CH662300A5 - METHOD AND DEVICE FOR THE CONTINUOUSLY POSITIONING OF MACHINE PARTS. - Google Patents

Description

The invention relates to a method and a device for the stepless positioning of machine parts or workpieces in a stop-limited position, with a stop that is adjustable in the course of a movement path of the machine part or workpiece and independently of this.

Devices for the stepless positioning of the intermediate carriers of handling devices - DE-OS 3 035 191 - are already known, in which several fixed stops are provided to limit the movement of the intermediate carriers in different positions. Depending on the desired position of the intermediate carrier, one of the stops is moved into the movement path of the intermediate carrier. Shock absorber arrangements are assigned to these stops in order to dampen the blows when the intermediate carriers run onto the fixed stops. Reaching the end position of the intermediate carrier can also be queried using the limit switch. Such devices have proven particularly useful when used on fully automatic assembly machines, since the desired end positions can be reproduced with high accuracy even with a large number of work cycles. However, the advantages of such devices could not be used in all applications, since the number of stop-limited end positions of the intermediate carrier to be achieved in this way is limited.

Handling devices are also known, the intermediate carriers or gripper arrangements of which can be moved on guideways can be stopped in any predetermined positions by the interaction of a drive and a device for position detection. In practice, such linear adjustment2

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directions often referred to as NC axes. If a handling device comprises at least three such drive units which can be continuously monitored in their position and which are arranged in different spatial directions, such handling devices are often also referred to as robots. These so-called freely programmable shifting devices make it possible to move to any position along their guideway, which makes it easy to store new positions via the control system when the operating sequence changes. The adaptation of the individual devices to the different stresses, in particular to different partial weights or speeds during movement processes, is however only possible to a limited extent, so that such devices are not suitable for all practical applications.

The present invention is based on the object of creating a method and a device for the stepless positioning of machine parts or workpieces, with which it is possible to position them precisely in a plurality of predetermined positions even with frequent repetition of the movement processes. In addition, rapid adjustment and positioning of the machine parts or workpieces in a wide variety of positions should be ensured.

This object of the invention is achieved in that the stop is brought into and held in a predeterminable position, whereupon the machine part or the workpiece carrier is moved into the position defined by the stop, independently of the stop. The surprising advantages of the solution according to the invention are achieved by dividing the adjustment movement into a positioning process and a displacement movement. This now makes it possible, in a surprisingly simple manner, to quickly and precisely set any end position along the path of movement of a machine part or workpiece, since the stop is designed with a low mass and can therefore be moved quickly and accurately. At the same time, however, this also means that simple and inexpensive measuring systems or dimensionally accurate drive devices, such as stepping motors, can be used. The surprising additional advantage offered by this solution according to the invention is, however, that the adjustment movement can take place very quickly and the high speed can be maintained even in the case of high masses of the intermediate carriers or workpieces down to the end region of the movement, since this end position or The position is properly fixed by the stop, which is fixed in its position. Since the positioning drive for the exact setting and positioning of the stop is only loaded with small masses, a long service life is achieved with high accuracy, so that the individual predeterminable positions along the movement path of a machine part or workpiece, even with a large number of work cycles are exactly reproducible.

According to a further feature of the invention it is provided that the stop is adjusted and fixed in the desired position while the machine part or the workpiece or the workpiece carrier is preferably in a position distant therefrom. As a result, a longer period of time is available for the exact positioning of the stop without the movement of the machine part or the workpiece being delayed.

Furthermore, it is also possible within the scope of the invention that one of two stops limiting a movement path of the machine part in opposite directions into a desired predeterminable position

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is spent while the further stop is in a fixed position. This ensures that the machine part or the workpiece is in a precisely defined position during the positioning of a stop and incorrect operation can be avoided. In addition, it is possible to monitor or position several stops in this position with one measuring system during this procedure.

It is furthermore advantageous if the stop is brought into a fixed stop-limited reference position after releasing the fixation and then, starting from this reference position, is adjusted by a predeterminable distance to another position and is fixed in this position. This enables the accuracy in the positioning of the stops to be increased, especially if the drive for moving the stop is simultaneously used for position monitoring.

Within the scope of the invention, a device for stepless positioning of machine parts or workpieces with at least one linear guideway on which a machine part or a workpiece coupled with an adjustment drive is displaceably mounted and with a stop assigned to this machine part or workpiece is particularly advantageous , which is coupled with an adjustment drive and is mounted so as to be displaceable in the longitudinal direction of the guideway, for carrying out the method.

