Patent Application
20230201990
The present invention relates to a changing station (grit changer) for changing a surface treatment media (e.g. a sheet member such as sandpaper) from a robot mounted surface treatment tool. The present invention also relates to a method for changing a surface treatment media from a robot mounted surface treatment tool.
There has recently been an increasing use of robot-assisted machining of surfaces. Grinding machines such as orbital grinding machines are typically employed in industries. In orbital grinding machines a rotational movement around an axis of rotation is superimposed over an oscillation movement. Grinding machines are typically applied for the final processing of surfaces when high demands are placed on the quality of the finished surface.
In many situations, robot-supported grinding apparatuses comprise a grinding tool such as an orbital grinding machine guided by an industrial robot. Grinding machines such as orbital grinding machines operate with sheet-formed, flexible and removable grinding discs (e.g. sandpaper) that are attached to a pad portion of a head of the grinding machine pad. There exist various types of grinding discs made of suitable materials such as paper or a fiber-reinforced material with a grained abrasive coating. The grinding discs are configured to be attached to the backing pad of the head of the grinding machine e.g. by a hook and loop fastener.
In robot-supported grinding devices, the grinding discs are often changed manually. There, however, exist various robot-supported changing stations for changing grinding discs. These solutions are, however, complex, require a great deal of effort to be realized and are therefore costly.
Thus, there is a need for an improved way of removing grinding discs from a grinding machine and mounting grinding discs onto a grinding machine.
Accordingly, it is an objective of the present invention to provide an improved method for removing grinding discs from a grinding machine and mounting grinding discs onto a grinding machine.
It is also an object to provide an improved robot-supported changing station for changing grinding discs.
A method for automatically attaching a surface treatment media to a surface treatment tool mounted on a robot arm of a robot having an articulated robot arm is disclosed, wherein the surface treatment tool comprises a head configured to receive the surface treatment media. The method comprises placing the head on a surface and applying a predefined force to press the head towards the surface when no surface treatment media has been attached to the head, and:
Hereby, it is possible to provide a method for removing grinding discs from a grinding machine and mounting grinding discs onto a grinding machine. The method makes it possible to verify if a surface treatment media is attached to the head or not in a simple, reliable and fast manner.
The surface treatment tool may be a grinding machine such as an orbital grinding machine configured to be mounted on the robot arm. The grinding machine may be mounted on the robot arm by using a tool changer.
The surface treatment tool comprises a head configured to receive the surface treatment media. The head may comprise a pad.
The method comprises the step of placing the head on a surface and applying a predefined force to press the head towards the surface when no surface treatment media has been attached to the head. Since a predefined force is applied a corresponding deformation of the head is experienced.
The method comprises the step of measuring the distance between the head and the surface using one or more positioning sensors of the robot arm or the surface treatment tool. Hereby, it is possible to take advantage of the functions that the robot arm or the surface treatment tool provides. Accordingly, no additional functionality has to be added to the robot arm or to the surface treatment tool.
The method comprises the step of attaching a surface treatment media to the head and placing the head on the surface when the surface treatment media is attached to the head.
The method comprises the step of measuring the distance between the head and the surface using the one or more positioning sensors of the robot arm or the surface treatment tool when the surface treatment media is attached to the head.
Hereby, it is possible to verify if a surface treatment media is attached to the head or not in a simple, reliable and fast manner.
In an embodiment, the surface treatment media is a sheet member. The surface treatment media may be formed as a coated abrasive. In an embodiment, the surface treatment media is an abrasive grain bonded to a flexible substrate using adhesives. In an embodiment, the surface treatment media is sandpaper.
It may be advantageous that the method comprises the following steps:
Hereby, it is possible to verify that the surface treatment media has been removed. If it has been verified that the surface treatment media has been removed a new piece of surface treatment media can be attached. If, however, it is not verified that the surface treatment media has been removed, the step of removing the surface treatment media from the head can be repeated.
It may be an advantage that the method comprises the step of detecting the orientation of the head by bringing the head into engagement with engagement structures.
