly advantageously designed so as to be adjustable. In this case, a stop of which the position can be changed, for example, makes it possible to reproduce the closed position.

A particularly preferred embodiment of the invention is characterized in that an arc-shaped sliding guide for the arch is provided on the frame. This allows a particularly short operating distance for the arch. Furthermore, a particularly compact design of the drive apparatus according to the invention having minimized installation space requirements is made possible because the arch overlaps the frame significantly in every position. Furthermore, a further advantage is that, when the arch is open, hardly any additional installation space, or none at all, is required in comparison with when the arch is closed.

The arc-shaped sliding guide and an accordingly curved basic shape of the arch result in a centre of gravity of the arch that is close to the centre of the circular path. On account of the resultant reduced leverage, and irrespective of the actual weight of the arch, only low gravitational torques act, which can be even further reduced by means of a balanced mass distribution on the arch. The invention thus makes it possible for the friction of even a very smooth-running mounting of the arch on the sliding guide to be sufficient to effectively prevent the arch from moving unintentionally and independently. This results in an intrinsic safety torque with regard to injuries, in particular crush injuries, even without corresponding safety measures, such as damping elements or other braking devices on the arch.

An embodiment of the invention that is particularly advantageous in this regard is characterized in that the frame and the arch surround the mounting position for the workpiece substantially concentrically with the axis of rotation.

If a further guide device is arranged on the arch, the first guide device and the further guide device in particular being arranged on opposite regions of the arch, it is also made possible, in addition to the mentioned advantages, for the belt to be carried along by the further guide device and loosely tensioned when the arch is opened. This prevents the belt from sagging excessively, and effectively prevents the belt from unintentionally getting caught when the arch is moved or any other kind of interruption to the guiding of the belt from occurring. This further simplifies the handling and further reduces the cycle time because it is no longer necessary to manually intervene to correct the guiding of the belt.

From geometric points of view, it has proven to be particularly advantageous, in the case of the described concentric arrangement, for the opening in the frame to correspond to between 100° and 130° of the transaxial periphery of the axis of rotation in order to allow the largest possible opening width and thus the largest possible maximum workpiece diameter. It is also advantageous for the closed position of the arch to be designed so as to be adjustable within an adjustment range, which corresponds to at least 45° of the transaxial periphery of the axis of rotation. This allows the guiding of the belt to be sufficiently adjustable in order to be able to process both workpieces that have a maximum diameter or circumference determined by the opening width and workpieces that have the smallest possible diameter or circumference.

The object of the invention is also achieved by a balancing machine for balancing a workpiece, comprising a mounting apparatus in order to rotatably mount the workpiece about an axis of rotation in a mounting position, and comprising a drive apparatus according to the invention.

The invention is made more variable if the balancing machine comprises a machine bed on which the drive apparatus is arranged so as to be longitudinally axially movable. This makes it possible to also process irregular workpieces that only have a cylindrical circumference in portions. In particular, for this purpose the drive apparatus is moved longitudinally axially on the machine bed and oriented such that the belt can act on a cylindrical portion of the workpiece. Further variability is also achieved if the mounting apparatus is also arranged so as to be longitudinally axially movable on the machine bed on at least one side in order to adjust, for example, the mounting position for the workpiece to the overall length of the workpiece.

Particularly synergistic advantages emerge from the invention if the balancing machine according to the invention further comprises a protective case, which surrounds at least the mounting apparatus, the mounting position for the workpiece and the drive apparatus and which has a loading and unloading opening, and a cover device for covering the loading and unloading opening. In this case, as a result of the described compact design of the drive apparatus which the invention makes possible, the protective case and in particular the cover device are accordingly also intended to be compact. This improves the ergonomics of a balancing machine according to the invention and reduces the cycle time during material changes, which of course also requires the cover device to be opened and closed. Since the invention also makes it possible to design the drive apparatus without the open arch requiring additional installation space, the cover device is prevented from colliding with the open arch, and it is therefore possible to dispense with corresponding safety or barrier devices.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1shows a schematic view of a balancing machine1according to the invention.

The balancing machine1comprises a workspace8in which two mounting devices2for rotatably mounting a rotor60in a mounting position6are arranged on a machine bed5. By way of example, a rotor60is also shown, which is shown as a wheel hub, without this limiting the invention. The mounting devices2can be moved on the machine bed5axially in parallel with the rotor60arranged as intended, in order to be able to carry out adjustments to different rotors60of different lengths.

A drive apparatus10according to the invention is arranged between the two mounting devices2in order to rotate a rotor60, mounted as intended, in a controlled manner in order to check for unbalanced mass. Sensor, control and analysis devices required for this purpose are also part of the balancing apparatus1according to the invention and are generally known. Said devices will therefore not be discussed in detail, for the sake of a concise description of the invention.

The drive apparatus10according to the invention is designed as per the principle of the winding belt drive. In this case, a drive belt4of the drive apparatus10acts on a portion of the rotor, which portion has to be cylindrical. In order to be able to process different rotors60, which may also have very complex shapes and of which only portions have to have cylindrical outer contours, the drive apparatus10is preferably also arranged so as to be movable along the machine bed5.

The workspace8is surrounded by a protective case7and is closed by a protective hood9for the operation of the balancing machine. As is shown inFIG. 1, the open protective hood9uncovers a generous loading and unloading opening in the protective case7in order to easily place rotors60in the provided mounting position6or remove said rotors therefrom, and in order to adjust the various elements of the balancing machine1according to the invention to a specific rotor60. The drive apparatus10of the balancing machine1according to the invention, which apparatus is inventive in its own respect, advantageously allows the construction of a protective hood9which is smaller and/or lighter than in the prior art, and a smaller opening distance of said hood.

