Vacuum gripper, method for detecting leaks in the gripper, and automated process using the gripper and use thereof - Patents.com

Abstract

A vacuum gripper having a suction area with enhanced leak detection, a method for detecting leakage of ambient fluid into such a vacuum gripper, a method for detecting leakage of ambient fluid into the gripper, and an automated operation involving engaging a sheet formed object with the vacuum gripper are disclosed.

Description

[Technical field]

[0001] The present invention relates to vacuum grippers, and more particularly to vacuum grippers having suction areas with enhanced leak detection, methods for detecting leakage of ambient fluids into such vacuum grippers, and the use of vacuum grippers in automated processes involving engaging sheet-formed objects with the vacuum gripper, such as loading operations. [Background technology]

[0002] Suction grippers, also called vacuum grippers, are known in the art and are conventionally used to lift, for example, sheet-formed objects having an essentially flat surface. One type of suction gripper comprises a housing having an internal vacuum chamber connected to a vacuum source and several suction holes in its suction area that engage the object to be processed, the holes being in fluid communication with the vacuum chamber in the gripper.

[0003] Problems can arise when an object to be engaged by a gripper is not properly aligned with the suction surface of the gripper. In such cases, particularly in automated operations, the object may be released in an unintended orientation, stacked on top of a previously released object, etc. Another problem can arise when a portion or area of ​​the object to be engaged by the gripper is wrinkled or folded. This can result, for example, in uneven stacking and / or undesirable gaps in the resulting stack.

[0004] It is desirable to be able to detect imprecise alignment of an object, or areas of an object that are wrinkled or folded. Summary of the Invention [Problem to be solved by the invention]

[0005] It is an object of the present invention to provide a vacuum gripper that overcomes one or both of the above problems. [Means for solving the problem]

[0006] According to the present invention, for a vacuum gripper 10 comprising a body 20 for gripping a sheet-formed object 100 and having an internal primary vacuum chamber 25, an opening 15 for connecting the internal primary vacuum chamber 25 to a vacuum source 17, an opening 30 for connecting a pressure sensor 33 configured to sense a pressure in the gripper body 20, a suction area A2, A1 for engaging the sheet-formed object 100 and at least one suction hole 3 provided in the suction area A1, A2, the above object is achieved by the features characterized in that the body 20 further comprises a secondary internal vacuum chamber 35 in fluid communication with the internal primary vacuum chamber 25 via a flow restriction 37, the at least one suction hole 3 being provided in the suction area A2 of the secondary internal vacuum chamber 35, the size of the cross-sectional area of ​​the flow restriction 37 being similar to the size of the cross-sectional area of ​​one of the at least one holes 3, and the opening 30 for connecting to the pressure sensor 33 being provided in the secondary internal vacuum chamber 35. Thus, the pressure sensor 33 is configured to sense the pressure within the secondary internal vacuum chamber 35 of the gripper body 20 .

[0007] Thus, in one aspect, the present invention relates to a vacuum gripper as described above.

[0008] In another aspect, the present invention relates to a method for detecting leakage of an ambient fluid into a vacuum gripper 10 for gripping a sheet-formed object 100, comprising the steps of engaging the sheet-formed object 100 with the vacuum gripper 10, monitoring a pressure in an internal vacuum chamber 35 of the gripper 10 using a pressure sensor 33 connected to the internal vacuum chamber 35 while the sheet-formed object 100 is engaged with the vacuum gripper 10, comparing the monitored pressure to a predetermined desired pressure, and determining a monitored pressure that is higher than a predetermined allowable maximum pressure, wherein the gripper 10 comprises a primary internal vacuum chamber 25 and a secondary internal vacuum chamber 35, which are fluidly connected to each other via a flow restriction 37, and wherein the monitored pressure is the pressure in the secondary internal vacuum chamber 35.

[0009] In a preferred embodiment, if the monitored pressure within the secondary internal vacuum chamber 35 of the gripper 10 is determined to be higher than a predetermined allowable maximum pressure, the method of the present invention is aborted.

[0010] The method of the present invention and the vacuum gripper of the present invention can preferably be used in automated operations that involve engaging sheet-formed objects 100, such as applications in which multiple sheet-formed objects 100 are stacked on top of each other.