Hereby, it is possible to make sure that the orientation of the surface treatment media being attached to the head is correct and corresponds to the desired orientation (in which the holes in the surface treatment media are aligned with holes in the head).
It may be beneficial that the head comprises several holes and the engagement structures comprise one or more detection pins arranged with a predefined mutual distance from each other or a predefined mutual distance from another structure that is arranged to be brought into engagement with a predefined structure of the head, wherein the one or more detection pins are configured to be brought into engagement with one or more holes of the head. Hereby, it is possible to arrange the head of a surface treatment tool in such a manner that the head of a surface treatment tool has a pre-defined and desired orientation.
In an embodiment, the head comprises several holes and the engagement structures comprise two detection pins arranged with a predefined mutual distance from each other, wherein the two detection pins are configured to be brought into engagement with the holes of the head.
In an embodiment, the head comprises several holes and the engagement structures comprise at least three detection pins arranged with a predefined mutual distance from each other, wherein the at least three detection pins are configured to be brought into engagement with the holes of the head.
It may be advantageous that the method comprises the step of applying a changing station that comprises a detachment portion configured to detach a surface treatment media from the head and an attachment portion designed and configured to attach a surface treatment media to the head.
In an embodiment, two guide pins are provided in an attachment portion and two detection pins are protruding from the surface of the detachment portion. Hereby, it is possible to provide a practical solution that makes it possible to arrange the head of a surface treatment tool in such a manner that the head of a surface treatment tool has a predefined and desired orientation.
In an embodiment, the method comprises the step of removing the surface treatment media from the head by moving the head along the surface of the detachment portion, wherein the detachment portion comprises a plate formed as a separation blade that is provided at a distance from the adjacent edge of the surface, wherein the plate is provided in a slightly higher level than the surface.
Hereby, a gap will be provided between the plate and the support member. It is essential that this gap is large enough to receive an edge portion of the surface treatment media.
In an embodiment, the step of removing the surface treatment media from the head can be accomplished by having the surface treatment media enter the gap between the plate and the support member and moving the robot mounted surface treatment tool in a direction along the surface of the support member towards the plate.
In an embodiment, the orientation of the head is detected by moving (rotating) the head until two holes in the head have been received by the two detection pins.
It may be an advantage that the method comprises the step of removing the lowermost surface treatment media by bringing at least the most distal portion of the head into contact with a media holder and moving the head along the length of the media holder.
It may be an advantage that, in case it has been detected that more than one surface treatment media have been attached to the head, the method comprises the step of removing the lowermost surface treatment media by bringing at least the most distal portion of the head into contact with a removal structure and moving the head along the length of the removal structure.
In an embodiment, the media holder is formed as a pin that comprises alternating portions of protruding structures and groove structures.
In an embodiment, the depth of the groove structure relative to the protruding structure is in the range 0.01-5 mm.
In an embodiment, the depth of the groove structure relative to the protruding structure is in the range 0.04-4 mm.
In an embodiment, the depth of the groove structure relative to the protruding structure is in the range 0.08-3 mm.
In an embodiment, the depth of the groove structure relative to the protruding structure is in the range 1.0-2.0 mm.
It is important to emphasize that the groove depth can be set based on the thickness of the surface treatment media.
The changing station disclosed herein is a changing station for automatically attaching a surface treatment media to a surface treatment tool mounted on a robot arm of a robot having an articulated robot arm, wherein the surface treatment tool comprises a head configured to receive the surface treatment media, wherein the changing station comprises a detachment portion and an attachment portion, wherein the detachment portion comprises a support member configured to receive the head, wherein the detachment portion comprises two detection pins protruding from the support member and being arranged with a predefined mutual distance.
Hereby, it is possible to arrange the head of a surface treatment tool in such a manner that the head of a surface treatment tool has a predefined and desired orientation.
The head may comprise a pad made of a compressible material. Hereby, it is possible to allow the head to at least partly adapt to the shape of the object that is to be treated by the surface treatment media.
In an embodiment, the detachment portion and the attachment portion are integrated into a one-piece body.
