WO2012117259A2 - Locking of threaded fasteners - Google Patents

Locking of threaded fasteners Download PDF

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Publication number
WO2012117259A2
WO2012117259A2 PCT/GB2012/050484 GB2012050484W WO2012117259A2 WO 2012117259 A2 WO2012117259 A2 WO 2012117259A2 GB 2012050484 W GB2012050484 W GB 2012050484W WO 2012117259 A2 WO2012117259 A2 WO 2012117259A2
Authority
WO
WIPO (PCT)
Prior art keywords
fastener
application head
delivery unit
sealing compound
application
Prior art date
Application number
PCT/GB2012/050484
Other languages
French (fr)
Other versions
WO2012117259A3 (en
Inventor
Tudor JONES
Simon THELWELL
Original Assignee
S&T Systems Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by S&T Systems Ltd filed Critical S&T Systems Ltd
Priority to GB1317128.5A priority Critical patent/GB2502756A/en
Publication of WO2012117259A2 publication Critical patent/WO2012117259A2/en
Publication of WO2012117259A3 publication Critical patent/WO2012117259A3/en

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
    • F16B33/00—Features common to bolt and nut
    • F16B33/004—Sealing; Insulation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C17/00—Hand tools or apparatus using hand held tools, for applying liquids or other fluent materials to, for spreading applied liquids or other fluent materials on, or for partially removing applied liquids or other fluent materials from, surfaces
    • B05C17/005—Hand tools or apparatus using hand held tools, for applying liquids or other fluent materials to, for spreading applied liquids or other fluent materials on, or for partially removing applied liquids or other fluent materials from, surfaces for discharging material from a reservoir or container located in or on the hand tool through an outlet orifice by pressure without using surface contacting members like pads or brushes
    • B05C17/00503—Details of the outlet element
    • B05C17/00516—Shape or geometry of the outlet orifice or the outlet element
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C11/00—Component parts, details or accessories not specifically provided for in groups B05C1/00 - B05C9/00
    • B05C11/10—Storage, supply or control of liquid or other fluent material; Recovery of excess liquid or other fluent material
    • B05C11/1002—Means for controlling supply, i.e. flow or pressure, of liquid or other fluent material to the applying apparatus, e.g. valves
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C17/00—Hand tools or apparatus using hand held tools, for applying liquids or other fluent materials to, for spreading applied liquids or other fluent materials on, or for partially removing applied liquids or other fluent materials from, surfaces
    • B05C17/005—Hand tools or apparatus using hand held tools, for applying liquids or other fluent materials to, for spreading applied liquids or other fluent materials on, or for partially removing applied liquids or other fluent materials from, surfaces for discharging material from a reservoir or container located in or on the hand tool through an outlet orifice by pressure without using surface contacting members like pads or brushes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C17/00—Hand tools or apparatus using hand held tools, for applying liquids or other fluent materials to, for spreading applied liquids or other fluent materials on, or for partially removing applied liquids or other fluent materials from, surfaces
    • B05C17/005—Hand tools or apparatus using hand held tools, for applying liquids or other fluent materials to, for spreading applied liquids or other fluent materials on, or for partially removing applied liquids or other fluent materials from, surfaces for discharging material from a reservoir or container located in or on the hand tool through an outlet orifice by pressure without using surface contacting members like pads or brushes
    • B05C17/00573—Hand tools or apparatus using hand held tools, for applying liquids or other fluent materials to, for spreading applied liquids or other fluent materials on, or for partially removing applied liquids or other fluent materials from, surfaces for discharging material from a reservoir or container located in or on the hand tool through an outlet orifice by pressure without using surface contacting members like pads or brushes the reservoir or container being pneumatically or hydraulically pressurized
