Patent Application
20200324393
Exemplary embodiments of the invention relate to a device for exchanging a polishing disc.
Polishing discs are used to finish the surfaces of workpieces. The polishing discs are made of a very soft material, for example foam, foam rubber, felt or lambskin. They are fastened to the support plate of the polishing tool by means of connecting elements, in particular a Velcro fastener.
The opposite working side of the polishing disc is usually provided with a highly viscous polishing paste, wherein it must be ensured that when the polishing disc is attached to the support plate, the polishing disc is attached to the support plate with the correct side.
For easier handling when replacing the polishing disc, i.e., to make it easier to remove, the polishing disc protrudes beyond the support plate at the edge.
For an optimum polishing result, the amount of polishing agent applied to the working side of the polishing disc is decisive. For a new polishing disc, a larger amount of polishing agent is first applied and worked into the polishing disc. In subsequent polishing operations, only a small amount of polishing agent is then applied for the respective polishing process, wherein preferably flat workpieces are polished by orbital, rotational and vibrating movements of the polishing tool.
In order to avoid polish splashes, it is important to position the polishing disc or polishing paste exactly, as well as its pattern on the polishing disc. Furthermore, the contact pressure and polishing time are decisive for the polishing result.
It is necessary to change the polishing disc if, for example, the polishing disc is clogged with clear lacquer or base lacquer with which the workpiece is coated, or if the polishing disc's service life has expired or the polishing agent has dried up due to longer breaks.
Replacing the polishing disc has so far been very time-consuming and requires extremely careful work due to the operational contamination. This means that the replacement of the polishing disc, which has been carried out up to now, is a clear obstacle to the cost optimization of the entire polishing process that is always required.
Exemplary embodiments of the invention are directed to a device that allows the replacement of a polishing disc in a shorter time and automatically.
By means of this device, the polishing disc, which practically is worn and held on the support plate of the grinding tool, is automatically replaced, i.e., exchanged for a new polishing disc.
For this purpose, only the polishing tool, usually the arm of the the robot, is to be moved with the connected support plate into the area of a removal opening of a dispenser until contact is made with the polishing disc lying at the top, wherein the positive connection is produced by the corresponding Velcro layers of the support plate on the one hand and the polishing disc on the other hand by means of appropriate pressure.
A sliding device arranged according to the invention on the side of the exchanging device opposite the removal opening, on which the stack of polishing discs rests, serves as an abutment in this case.
After a removal of the corresponding polishing disc, the remaining stack is shifted by the sliding device in such a way that the uppermost polishing disc reaches a removal position.
According to a first embodiment variant, the clear dimension of the removal opening is smaller than the associated outer dimension of the polishing discs, so that a stop is formed that limits the displacement path of the stack by means of the sliding device. In an embodiment variant, the formation of such a stop is not necessary, since the sliding device itself is set up in such a way that it does not push the stack of polishing discs too far forward.
The outer dimension of the support plate, on the other hand, is smaller than the clear dimension of the removal opening, so that the support plate can enter the dispenser unhindered for connection with the polishing disc. The capacity of the dispenser is such that a sufficient number of polishing discs is stored for one working shift. The sliding device can be driven pneumatically, hydraulically or electromechanically.
An extractor device is connected upstream of the exchanging device, by means of which the worn polishing disc is removed from the support plate. This extractor device is equipped with a clamping device, which can consist of gripping pliers, finger pliers or parallel grippers, and by means of which the polishing disc projecting over the edge of the support plate is removed from the support plate.
In this process, the clamping device is brought into a clamping position by a mechanical contact or a light barrier after a movement of the polishing tool into the effective range of the extractor device, preferably by laser detection. The polishing tool is then preferably moved vertically into the area of the exchanging device, wherein the Velcro connection between the polishing disc and the support plate is released.
Furthermore, a collecting container can be provided to hold the polishing disc detached from the support plate. The collecting container, which may be lined with a waste bag, is designed in such a way that it can be moved from the working area of the polishing tool to the area of the exchanging device.
According to a further idea of the invention, the exchanging device has several dispensers arranged on a table at equal distances from each other, wherein the table, which is designed as a round or linear table, is movable in cycles and the respective dispenser can be brought into correspondence with the sliding device. Below the table, a space can be provided for storing dispensers which are supplied ready-made and equipped with polishing discs.
