Drag and/or dip finishing machine for the surface machining of workpieces by means of grinding and/or polishing granules in the presence of a liquid machining agent

Abstract

A drag and/or dip finishing machine has at least one workpiece holder for the releasable fastening of the workpieces to be machined and a container, disposed beneath the workpiece holder, for accommodating the grinding and/or polishing granules, wherein the workpiece holder and the container are movable relative to each other in that at least the container is rotationally driven. The container has a chamber, which extends around the whole of the periphery thereof and is fluidically connected to the inside, accommodating the grinding and/or polishing granules, of the container, at least on a lower portion thereof, the chamber being equipped with a liquid discharge unit in order to be able to discharge the machining agent from the chamber in the event of an excess of machining agent in the container.

Claims

1. A drag or dip finishing machine for surface machining of workpieces using a bed of grinding or polishing granules having a liquid machining agent, wherein the workpieces are moved in and relative to the bed of grinding or polishing granules, the machine comprising: at least one workpiece holder for releasably fastening the workpieces to be machined; a container disposed beneath said workpiece holder to accommodate the grinding or polishing granules; a rotational drive mechanism cooperating with said container to rotate said container relative to said workpiece holder; an annular chamber disposed about and cooperating with said container for mutual rotation therewith, said annular chamber extending about an entire periphery of said container and in fluid connection, at least at a lower portion thereof, with an inside of said container containing the grinding or polishing granules; and a liquid discharge unit cooperating with said annular chamber to discharge machining agent from said annular chamber when an excess of machining agent is present in said container, wherein said liquid discharge unit comprises a suction lance connected to a pump, said suction lance projecting downwardly, directly into said annular chamber to penetrate through an upper surface of liquid machining agent located in said annular chamber, said annular chamber thereby being of a double-walled configuration and comprising both an inner peripheral wall and an outer peripheral wall, said inner peripheral wall separating an inside of said container, fillable with the grinding or polishing granules, from said annular chamber and said outer peripheral wall delimiting said annular chamber in an outward direction, wherein said suction lance is arranged adjustable in height in order to regulate a fill height of the machining agent in said annular chamber, thereby regulating, in view of said fluid connection between said annular chamber and said container, a desired fill height of machining agent in said container.

2. The machine of claim 1, wherein said annular chamber extends in substantially rotationally symmetric arrangement around an entire periphery of said container.

3. The machine of claim 1, wherein said fluid connection of said container to said annular chamber has at least one borehole.

4. The machine of claim 3, wherein said borehole is provided with at least one element selected from the group consisting of a screening element and a filter element.

5. The machine of claim 1, wherein a connection of said container to said annular chamber comprises at least one sintered metal insert.

6. The machine of claim 1, wherein both said container and said annular chamber are configured upwardly open, so that a same ambient pressure prevails in said container and said annular chamber, thereby providing free access to inner regions of said container and said annular chamber from an upward direction.

7. The machine of claim 1, further comprising a feed device cooperating with said container to add the liquid machining agent to said container.

8. The machine of claim 1, further comprising a cleaning device disposed downstream of said liquid discharge unit for cleaning machining agent discharged from said annular chamber.

9. The machine of claim 8, further comprising a device for feeding machining agent into said container, wherein said cleaning device is connected to said feeding device via a recirculation line.

10. The machine of claim 1, wherein said annular chamber has at least one fill height sensor in order to detect a fill height of machining agent in said annular chamber and to regulate a corresponding desired fill height of machining agent in said container.