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C17/00—Hand tools or apparatus using hand held tools, for applying liquids or other fluent materials to, for spreading applied liquids or other fluent materials on, or for partially removing applied liquids or other fluent materials from, surfaces
    • B05C17/005—Hand tools or apparatus using hand held tools, for applying liquids or other fluent materials to, for spreading applied liquids or other fluent materials on, or for partially removing applied liquids or other fluent materials from, surfaces for discharging material from a reservoir or container located in or on the hand tool through an outlet orifice by pressure without using surface contacting members like pads or brushes
    • B05C17/01—Hand tools or apparatus using hand held tools, for applying liquids or other fluent materials to, for spreading applied liquids or other fluent materials on, or for partially removing applied liquids or other fluent materials from, surfaces for discharging material from a reservoir or container located in or on the hand tool through an outlet orifice by pressure without using surface contacting members like pads or brushes with manually mechanically or electrically actuated piston or the like
    • B05C17/0103—Hand tools or apparatus using hand held tools, for applying liquids or other fluent materials to, for spreading applied liquids or other fluent materials on, or for partially removing applied liquids or other fluent materials from, surfaces for discharging material from a reservoir or container located in or on the hand tool through an outlet orifice by pressure without using surface contacting members like pads or brushes with manually mechanically or electrically actuated piston or the like with electrically actuated piston or the like
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C17/00—Hand tools or apparatus using hand held tools, for applying liquids or other fluent materials to, for spreading applied liquids or other fluent materials on, or for partially removing applied liquids or other fluent materials from, surfaces
    • B05C17/005—Hand tools or apparatus using hand held tools, for applying liquids or other fluent materials to, for spreading applied liquids or other fluent materials on, or for partially removing applied liquids or other fluent materials from, surfaces for discharging material from a reservoir or container located in or on the hand tool through an outlet orifice by pressure without using surface contacting members like pads or brushes
    • B05C17/015—Hand tools or apparatus using hand held tools, for applying liquids or other fluent materials to, for spreading applied liquids or other fluent materials on, or for partially removing applied liquids or other fluent materials from, surfaces for discharging material from a reservoir or container located in or on the hand tool through an outlet orifice by pressure without using surface contacting members like pads or brushes with pneumatically or hydraulically actuated piston or the like
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64F—GROUND OR AIRCRAFT-CARRIER-DECK INSTALLATIONS SPECIALLY ADAPTED FOR USE IN CONNECTION WITH AIRCRAFT; DESIGNING, MANUFACTURING, ASSEMBLING, CLEANING, MAINTAINING OR REPAIRING AIRCRAFT, NOT OTHERWISE PROVIDED FOR; HANDLING, TRANSPORTING, TESTING OR INSPECTING AIRCRAFT COMPONENTS, NOT OTHERWISE PROVIDED FOR
    • B64F5/00—Designing, manufacturing, assembling, cleaning, maintaining or repairing aircraft, not otherwise provided for; Handling, transporting, testing or inspecting aircraft components, not otherwise provided for
    • B64F5/10—Manufacturing or assembling aircraft, e.g. jigs therefor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
    • F16B37/00—Nuts or like thread-engaging members
    • F16B37/14—Cap nuts; Nut caps or bolt caps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16J—PISTONS; CYLINDERS; SEALINGS
    • F16J15/00—Sealings
    • F16J15/02—Sealings between relatively-stationary surfaces
    • F16J15/14—Sealings between relatively-stationary surfaces by means of granular or plastic material, or fluid
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
    • F16B39/00—Locking of screws, bolts or nuts
    • F16B39/02—Locking of screws, bolts or nuts in which the locking takes place after screwing down
    • F16B39/021—Locking of screws, bolts or nuts in which the locking takes place after screwing down by injecting a settable material after the screwing down

