Gas spring temporary fastener

Abstract

A temporary fastener 1 comprising a housing (2 fig1), a fastening portion 6 and a gas spring 5 wherein the gas spring is configured to move the fastening portion between an extended state and a clampi

Description

FIELD AND BACKGROUND

[0001] The present invention relates particularly, but not exclusively, to an improved temporary fastener. Temporary fasteners are used in assemblies, where parts need to be clamped or fastened together during drilling and during installation of permanent fasteners. For example, temporary fasteners may be used in the aircraft and other industries.

[0002] Existing temporary fasteners are designed to ensure that they do not damage the parts. Therefore they have an upper clamping force limit. If the clamping force is provided by screwing, the upper limit is generally achieved by tightening them to a certain tightness. This requires that the tightening motor stops reliably right before the maximum clamping force is achieved. The system is very sensitive for friction in the system, for instance caused by misalignment and forces during the tightening, which will stop the tightening motor earlier than intended. This might cause improper part fixation. It is therefore difficult, particularly in robotic applications where a robot might exert forces on the temporary fastener, to guarantee that temporary fasteners are tightened to the desired tightness.

[0003] Specifically, the challenge is to ensure that the clamping force is within the intended limits. A screw type temporary fastener reaches this using an electronic tightening motor torque limitation. Clamping force can also be provided by a coil spring. The first main advantage of temporary fasteners that use a coil spring to create the clamping force are the speed at which they can be installed. There is no waiting time for the screwing motion to finish. Force is applied to the temporary fastener, which compresses the coil spring, and is released, which applies the clamping force directly. The second advantage is the reliable clamping force if the assembly has the right thickness. Friction due to misalignment or external forces has no lasting influence on the clamping force.

[0004] However, there are a number of drawbacks of the use of coil springs in temporary fasteners. For example, coil springs are limited to low clamping forces only. Coil springs that can deliver higher clamping forces are too big for most temporary fastener applications. Furthermore, coil springs have a certain force at a certain compression distance. Therefore coil springs have a limited range where they apply the required clamping force. The clamping force is too low if put in a thin assembly. It is too high when put in a thick assembly. Higher loads in coil springs inevitably mean more energy stored in the coil. This energy can become kinetic energy, which propels the temporary fastener through the air at dangerous speeds.

[0005] There is therefore a desire to provide a means of applying a temporary fastener using a spring without the drawbacks such as limited force, limited assembly thickness range and also with an eliminated risk of the fastener being propelled through the air at dangerous speeds.

[0006] The inventors have discovered a new and counterintuitive way of supplying a spring force within temporary fasteners. The new apparatus and method developed by the inventor can advantageously be operated by a robot end effector, since it lacks sensitivity for misalignment and external forces. SUMMARY

[0007] Particular aspects and embodiments are set out in the appended claims.

[0008] Viewed from a first aspect, there is provided a temporary fastener comprising a housing, a fastening portion, and a gas spring. The gas spring is configured to move the fastening portion between an extended state and a clamping state.

[0009] The term 'temporary fastener' is known in the art. A temporary fastener is a device which is used to join two or more objects together temporarily without damaging the objects. The temporary fastener therefore enables the objects to be temporarily fixed together for example before / during fasteners that are more permanent are applied. The temporary fasteners are reusable. The temporary fastener may comprise a device that can enter a hole and latch on the hole edge at the rear of the assembly.

[0010] The term 'gas spring' is intended to mean a device that uses compressed gas to store energy. The term 'extended state' is intended to mean when the fastening portion is in an extended position. For example, the fastening portion may extend outside the housing. In this state, the fastening portion may be inserted into holes of two parts requiring temporary fastening. The term 'clamping state' is intended to mean when the fastening portion is in a retracted position and is able to hold the two parts together. In some examples, the fastening portion may be retracted at least partially inside the housing when in the clamping state.

[0011] There are a number of benefits associated with using a gas spring in a temporary fastener. The installation and removal of a gas spring type temporary fastener can be a lot simpler because no complex electronics or motors with gearboxes are needed. A simple holder with a pneumatic cylinder is enough. This reduces the size of the device and allows for easier integration / addition of a temporary fastener device on existing devices. As will be discussed later, it is for instance possible to add a temporary fastener install and remove capability to a drilling end effector on a robot. This will give the robot temporary fastener placement capability, so it becomes possible to perform the usually parallel process of drilling and placing temporary fasteners by one robot without the need for intervention.