In an embodiment, the changing station comprises a frame that surrounds at least a portion of the detachment portion and at least a portion of the attachment portion.
In an embodiment, the support member is substantially planar.
In an embodiment, the support member comprises a semi-circular portion.
It may be an advantage that the attachment portion comprises a base portion, wherein two guide pins protrude from the base portion, wherein the two guide pins are arranged with the same mutual distance as the two detection pins.
In an embodiment, the guide pins are detachably attached to the base portion. Hereby, it is possible to replace the guide pins with longer or shorter ones.
In an embodiment, the base portion is configured to receive a pair of detachably attached guide pins in various positions so that the position of the guide pins can be changed.
It may be advantageous that the attachment portion comprises a base portion configured to receive a stack of surface treatment media and that the attachment portion comprises a plurality of media holders shaped as pin-formed stop members that are arranged in a configuration in which the media holders surround the base portion.
In an embodiment, the media holders extend parallel to the guide pins and protrude from a frame surrounding the base portion.
In an embodiment, the media holders are formed and arranged to keep the correct surface treatment media orientation when a plurality of surface treatment media pieces are stacked in the attachment portion.
In an embodiment, the media holders have a cylindrical portion.
In an embodiment, the media holders have a proximal cylindrical portion and a distal rounded portion.
In an embodiment, several of the media holders comprise alternating portions of protruding structures and groove structures.
In an embodiment, at least a plurality of the media holders comprise alternating portions of protruding structures and groove structures.
It may be an advantage that the detachment portion comprises a separation blade that is provided at a distance from an adjacent edge of the support member, wherein the separation blade is provided at a higher level than the support member.
A robot system disclosed herein is a robot system comprising:
It may be an advantage that the robot system comprises:
In an embodiment, a predefined force is applied to press the head against the support member when measuring the distance between the head and the support member.
In an embodiment, the plate and the separation blade are attached to each other. In an embodiment, the plate and the separation blade are integrated to constitute a one-piece body.
In an embodiment, the separation blade is movably arranged with respect to the support member. Hereby, the magnitude of the gap can be changed by moving the separation blade. Attachment of the separation blade may be carried out using screws or other attachment members.
The invention will become more fully understood from the detailed description given herein below. The accompanying drawings are given by way of illustration only, and thus, they are not limitative of the present invention. In the accompanying drawings:
Referring now in detail to the drawings for the purpose of illustrating embodiments of the present invention, a changing station 2 is illustrated in
The detachment portion 4 comprises a plate-shaped support member 8 configured to receive a surface treatment media 24 (e.g. a sheet member such as sandpaper shown in
The detachment portion 4 comprises a plate 12 formed as a separation blade that is provided at a short distance from the adjacent edge of the support member 8. The plate 12 is provided in a slightly higher level than the support member 8. Hereby, a gap (see
Removal of the surface treatment media from a head of a surface treatment tool like the one shown in
The detachment portion 4 comprises two detection pins 14, 14′ arranged with a predefined distance in order to use the detection pins 14, 14′ for detecting corresponding holes in a head of a surface treatment tool configured to receive the surface treatment media. Hereby, it is possible to arrange the head of a surface treatment tool in such a manner that the head of a surface treatment tool has a predefined and desired orientation.
The attachment portion 6 comprises a circular base portion (configured to receive the media) 24. Two mounting structures 18, 18′ are provided at base portion 22. The mounting structures 18, 18′ are shaped to receive detachably mounted guide pins 34, 34′. When mounted, the guide pins 34, 34′ protrude from the base portion 22 along the Z axis.
A plurality of media holders 20 shaped as pin-formed stop members 20 surround the base portion 22. The media holders 20 extend parallel to the mounting structures 18, 18′ and the guide pins 34, 34′ and protrude from the frame 50 surrounding the base portion 22. Each of the mounting structures 18, 18′ is provided with a distal female receiving structure configured to receive a matching male portion of the proximal portion of the corresponding guide pin 34, 34′.
The pin-formed media holders 20 are formed and arranged to keep the correct surface treatment media orientation when a plurality of surface treatment media pieces are stacked in the attachment portion 6.