[0011] Further embodiments and advantages of the present invention will become apparent from the following detailed description and the appended claims.

[0012] As used herein, the term "flow restriction" is intended to refer to an open passageway that fluidly connects the primary vacuum chamber 25 with the secondary vacuum chamber 35. To fluidly connect the primary vacuum chamber 25 with the secondary vacuum chamber 35, the open passageway should always be open and should not have any moving parts to close the passageway or the like. [Brief description of the drawings]

[0013] [Figure 1]An embodiment of a gripper 10 according to the invention is shown, which comprises a gripper body 20 with suction areas A1, A2. As shown in FIG. 3A, the gripper of FIG. 1 comprises a primary vacuum chamber 25 with a number of suction holes 3 and two secondary vacuum chambers 35 with a number of suction holes 3 each. The gripper shown in FIG. 1 also comprises an ejector 17 and two openings 30 for connection to a pressure sensor 33. In FIG. 1, only one connection and pressure sensor 33 are shown, the other connection and pressure sensor 33 are removed for illustration purposes. FIG. 1 also shows a compressible foam sheet 50 with a number of holes 53 and a non-permeable adhesive backing 65, which can be attached to the suction areas A1, A2 of the gripper 10, a reinforcing sheet 60 with a number of holes 63, which can be attached to the compressible foam sheet 50, and a sheet-formed object 100 with two sensitive parts 70 that are engaged by the gripper. [Diagram 2] 1. Gripper body 20 of gripper 10 of FIG. 1 is shown having opening 15 connected to ejector 17 of the gripper of FIG. [Figure 3A] A view along section AA of the gripper body 20 in Fig. 2 is shown, in which one can see the primary vacuum chamber 25 provided with a number of suction holes 3 and two secondary vacuum chambers 35 each provided with a number of suction holes 3. The opening 15 shown in Fig. 2 leads into the primary vacuum chamber 25 and the openings 30 shown in Fig. 2 lead into each of the secondary vacuum chambers 35. [Figure 3B] A cross-sectional view of the gripper body 20 shown in Figure 3A is shown along section line BB. During evacuation of the two secondary chambers 35, the flow of fluid through the flow restriction 37 and the holes 39 and channels 38, respectively, is shown by arrows in Figure 3B. [Figure 4] 4 is a bottom view of the gripper body 20 shown in Fig. 2 showing the suction areas A1, A2. Fig. 4 also shows a detailed view C of the opening 39 and the passage 38, where the flow of fluid through the hole 39 via the passage 38 during evacuation of the associated secondary chamber 35 is shown by solid arrows in the view along cross section BB. [Diagram 5]5 shows a view along section CC of the gripper body 20 of FIG. 4 and detail D, with the fluid flow during evacuation of the left secondary chamber 35 of FIG. 5 indicated by solid arrows. [Figure 6] 2 is a perspective view of the gripper body 20, the compressible foam sheet 50, and the reinforcing sheet 60 from below. [Figure 7] A bottom view is shown of the gripper 10 engaged with an object 100, with the sensitive portion 70 of the object folded so as not to cover one of the holes 63 provided in the stiffening sheet 60, which is aligned with a corresponding hole 3 provided in the suction area A2 beneath the gripper body. The surrounding fluid flows from this uncovered hole 63 in the stiffening sheet 60, from the hole 63 into the corresponding underlying hole 53 in the foam sheet 50, and from the hole 53 into the hole 3 beneath the suction area A2 of the gripper body, thereby entering the secondary vacuum chamber 35 in which said hole 3 is provided. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The invention is based on separating a secondary vacuum chamber 35 from a primary vacuum chamber 25 in the vacuum gripper 10 and restricting the fluid communication between the two separated vacuum chambers by a flow restriction 37, the primary vacuum chamber being connected to a vacuum source. The fluid communication between the secondary vacuum chamber 35 and the primary vacuum chamber 25 is restricted to communication via the flow restriction 37. The suction area A2 corresponding to the secondary vacuum chamber has one or more suction holes 3. By appropriately selecting the cross-sectional area of ​​the flow restriction, the pressure in the secondary vacuum chamber 35 during the operation of the gripper is significantly higher than the pressure in the primary vacuum chamber, even if only a single suction hole 3 of the suction area A2 is not covered by the engaged object 100. A pressure sensor 33 connected to the secondary vacuum chamber 35 and arranged to sense the pressure in said chamber senses the high pressure in the secondary vacuum chamber 35. The cross-sectional area of ​​the flow restriction will generally be within ±50%, typically ±25%, preferably ±10% of the cross-sectional area of ​​one of the at least one holes 3 .