[0012] Gas springs can be filled up to different pressure levels. Therefore the same gas spring hardware can be used to apply different forces, depending on the pressure level. Traditionally, coil springs have been used for temporary fasteners. Coil springs however are limited to low clamping forces only. Coil springs that can deliver higher clamping forces are too big for normal temporary fasteners. Furthermore, coil springs have a certain force at a certain compression distance. Therefore coil springs have a limited range where they apply the required clamping force. The clamping force is too low if put in a thin assembly and is too high when put in a thick assembly. Gas springs have a more constant force at a wider range of compression distances. Furthermore, higher loads in coil springs inevitably mean more energy stored in the coil. This energy can become kinetic energy, which propels the temporary fastener through the air at dangerous speeds. Gas springs normally dampen the motion because the gas inside the gas spring physically has to move around the piston plunging plate inside the gas spring. This dampens any fast movement of the gas spring and prevents the gas spring from discharging the stored energy in a catastrophic way. Therefore, gas springs can be used to provide an improved temporary fastener.

[0013] The gas spring may comprise a chamber within the housing and a piston located within the chamber. The chamber may comprise gas and wherein the piston may be moveable inside the chamber. Movement of the piston may cause movement of the fastening portion. For example, the piston (and therefore the fastening portion) may be moveable in a first direction due to the gas in the gas spring (towards the extended state) and in a second direction due to an external force being applied to the piston (towards the clamping state). The gas may be nitrogen. In other examples and based on the application of the temporary fastener, a different gas may be used.

[0014] The piston may comprise a plunging plate moveable along the chamber, a first piston rod extending from the plunging plate through an opening in a first end of the housing and a second piston rod extending from the plunging plate towards a second end of the housing opposite the first end.

[0015] In some examples, the second piston rod is formed integrally with the fastening portion. Specifically, the fastening portion is formed from the end of the second piston rod. This therefore provides a simple design with a low part count. In other examples, the fastening portion may be a separate part to the second piston rod and may be releasably attached to the second piston rod for example by a screw fit. In this way, the fastening portion within the temporary fastener can be changed for example if the temporary fastener is to be used with a different diameter hole or for a different thickness range of the assembly.

[0016] The first piston rod may comprise a first diameter and the second piston rod may comprises a second diameter, wherein the first diameter may be larger than the second diameter. Since the second diameter is smaller than the first diameter, more of the plunging plate may be exposed to the gas pressure in the chamber adjacent the second piston rod. Therefore, a greater pressure may be applied to the plunging plate from the chamber on the side of the second piston rod than from the chamber on the side of the first piston rod. The gas pressure in the chamber may therefore cause the piston to move towards the first end of the housing.

[0017] As the fastening portion is moved between the extended state and the clamping state, the first piston rod may be configured to move out of the first end of the housing. In this way, an external force on the first piston rod extending from the first end can control movement of the piston and therefore the fastening portion at the second end. Specifically, as the first piston rod of the piston is forced into the housing by an externally applied force, the fastening portion moves into the extended state. In this configuration, the gas spring may be in a compressed state. As the force on the first piston rod of the piston is released, the force exerted on the piston by the gas pressure may cause the piston to return to the clamping state with the first piston rod of the piston outside of the housing. When the temporary fastener is being installed, the first piston rod and therefore the fastening portion may be held in the extended state so that the fastening portion can enter a hole through the parts it has to hold together. Specifically, the gas spring may be held in a depressed state so that the fastening portion can be brought into contact with parts it is to hold together. When the external force on the first piston rod is released, the fastening portion returns to the clamping state and the parts are held in place by the fastening portion.

[0018] A gap may be located between an outer diameter of the plunging plate and an inner diameter of the chamber. This leak path for the gas may also be complemented by one or more holes in the plunging plate. Gas may be configured to leak through the leak path between adjacent the first piston rod to adjacent the second piston rod as the plunging plate is moved within the chamber. The gas leakage may therefore provide a damping force inside the piston. The size of the leak path may be chosen based on the desired damping force. Specifically, a smaller leak path may provide a higher damping effect. The leak path may be designed in such a way that the resulting damping effect prevents catastrophic release of energy stored in the temporary fastener in the compressed state in all cases.