Definitions

  • This invention relates to locking of threaded fasteners.
  • Threaded fasteners have widespread use in mechanical engineering to secure components together. In addition to conventional nuts and bolts, these include other fasteners such as rivet nuts.
  • Securing threaded fasteners presents a particular problem to the aircraft construction industry.
  • An airliner may contain many tens or hundreds of thousands of fasteners, typically rivet nuts, each of which must be secured against loosening.
  • the conventional approach to securing rivet nuts is to manually apply a bead of resin locking compound to a component of an airframe to cover a line of fasteners. This prevents the fastener from turning with respect to the component of the airframe and also seals the fastener from its environment to provide resistance to corrosion.
  • An aim of the present invention is to provide a system whereby resin locking compound can be applied to a threaded fastener quickly, with a degree of automation, and that minimises the amount of locking compound in excess of that strictly necessary to secure the fastener that will be applied.
  • the present invention provides a system for application of locking compound to a fastener comprising a delivery unit and an application head, the delivery unit being operable to deliver a quantity of sealing compound to the application head, in which the delivery head has a recess into which the sealing compound is delivered, the recess being shaped and dimensioned to surround the fastener and a surface of a component that is secured by the fastener, whereby sealing compound delivered to the sealing head forms a body that surrounds the fastener and makes contact with the surface of the component surrounding the fastener.
  • sealing compound is delivered to just where it is needed, with a minimum of excess.
  • a typical system embodying the invention comprises a plurality of application heads of a range of sizes or shapes, any one of which can be connected to the delivery unit. Such a system can be used with a wide range of fasteners.
  • the delivery unit can be programmed to deliver a required amount of sealing compound to the application head. This is because different application heads and fasteners require a different amount of sealing compound for effective sealing.
  • the delivery unit may operate to deliver a quantity of sealing compound to the application head in response to operation of a user control.
  • the delivery unit can operate to deliver a quantity of sealing compound to the application head periodically. This latter mode of operation can speed up application of sealing compound to a plurality of similar fasteners.
  • the delivery unit may typically comprise an enclosure within which a cartridge containing sealing compound can be retained.
  • the delivery unit may include a source of compressed air that can be delivered to the enclosure to drive sealing compound from the cartridge to the application head.
  • the application head is connected to the delivery unit by a flexible pipe. This allows sealing compound to be applied to fasteners without moving the delivery unit after each fastener is treated.
  • the application head may comprise a body and an insert that can be inserted and retained in a space within the body, one or more flow channels being defined between the insert and a wall of the space.
  • Such an application head may be readily cleaned of resin by first removing the insert from the body.
  • the insert is a screw fit within the body.
  • Figure 1 is a diagrammatic overview of apparatus for applying resin locking compound to a threaded fastener being an embodiment of the invention
  • Figure 2 is a cross-section through a sealant cartridge container being a component of the apparatus of Figure 1;
  • Figure 3 shows the front panel of a control unit of the apparatus of Figure 1;
  • Figure 4 is a cross-sectional view of an application head of the apparatus of Figure 1 in place over a nut that is to be secured;
  • Figure 5 is an end view of the application head of Figure 4 showing an application chamber
  • Figure 6 is a cross-sectional view of an alternative application head of the apparatus of Figure 1 in place over a nut that is to be secured;
  • Figure 7 is an end view of the application head of Figure 6 showing an application chamber;
  • Figure 8 is a cross-sectional view of a further alternative application head of the apparatus of Figure 1 in place over a nut that is to be secured;
  • Figure 9 is an end view of the application head of Figure 8;
  • Figure 10 is a cross-sectional view of an alternative structure of an application head;
  • Figures 11 and 12 are side and end views of an insert for the application head of Figure 10.
  • the apparatus comprises the following principal components: a control unit 10, a source of compressed air 12, a resin cartridge container 14 and an application head 16.
  • the source of compressed air 12 comprises a compressor and an air reservoir, which provides a source of compressed air at a pressure of up to 7 bar.
  • An air input line 20 connects the source of compressed air 12 to an inlet port of the control unit 10.
  • the source of compressed air 12 is conventional and will not be described further.
  • the resin cartridge container 14 comprises a body 22 that is formed as a hollow cylinder with one open and one closed end.
  • the resin cartridge container 14 also includes a cap 24 that can be removably applied to the body 22 to close the open end, so as to form an air-tight seal with the body 22.
  • An air delivery line 26 connects the control unit 10 to an air inlet port 30 in the cap 24, and a sealant delivery line 28 connects a port 32 in the closed end of the body 22 to the application head 16.
  • the resin cartridge container 14 can receive a standard cylindrical resin cartridge 36 that contains the required resin locking compound.
  • the cartridge 36 has a delivery nozzle 38 that can connect with the port 32 in the closed end whereby resin from within the cartridge 36 can be delivered to the port 32.
  • the cartridge 36 has an open end, opposite the delivery nozzle.
  • There is a piston 40 within the cartridge 36 that separates a body of resin 42 within the cartridge 36 from its open end, the piston facing the cap 24. Compressed air that is fed into the resin cartridge container 14 acts upon the piston 40, and therefore tends to urge the resin 42 towards the delivery nozzle 38.
