EP2983864B1 - Method and device for the surface treatment of workpieces - Google Patents

Description

The invention relates to a method for the surface treatment of workpieces by the workpiece is moved relative to a bed of a grinding and / or polishing granules, wherein the workpiece is rotated with respect to the bed of the grinding and / or polishing granules about at least one axis wherein the workpiece is accelerated to different rotational speeds with respect to the bed of abrasive and / or polishing granules. The invention further relates to a device suitable for carrying out such a method for the surface treatment of workpieces by moving the workpiece relative to a bed of a grinding and / or polishing granules, with at least one workpiece holder for releasably securing a workpiece to be machined and optionally a container for receiving the grinding and / or polishing granules, wherein the workpiece holder and / or the container is associated with at least one rotary drive and the device further comprises a programmatically configured control device which is able to control at least the rotational drive of the workpiece holder and / or the rotational drive of the container.

Such devices for the surface treatment of workpieces using a granular grinding and / or polishing medium are known for example in the form of so-called drag and dip finishing machines. Their mode of action is based on dipping the workpiece to be machined in a container located in a bed of the grinding and / or polishing granules and the workpiece, in particular rotationally and possibly also translationally to move relative to the granules, whereby the surface of the workpiece depending grinded and / or polished according to granules. Towing and dipping machines represent a special form of vibratory finishing machines, wherein the workpieces to be machined, for example individually on one or more, by means of a rotary drive rotatable about its axis workpiece holders can be clamped. In order to move the workpieces translationally relative to the grinding and / or polishing granules, known drag finishing machines often comprise a generally rotating part substantially in the form of, for example, a motor driven by a suitable gear rotation plate on which the workpiece holder directly or, for example via lifting devices , are determined indirectly. This happens in particular eccentrically with respect to the axis of rotation of the rotating part of the drag finishing machine. If this part - the so-called plate - of the towing machine is rotated, the workpiece holders defined here describe a trajectory. The workpieces carried by the workpiece holders are immersed in the working container, which is filled with the bed of the particulate abrasive or polishing granules, often with the addition of liquid processing media, such as water, surfactants, etc. Due to the relative movement of the workpieces with regard to the granules, their surface treatment takes place in the form of a vibratory finishing process. Such drag finishing machines are for example from the DE 102 04 267 C1 . DE 200 05 361 U1 or DE 10 2010 052 222 A1 known.

The DE 10 2011 103 606 A1 and DE 10 2009 021 824 A1 are further devices for the surface treatment of large-sized workpieces, in particular in the form of turbines, refer to which comprise a rotationally driven workpiece holder, which dips into a stationary, receiving the granular bulk container. An associated with the workpiece holder movement unit provides for a rotating or alternating movement of the workpiece about its axis or for different movements of the workpiece in the abrasive granules (rotating and oscillating) with varied rotational speed and immersion depth. As an alternative or in addition to a translational movement of the workpieces clamped on the workpiece holders themselves, the container receiving the processing medium can also be moved relative to the workpieces, which in turn are rotated about their own axis, for example about its own axis and / or along a trajectory , eg in the form of a circular path. If only the container is moved and the workpieces themselves do not perform a translatory movement, then this is also referred to as "dip grinding" or "dip polishing", which thus represents a special form of drag finishing.

Modern for the surface processing of the workpieces usually used devices, such as the dipping and / or drag finishing machines of the aforementioned type, include for Achieving an automated operation usually a programmatically set up control device which at least the rotational drive of the workpiece holder and possibly also a translatory drive and / or a (rotary) drive of the container according to various, can be entered in an input device speeds, movement speeds and processing times able to control ,

The DE 10 2011 015 750 A1 describes a further method and a device for the surface treatment of workpieces, which are intended in particular for the gentle processing of very sensitive workpieces, in particular in the form of optical lenses, which must meet very tight tolerances. The workpiece holders are in this case carried by a programmed controllable manipulator, such as an industrial robot, to pivot about a workpiece clamped on the workpiece holder during machining about several different axes and thereby the angle of incidence of moving in the container grinding and / or polishing granules Change relation to discrete areas of the workpiece and thus to provide the desired grinding and / or polishing effect for the respective surface area of the workpiece can. The manipulator is able, as required, to continuously rotate the workpieces clamped on the workpiece holder at constant or adjustable different rotational speeds and / or rotational directions about the axis of the workpiece holder and / or to translate them in the bed from the grinding and / or polishing granules or To immerse workpiece only in the same. The container may in turn comprise a controlled rotary drive to rotate it at the respectively desired rotational speed offset and change the flow velocity of the granules relative to the workpiece. A similar method or a similar device is known from EP 2 572 829 A1 known.

The EP 1 362 669 A2 describes a generic Schleppfinishmaschine, in which the workpiece on the one hand in the vertical direction in the form of an oscillation translationally back and forth, on the other hand is rotated constant rotationally about its own central axis. A control device ensures a speed control and a reversal of the direction of rotation of the drives of the workpiece holder. From the DE 10 2010 052 222 A1 Another generic Schleppfinishmaschine is known, wherein the individual workpiece holder are arranged on a rotatable plate, which can be rotated in both directions of rotation to rotate the workpiece holder between a loading or unloading position and multiple processing positions back and forth. The clamping devices of the workpiece holder are controlled in rotation by means of motor drives in both directions of rotation. A programmable control device of the drag finishing machine can be programmed with regard to the processing parameters of the direction of rotation and the rotational speed of the workpiece holder as well as the residence time of the surface treatment.

