Device and method for exchanging a grinding wheel or grinding disc of a robotic grinding machine

Abstract

The invention relates to a device for automatically removing a grinding wheel or grinding blade from a grinding disc of a robot-assisted grinding machine, characterized in that the device has a body with an opening adapted to the grinding disc of the grinding machine for passing the grinding wheel and comprises a punch with a stop surface, wherein the body or opening and punch can be brought into contact with each other by means of an actuator in such a way that an outer grinding wheel or grinding blade area projecting beyond the edge of a grinding disc passed through the opening can be clamped between the body wall and the stop surface of the punch.

Description

[0001] The present invention relates to a storage magazine for storing grinding wheels or grinding blades for a robot-assisted grinding device, a system for automatically changing the grinding wheel or grinding blade of a robot-controlled grinding machine, and a grinding system.

[0002] Grinding machines are used to process various materials. A significant area of ​​application is automotive manufacturing. There, it is necessary to rework the applied paint on the vehicle body using grinding and polishing processes in order to effectively remove, for example, dust inclusions in the paint. In practice, this rework is already carried out semi-automatically using robot-controlled grinding machines.

[0003] These grinding machines comprise a manipulator whose movements are controlled by actuators. At the end of the manipulator, a grinding disc, rotating around its axis, is mounted to hold a grinding wheel or grinding tip. During the grinding process, the grinding wheel or tip experiences the usual wear and tear, requiring it to be replaced at regular intervals. The grinding wheel is detachable, typically attached to the grinding disc via a hook-and-loop fastener, allowing it to be easily removed and replaced with a new one once worn. Currently, the replacement of worn grinding wheels or tips in automotive manufacturing is mostly done manually, increasing machine downtime. Therefore, there is a desire for an automated grinding wheel replacement system.

[0004] Such a system is known, for example, from EP 2 842 689 B1. In the device described there, so-called removal fingers are provided, which engage in corresponding recesses on the outer edge of the grinding wheel to grip behind the mounted grinding wheel. This allows the latter to be pulled off the grinding wheel. However, the disadvantage of such a device is that the design with separate removal fingers is relatively complex and expensive. Furthermore, this approach requires special modifications to the grinding wheel and the mounted grinding wheel.

[0005] This reinforces the need for a simpler solution for automatically removing a grinding wheel / grinding disc from the grinding wheel of a robot-assisted grinding machine. Furthermore, it is desirable to be able to automatically mount new grinding wheels or discs onto the grinding wheel. This requires a method for keeping a sufficient quantity of new grinding wheels or discs readily available.

[0006] Corresponding storage magazines for holding grinding sheets are already known from DE 10 2017 130801 A1 and US 2016 / 039067 A1. According to DE 10 2017 130801 A1, which forms the basis for the preamble of claim 1, several grinding sheets are stacked on top of each other and pushed out of the magazine by means of a slide. US 2016 / 039067 A1 discloses an open magazine with a lifting mechanism.

[0007] This problem is solved by a storage magazine for storing grinding wheels or grinding blades for a robot-assisted grinding device according to the features of claim 1. Advantageous embodiments of the storage magazine are the subject of the dependent claims. Furthermore, the problem is solved by a system for automatically changing the grinding wheel or grinding blade of a robot-controlled grinding machine according to the features of claim 5, and by a grinding system according to the features of claim 6.

[0008] In the interest of fully automating the entire grinding process, the automatic loading of a new grinding wheel / grinding blade is also important. According to the invention, a storage magazine is proposed for this purpose, which allows the loading of several grinding wheels / grinding blades stacked on top of each other. The magazine includes a sufficiently large opening through which the grinding wheel can be inserted to remove a new grinding wheel / grinding blade.

