GB2581847A

GB2581847A - End effector

Info

Publication number: GB2581847A
Application number: GB1902823.2A
Authority: GB
Inventors: Mark Whitear Daniel
Original assignee: Millitec Food Systems Ltd
Current assignee: Millitec Food Systems Ltd
Priority date: 2019-03-01
Filing date: 2019-03-01
Publication date: 2020-09-02
Anticipated expiration: 2039-03-01
Also published as: GB2581847B; GB201902823D0

Abstract

An end effector 2 for a station of a production line comprises a carriage 4 attached to an external actuator 8 and an engagement member 6 for engaging a product 10 and supported by the carriage 4 via a coupling mechanism 14 which comprises a magnet 20 located on one of the carriage 4 and the engagement member 6 and a magnetic material 22 located on the other of the carriage 4 and the engagement member 6, such that the engagement member 6 is coupled to the carriage 4 in an at-rest condition by means of an attractive force between the magnet 20 and magnetic material 22 which provides for resilient movement between the carriage 4 and the engagement member 6 away from the at-rest condition. The movement may be linear relative motion. The magnet 20 and the magnetic material 22 may comprise a cylindrical protrusion extending into a cylindrical aperture in a sleeve. The end effector 2 may be used in a food manufacturing process and seeks to reduce the likelihood of impact damage to the end effector 2, the product 10 or a conveyor 12 and provides a coupling between the carriage 4 and the engagement member 6 without fasteners that can be easily removed and replaced hygienically.

Description

End Effector The present invention relates to an end effector in a manufacturing process, particularly for an end effector in a food manufacturing process.

INTRODUCTION

In manufacturing process, there is often requirement for an end effector to contact or manipulate a product in a variety of ways, for example, to pick up, hold, reorient, compact, cut or otherwise manipulate a product. The end effector is moved using an actuator, for example, a solenoid or a mechanical arm. Such actuators typically apply a fixed mechanical force to end effector.

The products are often located on a surface, such as a conveyor. In order to manipulate the product, the end effector may need to contact the conveyor, i.e. when picking up or positioning products on the conveyor. However, due to the fixed mechanical force of the actuator, the end effector may apply too great a force onto the product and/or the conveyor. This may result in damage to the product and/or the conveyor.

Even if a non-uniform movement profile is used, i.e. with reduced speed or force when adjacent to the conveyor, any misalignment or wander of the actuator during ongoing use can lead to damaging contact between the end effector and conveyor. Furthermore, it is typically desirable to operate a production line at high speed, thereby inhibiting the ability to slow down motion of the end effector to reduce the likelihood of damaging impact between the end effector and conveyor.

The present invention aims to overcome or ameliorate one or more of the above problems.

Figure 1 shows a schematic of an end effector in a manufacturing line.

Figure 2 shows a cross section through a coupling mechanism of the end effector Figure 3 shows a side view of the end effector Figure 4 shows an isometric view of the end effector with the guides in an open position Figure 5 shows an isometric view of the end effector with the guides in a closed position Figures 6a and 6b show operation of a coupling mechanism of the end effector.

Figure 1 shows an end effector 2 according to an example of the present invention within a manufacturing line. The end effector 2 comprises a carriage 4 operatively connected to an external actuator 8 configured to provide movement of the end effector 2. The external actuator 8 may be configured to move the end effector 2 in any or any combination of lateral/horizontal, vertical/perpendicular and/or angular or rotational direction, i.e. relative to a support surface 12.

The external actuator 8 may comprise a linear actuator, for example, a pneumatic actuator, a hydraulic actuator or a solenoid. In other embodiments, the external actuator 8 comprises a robot, for example, a robotic arm, or a delta robot. The robot arm could be electrically driven, e.g. by one or more electric motor.

The end effector 2 comprises an engagement member generally designated at 6.

The engagement member 6 is supported by the carriage 4 and is configured to engage a product 10. The end effector, including the engagement member 6 may be referred to as a picker and is used to pick up products 10 from the underlying support surface 12.

The products 10 may be located on a static or moveable surface, such as a conveyor 12. As products move into the vicinity of the end effector 2, the end effector 2 is actuated to pick up and manipulate, or perform an operation with, the products 12 The engagement member 6 may provide a surface to grip the product 10 in order to pick up or hold the product 10. Additionally or alternatively, the engagement member 6 may provide a lateral compression/contraction motion to provide alignment of a plurality of layers in a food product, e.g. a stacked food product (for example, to align two layers of bread in a sandwich).