[0019] The fastening portion may comprise an elongate portion comprising a first end proximate to the gas spring and a second end distal from the gas spring, and a plurality of hooked arms extending axially along the elongate portion. The first end of the elongate portion may comprise a conical end portion, and wherein movement of the conical end portion with respect to the hooked arms may cause radial movement of the hooked arms at the second end. Specifically, when the conical portion is drawn axially between the hooked arms, movement of the ends of the arms up the side of the conical portion cause them to be forced radially outwards. The term 'hooked arms' are intended to mean further elongate portions which extend along the elongate portion of the fastening portion and which have a outwardly radially extending portion at the end. In some examples, there may be between two and eight hooked arms.

[0020] When in use, a clamping force may be provided between a distal end of the hooked arms and the second end of the housing. The term 'in use' is intended to mean when the temporary fastener is being used to clamp parts together. Specifically, when the fastening portion is in the extended state due to the first piston rod of the piston being depressed, it may be inserted through holes in two or more objects to be joined together. Once the force on the first piston rod of the piston is released, the elongate portion may be retracted inside the hooked arms causing the hooked arms to be forced radially outwards and into the clamping state. At this point the arms cannot fit back through the hole so the clamping force is provided between the distal end of the hooked arms and the second end of the housing. In other examples, rather than being inserted through holes in objects, the apparatus may comprise a clamping beak that can be used at the edge of two or more objects to clamp them together.

[0021] The clamping force may be from about 10N to about 1000N. In other examples, the clamping force may be greater or smaller than this range. The clamping force may be variable based on the quantity of gas in the gas spring. The clamping force may be chosen (and the gas type and pressure in the gas spring varied) based on the objects to be joined together. Specifically, the force may be chosen so that the objects can be securely clamped together without them being damaged.

[0022] The temporary fastener may be held and manipulated by a robot end effector. In this way, the application of the temporary fasteners may be automated.

[0023] Viewed from a second aspect, there is provided a robot end effector, the robot end effector comprising a holding portion for holding the apparatus of the first aspect of the invention. In this way, the application of the temporary fasteners may be automated. For instance, it becomes possible to perform the usually parallel process of drilling and placing temporary fasteners by one robot without the need for intervention.

[0024] The robot end effector may comprise an end effector piston, wherein activation of the end effector piston may be configured to cause movement of the fastening portion from the clamping state to the extended state and wherein retraction of the end effector piston may be configured to enable movement of the fastening portion from the extended state to the clamping state by the gas spring. In some examples, the end of the end effector piston and the end of the first piston of the temporary fastener may have complimentary shapes so as to temporarily lock them together. The end effector piston may be actuated by compressed air, oil or an electric actuator.

[0025] The robot end effector may be for installation on a light industrial robot, larger robot or collaborative robot, 'cobot'. When a cobot is used, the robot may move to a known location for installation of a temporary fastener and can sense a force being applied to the end of the housing when the fastening portion is inserted.

[0026] The holding portion may be U-shaped in cross section. In this way, the temporary fastener may be easily inserted and removed from the holding portion. The term 'U-shaped' is intended to mean that the upper part of the holding portion is open.

[0027] The holding portion may comprise a first end proximate to the robot end effector and a second end distal from the robot end effector. The second end may comprise a shoulder portion configured to interact with a shoulder portion on the outer surface of the housing, wherein the interaction between the shoulder portions may limit movement of the apparatus in the distal direction along the holding portion. The term 'shoulder portion' is intended to mean a lip which protrudes out from the holding portion to interact with a shoulder portion or edge of the apparatus housing.

[0028] The holding portion may additionally comprise a collar between the shoulder portion of the second end and the holding portion. In use, an upper part of the collar may be configured to extend above the apparatus housing. Put another way, due to the collar, it is not possible to move the apparatus directly upwards since the gap between the upper parts of the collar is narrower than the diameter of the housing meaning the housing cannot fit past the collar. This may prevent the apparatus moving up and down in the U-shaped portion, which may cause the piston of the end effector to become misaligned with the first piston rod of the piston of the apparatus. In order to remove the temporary fastener from the holding portion, the end effector piston is fully retracted so that the temporary fastener can be removed from the collar.