[0009] One conceivable design of the storage magazine is a cylindrical container open at the end for inserting the grinding disc. Several grinding discs / abrasives can be stacked axially inside the container. As described in the introduction, the grinding discs / abrasives adhere to the grinding disc due to suitable adhesives. Hook-and-loop fasteners are commonly used. However, this can lead to mutual adhesion of the grinding discs / abrasives when stacked. To prevent this, the invention proposes separating adjacent grinding discs / abrasives from each other using separating agents.According to the invention, a brush-like separating agent is used, the individual brushes of which engage between stacked grinding discs / butterflies, so that these do not stick to each other or slip when the uppermost grinding disc / butterfly is picked up.

[0010] Instead of a single release agent, these can also be distributed around the circumference of the container, so that several individual release agents engage from different positions for each stacked abrasive disc / sheet. The multiple release agents can be arranged rotationally symmetrically to the axial axis of the magazine. Preferably, exactly three release agents are provided, arranged rotationally symmetrically to the axial axis of the magazine.

[0011] The invention also encompasses a system for the automatic changing of grinding wheels / abrasives on a grinding disc of a grinding machine. The system comprises a device for automatically removing the grinding wheels / abrasives and the storage magazine according to the invention. To avoid repetition, further descriptions of the individual components of the storage magazine are omitted. The device for automatically removing the grinding wheels / abrasives comprises a body with an opening adapted to the grinding disc of the grinding machine. The opening extends from one side of the body to the other and serves to guide the grinding disc through. The device also includes a plunger with a stop surface.In this arrangement, at least the body or the punch is movably mounted on the device by means of an actuator, so that the punch and its stop surface can be brought close to the body and the opening provided therein. Preferably, the punch can be moved towards the body or its opening by means of an actuator. However, there is nothing preventing the body from being moved towards the stationary punch by means of an actuator. Theoretically, both the punch and the body could be moved by means of an actuator.

[0012] Furthermore, the invention also encompasses a complete grinding system, consisting of at least one grinding robot with a corresponding grinding wheel and a storage magazine according to the present invention. The grinding system therefore offers the same advantages and properties as those already explained above with reference to the individual components. For this reason, a repetitive description is omitted.

[0013] Optionally, the grinding system can include the aforementioned device for automatically removing the grinding blades / discs.

[0014] The opening of the automatic squeegeeing device can be a closed opening; in this case, the sanding disc is inserted from one side of the housing through the opening to the other side. The opening does not necessarily have to be completely closed. If there is a corresponding opening around the perimeter, the sanding disc does not necessarily have to be inserted axially, but can alternatively be inserted through the perimeter opening.

[0015] A prerequisite for the device's functionality is that a grinding wheel or grinding disc mounted on the grinding disc protrudes at least slightly beyond the disc's circumference. This protruding portion of the grinding wheel can then be clamped between the plunger's stop surface and the body wall surrounding the opening by either positioning the plunger against the opening or positioning the body against the plunger. Once the grinding disc is withdrawn from the opening, the grinding wheel or grinding disc can be removed from the grinding disc.

[0016] The actuator for positioning the punch and / or the body can be a linear drive, particularly in the form of a positioning cylinder. However, other drive types are conceivable; the only requirement is that the stop surface of the punch can be positioned on the grinding wheel passing through the opening, in such a way that a protruding grinding wheel or grinding disc area can be clamped between the body wall and the stop surface of the punch.

[0017] According to an advantageous embodiment of the invention, the plunger can be formed by a cylindrical disc. The side of the disc facing the body forms the stop surface. Preferably, the actuator engages the opposite side of the disc; in particular, the free end of the actuating rod of an actuating cylinder is connected to this side of the disc.

[0018] The housing opening can advantageously be circular. Ideally, the shape of the opening is modeled on the shape of the sanding disc. The diameter of the housing opening is preferably slightly larger than the diameter of the sanding disc so that the latter can be easily inserted through the opening. For conical sanding discs with varying diameters, the diameter of the housing opening must be adapted to the largest diameter of the sanding disc, usually the diameter of the end face for attaching the sandpaper or sanding pad. In particular, the diameter of the opening must be at least as large as the diameter of the end face of the sanding disc.