Additionally or alternatively, the engagement member 6 provides a vertical compression of the product 10 (for example, to provide compaction of the product 10).

Additionally or alternatively, the engagement member may comprise a cutting member, for example, a blade, to cut the product 10.

The engagement member 6 is attached to the carriage 4 via a coupling mechanism 14. The coupling mechanism 14 comprises a magnet located on one of the engagement member 6 or the carriage 4 and a magnetic material (i.e. a material that produces a magnetic field in response to an applied magnetic field) located on the other of the engagement member 6 and the carriage 4, to provide a magnetic attraction between the engagement member 6 and the carriage 4.

The coupling mechanism 14 provides relative movement between the carriage 4 and the engagement member 6 whilst maintaining the magnetic attachment (i.e. the carriage 4 and the engagement member 6 are free to move relative to each other whilst still bound by the magnetic attraction between the magnet and the magnetic material, and without detachment of the carriage 4 and the engagement member 6).

The coupling mechanism 14 is configured to provide a resilient bias between the engagement member 6 and the carriage 4, i.e. towards an aligned/coupled or at-rest relative position between the engagement member 6 and carriage 4.

Examples of the invention will now be described in further detail according to the apparatus shown in figures 2-5.

The coupling mechanism 14 comprises a protrusion 16 extending from the engagement member 6 and configured to extend into an aperture 18 located in the carriage 4. The aperture 18 defines a bore or through-hole/channel having an axis. The protrusion 16 is configured to move linearly/axially within the aperture 18 to permit relative movement between the engagement member 6 and the carriage 4. The protrusion 16 is sized to snugly fit within the aperture 18 to prevent the ingress of dirt etc. therebetween, whilst still maintaining relative free movement. A seal could be provided on the interior of the aperture or exterior of the protrusion.

The protrusion 16 and the aperture 18 may be substantially cylindrical, such that movement is provided in a linear direction along the axis of the cylinder. Other sectional profiles/shapes could be used provided the protrusion and aperture are of corresponding shape and typically of uniform shape along their length.

The protrusion 16 comprises a magnet 20 located therein. The magnet 20 is arranged to be proximal to a magnetic material 22 surrounding the aperture to provide a magnetic attraction therebetween. The magnet 20 is substantially cylindrical and/or annular.

The thickness of the magnetic material surrounding the aperture 1 may vary along its axis to provide an area of increased magnetic attraction between the magnet 20 and the magnetic material 22 at a desired relative position between the protrusion 16 and aperture 18, e.g. a desired axial position along the aperture length/height.

Additionally or alternatively, the proximity of an inner surface of the aperture 18 relative to the protrusion 16 varies along the axis of the aperture 18 to provide an area of increased/closer proximity to the magnet 20. Similarly, this provides an area of increase magnetic attraction between the magnet 20 and the magnetic material 22.

The increased thickness and/or increased proximity provides an equilibrium location into which the magnet 20 is preferentially attracted, absent any external forces.

In an embodiment, a central portion 24 of the aperture 18 comprises a portion of increased thickness and/or increased proximity to the protrusion, providing an equilibrium location in a central portion of the aperture 18. The portion of increased thickness and/or increased proximity may be substantially annular to surround the magnet. In the example shown, the aperture is provided with a notch or land around its inner profile to provide both a closer proximity to the protrusion 16 and also increased material thickness of the magnetic material.

When the magnet 20 is in the equilibrium location, the end of the protrusion 16 may be in line with the end of the aperture 18 or slightly recessed therein.

The thickness of the magnetic material surrounding the aperture 18 may taper away from the central portion 24. The tapering may reduce the restoring force (i.e. the net force toward the equilibrium location) toward the central portion 24 due to the reduced amount of magnetic material 22 the magnet 20 is attracted to. In an embodiment, the magnetic material surrounding the upper end of the aperture 18 is tapered to reduce the restoring force of the engagement member 6 and carriage 4 for small movements away from the equilibrium position.