[0029] Viewed from a third aspect, there is provided a method for installing the temporary fastener the second aspect of the invention, moving, by the robot end effector, the temporary fastener to an installation location, wherein the fastening portion is in the extended state, locating the fastening portion at the installation location, and retracting the end effector piston such that the fastening portion is in the clamping state.

[0030] Locating the temporary fastener in the installation location may comprise inserting the temporary fastener through a hole or arranging it at the side of one or more parts to be fastened. When the fastening portion is retracted so that it is in the clamping state, the temporary fastener clamps on the distal side of a hole if it is inserted in a hole or clamps on the side of the one or more parts to be fastened.

[0031] Following retracting of the end effector piston, the method may further comprise moving the robot end effector towards the installation location. Movement of the robot end effector towards the installation location may enable removal of the temporary fastener from the robot end effector. Specifically, the end of the housing of the temporary fastener may come into contact with the one or more parts being fastened. This may push the temporary fastener along the holding portion of the end effector towards the end effector housing. This means the temporary fastener is no longer held in place by the collar. Thus the end effector can be moved away from the temporary fastener, leaving it in the installation location.

[0032] The method may additionally comprise adding a further temporary fastener in the robot end effector for installation in a further installation location. The further temporary fastener may be stored with a plurality of other temporary fasteners in a cassette at the end effector. This would remove the need for the robot to move between the installation locations and storage location all the time. In other examples, there may be a plurality of temporary fasteners installed in a cassette at a storage location.

[0033] Other aspects will also become apparent upon review of the present disclosure, in particular upon review of the Brief Description of the Drawings, Detailed Description and Claims sections. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Examples of the disclosure will now be described, by way of example only, with reference to the accompanying drawings in which:

[0035] Figures 1A and IB show side views of a temporary fastener with a fastening portion in extended and clamping states respectively;

[0036] Figures 2A and 2B show cross-sectional views of the temporary fastener with the fastening portion in the extended and clamping states respectively;

[0037] Figure 3 shows a perspective view of a robot end effector holding the temporary fastener;

[0038] Figure 4 shows a top view of the robot end effector holding the temporary fastener;

[0039] Figure 5 shows a cross-sectional view of a holding portion of the robot end effector for the temporary fastener; and

[0040] Figure 6 shows a cross-sectional side view of the robot end effector holding the temporary fastener;

[0041] While the disclosure is susceptible to various modifications and alternative forms, specific example approaches are shown by way of example in the drawings and are herein described in detail. It should be understood however that the drawings and detailed description attached hereto are not intended to limit the disclosure to the particular form disclosed but rather the disclosure is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the claimed invention.

[0042] As used in this specification, the words "comprises", "comprising", and similar words, are not to be interpreted in an exclusive or exhaustive sense. In other words, they are intended to mean "including, but not limited to".

[0043] It will be recognised that the features of the above-described examples of the disclosure can conveniently and interchangeably be used in any suitable combination. It will also be recognised that the invention covers not only individual embodiments but also combinations of the embodiments that have been discussed herein. DETAILED DESCRIPTION

[0044] The present teaching relates particularly, but not exclusively, to a temporary fastener and a robot end effector for applying the temporary fastener. This will be used in aircraft and other applications.

[0045] Figure 1 shows a side view of the temporary fastener 1 of the present invention. The apparatus comprises a housing 2, a fastening portion 6 and a gas spring 5 (within housing 2). The gas spring comprises a piston 4 (discussed further later). The piston 4 is configured to move the fastening portion 6 from an open or extended state (shown in figure 1A) to a clamping / fastening or retracted state (shown in figure IB).