[0019] Furthermore, the diameter of the housing opening may be smaller than the diameter of the grinding wheel or grinding disc being used. The strike surface of the punch therefore not only covers the housing opening but also contacts a section of the housing wall that forms the opening. Between this wall section and the strike surface of the punch, an edge of the grinding wheel or grinding disc that protrudes beyond the grinding wheel can thus be clamped.

[0020] After the grinding wheel has been automatically removed by the device, it is essential, as part of a fully automated process, to ensure that the grinding wheel / grinding blade has actually been completely removed. Ideally, the device is extended to include a testing device that can automatically check whether the grinding wheel / grinding blade has been completely removed after the automatic removal process. Such a measuring method can, for example, be pressure-based, in which the grinding wheel, particularly the end-face grinding wheel holder, is pressurized with compressed air or a vacuum. This method utilizes the fact that the inherently hollow grinding wheel is sealed by the mounted grinding blade / grinding wheel.If compressed air or a vacuum is applied to the front surface of the grinding disc, a pressure sensor can reliably detect whether the cavity is closed by a grinding wheel / grinding blade or not.

[0021] Alternative measurement methods are also conceivable, e.g. an optical measurement method.

[0022] If the testing unit operates using pressure-based technology, a test plate can be provided onto which the grinding wheel, with its end-face mounting surface, can be placed. A defined air pressure can then be blown towards the grinding wheel via a pressure nozzle integrated into the plate, or a corresponding vacuum can be created. A sensor located in the area of ​​the test plate detects the pressure conditions, which can change depending on whether a grinding wheel or disc is mounted on the plate.

[0023] A key feature of the grinding system is that the grinding pad allows for the attachment of a grinding disc or grinding pad via a hook-and-loop fastener. This ensures a sufficiently stable connection between the grinding disc / pad and the grinding pad, while simultaneously enabling the automatic removal of the grinding disc / pad from the grinding robot's pad and the automated attachment of a replacement.

[0024] Another characteristic of the grinding system is that the diameter of the grinding wheel / grinding flower is larger than the diameter of the grinding disc, resulting in a protruding edge of the grinding wheel or grinding flower which can be clamped by the device for automatically removing the grinding wheel / grinding flower.

[0025] Further advantages and features of the invention will be explained in more detail below with reference to an exemplary embodiment shown in the figures. The figures show: Figures 1a - 1d: different perspective views of the device for removing a grinding wheel from a grinding disc, Figure 2: a view of the compressed air-based testing unit, Figure 3: a top view and perspective side view of the storage magazine for grinding discs according to the invention, and Figure 4: a sectional view of the storage magazine according to the invention with a grinding disc inserted.

[0026] The representations of Figures 1a - 1d show different views of the device for the automated removal of a grinding wheel 2 from a grinding disc 1. Figure 1aFigure 1 shows in particular a perspective view of the device. The device comprises a base plate 13, to which a vertical plate 14 is arranged at one end. Opposite the vertical plate 14 is the body 11 with the body opening 12 for receiving or passing through a grinding disc 1 of a grinding machine (not shown in detail here).

[0027] The body 11 consists of a first plate-like vertical section 11a, a horizontal section 11b, and a second plate-like vertical section 11c. The first vertical section 11a includes the body opening 12, which is open circumferentially towards the top edge of the plate. Alternatively, the opening 12 could also be completely closed.

[0028] The diameter of the cone-shaped sanding disc 1, on whose front face 1a a sanding flower 2 is held by means of Velcro, is smaller than the diameter of the opening 12, so that the sanding disc 2 can either be passed through the opening 12 in an axial direction or inserted from above.

[0029] As well as the Figure 1a As can be seen, the sanding blade 2 has a larger surface area than the end face of the sanding disc 1, so that a certain edge of the sanding blade 2 extends beyond the circumference of the sanding disc 1. At the same time, the diameter of the sanding blade 2 is also larger than the diameter of the body opening 12, so that the protruding edge also extends beyond the opening 12.