The changing station 2 is provided with holes for being mounted to a mounting surface (e.g. a table or another working station).
During normal use, the changing station 2 is orientated in such a manner that the Z axis extends vertically.
A sensor 48 configured to detect force and/or torque is attached to the robot arm 28 or alternatively integrated in the robot arm 28 or the surface treatment tool 26.
The surface treatment tool 26 is arranged above an object 36 that needs a surface treatment.
A changing station 2 according to an embodiment is arranged next to the robot 30. The changing station 2 corresponds to the one shown and explained with reference to
It can be seen that each surface treatment medium 24 comprises holes 38 and that the attachment portion 6 comprises a guide pin 34 that extends through one of the holes in the surface treatment medium 24.
A head 40 of a surface treatment tool (not shown) rests on the support member of the detachment portion 4 of the changing station 2. A number of holes 42 are provided in the head 40. The holes 38 in the surface treatment media 24 are placed in such a manner that they can be aligned with the holes 42 provided in the head 40. Hereby, dust can be removed from a surface treatment medium 24 through these holes 38, 42 during use of the surface treatment medium 24.
The detachment portion 4 comprises two detection pins 14 (however, only one is visible in
A downwardly directed (along the axis Z) force F is applied to the head 40. Accordingly, the head 40 presses against the stack of surface treatment media 24 and one piece of surface treatment media 24 is attached to the head 40. In an embodiment, the applied force is within the range 5-100 N.
In an embodiment, the surface treatment medium 24 is a piece of sandpaper having a thickness of 0.5 mm. In this case, the expected value would be 0.5 mm.
In an embodiment, the surface treatment medium 24 is a piece of sandpaper having a thickness of 1.0 mm. In this case, the expected value would be 1.0 mm.
In an embodiment, the surface treatment medium 24 is a piece of sandpaper having a thickness of 1.5 mm. In this case, the expected value would be 1.5 mm.
The detachment portion 4 comprises a plate 12 having a distal portion formed as a separation blade 32. The separation blade 32 is provided a short distance from the adjacent edge of the support member 8. The top portion of the plate 12 and the separation blade 32 are provided in a slightly higher level than the support member 8. Hereby, a gap 10 is provided between the separation blade 32 and the support member 8. This gap 10 is large enough to receive an edge portion of the surface treatment medium 24.
In an embodiment, the plate 12 and the separation blade 32 are attached to each other. In an embodiment, the plate 12 and the separation blade 32 are integrated to constitute a one-piece body.
In an embodiment, the separation blade 32 is movably arranged with respect to the support member 8. Hereby, the magnitude of the gap 10 can be changed by moving the separation blade 32. Attachment of the separation blade 32 may be carried out using screws or other attachment members.
The distance between the head 40 and the support member 8 is measured by one or more positioning sensors of the robot arm, to which the surface treatment tool (see
If the distance between the head 40 and the support member 8 is de- creased as expected (so that the distance between the head 40 and the support member 8 corresponds to the value referred to when describing
In order to attach a surface treatment medium 24 to the head 40, a force F is applied from the head 40 towards the stack of surface treatment media 24.
If the lowermost surface treatment medium 24 protrudes relative to the uppermost surface treatment medium 24 and the head 40, it is possible to remove the lowermost surface treatment medium 24 by placing a part of it in a groove structure 46 and moving the uppermost surface treatment medium 24 and the head 40 along the length of the adjacent media holder 20.
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| Number | Date | Country | Kind |
|---|---|---|---|
| PA 2020 00989 | Sep 2020 | DK | national |
| PA 2021 00221 | Mar 2021 | DK | national |
This application is a continuation under 35 U.S.C. 111 of International Patent Application No. PCT/DK2021/050266, filed Aug. 31, 2021, which claims the benefit of and priority to Danish Application Nos. PA 2021 00221, filed Mar. 2, 2021, and PA 2020 00989, filed Sep. 2, 2020, each of which is hereby incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/DK2021/050266 | Aug 2021 | WO |
| Child | 18116045 | US |