[0046] When the fastening portion 6 is in the extended state, the piston 4 is located almost completely within the housing 2. When the fastening portion 6 is in the retracted state, part of the piston 4 extends through an opening 11 in the housing 2 and is located outside the housing 2. The gas spring 5 is configured to move the fastening portion 6 between a position outside the housing 2 and a retracted position inside the housing 2. The housing additionally comprises a shoulder 3 that may rest against a shoulder of an end effector when the piston of the end effector is pushing the piston 4 into the housing 2. This is discussed further later. The fastening portion 6 comprises an elongate portion 7 comprising a first end proximate to the gas spring 5 and a second end distal from the gas spring 5. The fastening portion 6 comprises a plurality of hooked arms 9 extending axially along the elongate portion 7. For example, the fastening portion 6 may comprise four hooked arms 9. In other examples, the fastening portion may comprise at least two and up to eight arms. The fastening portion 6 further comprises a conical end portion 8. The conical end portion 8 is configured to be drawn inside the hooked arms 9 causing the hooked arms 9 to spread radially outwards at the second end (i.e. into the clamping position).

[0047] Figure 2 shows a cross-sectional view of the temporary fastener 1 of the present invention. Figure 2A shows the fastening portion 6 in an extended position whereas figure 2B shows the fastening portion 6 in a retracted position.

[0048] The gas spring 5 comprises a chamber 10 within the housing 2, wherein the piston 4 is located within the chamber 10 and moveable inside the chamber 10. The chamber 10 is configured to be filled with gas.

[0049] The piston 4 comprises a plunging plate 4a moveable along the chamber 10, a first piston rod 4b extending from the plunging plate 4a through an opening 11 in a first end of the housing 2 and a second piston rod 4c extending from the plunging plate 4a towards a second end of the housing 2 opposite the first end and integral with or attached to the fastening portion 7. The plunging plate 4a splits the chamber into a first chamber portion 10a adjacent and surrounding the first piston rod 4b and a second chamber portion 10b adjacent and surrounding the second piston rod 4c.

[0050] The first piston rod 4b comprises a first diameter and the second piston rod 4c comprises a second diameter, wherein the first diameter is larger than the second diameter. As a result of this difference in piston rod diameters, the surface area of the plunging plate 4a which is acted on by gas pressure in the second chamber portion 10b is larger adjacent than the surface area of the plunging plate 4a which is acted on by gas in the first chamber portion 10a. As a result of this, gas pressure in the second chamber portion 10b exerts a greater force on the plunging plate 4a than gas in the first chamber portion 10c. This causes the piston 4 (and consequently the fastening portion 6) to move from the location shown in figures 1A and 2A to the location shown in IB and 2B.

[0051] In this way, the gas pressure in the chamber 10 is configured to cause force of the piston 4 towards the first end of the housing 2. As the fastening portion 6 is moved between the extended position and the retracted position, the first piston rod 4b is configured to move out of the first end of the housing 2.

[0052] In use, a gap 12 is located between an outer diameter of the plunging plate 4a and an inner diameter of the chamber 10. In this way, gas is configured to leak between the first and second chambers 10a, 10b as the plunging plate 4a is moved within the chamber 10. The leaking of gas provides a damping effect inside the gas spring 5.

[0053] When the temporary fastener is being used, an external force is applied to the end of the first piston rod 4b which extends out of the opening 11 to move the piston 4 from the position shown in figures IB and 2B to the position shown in figures 1A and 2A. When the piston 4 is in the position shown in position shown in figures 1A and 2A the gas spring 5 is in a compressed state. This is due to the larger exposed surface of the plunging plate 4a in the second chamber 10b meaning the gas pressure works to force the piston 4 towards the right when viewed as in figures 1 and 2. Therefore, when the force applied to the end of the first piston rod 4b is released, the first piston rod 4b is configured to move out of the first end of the housing 2 through the opening 11 such that the gas spring 5 is in a relaxed state. In use, the gas spring 5 is held in a compressed state as shown in figures 1A and 2A so that the fastening portion 6 extends outside the housing 2.

[0054] As can be seen from figures 2A and 2B, the fastening portion 6 is attached to the second piston rod 4c of the piston 4 by threading 14. In other examples, the fastening portion 6 may be formed integrally with the second piston rod 4c of the piston 4.

[0055] The temporary fastener 1 additionally comprises a plurality of balls 15 arranged at a proximal end of the hooked arms 9. The fastening portion 6 comprises a plurality of fastening portion recesses 16 and the housing 2 comprises a plurality of housing recesses 17. The recesses 16, 17 are configured to receive the balls 15 based on the positioning of the temporary fastener 1 with respect to the housing.