11. A drag or dip finishing machine for surface machining of workpieces using a bed of grinding or polishing granules having a liquid machining agent, wherein the workpieces are moved in and relative to the bed of grinding or polishing granules, the machine comprising: at least one workpiece holder for releasable fastening the workpieces to be machined; a container disposed beneath said workpiece holder to accommodate the grinding or polishing granules; a rotational drive mechanism cooperating with said container to rotate said container relative to said workpiece holder; a chamber disposed about said container, said chamber extending about an entire periphery of said container and in fluid connection, at least at a lower portion thereof, with an inside of said container containing the grinding or polishing granules; and a liquid discharge unit cooperating with said chamber to discharge machining agent from said chamber when an excess of machining agent is present in said container, wherein said chamber extends both around a periphery and around a base of said container in order to form a container-in-container system, said chamber and a base thereof thereby being stationary and said container being mounted inside said stationary chamber, wherein said liquid discharge unit comprises a suction lance, which is connected to a pump, said suction lance projecting downwardly, directly into said chamber to penetrate through an upper surface of liquid machining agent located in said chamber, wherein said suction lance is arranged adjustable in height in order to regulate a fill height of the machining agent in said annular chamber, thereby regulating, in view of said fluid connection between said annular chamber and said container, a desired fill height of machining agent in said container.

12. The machine of claim 11, wherein said liquid discharge unit comprises a drain line which is connected to said stationary chamber.

13. The machine of claim 12, wherein said drain line has a stop valve.

14. The machine of claim 12, wherein said drain line has a pump.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) FIG. 1 shows a schematic sectional view of an illustrative embodiment of a drag finishing machine for the surface machining of workpieces;

(2) FIG. 2 shows a schematic detailed view of the container of the drag finishing machine according to FIG. 1 in sectioned representation; and

(3) FIG. 3 shows a schematic detailed view, corresponding to FIG. 2, of an alternative embodiment of the container in sectioned representation.

DESCRIPTION OF THE PREFERRED EMBODIMENT

(4) In FIG. 1, an embodiment of an inventive drag finishing machine 1 for the surface machining of workpieces is represented. The drag finishing machine 1 is equipped with a workpiece holder 2, which is releasably fixed by means of a clamping connection 3 to a movablehere: rotatablecarrying part 4 of the drag finishing machine 1, the so-called plate or rotor. The workpiece holder 2 is here clamped to the carrying part 4 eccentrically in relation to the rotational axis 4a thereof, so that it describes a path curve upon the rotation of the carrying part 4. For its part, the workpiece holder 2 can be fixed on the carrying part 4 rotatably about an axis 2a, such as its longitudinal axis, which can be realized, for instance, by means of a planetary gearing which is disposed in the carrying part 4 and which, upon a rotation of the carrying part 4 about its rotational axis 4a, induces a rotation of the workpiece holder 2 about its rotational axis 2a. The equivalent applies to any further workpiece holders which might be provided (not represented), which can likewise be clampable to the bottom side of the carrying part 4 in eccentric position to its rotational axis 4a. The rotary drive of the carrying part 4 is realized via a motor/gear assembly 5 indicated merely in dashed representation in FIG. 1.

(5) The workpiece holder 2 can be configured, for instance, to accommodate a plurality of substantially vertically clampable workpieces (not represented) and, to this end, can have on its (in FIG. 1) bottom side facing away from the clamping connection 3 to the carrying part 4 a plurality ofin the present example threeworkpiece carriers 6 for the releasable clamping respectively of a workpiece, or else of a workpiece receiving fixture for the respective clamping in place of one or more workpieces (respectively not shown). The workpiece carriers 6 are arranged distributed around the periphery of the workpiece holder 2, i.e. eccentrically in relation to its rotational axis 2a. In order to impart to the workpiece carriers 6, in addition to the translatory motion due to rotation of the carrying part 4 and of the workpiece holder 2, a rotary motion about their respective longitudinal axis 6a, the workpiece carriers 6, for their part, can be mounted rotatably on the workpiece holder 2 and can in turn be set in motion, for instance, by means of a planetary gearing (not shown) disposed in the workpiece holder 2.