The grinding and / or polishing granules used in generic grinding or polishing process, moreover, in principle, depending on the treated workpieces of various nature and eg natural origin (eg organic material such as walnut or coconut shells, wood, cherry stone, etc.), mineral Origin (eg of silicates, oxides, etc.) and / or of synthetic origin (eg made of plastics). In addition, it is - as already indicated - possible to perform the vibratory finishing dry or - with the addition of a liquid processing medium, such as water, which may be mixed with additives such as surfactants - in the form of wet processing.

However, it has been shown that, even in the case of a rotational movement of the workpieces about the axis of the workpiece holder which is superposed by a translatory movement of the workpieces through the grinding and / or polishing granules, which may be both clockwise and anticlockwise, that is to say in different directions of rotation, can occur, at least partially unsatisfactory surface machining of the workpieces can come, which is particularly true for workpieces with relatively complex geometry, such as those with grooves, undercuts or even with more or less large cavities, wells or the like. The reason for this consists primarily in the fact that the granules are taken in the immediate vicinity of the rotated relative to the granulate workpiece from the latter, so that the relative movement of the granules in relation to the workpiece on the workpiece surface is significantly less than the rotational speed of the workpiece itself (or as the rotational speed of the granule bed rotated together with the container). This applies, as already stated, to a particular extent if the workpiece is provided with surface structures, such as grooves, undercuts, etc., or if the workpiece has one or more larger cavities or depressions into which the granulate particles can deposit during processing and be taken with the rotating workpiece.

In the prior art, this problem is primarily addressed by turning the workpiece with the highest possible rotational speeds, but this requires a high drive engineering effort and limits the maximum speed. In addition, it has been found that a mere reversal of the direction of rotation can not entirely remedy this problem even when the workpiece is rotated at high rotational speeds both clockwise and anticlockwise. As regards relatively large cavities or depressions of the workpiece, such as in the case of workpieces in the form of bottles or other vessels or a mold cavity having molds, so also very high rotational speeds only after (too) long processing time to a satisfactory surface processing of such cavities or To guide depressions of the workpiece surrounding inner walls.

The DE 20 2009 008 070 U1 describes a provided for Schleppfinishmaschinen workpiece holder whose rotatable displaceable workpiece carrier to which the workpieces are clamped at an inclination angle between 5 ° and 35 ° with respect to the clamping device of the workpiece holder itself are arranged, the angle of inclination in particular between said angular range and an angle of 0 (vertical arrangement) can be adjustable. In this way, the incorporation of granular particles in grooves or undercuts of the workpiece is effectively reduced because the particles are discharged due to the inclined axis of rotation during operation of such surface structures of the workpiece again. However, this is also true here the aforementioned problem of forming a velocity gradient, wherein the relative velocity of the granules decreases with respect to the rotated workpiece, the closer a granular particle is located on the workpiece.

The invention is therefore the object of a method and an apparatus for surface treatment of workpieces of the type mentioned in a simple and cost-effective way to the effect that the problem of entrainment of workpiece near granular particles with the rotated workpiece and consequent efficiency losses of the surface treatment can be effectively countered can and in particular a satisfactory surface processing of relatively large cavities or depressions having workpieces in economically acceptable processing time is possible.

In procedural terms, this object is achieved in a method of the type mentioned above in that the workpiece and / or the bulk of the grinding and / or polishing granules receiving container is rotated under continuous acceleration with continuously different rotational speeds or become ,

In terms of device technology, the invention according to claim 13 for solving this problem in a device for the surface treatment of workpieces of the type mentioned further, that the control device for continuously accelerating the rotational drive of the workpiece holder and / or the rotational drive of the container with continuously different rotational speeds during the Operation is set up.

According to an advantageous embodiment of the method according to the invention can be provided that the workpiece and / or a bed of the grinding and / or polishing granules receiving container in periodic cycles of at most 5 s between at least a first rotational speed and at least one second rotational speed back and forth is accelerated or become. A corresponding device is therefore advantageously distinguished by the fact that the control device for reciprocating the rotational drive of the workpiece holder and / or the rotary drive of the container is set up in periodic cycles of at most 5 s between at least a first rotational speed and at least one second rotational speed. The inventive design prevents in a very simple and cost-effective manner, the formation of a velocity gradient of the granular particles in the immediate vicinity of the rotated workpiece by the latter with continuously different rotational speeds in relation to the granular bed, especially in very short periodic cycles between different rotational speeds back and forth accelerated , Consequently, the workpiece or the granulate bed received in the container is in particular continually reciprocated between one or more first rotational speeds and one or more second rotational speeds, and within the short periodic intervals or cycles expediently in each case a maximum Rotation speed is reached, then slow down again (negative speed), then again (positive) to accelerate, etc. On this A temporally changed, in particular high relative speed between the workpiece and the grinding and / or polishing granules is always ensured directly on the workpiece surface, whereby a significantly increased processing efficiency and associated, shorter processing times can be achieved. This is especially true for workpieces with relatively large cavities or depressions, in which the granulate particles of the bed in the case of a more or less constant rotational speed of the workpiece according to the prior art after a relatively short time only be moved together with the rotating workpiece, without It comes to a significant relative movement more, but of course for a surface treatment is absolutely necessary. Any conversion of known towing and Tauchfinishmaschinen to the embodiment of the invention basically requires only a programmatic intervention in the control device to cause this, the rotational drive of the or the workpiece holder (s) or the container during operation in very short periodic cycles to accelerate back and forth between different rotational speeds and / or with continuously different rotational speeds.