The magnitude of the magnetic restoring force increases (i.e. ramps up) with further movement of the protrusion away from the equilibrium position up to a maximum resistance to movement as the magnet end attempts to pass the central portion 24. This allows the engagement member 6 to move away from the equilibrium position with lesser resistance initially thus providing a reduced initial impact force due to any contact with the product/conveyor. However, the resistance to movement increases with distance away from the equilibrium position, e.g. to resist detachment of the engagement member 6 or, in the opposing direction, physical abutment between the engagement member 6 and carriage 14 under compression.

The protrusion 16 comprises a sheath 26 on an outer surface thereon. The sheath 26 encapsulates the magnet 20 and other internal components of the protrusion.

The inner surface of the aperture 18 comprises an internal sheath 28. The internal sheath 28 may not be provided or may have reduced thickness at portions of the aperture with increased thickness/proximity to the protrusion, such that internal diameter of the aperture is substantially constant along the axis of the aperture.

The sheath 26/internal sheath 28 may comprise a polymer material. The sheath 26/internal sheath 28 may comprise a low-friction material to aid movement of the protrusion through the aperture, and/or a food safe material.

The engagement member 6 is removable from the carriage 4, by overcoming the magnetic attraction between the protrusion 16 and the aperture 18, i.e. by pulling the protrusion 16 fully out of the aperture 18.

The engagement member 6 comprises a guide 28 configured to engage the product 10.

The guide 28 may comprise a substantially V-shaped guide. The apex of the V-shaped guide is formed at 90 degrees to engage the corner of a rectangular product, for example, a corner of a sandwich. The guide 28 may be configured to hold the edge of the product 10 whilst the product 10 is lifted, or may provide alignment of a plurality of layers of the product 10.

The guide 28 may comprise a lip 30 at a lower end thereof configured to extend beneath a product in use. This may support the product 10 during lifting of the product 10, or other interaction with the underside of the product 10.

In other embodiments, the guide 28 may comprise a substantially flat surface, a different type/shape of picker and/or roller configured to roll over, align or compress the product 10.

As, shown in figures 4 and 5, the end effector 2 comprises an actuator 32 configured to move a first portion/side 34 of the end effector relative to a second portion/side 36 in order to permit relative movement of the plurality of guides 28.

The first and second portion comprise a respective carriage portion and engagement member 6 with a respective coupling mechanism 14 extending therebetween.

The guides 28 depending from each portion/side are opposingly arranged. The guides 28 may be moved from an open position (as shown in figure 4) where the guides 28 are spaced apart, to a closed position (as shown in figure 5) where the guides 28 are moved closer together and/or into engagement with one another. In this example both guide/portion is moveable but in other examples, a suitable relative motion could be achieved by moving only one guide/portion.

The actuator 32 extends between the respective carriages 4 on the first and second portions. The actuator may comprise one or more of: a pneumatic actuator; a hydraulic actuator or an electrical actuator.

The actuator 32 comprises an actuable axle or piston 38 extending therefrom. The axle 38 is rigidly mounted to the respective carriages 4 to effect relative movement between the actuator 32 and the carriages 4.

A guide rod 40 is rigidly mounted to the respective carriages 4 and extends therefrom. An engagement formation 42 mounted to the actuator 32 movably receives the guide rod 40 to prevent relative rotation between the actuator 32 and the respective carriages 4. In this example, the engagement formation 42 comprises a recess or depression receiving the guide rod.

The actuator 32 comprises a mounting formation 44 configured to attach to external actuator. The mounting formation 44 in this example comprises a fluid pressure, e.g. pneumatic, attachment point.

The axles 38 take the form of pistons in this example, extending outwardly from a central cylinder. Thus by application of positive/negative fluid pressure, the axles 38 can be extended and/or retracted relative to the central cylinder of the actuator 32. In different examples, positive pressure could be used for both extension and retraction strokes, negative pressure could be used for both strokes, or a combination of positive and negative pressure could be used for the different strokes.

An pressing plate 45 may be attached to the engagement member 6 (e.g. the actuator 32) and/or carriage 4, e.g. beneath the carriage 4. The pressing plate 45 comprises a substantially flat surface to provide compaction/alignment of the upper surface/surface of the product 10 there-beneath and/or to provide a guard preventing the product 10 contacting other portions of the carriage 6 and/or actuator 32.

In this example, the pressing plate 45 is attached to the carriage 4, e.g. rigidly or resiliently. The guides 28 are thus resiliently moveable relative to the pressing plate 45 under the compression of the engagement member 6 towards the carriage 4, i.e. under the resilience provided by the coupling mechanism.