[0056] When the gas spring 5 is in a relaxed state as shown in figure 2B, the balls 15 are located within the fastening portion recesses 16. As can be seen from this figure, in this position, the hooked arms 9 are in the radially outwards position. This is due to the distal end of the arms 9 interacting with the widest portion of the conical end portion 8 which forces the arms outwards. As the piston 4 is depressed, the balls 15, fastening portion 7 and arms 9 travel axially inside the housing 2 until the balls 15 are radially aligned with the housing recesses 17. At this point, the balls 15 move radially outwards from the fastening portion recesses 16 and into the housing recesses 17. Once the balls 15 have moved out of the fastening portion recesses 16, the fastening portion 7 can continue to move axially with respect to the housing whilst the hooked arms 9 remain axially fixed by the balls 15. Due to the movement of the fastening portion 7 with respect to the hooked arms 9, the distal ends of the hooked arms 9 move down the sides of the conical end portion 8 and radially inwards (as shown in figure 2B). At this point, the temporary fastener can be inserted through a hole requiring temporary fastening with a diameter the same diameter as the conical end portion 8. Once the temporary fastener has been inserted in the hole, the force provided to the piston 4 is released. Since the gas spring 5 is in a compressed state at this stage, the piston 4 is forced towards the first end of the housing 2 by the pressure in the second chamber 10b. The balls 15 return to the fastening portion recesses 16 which cause the fastening portion 7 to move axially with respect to the hooked arms 9. The hooked arms 9 therefore are forced radially outwards as the conical end portion 8 is drawn between them. The hooked arms 9 attach to the distal side of the hole and prevent the temporary fastener leaving the hole. In order to remove the temporary fastener from the hole, the piston is depressed again to enable the conical end portion 8 to move with respect to the distal end of the hooked arms 9 so that the arms spring back radially inwards.

[0057] When the temporary fastening device is inserted in the hole, either side of the holes are subjected to a clamping force between a distal end of the hooked arms 9 and the second end of the housing. The clamping force is from about 10N to about 1000N. In some examples, the clamping force is variable based on the quantity of gas in the gas spring. For example, if a higher clamping force is desired, the quantity of gas in the gas spring is increased so that it applies a greater force on the piston 4. The gas spring 5 is filled through the filling valve 18 and opening 19.

[0058] Figure 3 to 6 show the temporary fastener 1 being held by a robot end effector 20. In each of these figures, the fastening portion 6 is held in the extended position.

[0059] Figure 3 is an isometric view of the robot end effector 20. The robot end effector 20 comprises a holding portion 21 for holding the temporary fastener 1 and an end effector housing 22. As can be seen from this figure, the holding portion a is U-shaped in cross section so that the temporary fastener 1 can be easily inserted and removed from the holding portion 21 from above. The end effector housing 22 contains an end effector piston 23. The piston 23 is controlled by fluid being forced into / drawn out of the end effector housing 22 through inlets 24, 25. The end effector piston 23 controls the position of the piston 4 in the temporary fastener 1. Specifically, extension of the end effector piston 23 causes depression of the piston rod 4b and therefore movement of the fastening portion 6 from the retracted position inside the housing 2 to the extended position outside the housing 2. When the end effector piston 23 is retracted, a force is no longer applied to the piston rod 4b. This enables movement of the piston rod 4b towards the end effector housing 22. The fastening portion moves from the extended position outside the housing to the retracted position inside the housing by the force of the gas spring 5.

[0060] Figure 4 is a top view of the robot end effector 20. The holding portion 21 comprises a first end proximate to the end effector housing 22 and a second end distal from the end effector housing 22. The second end comprises a shoulder portion 26 configured to interact with a shoulder portion 3 on the outer surface of the housing 2 of the temporary fastener 1. The interaction between the shoulder portion 26 of the holding portion 21 and the shoulder portion 3 of the housing 2 (i.e. the distal end) of the temporary fastener 1 limits movement of the temporary fastener 1 in the distal direction along the holding portion 21. The holding portion 21 additionally comprises a collar 27 between the shoulder portion 26 of the second end and the holding portion 21. When the temporary fastener and end effector are arranged as in figures 3 and 4, an upper part of the collar 27 extends above the housing 2 of the temporary fastener 1. This prevents movement out of the U-shaped holding portion 21. The configuration of the temporary fastener 1 and the shoulder portion 26 and collar 27 of the holding portion 21 can best be seen from figure 5. Figure 5 is a cross-sectional view across the holding portion 21 looking away from the housing 22.