By "accelerating" in the sense of the invention, moreover, both a positive acceleration and a negative acceleration or deceleration of the rotating workpiece or of the workpiece holder and / or the rotating container carrying it are addressed. In this context, "cycles" refer to the successive-identical or possibly also different-durations during the surface treatment, in which the workpiece or the granulate bed received in the container is moved once back and forth between at least a first and at least a second rotational speed.

In an advantageous embodiment it can be provided that the workpiece and / or the container with the granulate bed located therein is accelerated to and fro at least temporarily or temporarily between at least a first rotational speed of substantially equal to zero and at least a second rotational speed not equal to zero , Accordingly, a rotational speed profile described above is preferably set in which the first rotational speed is approximately equal to zero, and it is generally sufficient to achieve the effect according to the invention, the workpiece or the granules received in the container not to absolute standstill (negative) accelerate, but the workpiece or the container, for example continuously accelerated to a very low (first) rotational speed of, for example, a maximum of about 50 rpm, preferably a maximum of about 10 rpm (negative) and then returned to the desired, e.g. maximum (second) rotation speed (positive) can be accelerated.

As will be explained in more detail below, in both cases, the rotational speed of the workpiece and / or the container with the granulate therein may preferably be substantially sinusoidal (ie both periodically between at least two rotational speeds back and forth as well as under continuous acceleration temporally changed rotational speed), whereby the amplitude (speed) such a sinusoid may be approximately constant (eg, between a rotational speed of about zero and the same maximum rotational speed), or may be different, for example, when the initial rough machining has very high (or rather low) rotational speeds and later (fine) processing is lower (or higher). Speeds are desired (in this case, the amplitude of such a sinusoid decreases, for example, with increasing processing time or to).

In an advantageous embodiment can also be provided that the workpiece and / or the container with the granulate therein herein at least temporarily or temporarily between at least a first rotational speed not equal to zero and at least a second rotational speed with respect to the first rotational speed opposite direction of rotation back and forth is accelerated or become. Such reversal of the direction of rotation during machining, which takes place in continuously periodic cycles, prevents the formation of a velocity gradient of the granulate particles in the vicinity of the workpieces rotated relative to these, in particular also in the case of grooves, depressions or similar surface structures. The same applies to a filled in a relatively large cavity or such recess of the workpiece granule bed when the workpiece is accelerated in the aforementioned manner. The amounts of rotational speeds in or counterclockwise can in turn be either constant or variable over the processing time and the same or different from each other.

The maximum rotational speed (s) can basically correspond to the rotational speeds which are usually set and suitable for the respective workpiece, wherein the workpiece and / or the container with the granulate bed located therein in particular at least one (first and / or second) Rotation speed of at least about 200 U / min, in particular of at least about 500 U / min, preferably of at least about 1000 U / min, can be accelerated. Particularly preferred maximum rotational speeds are at least about 1500 rpm, or more preferably at least about 2000 rpm. Corresponding values apply to the amount of the speed difference between at least one first and at least one second rotational speed between which the workpiece and / or the container is accelerated back and forth.

On the occasion of the rotational movement of the workpiece and / or the container between the at least one first and the at least one second rotational speed back and forth, the periodic cycles should be chosen as short as possible in terms of effective and time-efficient surface processing, wherein it may preferably be provided that the workpiece and / or the container having the granulate bed therein at least temporarily in periodic cycles of at most about 4 seconds, more preferably at most about 3 seconds, preferably at most about 2 seconds, for example at most about 1 second or even at most about 0.5 second the at least one first and the at least one second rotational speed are accelerated back and forth.

• in periodischen Zyklen von höchstens 5 s zwischen wenigstens einer ersten Rotationsgeschwindigkeit und wenigstens einer zweiten Rotationsgeschwindigkeit hin und her beschleunigt als auch
• unter fortwährender Beschleunigung mit fortwährend unterschiedlichen Rotationsgeschwindigkeiten rotiert

wird bzw. werden. In diesem Zusammenhang wird bzw. werden das Werkstück und/oder der Behälter mit der hierin befindlichen Granulatschüttung mit Vorteil zumindest vorübergehend bzw. zeitweise mit einem im Wesentlichen sinusförmigen Verlauf der Rotationsgeschwindigkeit über die Zeit hin und her beschleunigt, wobei die Periode bzw. der Zyklus des im Wesentlichen sinusförmigen Verlaufes der Rotationsgeschwindigkeit insbesondere höchstens etwa 5 s betragen kann (aber auch länger andauern kann, sofern eine fortwährende Rotationsgeschwindigkeitsänderung sichergestellt ist).As already indicated, a particularly advantageous embodiment of the method according to the invention provides that the workpiece and / or a container receiving the filling from the grinding and / or polishing granules both

• in periodic cycles of at most 5 s between at least a first rotational speed and at least a second rotational speed accelerated back and forth as well
• rotated under continuous acceleration with continuously different rotational speeds

will or will be. In this context, the workpiece and / or the container with the granulate bed located therein is advantageously accelerated over time, at least temporarily or temporarily with a substantially sinusoidal profile of the rotational speed over time, the period or the cycle of the may be substantially sinusoidal course of the rotational speed, in particular at most about 5 s (but may also last longer, provided that a continuous rotation speed change is ensured).

In this case, the workpiece and / or the container with the granulate bed located therein can at least temporarily with a substantially sinusoidal course of the rotational speed over time with approximately constant amplitude (ie with approximately constant distance between the minima or maxima of the rotational speeds ) or with amplitude that varies over time (ie with different distances between the minima or maxima of the rotational speeds) can be accelerated back and forth.