(6) During running of the drag finishing machine 1, at least those workpieces which can be fixed on the workpiece carriers 6 of the workpiece holder 2, for instance by means of suitable clamping devices, plunge into a working container 8, which is filled with powdery or particulate grinding and/or polishing granules 9 with the addition of liquid machining agents, such as water, surfactants, further additives and the like. For the surface machining of workpieces (not shown) clamped to the workpiece carriers 6, the carrying part 4 of the drag finishing machine 1 is set in rotation by means of the motor/gear assembly 5, so that the workpiece holder 2 is dragged on a specific motional pathhere a circular pathin translatory motion through the working container 8 or through the granules bed 9, contained herein, with the liquid machining agent. Furthermore, the planetary gearings accommodated in the carrying part 4 or in the workpiece holder 2 ensure a self-rotation both of the workpiece holder 2 and of the workpiece carriers 6, or of the workpieces fixed hereon, about anhere substantially verticalaxis, which can also however be arranged inclined in relation to the vertical by a finite angle. Due to the relative motion between the workpieces and the bed of grinding and/or polishing granules 9 with the machining agent, a surface machining of the workpieces ensues.

(7) In the present illustrative embodiment, such a relative motion is supported by an additional mobility of the working container 8, namely by a rotation of this same about its center axis 8a (see the arrow 8b according to FIGS. 2 and 3). For this purpose, the container 8 is connected to a controllable rotary drive (not represented diagrammatically in detail), so that the grinding and/or polishing granules 9, upon the rotation of the container 8 about its center axis 8a, due to centrifugal forces, form a concave surface 9a.

(8) Of course, the drag finishing machine 1 can also be configured as a dip finishing machine having substantially stationary workpiece holders, which, if need be, can likewise be rotationally driven about their axis. Furthermore, the workpiece holder can be arranged, for instance, also on the hand of a robot, such as, for example, a six-axis industrial robot, in order to ensure more or less complex path curves of the tool to be machined (respectively not shown) in the granules bed 9 of the container 8.

(9) In FIG. 2, the workpiece holder 2 with a workpiece 10 fixed hereon, inclusive of its drive components 3, 4, 5 (cf. also FIG. 1), is sketched purely schematically. As can be seen, in particular, from FIG. 2, the container 8 of the drag finishing machine 1 is of double-walled configuration and comprises an inner peripheral wall 11 and an outer peripheral wall 12. The inner peripheral wall 11 separates the actual container 8 filled with the grinding and/or polishing granules 9 from an annular chamber 13 extending rotationally symmetrically around its periphery, while the outer peripheral wall 12 delimits the chamber 13 in the outward direction. During running, the chamber 13 hence co-rotates with the container 8, which chambereven if not necessarilycan be designed in one piece with the container 8. The inner peripheral wall 11 separating the container 8or, more precisely, the interior thereoffrom its chamber 13 retains the granules particles 9 in the inside of the container, yet ensures a fluidic connection of the inside of the container to the chamber 13, as is indicated in FIG. 2 by means of the arrows 14. The liquid machining agent, the surface level of which is provided with the reference symbol 15, is hence capable of penetrating into the inner peripheral wall 11. To this end, the inner peripheral wall 11 can have, for instance, at least in its lower portion, one or more boreholes provided with screen or filter elements, or it can also instead be made, at least in some sections, of liquid-permeable sintered metal, for instance.

(10) The peripheral chamber 13 of the container 8 is equipped with a liquid discharge unit, which, in the present illustrative embodiment, comprises a suction lance 17 connected to a pump 16 and projecting into the container 8 from above in order to be able to discharge the liquid machining agent, where necessary during running of the drag finishing machine 1, from the container 8 fluidically communicating with the chamber 13 (arrow 18 of FIG. 2). The pump 16 is expediently constituted by a pump which is largely also insensitive to fine-particle impurities, such as, for instance, a compressed air diaphragm pump or the like. The suction lance 17 can be arranged, in particular, in the direction of the arrow 19, for example on a support (not shown), below an adjustable height level in order to be able to adjust its suction opening(s) to the fill height level 15 of the liquid machining agent in the chamber 13, which corresponds with the desired fill height of the liquid machining agent in the container 8. Furthermore, the chamber 13 of the container 8 is equipped, in particular, with a fill height sensor (not shown) in order to be able to sensorily detect the respective fill height level 15 of the machining agent in the chamber 13, whichas already mentioneddue to the fluidic connection 14, corresponds with the fill height of the liquid machining agent in the container 8.