  • the main purpose of the control unit 10 is to control flow of air from the source of compressed air to the resin cartridge container 14.
  • the control unit 10 has an air outlet port 46 on its front panel to which the air delivery line 26 can be connected.
  • the front panel has a pressure gauge 48, a pressure control 58, and a control panel 44.
  • the control unit 10 is provided with an operating control 18 connected to it by a cable.
  • a typical example of an application head 16 is shown in Figures 4 and 5.
  • the application head 16 is formed from a body of metal.
  • a dome-shaped recess 50 is formed into a lower surface of the body.
  • An inlet port 52 is formed into an upper surface of the body in communication with internal bored flow channels 54, 56.
  • the inlet port 52 has a threaded region to allow connection of the sealant delivery line 28.
  • the flow channels 54 extend radially from the inlet port 52 and then downwardly 56 to open into the dome-shaped recess 50.
  • the dome-shaped recess 50 is shaped and dimensioned to fit over an installed nut 60 that is to be sealed leaving a space of substantially uniform width surrounding the nut 60.
  • the space is sufficiently large to accommodate sufficient material to form an effective seal, while minimising excess.
  • a user places the application head 16 over a nut 60 to be sealed such that the lower surface is pressed into close contact with a surface 62 of a component that is clamped by the nut 60.
  • the user activates the operating control 18. This instructs the control unit 10 to cause compressed air to be delivered to the resin cartridge container 14, which, in turn, causes resin to be delivered through the delivery line 28 to the application head 16.
  • the resin flows through the delivery channels 54, 56, as shown by the dashed line in Figure 4 to substantially fill the space within the dome-shaped recess 50.
  • the application head 16 is removed, leaving the nut completely encapsulated by resin, which is also bonded onto the surface 62.
  • the resin is both forced onto the surface 60 and forced to flow around and over the nut 60, whereby the nut is completely covered in resin. In this way, a reliable, effective seal is produced. It should also be remembered that the flow ducts cause resin to be directed against the fastener for circumferentially spaced directions, such that it flows all around the fastener.
  • the control unit 10 is set up to deliver the correct amount of resin for each particular application.
  • the shape and size of the application head 16 and, in particular, the dome-shaped recess 50 is selected to accord with the shape and size of nut to be sealed.
  • An alternative example of an application head 16 is shown in Figures 6 and 7.
  • the body has a cross-section that is L-shaped, such that the dome-shaped recess 50 is formed in a short foot of the "L”, and the delivery line 28 is attached to a port on the longer upright of the "L", which extends generally parallel to the surface 62 when the application head 16' is in use. In this way, the clearance required above the nut is minimised.
  • the control unit can be operated in several modes.
  • the first step is for the operator to identify the fastener to be sealed, and consult application charts to select an appropriate application head 16 and to determine the amount of sealant that is required for each fastener.
  • a manual mode the operator activated the user activates the operating control 18 until sealing compound is seen to emerge from all of the flow ducts 56 into the dome- shaped recess 50.
  • the control unit 10 is then operated in a timer mode. In this mode, the correct amount of sealing compound is entered into the control panel 44. Thereafter, each time the user activates the operating control 18, the correct amount of sealing compound is delivered to the application head 16.
  • control unit can be set to operate in a continuous mode.
  • the system operates in cycles in which the predetermined amount of sealing compound is delivered to the application head 16, followed by a pause of predetermined length of time, in which the operator can move the application head 16 on to the next fastener that is to be treated.
  • the application head 16 could be manipulated automatically rather than manually, for example, using an industrial robot.
  • an inspection lamp and video camera may be provided in association with the application head 16. This can help a user to directly inspect secured fasteners in locations where direct examination is difficult either due to lack of light or difficulty of access.
  • the output from the camera can be recorded to provide a record of the securing operations that have been performed.
  • FIG. 10 to 12 An alternative form of application head 116, suitable for use with many embodiments of the invention, is shown in Figures 10 to 12.
  • This application head comprises two components: a tubular body 118 and an insert 120.
  • the tubular body 118 has an inlet 152 that receives resin from the sealant delivery line 28 and an outlet region 160 that is internally threaded.
  • the inlet 152 and the outlet region 160 are at right angles to one another, but a similar construction can be used to form an application head 116 that is straight or another shape.
  • An insert 120 has an external thread that can be inserted into the outlet region 160 and retained there in threaded engagement.
  • the insert 120 has a cross-sectional shape that has threaded lobes 162 that engage with the wall of the outlet region 160 between which are recesses 156 and a recess 150.
  • a flow channel is formed within each recess 156, being bounded by the insert 120 and the wall of the outlet region 160, and the recess 150 forms a dome into which a nut can be received.
  • This form of construction may be advantageous because it allows the size of the flow channels to be changed by changing the insert. It also allows easier cleaning of the application head 116 by first removing the insert.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Transportation (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Geometry (AREA)
  • Coating Apparatus (AREA)