If the latter method variant is selected and the workpiece and / or the container with a substantially sinusoidal course of the rotational speed with variable amplitude over time is accelerated back and forth, such as on the occasion of an above-mentioned initial coarse grinding, which gradually into a Finishing passes, preferably the amplitude of the substantially sinusoidal course of the rotational speed over time, at least temporarily, in particular substantially steadily, decrease or increase, so that the minima or maxima of the rotational speeds converge or diverge.

According to an advantageous embodiment may also be provided that at least one cavity or at least one recess of the workpiece with the bed of the grinding and / or polishing granules filled and the workpiece at least about an axis, in particular substantially around the central axis of the cavity or the Deepening is rotated under continuous acceleration with continuously different rotational speeds to grind and / or polish at least the wall or the cavity surrounding the wall of the workpiece. As already mentioned, it may also be expedient in such an embodiment variant if the workpiece is accelerated back and forth about the at least one axis in periodic cycles of at most 5 s between at least one first rotational speed and at least one second rotational speed. Furthermore, it is of course also possible to set velocity profiles of the above-mentioned type. In this way, in particular, the inner walls of the workpiece surrounding such cavities and / or depressions, such as a workpiece in the form of a mold, a bottle or any other vessels, etc., grind and / or polish in a very effective and time-efficient manner, the granules filled in the cavity / cavity of the workpiece accelerated several times to different rotational speeds not due to inertia ( appreciable) of the always differently rotated workpiece is taken. If only the recess or the cavity is to be surface-treated in such a workpiece, it goes without saying that a device suitable for this purpose does not necessarily have to have a container for holding (further) grinding and / or polishing granules. Moreover, it may be useful in such a case, when the hollow workpiece is rotated about the central axis of its cavity or its recess in the manner according to the invention, which in particular can be arranged substantially horizontally during the surface processing in order to take advantage of the gravity of the granular bed do.

If such cavities and / or depressions having workpieces (also) should be surface-treated on the outside and / or provided that workpieces with only relatively small grooves / undercuts or workpieces without such surface contours should be effectively surface-treated in a relatively short time, so may alternatively or additionally be provided in an advantageous embodiment, of course, that the workpiece immersed in such a known manner in the container given a charge of the grinding and / or polishing granules and the workpiece under continuous acceleration with continuously different rotational speeds The workpiece can be accelerated back and forth, in particular in periodic cycles of at most 5 s between at least one first rotational speed and at least one second rotational speed. Compared to a rotational movement of the container with such a speed profile, this alternative (active rotation of the workpiece itself) due to the usual inertia of a particle bed and the consequent delay entrainment with an accelerated container is usually preferred, but it can be especially at Of course, relatively heavy workpieces and consequent high torques during deceleration / acceleration of the same also offer, instead of such a rotational movement of the workpiece itself to provide an active turning of the container with the granular bed with such a rotational speed profile. Moreover, of course, a combination of both alternatives is conceivable, with the workpiece and container should be expediently at least largely rotated in opposite directions. As will be explained in more detail below, it is further conceivable, for example, to accelerate only the workpiece in the manner according to the invention to different rotational speeds and to let the container rest or if necessary to move more or less uniformly to the workpiece in addition to the container or otherwise only to accelerate the container in the manner according to the invention to different rotational speeds and to immerse the workpiece in the granulate bed located in the container and optionally in turn in addition more or less uniformly, eg translationally, to move, etc.

• stationär gehalten (ruhender Behälter); und/oder
• translatorisch hin und her bewegt;
• translatorisch entlang einer Bahnkurve, insbesondere entlang einer Kreisbahn, bewegt; und/oder
• rotatorisch um seine Mittelachse (gleichförmig oder mit unterschiedlicher Drehgeschwindigkeit und/oder -richtung) rotiert

wird. Im letztgenannten Fall wird der Behälter zweckmäßigerweise - sei es im Wesentlichen konstant oder sei es mit einer zeitlich veränderten Rotationsgeschwindigkeit - um seine Mittelachse rotiert, um Unwuchten zu vermeiden. Entsprechendes gilt grundsätzlich mit Vorzug auch für das rotierte Werkstück.Consequently, in particular when the workpiece is accelerated with a rotational speed profile according to the invention, it can be advantageously provided that the container is at least temporarily or temporarily

• kept stationary (resting container); and or
• translationally moved back and forth;
• translationally along a trajectory, in particular along a circular path, moves; and or
• rotated about its central axis (uniform or with different rotational speed and / or direction)

becomes. In the latter case, the container is expediently - be it substantially constant or be it with a temporally changed rotational speed - rotated about its central axis to avoid imbalances. The same applies in principle with preference also for the rotated workpiece.

The control device of a device according to the invention for the surface treatment of workpieces is therefore expediently set up for setting at least one, in particular several or preferably all above-described rotational speed profiles of the rotary drive of the workpiece holder and / or the container during operation.

As already mentioned, the invention of course also offers the possibility that the workpiece further - ie in addition to the rotational acceleration of the workpiece itself or in particular of the container - translationally, in particular along a trajectory, relative to the bed of the grinding and / or polishing granules is moved. This can be done, for example, by by the container moves with the bed of the grinding and / or polishing granules relative to the workpiece, in particular rotated, so that a continuous flow of the workpiece with the grinding and / or polishing granules in the direction of relative movement between the latter and the workpiece results, in particular when the workpiece, which in turn is rotated, is immersed eccentrically to the axis of rotation of the container in the granulate bed or even moved translationally. In terms of device technology, it can be expediently provided in this connection that the control device is also set up to control the rotational drive of the container to a rotational speed that is essentially constant in time but preferably variable, or else temporally variable.