Operation of the invention The end effector 2 begins the process in a retracted state, away from the support surface/conveyor 12. The engagement member 4 is supported by the carriage 6 via the coupling mechanism 14.

As shown in figure 6a, the magnetic forces 46 between the magnetic material 22 and the magnet 20 are balanced, such that the magnet 20 lies in the equilibrium position 48.

The product 10 is moved into a position below the end effector 2, e.g. using the conveyor. In other embodiments, the end effector is moved into position above the product 10.

The end effector 2 is moved using the external actuator 8 toward the conveyor 10, e.g. downwards from above, to engage the product 10.

A sensor and/or controller arrangement may be used to determine the product 10 is in the correct position relative to the end effector before actuation.

The end effector 2 engages the product 10. The lower end of the guide 28 contacts the conveyor 12, such that the lip 30 can be inserted underneath the edge of the product 10. Contact between the guide 28 and the conveyor 12 causes relative movement between the engagement member 6 and the carriage 4, thus moving the protrusion 16 upwards through the aperture 18.

As, shown in figure 6b, the magnet 20 moves upwards and away from the equilibrium location 48 (shown in dashed lines). The magnetic forces 46 between the magnetic material 22 and the magnet 20 (i.e. the restoring force) now bias the magnet 20 downwards towards the equilibrium location 48.

The magnet 20 and the magnetic material 22 remain bound during the movement of the protrusion 16 (i.e. the magnetic force is not fully overcome). Thus, the coupling mechanism provides a resilient bias towards an equilibrium position 48 (i.e. acts as a 'magnetic spring') between the engagement surface 6 and the carriage 4. The restoring force of the coupling mechanism is less than force provided by external actuator 8 (due to the stored magnetic energy), thus transferring a reduced force through the engagement member onto the food product 10 and/or conveyor 12. Any force transferred to the conveyor 12 via the engagement member 6 is significantly reduced relative to the force provided to the carriage by the external actuator 8.

The tapering of the aperture 18 at the upper end reduces the restoring force towards the equilibrium location 46, thus reducing the force the compressive force of the engagement member 4 and reducing damage of the product 10 and/or conveyor 12.

The actuator 32 moves the guides 28 into the closed position to engage/constrain the product 10 laterally, for example, to align layers of the product or to locate the product centrally between the opposing guides 28.

The actuator 8 may provide an additional pressing force onto the product 10 from above via the pressing plate 45. The actuator may press down on the carriage 4, which in turns presses the plate 45 onto the product from above. Whilst pressing/compacting the product in this manner, the magnetic coupling mechanism allows relative/passive movement of the carriage 4 and plate 45 relative to the guides. Thus the guides do not damage the support surface/conveyor 12 during actuation of the pressing plate. This passive, resilient movement means that a separate actuator for the pressing plate is not needed and instead the primary actuator 8 can be used.

The engagement member 4 may or may not be used to pick up/move the product.

A pressing step could be applied before and/or after moving the product 10.

The actuator 32 then moves the guides into the open position to disengage the product 10.

The external actuator 8 moves the end effector 2 in an upwards direction away from the conveyor 12 to the retracted position. The restoring force of the coupling mechanism 14 moves the magnet 20 toward the equilibrium location 46 and 25 therefore moves the engagement member 6 away from the carriage 4.

The conveyor 12 moves the product 10 further along the manufacturing line for further processing or packaging etc. The carriage 4 and the engagement member 6 may be separated by pulling the engagement surface 6 away from the carriage 4 in order to overcome the magnetic attraction of the coupling mechanism 14. The engagement member 6 may be removed to allow cleaning of the engagement member 6 and/or the carriage 4. The engagement member 6 may be substituted by an engagement member 6 comprising a different shaped guide 28, for example, for a different product run.

The present invention reduces the force transferred from the end effector 2 to the product 10 and/or conveyor 12 compared with the force provided by the external actuator 8, thus reducing the risk of damage to the product 10 and/or conveyor 12. Additionally or alternatively, the likelihood of damage to the end effector by impact can be significantly reduced.

The force transferred to the end effector via the coupling mechanism can be tailored to accommodate the force required to manipulate the product 10, without damage to the product 10 or conveyor. This increases the universality of the manufacturing process, as the end effector can de adapted for a variety of products without changes to the external actuator.