Especially polishing tools that perform orbital and/or eccentric movements can remain in one position indefinitely if the drive power is interrupted. They must therefore be aligned with the polishing disc to be picked up, for which purpose an alignment station for the support plate is located above the exchanging device.
This alignment station has a prism-shaped receptacle that is moved in a horizontal movement towards the support plate and positions it in the center position, exactly to the axis of the exchanging device, by means of an orbital or eccentric movement. Afterwards the prism-shaped holder moves back into a parking position.
The movement sequences of the polishing tool, i.e., the robot, are computer-controlled, wherein the necessity of changing the polishing disc is also detected by a corresponding sensor system.
The automatic work sequence also includes the application of a polishing agent, especially a polishing paste, to the polishing disc. For this purpose, a dosing device is arranged downstream of the exchanging device, which is equipped with a nozzle tip that allows an exact application to the working side of the polishing disc and closes it without dripping.
Alternatively, the polishing agent can be dosed through a polishing agent nozzle from the rear side into the polishing disc, which is preferably designed as a polishing sponge, or through the polishing disc.
This dosing device is equipped with a storage container connected to the nozzle tip via a supply line.
The nozzle tip can be arranged on the robot arm, in the area of the support plate, wherein the polishing disc is provided with the polishing agent after a rotational movement in a time- and path-optimized manner.
Alternatively, the nozzle tip can be placed above the exchanging device, in which case the polishing tool moves towards the nozzle tip.
The output quantity on the polishing disc is also computer-controlled.
A necessary filling of the dispenser with polishing discs can be carried out by an operator, wherein a visual, acoustic or electrical signal gives a corresponding indication to the person. An electronic message can also be sent from the system control, i.e., the computer. In addition, the operator can supply several devices accordingly.
The computer can be used to solve logistical tasks or initiate orders, wherein the consumption of polishing discs and polishing agents per processed workpiece, shift or time period is determined and reported, which ultimately contributes to a continuous improvement of the work process.
This applies equally to the detection of the consumption of polishing discs and polishing agents, which can be used to detect maintenance measures, such as changing the support plate due to wear.
According to another aspect, the working area of the polishing tool is separated from the set-up area, i.e., the area where the exchanging device is loaded. Here the working area is secured by a safety fence, light barriers, light curtains, grids and/or doors, wherein when the doors are opened, the polishing tool is stopped in its movement or moved to a basic position and switched off.
According to an alternative embodiment variant, the clamping device is designed as a jaw tool with at least one displaceable piston with a piston tip that can be pressed laterally into the polishing disc.
According to a further alternative embodiment variant, the clamping device has a main body with a circular opening serving as a toothed pulley holder, the main body having an inlet opening widening away from the toothed pulley, into which the support plate of a polishing tool with a polishing disc adhering thereto can be inserted, and an outlet opening widening away from the toothed pulley, through which a polishing disc released from the support plate can be removed from the clamping device.
According to another idea, the dispenser has limiting rods fixed to a floor and an intermediate floor penetrated by the limiting rods, on which the polishing discs can be stacked, wherein the length of the limiting rods forming a receiving cage for the polishing discs is designed to be adaptable to the stacking height of the polishing discs.
The floor is preferably firmly connected to a positioning rod which, when the polishing tool is lowered, can be moved relative to the stacked polishing discs with the support plate arranged on it until the support plate comes into contact with the uppermost of the polishing discs and can be locked in this position.
According to a further alternative embodiment variant of the invention, the device has an exchanging device with at least one dispenser, wherein the dispenser has a magazine shaft positioned at an incline, with an upper filling region for supporting at least one polishing disc, which can be brought along the magazine shaft into a removal station at a lower end of the magazine shaft, to which the support plate can be moved for attaching the polishing disc to the support plate.
The removal station has position pins for the exact positioning of the polishing disc in a preferred further development.
Embodiment examples of the invention are described below using the attached drawings, wherein:
In
According to the invention, the device has an exchanging device 2 positioned on a worktable 6, which in the example has several dispensers 3 held on a rotary table, which can be brought at equal distances to each other in cycles into the transfer area with the support plate 4.