[0030] An actuator 23 is arranged on the side opposite the end face of the grinding wheel 1 and is supported by the second vertical plate 14. The actuator is designed as a cylinder, the cylinder rod 24 of which can be extended linearly towards the opening 12 of the housing. A punch 21 in the form of a cylindrical disc is mounted at the free end of the cylinder rod 24. The punch 21 has a stop surface 21a that can be moved towards the opening 12 of the housing 11, so that the protruding edge of the grinding blade 2 can be clamped between the housing surface 11a and the stop surface 21a of the punch 21.

[0031] If the protruding area of ​​the sanding blade 2 is clamped, the sanding disc 1 can be pulled backwards out of the opening 12 while simultaneously being moved vertically, so that the sanding blade 2 can be easily detached from the sanding disc 1.

[0032] The presentation of Figure 2The device's test unit is used to query the condition of the grinding disc, i.e., whether a grinding blade 2 is present or not.

[0033] The test unit consists of a test plate 30, which includes a compressed air supply 31. A sensor 35 is also located within the test device 30. The grinding disc 1 is positioned from above onto the surface of the test plate 31, so that its end face rests on the surface. Compressed air is then supplied to the grinding disc 1 via the compressed air supply 31 of the test plate. The pressure sensor then determines whether a grinding wheel 2 is still attached to the grinding disc 1.

[0034] In the Figures 3a, 3bFigure 1 shows different representations of a storage magazine according to the invention for storing a plurality of abrasive blades 2. The magazine essentially consists of a cylindrical container 40, which has a total of three longitudinal grooves 41 on its outer circumference in the axial direction. Projecting brackets 42 are arranged in the area of ​​these longitudinal grooves 41, which serve to receive suitable release agents. Brush elements are used as release agents, the brush holders 50 of which are mounted on the brackets 42. The individual brush fibers 51 then extend through the grooves 41 into the cylindrical interior of the storage container 40, so that they can lie between axially stacked abrasive blades 2 as a release agent.

[0035] As is particularly evident in the Figure 3aAs can be seen, these separating agents 50, 51 are arranged rotationally symmetrically to the axial axis of the storage system, thereby achieving good separation between adjacent grinding discs 2. The principle of separation is better illustrated in the sectional view of the Figure 4This is illustrated. The figure shows an axial section through the storage system 40 with a multitude of abrasive pads 2 stacked axially. A corresponding separating agent 50 with individual brush elements 51 is also visible. The individual brush elements 51 are passed through the groove 41 and thus lie between adjacent abrasive pads 2, so that they are separated from each other at least at their edges. The illustration also shows the grinding disc 1 of the grinding system, which is inserted from above into the cylindrical storage container 40 to receive the uppermost abrasive pad 2 via the hook-and-loop fastener. The separation of the uppermost abrasive pad 2 from the abrasive pad below it by means of the separating agent 51 ensures that when the uppermost abrasive pad 2 is lifted out, all other abrasive pads remain correctly positioned.

Claims

1. Storage magazine for storing grinding wheels or abrasive discs (2) for a robot-assisted grinding device, characterized in that the magazine comprises a cylindrical container (40) which comprises, in the region of the cylindrical wall, one or more brush-type separating means (50, 51) for separating from one another grinding wheels or abrasive discs (2) stacked on top of one another.

2. Storage magazine according to claim 1, characterized in that several, in particular three, brush-type separating means (50, 51) are provided, which are arranged rotationally symmetrically with respect to the axial axis of the storage magazine.

3. Storage magazine according to any one of claims 1 or 2, characterized in that the cylindrical container (40) has an opening through which a grinding plate (1) of the robot-assisted grinding device can be introduced to remove a new grinding wheel / a new abrasive disc (2).