Each ofFIGS. 2 and 3is a perspective view of the drive apparatus10according to the invention of the balancing machine1according to the invention from two different points of view, which machine is given by way of example.

The drive apparatus10comprises a frame20which surrounds a mounting position6for a workpiece to be balanced. A rotor60is also shown here by way of example. An axis of rotation62of the rotor60is also shown schematically, the frame20surrounding part of the rotor60transversely to the axis of rotation62.

The frame20has an opening22in order to place a rotor60in the mounting position6provided therefor, which position is defined crucially by the mounting devices2and is surrounded by the frame20, or in order to remove said rotor from said mounting position.

An arch30is provided in order to close the opening22. The arch30is held, by means of a bearing34, on a rail24attached to the frame20and is mounted so as to be movable along the rail24. For easier and safer handling, the arch30comprises, by way of example, an operating lever32or a different handle.

In the closed position, the arch30is releasably locked such that, by means of both the bearing34and a suitable locking mechanism36, the frame20and the closed arch30form a mechanically stable and robust structure that surrounds the mounting position and/or the rotor60. In the embodiment of the invention shown, the locking mechanism36is formed, by way of example, as a clamping locking mechanism which can be pretensioned by means of an eccentric tension lever37and then frictionally locks the arch30in the closed position.

For balancing, the rotor60is rotated about the provided axis of rotation62. This takes places by means of a motor48, which is attached to the frame and drives a closed or endless drive belt4by means of a belt pulley49. The drive belt4is guided over guide rollers40,41,42on the frame20and/or the arch30such that belt4winds around the rotor60in a cylindrical region and the rotor is thus driven by the looping belt4.

In the embodiment of the invention shown by way of example, the belt4is in particular guided over the rotor60between a first guide roller40on the arch30and a second guide roller41. Depending on the loop direction of the belt, the belt therefore runs from the first guide roller40upwards, then over the rotor, and down again to the second guide roller41, or vice versa.

Further guide rollers42,43are provided and suitably arranged to guide the belt in a closed loop and in a defined manner between the first guide roller40, the belt pulley49and the second guide roller41. The guide rollers42and43are arranged, by way of example, on the arch such that the belt is guided around the outside of the rotor60at a sufficient distance.

The first guide roller40on the arch30is arranged, for example, on the free end of the arch30, i.e. in particular on the end thereof opposite the bearing34. Movement of the closed position of the arch30leads to movement of the first guide roller40and to the belt being guided to and/or from the rotor60in a different manner. In particular, it is made possible in this respect to adjust the guiding of the belt to the diameter of the rotor60such that it is in particular made possible to particularly advantageously guide the belt vertically between the first guide roller40and the rotor60for any desired rotor diameters.

In the case of the drive apparatus10according to the invention that is shown by way of example, the desired closed position of the arch30can be reproducibly specified by means of a movable stop26on the frame20, it being possible, even after the stop26has been moved, to reset a previously defined closed position to a high degree of precision by means of, for example, a scale28along the movement path. A structurally simple solution consists, by way of example, in moving the stop26, which has a suitable securing device26′, continuously along a slot28and fixing said stop in the desired position by tensioning the stop26and the securing element26′ in the slot.

In a comparable manner, in the case of the embodiment shown, the guiding of the belt between the rotor60and the second guide roller41can be adjusted by the bearing of the second guide roller41on the frame20being designed so as to be movable. In this case too, a scale47may be provided to simplify the adjustment. A simple structural solution consists, by way of example, in releasably tensioning the shaft of the guide roller41in a slot45by means of a suitable securing device44′.

A tensioning roller44of which the position can be changed is also provided in order to specify the tensioning of the belt. A comparably large adjustment range also makes it possible to cover a very wide range of possible rotor diameters by means of just a single belt4of a specified length.

Belt guide plates46on the guide rollers40,41,42,43and on the tensioning roller44prevent the belt from jumping off unintentionally; however, said plates are preferably arranged so as not to touch the belt4as it loops as intended. Within the scope of the invention, said belt guide plates46, which are shown by way of example, may also alternatively be designed as other kinds of retaining devices for the belt4; retaining devices in general, and belt guide plates46in particular, are generally advantageous, but not essential to the invention.

A further advantage of the invention can be seen when the arch30is open. This position is shown inFIG. 3.

By means of the belt guide plate46on the guide roller43, which roller is arranged on the bearing end of the arch30, the belt4is carried along and loosely tautened in the region between the guide roller42and the tensioning roller44or the belt pulley49when the arch is opened. In place of the belt guide plate46on the guide roller43, this advantage may also be achieved by any desired guide or retaining device arranged on the bearing end of the arch30.

At the same time, the guide roller43picks the belt up in the region between the guide roller40and the guide roller41and further tautens the belt, though without tightly tensioning the belt4. As a result, the belt4never sags and cannot therefore unintentionally become tangled or stuck either.

As can also be seen from the view inFIG. 4, the arch30does not project beyond the frame20in any position, apart from when the opening22is closed as intended, of course. The installation space occupied by the drive apparatus10is therefore not linked to the position of the arch30. As a result, the protective hood7is advantageously prevented from colliding with the open arch30.

LIST OF REFERENCE NUMERALS