[0015] The suction area A2 of the present invention is preferably used to contact and engage sensitive portions 70 of the object 100, such as portions suitable for enhancing flexibility during handling of the object. The object 100 has a plurality of such sensitive portions 70. Thus, in one embodiment, the gripper of the present invention has a plurality of suction areas A2, each such additional suction area A2 corresponding to an additional secondary vacuum chamber 35 in communication with the primary vacuum chamber 25 via a corresponding additional flow restriction 37.

[0016] In one embodiment of the gripper 10 of the present invention, the primary vacuum chamber 25 has one or more suction holes 3 in the suction area A1. In such an embodiment, the suction area A1 typically provides the majority of the suction force to the gripper. Thus, in such an embodiment, the suction area A1 is typically larger than the suction area A2. Also, in such an embodiment, the cross-sectional area of ​​the suction holes 3 in the suction area A2 is typically smaller than the cross-sectional area of ​​the suction holes 3 in the suction area A1.

[0017] In an alternative embodiment, the primary vacuum chamber 25 of the gripper 10 does not have suction holes 3, and instead the primary vacuum chamber to which the vacuum source 17 is connected is only in fluid communication with a number of secondary vacuum chambers 35 via a corresponding number of flow restrictions 37. In such an embodiment, the suction area of ​​the gripper only comprises a number of suction areas A2 corresponding to the number of secondary vacuum chambers 35.

[0018] In principle, for a given internal secondary vacuum chamber 35, multiple flow restriction sections 37 can be provided, inter alia for more reliable operation and better sensitivity to leak detection, but it is preferred that only one flow restriction section 37 is provided for each one internal secondary vacuum chamber 35.

[0019] The number of internal secondary vacuum chambers 35 is not limited in principle as long as the overall volume is not too large compared to the number of primary vacuum chambers 25, allowing the number of pressure sensors to be kept reasonably small. For example, the number of internal secondary vacuum chambers 35 could be in the range of 1 to 10, such as 2, 3, 4, 5, 6, 7, 8 or 9 chambers. In general, embodiments having one, two or three internal secondary vacuum chambers 35 are preferred.

[0020] A pressure sensor 33 is provided for each internal secondary vacuum chamber 35 to sense the pressure within said internal secondary vacuum chamber. Although multiple pressure sensors 33 can be provided for any given internal secondary vacuum chamber, e.g., for redundancy purposes, it is preferred that only one pressure sensor is provided for each internal secondary vacuum chamber 35 to reduce the complexity of the vacuum gripper 10 of the present invention.

[0021] In a preferred embodiment, the gripper has a flow channel 38 in fluid communication with the secondary internal vacuum chamber 35 and the primary vacuum chamber 25. The flow channel has two openings 39 on the surface of the suction area of ​​the gripper, one of which enters the secondary internal chamber 35 and the other of which enters the primary vacuum chamber 25. Closing the openings 39 and the flow channel 38 by the closing means forms a flow restriction 37 with the flow channel 38 and the closing means. Closing the openings 39 can be achieved, for example, by an adhesive sheet with an impermeable portion that can be positioned such that the impermeable portion covers the openings 39. Such flow channels 38 and holes 39 are shown in more detail in Figures 3, 4 and 5. Such an embodiment with the flow channels 38 and holes 39 is particularly suitable for being manufactured by additive manufacturing. Such an embodiment also allows for easier subsequent adjustment of the flow restriction 37, such as by simply enlarging the flow channels 38 and possibly the holes 39. Also, such a restriction 37 may be easier to inspect and clean, for example for possible contamination or clogging of the restriction 37, by simply removing the closure means and inspecting the flow passage 38 and the hole 39. The flow passage 38 may be provided with one or more replaceable portions (not shown), allowing the cross-sectional area of ​​the flow passage 38 to be adjusted by simply replacing one or more portions with another portion having a particular smaller or larger cross-sectional area.