Alternatively or additionally, for example, another, e.g. be provided translationally reciprocating reciprocating motion or vibration drive of the container, which is in operative connection with the control device.

Alternatively or additionally, moreover, a translational movement of the workpiece in the bed of the grinding and / or polishing granules relative to this can take place by the workpiece translationally along a trajectory, in particular in the form of a circular path or any other trajectory in the bed is moved from the grinding and / or polishing granules relative thereto. In this case, the workpiece can be moved in translation at a substantially constant speed relative to the charge from the grinding and / or polishing granules or, of course, at a variable speed become. In terms of device technology, it can be expediently provided in this connection for the work holder and / or the container also to be assigned a translatory motion drive and for the control device to be able to control the translational motion drive of the workpiece holder, in particular along a path curve, such as a circular path or any other desired path other trajectory. Such translational motion drives of the workpiece holder are known inter alia from the cited prior art and may for example comprise a rotating part of a drag finishing machine, the so-called plate, on which one or more workpiece holders are arranged eccentrically; or, for example, they may also include manipulators, such as robots and the like, carrying the workpiece holder (s).

As already mentioned, an advantageous embodiment of the method according to the invention also provides that at least the rotational movements of the workpiece and / or of the container with the granulate bed located therein and optionally the further (n) - translational and / or rotary (s) - Movement (s) of the workpiece and / or the container controlled, in particular programmed to be performed.

Servo motors, which can be preferably provided for rotationally driving the workpiece holder and / or the container of a device according to the invention, have finally proved particularly suitable for the high accelerations according to the invention within short cycles. Depending on the weight and conditional moment of inertia of the workpiece or the container can the respective rotary drive also be associated with a lower or transmission gear.

Fig. 1

eine schematische perspektivische Ansicht einer Ausführungsform einer erfindungsgemäßen Vorrichtung zur Oberflächenbearbeitung von Werkstücken in Form einer Schlepp- oder Tauchfinishmaschine;

Fig. 2

eine schematische perspektivische Explosionsdarstellung einer weiteren Ausführungsform einer erfindungsgemäßen Vorrichtung zur Oberflächenbearbeitung von Werkstücken;

Fig. 3

ein Schaubild eines Ausführungsbeispiels eines während des Betriebs der Vorrichtungen gemäß Fig. 1 und/oder 2 steuerungstechnisch einstellbaren vorteilhaften Rotationsgeschwindigkeitsprofils eines Werkstückhalters mit einem hieran gespannten Werkstück über die Zeit; und

Fig. 4

ein der Fig. 3 entsprechendes Schaubild eines Ausführungsbeispiels eines weiteren vorteilhaften Rotationsgeschwindigkeitsprofils.

Further features and advantages of the invention will become apparent from the following description of exemplary embodiments with reference to the drawings. Showing:

Fig. 1

a schematic perspective view of an embodiment of a device according to the invention for the surface treatment of workpieces in the form of a towing or dip finishing machine;

Fig. 2

a schematic perspective exploded view of another embodiment of a device according to the invention for the surface treatment of workpieces;

Fig. 3

a diagram of an embodiment of a during operation of the devices according to Fig. 1 and / or 2 technically adjustable advantageous rotational speed profile of a workpiece holder with a workpiece clamped thereto over time; and

Fig. 4

one of the Fig. 3 corresponding diagram of an embodiment of a further advantageous rotational speed profile.

This in Fig. 1 reproduced embodiment of an apparatus for the surface treatment of workpieces in the form of a towing or dip finishing machine has a frame 1, at its upper end a about a vertical axis 2 in the direction of arrow P ₁ back and forth rotating part 3 in the form of a rotatable support plate according to Art a plate is stored. The rotatable part 3 is for this purpose with a likewise equipped on the frame 1, controllable motor drive 4 equipped. At the bottom of the rotatable member 3 eccentric to the rotational axis 2 and circumferentially thereof at the same distance from one another and at the same radial distance from the axis of rotation 2 of the rotatable member 3 arranged lifting devices 5 are fixed, in the present embodiment, three such lifting devices 5 are provided but of course only two or more than three lifting devices 5 can be provided. The lifting devices 5 each carry a workpiece holder 6, which may be provided with one or more clamping devices 7, for example, in order to releasably clamp workpieces (not shown) to be machined on the occasion of their surface treatment. The drive 4 of the rotatable part 3 can serve in this way as a translational motion drive of the eccentrically arranged on the rotatable part 3 workpiece holder 6, which are moved in the case of rotation of the part 3 along a circular path.

Each lifting device 5 comprises in the present embodiment, for example, along a vertical guide 8 back and forth movable support unit 9, which for example by means of a chain or belt drive can be moved up and down. Further, the lifting devices 5 in the present embodiment, individually and independently of the other lifting devices 5 by means of a motor also attached to the underside of the rotatable member 3 (not visible in the drawings) independently movable up and down. At the vertically displaceable support unit 9 each one of the workpiece holder 6 is fixed, wherein the workpiece holder 6 by means of a controllable rotary drive 10 in rotation are displaceable in order to set a, for example by means of the clamping device 7, on the workpiece holder 6 clamped workpiece on the occasion of its surface processing in rotation (arrow P ₄ ).