This device is characterized in that a device for position detection is assigned to the stop and that the adjustment drive of the stop is connected to a control device which acts on the adjustment drive when an output signal of an adjusting element for the stop position and the device for position detection of the stop match. It is advantageous with this solution that the stop can be brought into its exact position in connection with the control device and the adjustment drive and is held in this position. This makes it possible to use stops with small masses to brake or position machine parts or workpieces with large masses.

Furthermore, it is also possible for a fixing device to be assigned to the stop and for the fixing device to be connected to the control device. As a result, only the fixing force of the stop is to be measured as a function of the energy to be intercepted in order to enable correct positioning.

According to another embodiment of the invention it is provided that the stop is slidably mounted in particular on guide columns of the guideway for the machine parts and is coupled via a traveling nut to a threaded spindle of an adjusting drive, the drive motor for the threaded spindle simultaneously forming the device for detecting the position of the stop.

This embodiment achieves a compact construction of the device for positioning the stop. Due to the self-locking between the traveling nut and the threaded spindle, the stop is fixed in any position when the drive is stopped relative to the guide device and the drive can be used directly to position the stop. Another advantage of this design is that the adjustment drive for the stop can have the same length as the guideway for the machine part or the workpiece.

According to the invention, it is also possible that the stop is mounted on a guideway running parallel to the conveying path for the machine parts and that the guideway is part of the adjustment drive, e.g. a

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Rack for a pinion or the like arranged at the stop, supports and has braking surfaces interacting with a braking device arranged at the stop. The arrangement of additional complex support devices can be saved because the guide device for the machine parts or workpieces are dimensioned on the basis of the masses of the machine parts or workpieces and thus can also absorb the energy for catching the machine parts when they collide with the stops. In addition, in this embodiment, the force in almost the same areas where it acts on the stop is diverted to the guiding devices serving as supporting elements, so that a very light construction of the stop can be used even with large deceleration energies.

According to a further embodiment of the invention, it is provided that the device for detecting the position of the stop is formed by a circumferential cable pull running parallel to its movement path, in the course of which a sensor, preferably connected to a deflection pulley of the cable pull, e.g. a rotary potentiometer is arranged, which creates a very cost-saving and precise measuring system for position detection of the stop.

Furthermore, it is advantageous if the device for detecting the position of the stop simultaneously forms the adjustment drive, which is adjustable depending on the path and which is preferably connected to the deflection roller of the cable pull of the device for detecting the position of the stop. This means that the advantages of exact position detection can be combined with the advantages of an economical construction.

According to the invention, it is also possible for a shock absorber and a limit switching element, which interacts with the machine part, to act on the stop on the side facing the machine part, e.g. an electrical proximity switch is arranged. This makes it possible to brake and stop the machine part by means of a precisely predetermined deceleration process and at the same time to determine that the end position of the machine part has been reached at the stop.

Finally, it is also possible within the scope of the invention that an adjustable stop plate for a machine part is arranged on the stop and that the limit switch or the shock absorber arranged on the stop plate or the stop in the direction of movement of the machine part, e.g. is adjustable via a thread. Due to the sensitive adjustment option of the stop plate or the limit switch element arranged on the stop or the adjustable stop plate and the shock absorber arrangement, a safe function of the limit switch element as well as an exact deceleration of the machine part when it hits the stop is possible, and it can be done more easily The end positions of the machine part are adjusted and adjusted in addition to the control of the stop. This enables extremely precise positioning of the machine parts or tools or workpieces or the like.

For a better understanding of the invention, it is explained in more detail below with reference to the exemplary embodiments shown in the drawing.

Show it

1 shows a device according to the invention for the stepless positioning of a machine part with the control device associated therewith in a highly simplified schematic illustration and in plan view;

2 shows the device according to FIG. 1 in a front view and cut according to lines II-II in FIG. 1;

3 shows an embodiment variant of a device for the stepless positioning of machine parts, likewise in a highly simplified schematic illustration and in a top view;

4 shows an end view of the device according to FIG. 3 in section along the lines IV-IV in FIG. 3;

5 shows a possible application of the device according to the invention for the stepless positioning of machine parts in the course of a production system for the assembly of workpieces in a highly simplified schematic illustration and top view;

6 shows an end view of the device according to FIG. 5 in section along the lines VI-VI in FIG. 5.