[0061] Figure 6 is a cross-sectional side view of the robot end effector 20. From this view, the end effector piston 23 can be seen in more detail. When a medium is inserted through inlet 25, the end effector piston 23 is forced to the right as shown in the figure and the medium leaves through inlet 24. When a medium is inserted through inlet 24, the end effector piston 23 is forced to the left inside the housing and the medium leaves through inlet 25.

[0062] The robot end effector may be fully automated. In some examples, the end effector may be installed in a cobot. For example, the robot may be preprogramed with coordinates of a hole for insertion of the temporary fastener 1. In this way, once the robot end effector 20 has reached the desired location, the end effector piston 23 may be retracted to cause the temporary fastener to be in the fastening state. When a cobot is used, this may be able to sense the resistance when the housing 5 touches the product to be fastened.

[0063] Although figures 1 to 6 show the temporary fastener 1 having the fastening portion 6 which moves between the extended state where it is fully extended outside of the housing 2 and the retracted / clamping state where it is almost fully received within the housing 2, other types of temporary fasteners may be used. For example, a temporary fastener may be used which include two clamping portions as part of the temporary fastener. Specifically, as the fastening portion is moved into the extended state by a manual force, the clamping portions are separated. As the fastening portion is moved into the clamping state by the gas spring, the clamping portions are brought together. This sort of temporary fastener may be used at the edge of two or more parts to temporarily join them together. This type of temporary fastener is known in the art where a coil spring is used. Still further types of temporary fasteners may be used with the gas spring of the present invention.

[0064] A method of operating the temporary fastener 1 will now be described. The method comprises locating the temporary fastener 1 in the robot end effector 20, moving, by the robot end effector 20, the temporary fastener 1 to an installation location, wherein the fastening portion 6 is in the extended state, locating the fastening portion at the installation location, and retracting the end effector piston 23 such that the fastening portion 6 is in the clamping state.

[0065] Locating the temporary fastener 1 in the installation location may comprise inserting the temporary fastener 1 through a hole or arranging it at the side of one or more parts to be fastened. When the fastening portion 6 is retracted so that it is in the clamping state, the temporary fastener 1 clamps on the distal side of a hole if it is inserted in a hole or clamps on the edge of the one or more parts to be fastened.

[0066] Following retraction of the end effector piston 23, the method may further comprise moving the robot end effector 20 towards the installation location. Movement of the robot end effector 20 towards the installation location may enable removal of the temporary fastener 1 from the robot end effector 20. Specifically, the end of the housing 2 of the temporary fastener 1 may come into contact with the one or more parts being fastened. This may push the temporary fastener 1 along the holding portion 21 of the end effector 20 towards the end effector housing 22. This means the temporary fastener 1 is no longer held in place by the collar 27 and can be moved out of the holding portion 21 due to its U-shaped cross-section. Thus, the end effector 20 can be moved away from the temporary fastener 1, leaving it in the installation location. The end effector 20 may also be able to come back to the installation location to remove the temporary fastener 1.

[0067] The method may additionally comprise adding a further temporary fastener in the robot end effector 20 for installation in a further installation location. The further temporary fastener may be stored with a plurality of other temporary fasteners in a cassette at the end effector. This would remove the need for the robot to move between the installation locations and storage location all the time. In other examples, there may be a plurality of temporary fasteners installed in a cassette at a storage location.

[0068] The various embodiments described herein are presented only to assist in understanding and teaching the claimed features. These embodiments are provided as a representative sample of embodiments only, and are not exhaustive and / or exclusive. It is to be understood that advantages, embodiments, examples, functions, features, structures, and / or other aspects described herein are not to be considered limitations on the scope of the invention as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilised and modifications may be made without departing from the spirit and scope of the claimed invention. Various embodiments of the invention may suitably comprise, consist of, or consist essentially of, appropriate combinations of the disclosed elements, components, features, parts, steps, means, etc., other than those specifically described herein. In addition, this disclosure may include other inventions not presently claimed, but which may be claimed in future.

Claims

1. A temporary fastener comprising:a housing,a fastening portion; anda gas spring, wherein the gas spring is configured to move the fastening portion between an extended state and a clamping state .