Below the equipped with the workpiece holders 6 lifting devices 5, a container 11 for receiving a grinding and / or polishing granules (not shown) is arranged, which is rotatable about a vertical axis by means of a rotary movement drive, wherein the axis of rotation of the container 11 here, for example with the The axis of rotation 2 of the rotatable part 3 is aligned, so that the relative movement between the workpieces fixed to the workpiece holders 6 and the granulate bed located in the container 11 is the same. Each lifting device 5 is capable of supporting the workpiece holder 6 fastened to its support unit 9 along the arrow P ₂ between an upper position above the container 11, in which workpieces 6 can be removed from the clamping device 7 of the respective workpiece holder and these are equipped with raw workpieces can, and a lower position in which the tensioned on the clamping device 7 of the workpiece holder 6 workpieces 17 dip into the container 11 in order to process this, to move vertically back and forth.

In addition, the rotatable member 3 is movable in the direction of the arrow P ₁ about its axis 3 so that it can successively transfer each workpiece holder 6 with a respective workpiece attached thereto into a loading / unloading position, such a loading / unloading position for example, the in Fig. 1 right workpiece holder 6 occupies, in which he - after he from the Lifting device 5 has been moved to its upper position - is freely accessible from the side.

How to continue Fig. 1 it can be seen, the workpiece holder 6 may be inclined with their clamping devices 7 at a finite angle with respect to the vertical, said angle in the present case, for example, is about 30 °. This has proved to be advantageous in many cases in terms of a uniform and effective surface treatment. The angle of inclination of the workpiece holder 6 can be individually adjusted, for example, by the supporting the respective workpiece holder 6 support unit 9 of each lifting device 5 about a - here approximately horizontal - axis is pivotable. In this case, it is usually advantageous if the workpiece holders 6 have a tilting direction component arranged counter to the direction of rotation of the container 11 (arrow P ₃ ), ie the workpieces fixed to the workpiece holders 6 dive under an inclination counter to the direction of rotation of the container 11 into the granulate bed located therein a, so that a surface treatment can take place the lower end side.

How continues the Fig. 1 can be found, the container 11 may be arranged to receive the grinding and / or polishing granules in the present embodiment on a movable carriage 12 by rollers 12 to provide a simple and quick replacement of the granules by a container 11 against another Container is replaced. The carriage 13 includes the example arranged on its underside rotary drive (in Fig. 1 not recognizable) of the container 11. In order to ensure an exact alignment of the container 11 with respect to the supported by the frame 1 device, both the carriage 13 as Also, the frame 1 be provided with mutually complementary centering devices 16, which are arranged for example on three of four sides of the carriage 13 and the frame 1 and a lateral insertion of the carriage 13 in the frame 1 for a self-centering of the carriage 13 with respect to provide the frame 1, so that the axis of rotation of the container 11 coincides with the axis of rotation 2 of the rotatable member 3.

The device further comprises a (not shown in the drawing) programmatically configured control device, which may be, for example, an electronic data processing unit with a processor and which is capable of controlling the rotary actuators 10 of the workpiece holder 6 such that the latter during operation in periodic cycles Z of at most 5 s between at least a first rotational speed R ₁ and at least one second rotational speed R ₂ accelerated back and forth and / or rotated under continuous acceleration with continuously different rotational speeds, the corresponding desired rotational motion profiles expediently programmed and in a (also not graphically shown) input unit of the control device can be entered. In addition, it can also be provided, for example, that it is able to control the control device of the rotary drive of the container 11 in such a way that during operation in periodic cycles Z of at most 5 s between at least one first rotational speed R ₁ and at least one second Rotation speed R ₂ accelerated back and forth and / or rotated under continuous acceleration with continuously different rotational speeds, with the desired Rotation profiles can also be appropriately programmed and entered into the input unit of the control device. Exemplary rotational motion profiles are described below with reference to FIGS 3 and 4 explained by way of example. The control device is furthermore capable of controlling the rotational movement drive of the container 11 in such a way as to apply it to one or more desired, more or less constant rotational speeds and / or directions.

In addition, the control device is operatively connected to both the drive 4 of the rotatable member 3 and with the drives of the lifting devices 5, wherein in the input unit of the control device, for example, the desired processing times of the workpieces and the placement / removal position including the residence time of each workpiece holder. 6 can be entered in the placement / removal position. In this case, the control device can be set up in such a way that it moves the rotatable part 3 at periodic intervals to transfer each workpiece holder 6 into the placement / removal position after the respectively preset machining time and there via a likewise preset period for the removal / loading of workpieces holds. In this way, a semi-continuous workpiece assembly or release is achieved. In this connection, the control device furthermore ensures that each lifting device 5 of the respective workpiece holder 6, at the clamping device 7 of which the respective workpiece (s) is to be exchanged, is after, before or during the method the workpiece holder 6 is displaced vertically upward from the lower working position into the upper loading / unloading position by means of the rotatable part 3, held there at least over the sufficient for removal / placement of workpieces, also preset period, and then - after, before or during the process of the workpiece holder 6 by means of the rotatable member 3 - is again transferred vertically down to the working position.

In Fig. 2 a further embodiment of a device for the surface treatment of workpieces is shown, wherein the same or equivalent components with the same reference numerals as in Fig. 1 are provided. The device according to Fig. 2 in turn comprises a container 11 for receiving a grinding and / or polishing granules (not shown), which is rotatable about a vertical axis 2 by means of a rotary movement drive. In the present embodiment, the container 8 is on a carriage 13 according to Fig. 1 corresponding carriage 13 is arranged, on which, for example on its underside, turn the rotary drive (in Fig. 2 not fully recognizable) of the container 11 is arranged and which comprises a provided with a driving shaft 17 support plate 18 to which the container 11 rotatably and self-centering can be placed.