The present invention provides an end effector in which the engagement member 6 can be attached to the carriage 4 without the use of fastening members, and thus provides a hygienic solution that can be easily removed and replaced.

The examples described above are particularly well suited to sandwich production lines, or similarly stacked food product assemblies. The end effector 2 can consolidate the layers laterally, i.e. to ensure each layer is aligned, whilst also allowing a pressing force onto the consolidated layers from above, i.e. to press or pat down the filled sandwich.

In other examples, the relative arrangement of the projection 16 and aperture 18 could be reversed, i.e. the projection(s) 16 being provided on the carriage 4 and the aperture(s) 18 being provided on the engagement member 6. The relative arrangement of the magnet and magnetic material could also be swapped between the projection(s) and aperture(s), if desired. Additionally or alternatively, the magnetic material could comprise or be replaced by a further magnet, such that the coupling is formed by relative alignment between two magnets so as to cause attraction there-between.

The above examples a plurality of magnetic couplings, e.g. with each opposing guide 28 having at least one or two magnetic coupling. In other examples, a single magnetic coupling, or plurality of magnetic couplings, could be provided for the engagement member 6 or end effector 2 as a whole. For example the carriage 4 and/or end effector 2 could be attached to the actuator via one or more magnetic coupling of the type described herein.

Claims

Claims: 1. An end effector for a station of a production line comprising: a carriage arranged to be operatively attached to an external actuator in use an engagement member for engaging a product in use and supported by the carriage via a coupling mechanism; where the coupling mechanism comprises a magnet located on one of the carriage and the engagement member, and the other of the carriage and the engagement member comprises a magnetic material, such that the engagement member is coupled to the carriage in an at-rest condition by means of an attractive force between the magnet and magnetic material; and where the attractive force between the magnet and magnetic material provides for resilient movement between the carriage and the engagement member away from the at-rest condition.
2. An end effector according to claim 1, where the magnet and magnetic material are constrained to linear relative motion.
3. An end effector according to any preceding claim, where one of the carriage and the engagement member comprises a protrusion and the other of the carriage and the engagement member comprises an aperture, the protrusion at least partially extending into the aperture; and where one of the protrusion and the aperture comprises a magnet and the other of the protrusion and the aperture comprises a magnetic material.
4. An end effector according to claim 3, where the protrusion is located on the engagement member and the aperture is located on the carriage.
5. An end effector according to claim 3 or 4, where the aperture takes the form of a sleeve having an axis and the protrusion is axially moveable along the sleeve.
6. An end effector according to claim 5, where the aperture and/or protrusion is substantially cylindrical.
7. An end effector according to any of claims 3-6, where the magnet is biased toward a central portion of an axial length of the aperture.
8. An end effector according to any of claims 3-7, where the thickness of the magnet or magnetic material varies along an axis of the aperture and/or protrusion.
9. An end effector according to claim 7 or 8, where the thickness of magnetic material surrounding the aperture tapers away from the central portion.
10. An end effector according to any of claims 3-9, where the proximity of magnet and magnetic material varies along the axis of the aperture.
11. An end effector according to claim 10, where the profile of the magnet or magnetic material varies with axial position relative to the aperture such that the proximity of the magnet and magnetic material is greater at a central portion of the axial length of the aperture and/or protrusion.
12. An end effector according to any preceding claim, where the engagement member comprises one or more guides, the guides configured to perform one or more of: grip/hold a product; align a plurality of layers of the product; or flatten/compress a product.
13. An end effector according to claim 12, where the end effector comprises an actuator, the actuator configured to provide relative movement between a plurality of guides.
14. An end effector according to claim 13, where the actuator is configured to move either or both of the plurality of guides in a direction substantially orthogonal to the direction of the relative movement of the coupling mechanism.
15. An end effector according to any of claims 13 or 14, where the actuator comprises a fluid pressure actuator.
16. An end effector according to any of claims 12-15, where the one or more guides comprise a V-shaped plate.
17. An end effector according to any one of claims 12-14, wherein the one or more guide comprises a member or wall portion arranged to extend beneath a product.
18. An end effector according to any preceding claims, where the magnet and/or magnetic material are encapsulated within a sheath material.
19. An end effector according to claim 18, where the sheath comprises a low-friction material.
20. An end effector according to any preceding claim, where the engagement member comprises a cutting member, the cutting member configured to cut the product.