A partition wall 5 separates a set-up area 15 from a working area 16, wherein in working area 16 the robot 1 is arranged with a part of the exchanging device 2, while set-up area 15 is intended to equip exchanging device 2 with dispensers 3 by means of an operator 7.
A dispenser 3 is shown as a detail in
These polishing discs 8 have, in a manner known per se, a connecting surface and opposite them a working surface, wherein the connecting surface is provided in particular with a Velcro layer which can be brought into contact with a Velcro layer of the support plate 4.
The polishing discs 8 are accommodated in the dispenser 3 in such a way that the connecting surface of the uppermost polishing disc 8 is exposed, while the lowermost polishing disc 8 is supported with its working surface on a sliding device 9, which is axially displaceable and in so doing moves the stack so far that after removal of the uppermost polishing disc 8 the following polishing disc 8 is brought into a removal position.
Especially in
To connect the polishing disc 8 with the facing side of the support plate 4, the support plate 4 is brought under pressure against the connecting surface of the polishing disc 8, wherein the outer dimension of the support plate 4 is smaller than the clear distance between the opposing stops 10. This results in an edge projection of the polishing disc 8 relative to the support plate 4.
In order to apply the pasty polishing agent to the working surface of the polishing disc 8, a dosing device 12 is arranged downstream of the exchanging device 2, which is shown as a detail in
This dosing device 12 has a cartridge 13 filled with the polishing agent and a nozzle 14 with which the polishing agent can be applied to the working surface of the polishing disc 8 in a defined quantity and in a defined application pattern.
The dosing device 12 can be positioned stationary, in the area of the exchanging device 2 or on the robot arm of the robot 1, wherein the support plate 4 is brought into the application area of the nozzle 14 by a corresponding movement.
It can be seen that the receptacle 18 can be moved with the help of a slide, wherein the movement can be carried out by a pneumatic, hydraulic or electromechanical drive.
In operation, the support plate, whose base is circular, lies with its edge against the prism formed, which thus forms a centering for the support plate.
According to a further embodiment variant, in which the polishing tool on the robot arm of robot 1 can be controlled electronically on the basis of an absolute value encoder, the use of such an alignment station 17 can be dispensed with, since the angle measurement allows robot arm of robot 1 to be positioned exactly centrally above the exchanging station.
According to a further embodiment variant, in which the polishing tool on the robot arm of robot 1 can be controlled electronically incrementally, the use of the alignment station 17 is only necessary if the power supply to the robot arm of robot 1 has been interrupted.
It is preferable to have an extractor device upstream of the exchanging device 2, with which a polishing disc 8 can be removed from the support plate 4.
For this purpose, the extractor device is equipped with a clamping device with which, according to one embodiment variant, a marginal area of the polishing disc 8 projecting from the support plate 4 can be clamped.
The clamping device can be actuated for closing by laser detection, a mechanical contact or a light barrier, depending on the position of the support plate 4.
Below the clamping device, a collecting container can be arranged to accommodate the polishing disc 8 which is released from the support plate 4.
According to a preferred embodiment variant, as shown in
As shown in
To remove the polishing disc 8 from the support plate 4, the polishing disc 8 attached to the support plate 4 is pressed into the opening of the jaw tool 19.
Subsequently, a piston tip 22 of at least one preferably pneumatically displaceable piston is pressed laterally into the polishing disc 8 and thus holds the polishing disc 8 firmly in engagement in the jaw tool 19.
It is also conceivable to arrange several such pistons 21 with piston tips 22 for fixing the polishing disc 8.
After the piston tip 22 or the piston tips 22 have been pressed laterally into the polishing disc 8, the support plate 4 is moved away from the polishing disc 8 perpendicularly to the fixing surface of the support plate 4, thus releasing the polishing disc 8 from the support plate 4.
Then the pistons 21 are returned to their initial position. During this process, the piston tip 22 or the piston tips 22 move back out of engagement with the polishing disc 8.
The polishing disc 8 can then preferably be disposed of downwards into a collecting container positioned below the jaw tool 19.
According to another embodiment variant, as shown in
As shown in
To remove the polishing disc 8, the polishing disc 8 is also moved by moving the polishing tool 24 in the direction of the toothed pulley 25 until the polishing disc 8 is pressed through the inlet opening 27 into the toothed pulley 25.