In the Fig. 2 The reproduced device further comprises a manipulator, generally designated by the reference numeral 110, in the form of a robot, which carries the workpiece holder or holders 6 for detachably fixing a workpiece to be machined (not shown). The robot 110 is, for example, a multi-axis industrial robot which has a frame 112 on which a carousel 113 is pivotably mounted about a vertical axis. On the carousel 113 sits a console 114 with a horizontal bearing for a rocker 115, at the console 114 facing away from the (upper) end turn a boom 116 is mounted on a horizontal, parallel to the pivot axis of the console 114 arranged axis. The boom 116 is equipped at its end with a three-axis robot hand 117, which carries the workpiece holder 6. While the carousel 113 is driven by a control motor 118 relative to the stationary frame 112, a control motor 119 serves to drive the rocker 115 and a control motor 120 for driving the boom 116. The three-axis robot hand 117 is of three further control motors 121, 122, 123 driven, which are mounted, for example, on the robot hand 117 remote from the end of the boom 116.

The three-axis robot hand 117 with the workpiece holder 6 can thus pivot the latter under any orientation in three-dimensional space to align a workpiece releasably secured to the workpiece holder 6 in the desired position with respect to the granules in the container 11, as well as the Workpiece holder 6 to move translationally in any spatial directions. In addition, the three-axis robot hand 117 can rotate the workpiece holder 6 in particular in the direction of the arrow P ₄ about its longitudinal axis, wherein the rotational movement control is in turn arranged to hold the workpiece holder 6 with a workpiece attached thereto during operation in periodic cycles Z of at most 5 s between at least a first rotational speed R ₁ and at least a second rotational speed R ₂ to accelerate back and forth and / or to rotate under continuous acceleration with continuously different rotational speeds (see below with reference to the 3 and 4 ), wherein the corresponding desired rotational motion profiles can be programmed and entered into an input unit (also not shown in the drawing). The same can in turn apply to the rotational movement control of the container 11.

In 3 and 4 are advantageous rotational speed profiles of the workpiece holder 6 (and / or the container 11), as by means of the devices according to Fig. 1 and 2 can be performed, reproduced by way of example. It is in the graphs of 3 and 4 in each case on the y-axis rotational speed n representative of the rotational speed (eg in revolutions [U] per minute [min]) against the machining time t (eg in seconds [s]) on the x-axis. How out Fig. 3 As can be seen, the local rotational speed profile of the workpiece holder 6 or the workpiece clamped thereto (or the container 11) is substantially sinusoidal or in the form of an undamped oscillation, the workpiece in periodic cycles Z continuously under constant (positive or negative) acceleration between a first rotational speed R ₁ of about zero and a second rotational speed R ₂ , which may be, for example, about 2000 rpm, is accelerated back and forth. However, the second rotational speed does not necessarily have to be constant, but may also change over the processing time t, ie the amplitude A of the approximately sinusoidal curve may change with increasing processing time (not shown). Likewise, the first rotational speed R ₁ does not necessarily have to be equal to zero, but in particular can also have a rotational speed which is appreciably lower than the second rotational speed R ₂ , for example between be about 0 and about 100 rpm. The duration of the periodic cycles Z may be, for example, between about 1 s and about 10 s. This in Fig. 4 exemplary reproduced rotational speed profile of the workpiece holder 6 and the workpiece clamped thereto (or the container 11) differs from that according to Fig. 3 primarily in that the workpiece in periodic cycles Z is continuously accelerated back and forth between a first rotational speed R ₁ not equal to zero and a second rotational speed R ₂ also not equal to zero, but with opposite rotational direction. The curve is also essentially sinusoidal with an inertia-related flattening in the region of the standstill (n = 0) when the direction of rotation of the workpiece is reversed. The rotational movement takes place again under continuous (positive or negative) acceleration. The amounts of the first R ₁ and / or second rotational speed R ₂ may in turn be about 2000 rpm, for example, but they may not be any different from one another in terms of their sign. Again, both rotational speeds R ₁ , R ₂ do not necessarily have to be constant, but one or both rotational speeds R ₁ , R _{1 can} also change over the processing time t, ie the "amplitude component" A _{1 of} the first rotational speed R ₁ up to the zero point (Selective standstill of the workpiece in the direction of rotation reversal) and / or the "amplitude component" A _{2 of} the second rotation speed R ₂ to the zero point of the approximately sinusoidal curve can change with increasing processing time (not shown). The period of the periodic cycles Z may be, for example, between about 0.25 s and about 5 s.

Claims (18)

1. Method for the surface finishing of workpieces by the workpiece being moved relative to a bed of a granular grinding and/or polishing material, wherein the workpiece is rotated about at least one axis (P₄) in relation to the bed of granular grinding and/or polishing material, wherein the workpiece is accelerated to different speeds of rotation (R₁, R₂) in relation to the bed of granular grinding and/or polishing material, characterized in that the workpiece and/or a container (11) containing the bed of the granular grinding and/or polishing material is rotated with continuous acceleration with continuously different speeds of rotation.
2. Method in accordance with claim 1, characterized in that the workpiece and/or the container (11) containing the bed of granular material is accelerated to and fro in periodic cycles (Z) of at most 5 sec between at least one first speed of rotation (R₁) and at least one second speed of rotation (R₂).
3. Method in accordance with claim 1 or 2, characterized in that the workpiece and/or the container (11) containing the bed of granular material is accelerated to and fro at least temporarily

   - between at least one first speed of rotation (R₁) essentially equal to zero and at least one second speed of rotation (R₂) not equal to zero; or