4. Storage magazine according to any one of claims 1 to 3, characterized in that the cylindrical container (40) comprises, on its outer circumference, several longitudinal grooves (41) extending in the axial direction, in the region of which projecting brackets (42) are respectively arranged, a brush holder (50) being mounted respectively on the brackets (42), the brush fibers (51) of which extend through the longitudinal groove (41) into the cylindrical interior space of the cylindrical container (40), such that these are located between grinding wheels or abrasive discs (2) stacked axially on top of one another as separating means.

5. System for the automatic change of the grinding wheel or abrasive disc (2) of a robot-controlled grinding machine, comprising at least one storage magazine according to any one of claims 1 to 4 and at least one device for automatically removing a grinding wheel or an abrasive disc (2) from a grinding plate (1) of the grinding machine, wherein the device comprises a body (11) with an opening (12) adapted to the grinding plate (1) of the grinding machine for the passage of the grinding plate (1) and comprises a piston (21) with an abutment surface (21a), and wherein the body (11) or the opening (12) and the piston (21) are capable of being brought closer together by means of an actuator (23) such that an outer region of the grinding wheel or abrasive disc protruding from the edge of a grinding plate (1) passed through the opening (12) can be clamped between the body wall (11a) and the abutment surface (21a) of the piston (21).

6. Grinding system comprising at least one robot-controlled grinding machine and a storage magazine according to any one of claims 1 to 4.

7. Grinding system according to claim 6, characterized in that a grinding plate (1) of the grinding machine can receive a grinding wheel or an abrasive disc (2) by means of a hook-and-loop connection.

8. Grinding system according to claim 7, characterized in that the diameter of the grinding wheel or abrasive disc (2) is greater than the diameter of the grinding plate (1).

9. Grinding system according to any one of claims 6 to 8, characterized in that the system comprises a device for automatically removing a grinding wheel or an abrasive disc (2) from a grinding plate (1) of a robot-assisted grinding machine, the device comprising a body (11) with an opening (12) adapted to the grinding plate (1) of the grinding machine for the passage of the grinding plate (1) and a piston (21) with an abutment surface (21a), and the body (11) or the opening (12) and the piston (21) being capable of being brought closer together by means of an actuator (23) such that an outer region of the grinding wheel or abrasive disc protruding from the edge of a grinding plate (1) passed through the opening (11) can be clamped between the body wall (11a) and the abutment surface (21a) of the piston (21).

10. Grinding system according to claim 9, characterized in that the body (11) and / or the piston (21) can be moved linearly towards one another by means of an actuator (23), preferably an adjusting cylinder being used as actuator.

11. Grinding system according to any one of claims 9 or 10, characterized in that the abutment surface (21a) of the piston (21) is formed by the surface of a cylindrical disc facing the body (11), and whose opposite side is connected to the actuator (23), in particular to the adjusting rod (24) of the adjusting cylinder.

12. Grinding system according to any one of claims 9 to 11, characterized in that the opening (12) of the body (11) is a circular opening whose diameter is greater than the diameter of the grinding plate (1) but smaller than the diameter of the grinding wheel or abrasive disc (2).

13. Grinding system according to any one of claims 9 to 12, characterized in that the cross-sectional area of the opening (12) of the body (11) is smaller than the abutment surface (21a), in particular the diameter of the opening (12) being smaller than the diameter of the abutment surface (21a).

14. Grinding system according to any one of claims 9 to 13, characterized in that the device comprises a control unit with a compressed air or vacuum supply (31) and a pressure sensor (35), the compressed air or vacuum supply (31) and the pressure sensor (35) making it possible to determine whether a grinding wheel or an abrasive disc (2) adheres to the grinding plate (1).

15. Grinding system according to any one of claims 9 to 14, characterized in that the control device comprises a control plate (30) with integrated compressed air or vacuum supply (31), on which the grinding plate (1) can be placed in order to supply the front side of the grinding plate (1) with compressed air or vacuum.

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