(11) In order to ensure a lowest possible resistance of the fluidic connection 14 formed between the container 8 and its chamber 13, both the container 8 and the its chamber 13 are configured upwardly open, so that on both sides of the inner peripheral wall 11 separating the container 8 from its chamber 13 the same gas pressurehere: ambient pressureprevails. The driving force for an exchange of liquid between the container 8 and its chamber 13 is hence primarily the hydrostatic pressure of the machining agent in the container 8 or in its chamber 13, plus the centrifugal forces conforming to the rotation speed of the rotationally driven container 8.

(12) A feed device for the liquid machining agent is also assigned to the container 8 in order to be able, where necessary, to add this liquid machining agent to the container 8. The feed device comprises, for instance, a feed line 20 equipped with a control valve 19. Furthermore, downstream of the suction lance 17 or its pump 16 can be arranged, in particular, a cleaning device (not shown) for the liquid machining agent, which can comprise, for example, a filter unit (likewise not shown) and into which the suction line 21 opens. The cleaning device can in turn be connected to the feed line 20 via a recirculation line (likewise not shown), if need be with the interposition of a liquid storage container (likewise not shown), so that the machining agent can be recycled continuously or semicontinuously.

(13) The drag finishing machine 1 hence enables, in particular, a control of the desired quantity of grinding and/or polishing granules accommodated in the container 8 during the surface machining, wherein both a continuous or semicontinuous feed of the machining agent into the container 8 and a continuous or semicontinuous discharge of this same from the container 8 via the chamber 13 fluidically to said container is possible. To this end, on the one hand the suction lance 17 can be arranged in the chamber 13 at a height level corresponding to the fill height 15 of the machining agent in the chamber 13, which corresponds with the desired fill height of the machining agent in the container 8, so that the machining agent above this height level at which the suction lance 17 has been positioned is discharged from the chamber 13. Furthermore, the sensorily detected fill height 15 of the machining agent in the chamber 13 can be used to compare it with a desired target value of the fill height of the machining agent in the container 8, so that, by opening of the control valve 19 in the feed line 20, fresh or cleaned machining agent can always then be added to the container 8 insofar as the sensorily detected fill height 15 of the machining agent in the chamber 13 is less than the target value of the herewith corresponding fill height of the machining agent in the container 8.

(14) In the illustrative embodiment represented in FIG. 3, identical or same-acting components are provided with the same reference symbols and to this extent require no further discussion. The illustrative embodiment according to FIG. 3 differs from the illustrative embodiment shown in FIG. 2 primarily by virtue of the fact that the chamber 13 extends not only around the whole of the periphery of the container 8, but also around the base thereof, so that a container-in-container system is formed. The outer peripheral wall 13 which reaches under the base of the container 8 can in this case be arranged immovably, thus non-rotatably, and can have, for instance, a drain 12a arranged coaxially to the rotational axis 8a of the container, which drain is closed during running and, where necessary, can be opened in order to be able easily to discharge sedimented impurities of the liquid machining agent from the chamber 13.

(15) In the illustrative embodiment shown in FIG. 3, having an immovably arranged chamber 13, it is possible, alternatively or additionally to the liquid discharge unit comprising the suction lance 18, the pump 16 and the suction line 21, to provide a different type of liquid discharge unit (shown in dashed representation in FIG. 3). The latter comprises, for instance, a drain line 22, which is connected to the lower region of the stationary chamber 13 and is equipped with a stop valve 23. Insofar as the drain line 22, as shown schematically in FIG. 3, extends downward to a lower height level, the liquid machining agent can be discharged from the chamber 13 purely by force of gravity by opening of the stop valve 23. Otherwise, the drain line 22 can also be provided, for instance, with a pump (not represented diagrammatically).