The diameter of the toothed pulley 25 is slightly smaller than the diameter of the polishing disc 8.
The polishing tool 24 is then moved out of the inlet opening 27 back to its initial position, in
The polishing disc 8 remains stuck in the teeth of the toothed pulley 25 until the next polishing disc 8 is pressed through the inlet opening 27 and the toothed pulley 25 and the previously stuck polishing disc 8 is released from the engagement with the toothed pulley 25.
In this embodiment example, a collecting container can also be positioned below the clamping device to collect the used or worn polishing disc 8.
As shown in
This channel 23 is used to accommodate an application nozzle 29, which is located centrally in the support plate 4 and which is connected to a polishing agent reservoir. Through this polishing agent nozzle 29 the polishing agent can be dosed into the polishing disc 8.
Further special embodiment variants of a dispenser 31, 42 are shown in
In the embodiment variant shown in
The limiting rods 11 of the dispenser 31 are fixed on a floor 32 and pass through an intermediate floor 33 on which the polishing discs 8 can be stacked. The length of the part of the limiting rods 11 projecting upwards from the intermediate floor 33 is designed to be adaptable to the stacking height of the polishing discs 8.
For this purpose the floor 32 is firmly connected to a positioning rod 34 as can be seen clearly in
This positioning rod 34 has a pressure surface 35 at its upper end close to the polishing machine 24, which, when the polishing tool 24 is lowered with the support plate 4 arranged on it, is pressed downwards relative to the stacked polishing discs 8, in
The vertical displacement of the positioning rod 34 is accompanied by a lowering of the limiting rods 11.
The polishing discs 8 are not stacked on the floor 32, to which the limiting rods 11 are attached, but on an intermediate floor 33 located above the floor 32, through which the limiting rods 11 pass.
In contrast to floor 32, to which the limiting rods 11 are attached, this intermediate floor 33 always remains at the same height relative to the starting position of the support plate 4.
The positioning rod 34 is designed as a locking shaft at least in the lower area below the base 32, with ratchet teeth 36.
These ratchet teeth 36 are engaged by a locking pawl 37 fixed to a lower base 38, which is connected to the base 32 by connecting rods 39, with which the positioning rod 34 is locked in the respective position in which the polishing disc 8, which was previously received by the support plate 4, was accommodated.
This allows the distance between the pressure surface 35 of the positioning rod 34 and the upper edge of the respective uppermost polishing disc 8 to remain constant until all polishing discs 8 have been removed from the dispenser 3.
In order to refill the dispenser 31 with polishing discs 8, the locking pawl 37 can be released by turning the positioning rod 34, for example by means of an operating lever 41 attached to it perpendicular to its longitudinal extension, and moved back to its initial position by the force of springs 40 attached to the connecting rods 39 of the floor 32 with the lower base 38.
In doing so, the limiting rods 11 are moved upwards relative to the intermediate floor, thus forming a cage which can be filled with new polishing discs 8 until the stack of polishing discs 8 reaches the upper edge of the limiting rods 11 again.
In the alternative embodiment variant, as shown in
The polishing discs 8 then slide along the magazine shaft 43 to a removal station 47.
At this removal station 47, shown in detail in
As further shown in
In order to prevent more than one polishing disc 8 being present on top of each other at the removal station 47, a monitoring element, for example in the form of a light barrier, is preferably provided in the area of removal station 47.
Although the invention has been illustrated and described in detail by way of preferred embodiments, the invention is not limited by the examples disclosed, and other variations can be derived from these by the person skilled in the art without leaving the scope of the invention. It is therefore clear that there is a plurality of possible variations. It is also clear that embodiments stated by way of example are only really examples that are not to be seen as limiting the scope, application possibilities or configuration of the invention in any way. In fact, the preceding description and the description of the figures enable the person skilled in the art to implement the exemplary embodiments in concrete manner, wherein, with the knowledge of the disclosed inventive concept, the person skilled in the art is able to undertake various changes, for example, with regard to the functioning or arrangement of individual elements stated in an exemplary embodiment without leaving the scope of the invention, which is defined by the claims and their legal equivalents, such as further explanations in the description.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2017 130 805.9 | Dec 2017 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2018/085932 | 12/19/2018 | WO | 00 |