[0022] The non-permeable adhesive sheet 65 can be used as a means to close desired holes 3 in the suction surface, for example to adapt the gripper to engage slightly differently shaped objects and / or to change the pattern of suction holes 3 in the overall suction area of ​​the gripper, such as to close one or more openings 39 in the surface of the suction area of ​​the gripper. As will be appreciated, such a sheet will have openings that correspond to the desired active holes 3 of the gripper.

[0023] The compressible foam sheet 50 can be used together with the gripper, for example, to achieve a certain limited flexibility of the gripper, for example to provide a cross-over for small non-parallel imperfections in the horizontal alignment of the gripper with a horizontally oriented object to be handled, and / or to provide a more manageable, soft and pliable contact with the object 100, such as when a generally sensitive object 100 and / or an object 100 with a sensitive surface is handled by the gripper 10. To improve the ease of mounting and replacing the foam sheet 50, said sheet preferably comprises an adhesive layer. The adhesive layer is preferably provided on the impermeable backing 65 of the foam sheet 50. The impermeable backing 65 of the foam sheet 50 can preferably function as the adhesive sheet described above. The foam sheet 50 has one or more holes 53 corresponding to one or more holes 3 of the suction area A2 of the secondary internal vacuum chamber 35. Also, if suction area A1 is present, foam sheet 50 has one or more holes 53 corresponding to one or more holes 3 of suction area A1 of primary internal vacuum chamber 25. The foam material of the compressible foam sheet is not critical. A suitable material is, for example, ethylene propylene rubber, such as EPDM. The thickness and material of foam sheet 50 should be selected such that it can be substantially compressed when engaged with object 100.

[0024] Together with the compressible foam sheet 50, a stiffening sheet 60 is preferably used. The stiffening sheet should essentially cover the foam sheet. The stiffening sheet has one or more holes 63 corresponding to the holes 3 of the suction area A2 of the secondary internal vacuum chamber 35. Preferably, the stiffening sheet is attached to the foam sheet 50 by an adhesive layer, for example so that it is replaceable. The material of the stiffening sheet 60 is not critical and can be selected to be compatible with the material of the object to be handled. By way of example, a commonly suitable material for the stiffening sheet is polycarbonate (PC).

[0025] The stiffening sheet 60 can also be used to close desired suction holes 3 and corresponding holes 53 in the suction area A2, so that by replacing one stiffening sheet 60 with another stiffening sheet 60 closing other desired suction holes 3 and corresponding holes 53 in the suction area A2, the gripper of the present invention can be conveniently adapted to grip objects having slightly different geometries and / or having different locations of the sensitive portions 70.

[0026] In a preferred embodiment, the gripper body 20 has raised perimeters (not shown) around the suction areas A1, A2, raised guide elements (not shown) along the perimeters of the suction areas A1, A2, or the suction areas A1, A2 can be received in recesses (not shown) in the bottom of the gripper body 20 to receive the compressible foam sheet 50 and stiffening sheet 60 in said recesses. Such raised perimeters, raised guide elements, or recesses can make it easier to align the compressible foam sheet 50 and stiffening sheet 60 to the gripper body 20.

[0027] In principle, multiple flow restrictions 37 can be used in a given single secondary internal vacuum chamber 35. However, such an embodiment is not preferred.

[0028] The vacuum gripper 10 of the present invention preferably only has a single point vacuum connection 15.

[0029] As the vacuum source 17, preferably an ejector is used, as shown in FIG. 1. When an ejector is used as the vacuum source, such an ejector is preferably attached to the gripper 10, such as to the gripper body 20. By using a distributed vacuum source, such as an injector, the initiation and termination of the vacuum to the gripper can be achieved much more quickly compared to when a central vacuum source is used. Also, by using a distributed vacuum source close to the gripper, the volume to be evacuated is reduced, since vacuum tubes are essentially not required.

[0030] In a preferred embodiment, the pressure sensor 33 takes the form of a vacuum switch as shown in Figure 1. The vacuum switch is preferably configured to provide a signal when the pressure in the secondary internal vacuum chamber 35 to which it is connected is higher than a predetermined allowable maximum pressure. The signal so generated corresponds to a detected leakage of ambient fluid into said secondary internal vacuum chamber 35.