FIG. 1 shows a device 1 for the stepless positioning of machine parts 2, for example a slide 3 of a handling device 4. The machine part is equipped with an adjustment drive 5, e.g. a rodless cylinder-piston arrangement 6 connected via a driver 7 and movable along a movement path 8, which is formed by guide columns 9 of a guide path 10, in the longitudinal direction of the guide path - arrow 11. For the infinitely variable setting of different positions along the movement path 8, two adjustable stops 12, 13 are assigned to the machine part 2. The stop 12 is in a position 14 indicated by dash-dotted lines, in which the machine part 2 with the stop 12 is positioned in an exact position. By moving the stop 13 into the position drawn with dashed lines into a position 15 marked with a dash-dotted line, this is defined as the end position for the movement of the machine part 2 while it is still in the region of the stop 12. Each of the two stops 12, 13 is displaceably mounted with an adjustment drive 16, 17 along the guide track 10 on the guide columns 9 for the machine part 2. The adjustment drives 16 and 17 are of the same design, which means that the same reference numerals are used for the same parts, and consist of a threaded spindle 18 which is coupled to a drive motor 19, preferably a stepping motor 20. If a stepping motor 20 is used as the drive motor 19, it also serves as a device 21 for position detection. The device is therefore connected via a switching element 22 to an energy source 23 and to a control device 24. The control device 24 is assigned separate setting members 25, 26 for each stop 12, 13. Furthermore, the adjustment drive 5 and the limit switches 27, 28, which define a reference position 29 for the two stops 12, 13, are also connected to the control device 24. Furthermore, limit switching elements 30, 31, which are arranged on a stop 13 or on the machine part 2, can also be coupled to the control device 24. Furthermore, a shock absorber 32 is arranged on the stop 13, while a shock absorber 32 is fastened to the machine part 2 during interaction with the opposite stop 12. Of course, without deviating from the subject matter of the invention, it is possible to arrange both shock absorbers 32 either on the machine part 2 or respectively on the stop 12 and 13.

It can be seen in FIG. 2 that the two guide columns 9 of the guideway 10 are arranged in a plane inclined at 45 ° to the horizontal, which results in approximately the same stability of the guideway 10 in the horizontal and vertical directions. This increases the guiding accuracy for the machine part 2. The position of the threaded spindles 18 can also be seen and it can also be seen that the adjusting drive 5 is below one of the two threads.

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despindel 18 is arranged. The machine part 2 is equipped with a gripper 33 for gripping a component 34. In order to stiffen the guideway 10, the two end plates 35, FIG. 1, are connected parallel to the latter via upright side plates 36. As a result, the guide columns are arranged in a fixed housing and the bending stresses exerted on the guide columns 9 by the machine part 2 can be divided into two bearing points in a solid housing.

FIG. 3 shows a device 37 for the stepless positioning of a stop 38 for a machine part 2, for example a holder 39 of a machine tool 40. A shock absorber 41 and a limit switch 42 are arranged on the stop 38. Both the shock absorber 41 and the limit switching element 42 are provided with a thread 43 on their circumference in order to be continuously positioned in relation to a stop 38.

A device 44 is assigned to the stop 38 to detect its position, which device comprises a rotating cable 45 which is guided on deflection rollers 46, 47. The deflection roller 47 is connected to a rotary potentiometer 48 coupled to it. The movement of the cable pull and thus of the stop 38 along the movement path 8 of the machine part 2 can thus be monitored. The rotary potentiometer 48 serves as a measuring value transmitter 49 for the control device 24.

In the present exemplary embodiment, the device 44 for detecting the position of the stop 38 simultaneously serves as a drive 50, for which purpose the deflection roller 47 is coupled to a drive motor 51. Due to the continuous monitoring of the movement of the cable 45 with the sensor 49, any drive motor can be used to move the cable 45. When the stop 38 has reached the desired position, it is held or fixed in its position by a fixing device 52. FIG. 4 shows that this fixing device 52 for the stop 38 is formed by braking devices 53. These braking devices interact with guide columns 54, on which the machine part 2 and the stop 38 are slidably mounted. To brake or fix the stop 38, the two pliers-like levers are moved towards one another by a drive 55 and thus clamped onto the guide columns 54. The longitudinal movement of the machine part 2 takes place with an adjustment drive 5. In the illustrated embodiment, the adjustment drive 5 is used, e.g. the housing of a rodless cylinder-piston arrangement 6 as a side cheek for connecting the two end plates of the housing receiving the guide columns 54. When using ball guides for the guide columns 54, the stop 38 can be moved along the movement path 8 with extremely little effort, so that it is also possible to use a stepping motor instead of the combination of drive motor 51 and sensor 49, which combines both functions. The accuracy of such stepper motors is very high if the moving masses are very low.