2. The temporary fastener of claim 1, wherein the gas spring comprises a chamber within the housing and a piston located within the chamber, wherein the chamber is configured to comprise gas and wherein the piston is moveable inside the chamber.

3. The temporary fastener of claim 2, wherein the piston comprises a plunging plate moveable along the chamber, a first piston rod extending from the plunging plate through an opening in a first end of the housing and a second piston rod extending from the plunging plate towards a second end of the housing opposite the first end and integral with or attached to the fastening portion.

4. The temporary fastener of claim 3, wherein the first piston rod comprises a first diameter and wherein the second piston rod comprises a second diameter and wherein the first diameter is larger than the second diameter.

5. The temporary fastener of any of claims 3 to 4, wherein the gas pressure in the chamber is configured to cause movement of the piston towards the first end of the housing.

6. The temporary fastener of any of claims 3 to 5, wherein, as the fastening portion is moved between the extended state and the clamping state, the first piston rod is configured to move out of the first end of the housing.

7. The temporary fastener of any of claims 3 to 6, wherein a gap is located between an outer diameter of the plunging plate and an inner diameter of the chamber or one or more holes are located in the plunging plate.

8. The temporary fastener of claim 7, wherein gas is configured to leak through the gap or holes from adjacent the first piston rod to adjacent the second piston rod as the plunging plate is moved within the chamber.

9. The temporary fastener of any of claims 3 to 8, wherein, when an external force is applied to the first piston rod to move the second piston rod out of the housing, the gas spring is in a compressed state, and wherein when the force is released, the first piston rod is configured to move out of the first end of the housing.

10. The temporary fastener of any of claims 3 to 9, wherein the fastening portion comprises an elongate portion comprising a first end proximate to the gas spring and a second end distal from the gas spring, and a plurality of hooked arms extending axially along the elongate portion, wherein the first end of the elongate portion comprises a conical end portion, wherein movement of the conical end portion with respect to the hooked arms causes radial movement of the hooked arms at the second end.

11. The temporary fastener of claim 10, wherein when in use, a clamping force is configured to be provided between a distal end of the hooked arms and the second end of the housing.

12. The temporary fastener of claim 11, wherein the clamping force is from about ION to about 1000N.

13. The temporary fastener of claim 11 or 12, wherein the clamping force is variable based on the quantity of gas in the gas spring.

14. The temporary fastener of any preceding claim, wherein the temporary fastener is manipulated by a robot end effector.

15. A robot end effector, the robot end effector comprising a holding portion for holding the temporary fastener of any of claims 1 to 13.

16. The robot end effector of claim 15, additionally comprising an end effector piston, wherein activation of the end effector piston is configured to cause movement of the fastening portion from the clamping state to the extended state and wherein retraction of the end effector piston is configured to enable movement of the fastening portion from the extended state to the clamping state by the gas spring.

17. The robot end effector of claims 15 or 16, wherein the holding portion is U-shaped in cross section.

18. The robot end effector of claims 15 to 17, wherein the holding portion comprises a first end proximate to the robot end effector and a second end distal from the robot end effector, wherein the second end comprises a shoulder portion configured to interact with a shoulder portion on the outer surface of the temporary fastener housing, wherein the interaction between the shoulder portions limits movement of the apparatus in the distal direction along the holding portion.

19. The robot end effector of claim 18, wherein the holding portion additionally comprises a collar between the shoulder portion of the second end and the holding portion, wherein, in use, an upper part of the collar is configured to extend above the apparatus housing.

20. A method for installing the temporary fastener of any of claims 1 to 14, the method comprising:locating the temporary fastener in the robot end effector of claims 15 to 19;moving, by the robot end effector, the temporary fastener to an installation location, wherein the fastening portion is in the extended state;locating the fastening portion at the installation location;retracting the end effector piston such that the fastening portion is in the clamping state.

21. The method of claim 20, additionally comprising, following retracting of the end effector piston, moving the robot end effector towards the installation location, wherein movement of the robot end effector towards the installation location enables removal of the temporary fastener from the robot end effector.

22. The method of claim 21, additionally comprising, adding a further temporary fastener in the robot end effector for installation in a further installation location.19

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