[0031] It is preferable to keep the secondary internal vacuum chamber 35 relatively small because, in the event of a leak, the pressure is affected more quickly and more clearly in a chamber having a smaller volume than in a chamber having a larger volume, so that pressure changes in the secondary internal vacuum chamber 35 due to fluid leaking into said chamber through one of the holes 3 can be more reliably detected.

[0032] The gripper 10 of the present invention is suitable for handling sheet-formed objects such as a sheet 100, particularly a sheet having a sensitive portion 70. The sensitive portion 70 of the object 100 may be, for example, a portion of reduced thickness compared to the thickness of the remainder of the object 100. By way of example, reduced thicknesses in the range of about 5-15 μm have been successfully handled with the gripper of the present invention. The gripper of the present invention is particularly suitable for use with sheets stacked on top of each other, preferably in an automated process. The sheets may form part of, for example, an electrode, an electrode assembly, a membrane electrode assembly.

[0033] Other examples of sheet-formed objects 100 that can be handled by the grippers of the present invention are electrical insulating films or foils, such as battery insulating films, carbon fiber sheets, silicon wafers or sheets, e.g., wafers for solar panels, and thin labels.

[0034] Sheet-formed objects 100 are typically flexible.

[0035] The sheet formed object 100 may typically have a thickness of up to 2 mm, preferably 1 mm or less, for example from 5 μm to 500 μm.

[0036] The sheet formed object 100 may be made of a polymeric material, such as plastic or rubber, or a metallic material, or a combination thereof.

[0037] For example, if too much pressure is detected in the secondary internal vacuum chamber 35 in an automated operation, this may typically be due to the sensitive portion 70 of the sheet-formed object 100 not being properly aligned with the suction area A2 of the gripper, and / or the presence of wrinkles or folds in the sensitive portion 70 of the sheet-formed object 100 currently engaged with the gripper, or a portion such as a corner of the sensitive portion 70 may be bent during handling of the object 100, such as by the relative action of the surrounding fluid, typically the surrounding air, during the movement of the object 100 by the surrounding fluid, such that one or more holes 3 of the suction surface A2 are no longer covered by the sensitive portion 70, as shown in FIG. 7. When too much pressure is detected in the secondary internal vacuum chamber 35, the automated operation is preferably stopped. When the automated operation is stopped, an operator can conveniently remove any misaligned, wrinkled, folded, or otherwise defective sheets and then resume or continue the automated process. [Explanation of symbols]

[0038] 10 Vacuum Gripper 100 Engaged sheet-formed object 20 Vacuum gripper body 25 Inner primary vacuum chamber 15 Opening for connecting the primary vacuum chamber to a vacuum 17 Vacuum source 30 Opening for connecting to pressure sensor 33 Pressure Sensor A2 Suction area of ​​the secondary internal vacuum chamber A1 Primary vacuum chamber suction area 3 Suction hole 35 Secondary internal vacuum chamber 37 Flow Restrictor 38 Flow Path 39 Opening of the suction area to the flow channel 50 Compressible foam sheet 53 (in foam sheet 50) one or more holes 60 Reinforcement sheet 63 (Reinforcement sheet 60) One or more holes 65 Impermeable backing 70 Highly sensitive portion of the target object 100 formed into a sheet

Claims

1. Grasping the sheet-formed object (100); an internal primary vacuum chamber (25); an opening (15) for connecting the primary vacuum chamber (25) to a vacuum source (17); an opening (30) for connection to a pressure sensor (33) configured to sense pressure within the gripper body; a suction area (A2, A1) for engaging a sheet-formed object (100); At least one suction hole (3) provided in the suction area (A1, A2); In a vacuum gripper (10) comprising a body (20) having the body (20) further comprising a secondary internal vacuum chamber (35) in fluid communication with the primary vacuum chamber (25) through a flow restriction (37); The at least one suction hole (3) is provided in a suction area (A2) of the secondary internal vacuum chamber (35), The size of the cross-sectional area of ​​the flow restriction (37) is similar to the size of the cross-sectional area of ​​one of the at least one suction holes (3), and the opening (30) for connecting to a pressure sensor (33) is provided in the secondary internal vacuum chamber (35). Characterized by Vacuum gripper (10).