The advantage achieved by this embodiment is that the stop can have a low mass and can therefore be moved at high speed and without great effort with large accelerations in different positions and can be braked exactly there with little energy expenditure. The absorption of the large deceleration forces for positioning the machine part, which has a large mass and kinetic energy, is achieved by clamping the stop 38 on the guide columns 54 with the braking devices 53. Appropriate control of the braking devices 53 means that practically any holding force can be achieved, impact loads when the machine part 2 strikes the stop 38 can be absorbed by shock absorbers 41. This makes it possible to apply full force to the adjustment drive 5 for the machine part 2 and to move it at high speed without complicated delay controls being required to maintain the desired end position of the machine part 2.

FIG. 5 shows a device 56 for positioning workpiece carriers 57 of a production system 58 for assembling workpieces composed of several individual parts. In this case, the workpiece carriers 57 represent the machine parts 2 to be positioned continuously.

The device 56 comprises a stop 59, which is mounted displaceably along a guideway 60. This guideway consists of two parallel guide columns 61, 62, which in turn are aligned parallel to a conveying path 63 for the workpiece carriers 57. As is further indicated by dashed lines, a plurality of stops 59 can also be arranged on this guideway 60 and can be moved independently of one another along this guideway. In order to bring a stop lever 64 of the stop 59 out of engagement with the workpiece carrier 57, the latter can be adjusted with a drive 65 relative to the guide columns 61, 62 and perpendicular to these. With 66 drive rollers are designated with which the workpiece carriers 57 are moved along the conveying path 63. These drive rollers 66 are preferably connected to drive elements, such as toothed belts or the like, via slip clutches, so that when workpiece carriers 57 strike a stop lever 64, the drive rollers 66 are automatically stopped and excessive wear is prevented.

FIG. 6 shows that the guide column 62 is flattened on its underside and has a braking surface 67. A rack 68 is arranged on the opposite top of the guide column 62. The braking surface 67 is a brake device 69 mounted on the stop 59 and the rack is a via an adjustment drive 70, for. B. assigned a stepping motor 71, driven pinion 72. The braking device 69 forms the fixing device 52 for the stop 59. The design of the device 56 for the stepless positioning of workpiece carriers 57 means that the method according to the invention can be realized again here, namely to separate the positioning movement from the travel movement of the machine part 2. The stops can thus be moved into the desired position at high speed and precisely regardless of the movement of the workpiece carriers, and these can then be fixed and fixed in the desired position with the braking device 69. By using a stepping motor, the adjustment drive 70 also serves as a device 73 for position detection and additional components can be saved.

The sequence when positioning the stops 12, 13, in particular using the device 1 shown in FIGS. 1 and 2, is now as follows:

While the machine part 2 is in the position 14 defined by the stop 12, the stop 13 is moved from its position drawn in full lines to the reference position 29 in order to obtain an exact starting point for the measurement value determination of a distance 74 between the reference position 29 and to be able to determine the new desired target position 15 with the stepping motor 20 of the adjusting drive 17 assigned to the stop 13.

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After the new position 15 has been reached, the stepping motor 20 is stopped and the machine part 2 can then be moved into the new position 15 at high speed with the actuation drive 5 fully loaded. In order to reduce impacts on the machine part 2 or on the stop 13, a shock absorber 32 is arranged on the stop 13, which in the final phase of the movement of the machine part 2 destroys its kinetic energy and enables a soft stop on the stop 13. In this exemplary embodiment, the stop 13 is fixed or blocked by the self-locking effect of the traveling nut arranged in the stop 13 and guided on the threaded spindle 18. By appropriate design of the thread flanks, in particular the training as a trapezoidal thread, sufficient fixation against evasive movements of the stop can be achieved at not too high loads. In addition, it is also possible in this exemplary embodiment to arrange braking devices on the stop 12 or 13, so that machine parts which have a high kinetic energy, for example due to a high mass and high adjustment speed, stop precisely and also reproducibly with a large number of positioning games can be.

The invention is in no way limited to the exemplary embodiments shown in the drawings. Both the device for position detection assigned to the stop and the fixing device or the adjusting drive for the stop can be modified as desired. Instead of the device for position detection combined with the adjustment drive for the stop, a separate device for position detection can also be provided in each case. Instead of the mechanical or electromechanical transducers shown in FIG. 3 for better understanding of the present invention, this can be formed by contactless electrical or electro-optical measuring devices, such as capacitive or light beam measuring systems. In addition, it is also possible to use any kind of propulsion, for example independent drive rollers or linear motors or pressurized and infinitely adjustable cylinder-piston arrangement, as an adjustment drive for the stop instead of the threaded spindle or rack arrangements shown or rotating cables. The type of guidance of the stops is also not restricted. Instead of the column guides shown, dovetail guides or other guide systems known in the prior art can also be used, and the guide track for the machine part can also be independent of the guide system for the stop. It is thus also readily possible to arrange the stop on slides that can be moved along rollers along guideways. Accordingly, the design of the fixing device is subject to change. Thus, both Rastensy-su, ne, as well as brake devices acted upon by pressure medium as well as clamping systems and the like can be used. The number of stops arranged in the course of a movement path of machine parts, tools, workpieces or other moving elements is also not limited. In order to allow such machine parts or other devices to drive past stops that are not in use, they can be provided with adjustable stop parts.