   - between at least one first speed of rotation (R₁) not equal to zero and at least one second speed of rotation (R₂) with a direction of rotation opposite that of the first speed of rotation (R₁).
4. Method in accordance with one of the claims 1 through 3, characterized in that the workpiece and/or the container (11) containing the bed of granular material is accelerated at least temporarily to at least one speed of rotation (R₁; R₂) of at least 200 rpm, especially at least 500 rpm, and preferably at least 1,000 rpm.
5. Method in accordance with one of the claims 1 through 4, characterized in that the workpiece and/or the container (11) containing the bed of granular material is accelerated to and fro at least temporarily in periodic cycles (Z) of at most 4 sec, especially at most 3 sec, and preferably at most 2 sec, between at least one first speed of rotation (R₁) and at least one second speed of rotation (R₂).
6. Method in accordance with one of the claims 1 through 5, characterized in that the workpiece and/or the container (11) containing the bed of granular material is accelerated at least temporarily at a speed of rotation described essentially by a sinusoidal curve over time (t), wherein the period or the cycle (Z) of the essentially sinusoidal curve of the speed of rotation is especially at most 5 sec.
7. Method in accordance with claim 6, characterized in that the workpiece and/or the container (11) containing the bed of granular material is accelerated to and fro at least temporarily

   - at a speed of rotation described by an essentially sinusoidal curve over time (t) with an amplitude (A) that is essentially constant over time; or

   - at a speed of rotation described by an essentially sinusoidal curve over time (t) with an amplitude (A) that is variable over time (t), wherein the amplitude (A) of the essentially sinusoidal curve of the speed of rotation over time (t) especially decreases or increases at least temporarily.
8. Method in accordance with one of the claims 1 through 7, characterized in that at least one cavity or at least one depression of the workpiece is filled with the bed of the granular grinding and/or polishing material, and the workpiece is rotated at least about one axis, especially essentially about the central axis of the cavity or of the depression, with continuous acceleration at continually different speeds of rotation in order to grind and/or polish at least the wall of the workpiece enclosing the cavity or the depression.
9. Method in accordance with one of the claims 1 through 8, characterized in that the workpiece dips into the bed of granular grinding and/or polishing material charged into the container (11) and the workpiece is rotated with continuous acceleration at continuously different speeds of rotation, wherein the workpiece is accelerated especially to and fro in periodic cycles (Z) of at most 5 sec between at least one first speed of rotation (R₁) and at least one second speed of rotation (R₂).
10. Method in accordance with claim 9, characterized in that at least temporarily, the container (11)

    - is held stationary;

    - is moved to and fro by a translatory motion;

    - is moved by a translatory motion along a trajectory, especially along a circular path; and/or

    - is rotated rotatorily about its central axis (2), especially at a speed of rotation that is essentially constant or changes over time.
11. Method in accordance with one of the claims 1 through 10, characterized in that the workpiece is moved (P₁), furthermore, by a translatory motion, especially along a trajectory, relative to the bed of granular grinding and/or polishing material.
12. Method in accordance with one of the claims 1 through 11, characterized in that at least the rotary motions of the workpiece and/or of the container (11) containing the bed of granular material and optionally the additional motion(s) of the workpiece and/or of the container (11) are carried out in a controlled, especially programmed manner.
13. Device for the surface finishing of workpieces by moving the workpiece relative to a bed of granular grinding and/or polishing material, especially for carrying out a method in accordance with one of the above claims, with at least one workpiece holder (6) for the detachable fastening of a workpiece to be finished and optionally with a container (11) containing the granular grinding and/or polishing material, wherein the workpiece holder (6) and/or the container (11) is associated with at least one rotary drive (10; 17, 18), and the device comprises, furthermore, a program-based control device, which is capable of controlling at least the rotary drive (10) of the workpiece holder (6) and/or the rotary drive (17, 18) of the container (11), characterized in that the control device is designed for the continuous acceleration of the rotary drive (10) of the workpiece holder (6) and/or of the rotary drive (17, 18) of the container (11) at continuously different speeds of rotation during the operation.
14. Device in accordance with claim 13, characterized in that the control device is designed to accelerate the rotary drive (10) of the workpiece holder (6) and/or the rotary drive (17, 18) of the container (11) to and fro in periodic cycles (Z) of at most 5 sec between at least one first speed of rotation (R₁) and at least one second speed of rotation (R₂) during the operation.
15. Device in accordance with claim 13 or 14, characterized in that the control device is designed to continuously accelerate the rotary drive (10) of the workpiece holder (6) and/or the rotary drive (17, 18) of the container (11) at continuously different speeds of rotation during the operation with at least one speed of rotation profile in accordance with one of the claims 3 through 7.
16. Device in accordance with one of the claims 13 through 15, characterized in that the control device is designed at least to continuously accelerate the rotary drive (10) of the workpiece holder at continuously different speeds of rotation as well as, furthermore, to control the rotary drive (17, 18) of the container (11) to a speed of rotation that is essentially constant or variable over time during the operation.
17. Device in accordance with one of the claims 13 through 16, characterized in that the workpiece holder (6) and/or the container (11) is, furthermore, associated with a translatory motion drive (4), and that the control device is, furthermore, capable of controlling the translatory motion drive (4) of the workpiece holder (6) and/or of the container (11), especially along a trajectory (P₁).
18. Device in accordance with one of the claims 13 through 17, characterized in that

    - servo motors are provided for the rotary drive (10) of the workpiece holder (6) and/or of the container (11), and/or

    - a gear mechanism is associated with the rotary drive of the workpiece holder (6) and/or of the container (11).

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