2. 2. The vacuum gripper (10) of claim 1, wherein the cross-sectional size of the flow restriction (37) is equal to or smaller than the cross-sectional size of one of the at least one suction holes (3).

3. 3. The vacuum gripper (10) according to claim 1 or 2, wherein the vacuum source (17) is an ejector, preferably attached to the gripper body (20).

4. 4. The vacuum gripper (10) according to claim 1, further comprising a flow passage (38) in fluid communication with the secondary internal vacuum chamber (35) and the primary vacuum chamber (25), the flow passage having two openings (39) respectively provided in the surfaces of the suction areas (A1 and A2), the flow passage (38) being capable of forming a flow restriction (37) when the openings (39) and the flow passage (38) are sealed.

5. 5. The vacuum gripper (10) according to any one of claims 1 to 4, further comprising a compressible foam sheet (50) essentially covering said suction areas (A1, A2).

6. 6. The vacuum gripper (10) of claim 5, wherein the compressible foam sheet (50) has one or more holes (53) corresponding to one or more holes (3) in the suction area (A2) of the secondary internal vacuum chamber (35), and preferably the foam sheet (50) is attached to the suction area (A1, A2) by adhesive so as to be replaceable.

7. 7. The vacuum gripper (10) according to claim 5 or 6, further comprising a reinforcing sheet (60) essentially covering the foam sheet (50) and having one or more holes (63) corresponding to the holes (3) of the suction area (A2) of the secondary internal vacuum chamber (35), preferably the reinforcing sheet being attached to the foam sheet (50) by means of an adhesive so as to be replaceable.

8. 7. The vacuum gripper (10) of claim 5 or 6, wherein the porous foam sheet (50) has an adhesive, non-permeable backing (65) for covering and sealing desired suction holes (3) and / or openings (39).

9. 9. The vacuum gripper (10) according to any one of claims 1 to 8, wherein the suction area (A1) of the primary vacuum chamber (25) has a multiplicity of suction holes (3), preferably the holes being uniformly distributed over the suction area (A1) of the primary vacuum chamber (25).

10. 10. The vacuum gripper (10) according to claim 1, wherein the suction area (A2) of the secondary internal vacuum chamber (35) has a multiplicity of suction holes (3), preferably the holes being uniformly distributed over the suction area (A2) of the secondary internal vacuum chamber (35).

11. 11. The vacuum gripper (10) of claim 10, wherein the cross-sectional area of ​​the flow restriction portion (37) is equal to or smaller than the cross-sectional area of ​​the smallest hole (3) among the multiple suction holes (3) distributed across the suction area (A2) of the secondary internal vacuum chamber (35).

12. 12. The vacuum gripper (10) according to claim 1, further comprising one or more additional secondary internal vacuum chambers (35), each having a suction area (A2) with at least one suction hole (3), each connected to the primary vacuum chamber (25) via a flow restriction (37), the cross-sectional area of ​​the flow restriction (37) corresponding to the cross-sectional area of ​​one hole (3) of the at least one suction hole (3) provided in the respective suction area (A2).

13. A method for detecting leakage of an ambient fluid into a vacuum gripper (10) for gripping a sheet-formed object (100), comprising: Engaging a sheet-formed object (100) with a vacuum gripper (10); monitoring the pressure in an internal vacuum chamber (35) of the gripper (10) while the sheet formed object (100) is engaged with the vacuum gripper (10) using a pressure sensor (33) connected to the internal vacuum chamber (35); comparing the monitored pressure to a predetermined desired pressure; determining a monitored pressure that is greater than a predetermined allowable maximum pressure; In a method comprising: characterised in that the gripper (10) comprises a primary internal vacuum chamber (25) and a secondary internal vacuum chamber (35), said chambers being fluidly connected to one another via a flow restriction (37), and the monitored pressure is the pressure in the secondary internal vacuum chamber (35). method.

14. 14. The method according to claim 13, wherein the method is interrupted if the monitored pressure in the secondary internal vacuum chamber (35) of the gripper (10) is determined to be higher than the predetermined allowable maximum pressure.

15. Use of a gripper according to claim 1 in a stacking operation for stacking a number of sheets (100) on top of one another, said stacking operation being preferably automated.

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