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1 sheet of drawings

Claims (12)

662 300 PATENT CLAIMS 1. A method for the stepless positioning of machine parts or workpieces in a stop-limited position, with a stop which is adjustable in the course of a movement path of the machine part or workpiece and which is independent of this, characterized in that the stop (12, 13, 38, 59) is in a Predetermined position is brought and held in this, whereupon regardless of the stop (12, 13, 38, 59) the machine part (2) or the workpiece carrier (57) in the position defined by the stop (12, 13, 38, 59) (14.15) is spent. 2. The method according to claim 1, characterized in that the stop (12, 13, 38, 59) is adjusted and fixed in the desired position (14, 15), while preferably the machine part (2) or the workpiece or the Workpiece carrier (57) is in a position (14) distant therefrom. 3. The method according to claim 1 or 2, characterized in that one of two stops (12, 13) delimiting a movement path of the machine part (2) in opposite directions is brought into a desired predeterminable position (15) while the further stop (12) is in a fixed position (14). 4. The method according to any one of claims 1 to 3, characterized in that the stop (12, 13, 38, 59) is brought into a fixed stop-limited reference position (29) after releasing the fixation and then, starting from this reference position ( 29) by a predeterminable distance (74) in another position (15) and is fixed in this. 5. Device for the stepless positioning of machine parts or workpieces with at least one rectilinear guideway, on which a machine part or a workpiece coupled with an adjusting drive is slidably mounted and with a stop associated with this machine part or workpiece, which is coupled with an adjusting drive and is slidably mounted in the longitudinal direction of the guideway for carrying out the method according to one of claims 1 to 4, characterized in that a device (21, 44) for position detection is assigned to the stop (12, 13, 38, 59) and that the adjustment drive (5 , 70) of the stop (12, 13, 38, 59) is connected to a control device (24) which acts on the adjustment drive (5, 70) when an output signal of an adjusting member (25) for the stop position and the device (21, 44) for detecting the position of the stop (12, 13, 38, 59). 6. Device according to claim 5, characterized in that the stop (12, 13, 38, 59) is assigned a fixing device (52) and that the fixing device (52) is connected to the control device (24). 7. Device according to one of claims 5 or 6, characterized in that the stop (12, 13), in particular on guide columns (9) of the guide track (10) for the machine parts (2), is displaceably mounted and via a traveling nut with a threaded spindle ( 18) of an adjustment drive (16, 17) is coupled, the drive motor (19) for the threaded spindle (18) simultaneously forming the device (21) for detecting the position of the stop (12, 13). 8. Device according to one of claims 5 to 7, characterized in that the stop (59) on a parallel to the conveyor path (63) for the machine parts (2) running guide track (60) is mounted and that the guide track (60) is a part the adjusting drive (70), e.g. a toothed rack (68) for a pinion (72) or the like arranged on the stop (59) is supported, and also with one on the stop (59) arranged braking device (69) has interacting braking surfaces (67). 9. Device according to one of claims 5 to 8, characterized in that the device (44) for detecting the position of the stop (38) is formed by a circumferential cable pull (45) running parallel to its movement path (8), in the course of which a preferably a sensor (49) connected to a pulley (47) of the cable (45), eg a rotary potentiometer (48) is arranged. 10. The device according to claim 9, characterized in that the device (21, 73) for detecting the position of the stop (12, 13, 59) simultaneously forms the adjusting drive, which is adjustable depending on the path and which is preferably with the deflection roller (47) of the cable ( 45) of the device (44) for detecting the position of the stop (38). 11. Device according to one of claims 5 to 10, characterized in that at the stop (12, 13, 38, 59) on the side facing the machine part (2) a shock absorber (32, 41) and one with this or the machine part (2) interacting limit switching element (30, 31, 42), for example an electrical proximity switch is arranged. 12. Device according to one of claims 5 to 11, characterized in that an adjustable stop plate for a machine part (2) is arranged on the stop (12, 13, 38, 59) and that on the stop plate or the stop (12, 13, 38, 59) arranged limit switching element (30, 31, 42) or the shock absorber (32, 41) in the direction of movement of the machine part (2), for example is adjustably mounted via a thread (43).