Abstract

A system for application of locking compound to a fastener is disclosed. The system comprises a delivery unit connected to an application head (16). The delivery unit is operable to deliver a quantity of sealing compound to the application head (16). The delivery head has a recess (50) into which the sealing compound is delivered. The recess (50) is shaped and dimensioned to surround the fastener (60) and a surface of a component (62) that is secured by the fastener (60). This arrangement ensures that sealing compound delivered to the sealing head (60) forms a body within the recess that surrounds the fastener (60) and makes contact with the surface (62) of the component surrounding the fastener (60).

Description

Locking of threaded fasteners
This invention relates to locking of threaded fasteners.
Threaded fasteners have widespread use in mechanical engineering to secure components together. In addition to conventional nuts and bolts, these include other fasteners such as rivet nuts.
When a threaded fastener is used in a safety-critical application, especially when subject to vibration, steps must be taken to ensure that the fasteners do not work loose over time. Many alternative approaches to this problem have been proposed including mechanical means such as locking pins or tabs and spring washers, and adhesive means that either act between interengaged, threaded fasteners or between a fastener and a component that is being secured. This is complicated by the typical requirement that the fastener should be able to be loosened when required.
Securing threaded fasteners presents a particular problem to the aircraft construction industry. An airliner may contain many tens or hundreds of thousands of fasteners, typically rivet nuts, each of which must be secured against loosening. The conventional approach to securing rivet nuts is to manually apply a bead of resin locking compound to a component of an airframe to cover a line of fasteners. This prevents the fastener from turning with respect to the component of the airframe and also seals the fastener from its environment to provide resistance to corrosion.
Disadvantages of this approach include it being a manual, time-consuming operation, and that it uses an excess of resin in regions around and between the fasteners, which is required to ensure a proper seal. This latter disadvantage adds a significant amount of weight to the completed aircraft, which works against the aim of saving weight that pervades aircraft design.
An aim of the present invention is to provide a system whereby resin locking compound can be applied to a threaded fastener quickly, with a degree of automation, and that minimises the amount of locking compound in excess of that strictly necessary to secure the fastener that will be applied.
To this end, the present invention provides a system for application of locking compound to a fastener comprising a delivery unit and an application head, the delivery unit being operable to deliver a quantity of sealing compound to the application head, in which the delivery head has a recess into which the sealing compound is delivered, the recess being shaped and dimensioned to surround the fastener and a surface of a component that is secured by the fastener, whereby sealing compound delivered to the sealing head forms a body that surrounds the fastener and makes contact with the surface of the component surrounding the fastener. Thus, sealing compound is delivered to just where it is needed, with a minimum of excess.
A typical system embodying the invention comprises a plurality of application heads of a range of sizes or shapes, any one of which can be connected to the delivery unit. Such a system can be used with a wide range of fasteners. Preferably, the delivery unit can be programmed to deliver a required amount of sealing compound to the application head. This is because different application heads and fasteners require a different amount of sealing compound for effective sealing.
The delivery unit may operate to deliver a quantity of sealing compound to the application head in response to operation of a user control. Alternatively or additionally, the delivery unit can operate to deliver a quantity of sealing compound to the application head periodically. This latter mode of operation can speed up application of sealing compound to a plurality of similar fasteners.
The delivery unit may typically comprise an enclosure within which a cartridge containing sealing compound can be retained. In such embodiments, the delivery unit may include a source of compressed air that can be delivered to the enclosure to drive sealing compound from the cartridge to the application head.
Most advantageously, the application head is connected to the delivery unit by a flexible pipe. This allows sealing compound to be applied to fasteners without moving the delivery unit after each fastener is treated.
The application head may comprise a body and an insert that can be inserted and retained in a space within the body, one or more flow channels being defined between the insert and a wall of the space. Such an application head may be readily cleaned of resin by first removing the insert from the body. Conveniently, the insert is a screw fit within the body.
An embodiment of the invention will now be described in detail, by way of example, and with reference to the accompanying drawings, in which:
Figure 1 is a diagrammatic overview of apparatus for applying resin locking compound to a threaded fastener being an embodiment of the invention; Figure 2 is a cross-section through a sealant cartridge container being a component of the apparatus of Figure 1;
Figure 3 shows the front panel of a control unit of the apparatus of Figure 1;
Figure 4 is a cross-sectional view of an application head of the apparatus of Figure 1 in place over a nut that is to be secured;
Figure 5 is an end view of the application head of Figure 4 showing an application chamber;
Figure 6 is a cross-sectional view of an alternative application head of the apparatus of Figure 1 in place over a nut that is to be secured; Figure 7 is an end view of the application head of Figure 6 showing an application chamber;
Figure 8 is a cross-sectional view of a further alternative application head of the apparatus of Figure 1 in place over a nut that is to be secured; Figure 9 is an end view of the application head of Figure 8; Figure 10 is a cross-sectional view of an alternative structure of an application head; and
Figures 11 and 12 are side and end views of an insert for the application head of Figure 10.
The apparatus comprises the following principal components: a control unit 10, a source of compressed air 12, a resin cartridge container 14 and an application head 16. The construction and function of each of these components will be described below. The source of compressed air 12 comprises a compressor and an air reservoir, which provides a source of compressed air at a pressure of up to 7 bar. An air input line 20 connects the source of compressed air 12 to an inlet port of the control unit 10. The source of compressed air 12 is conventional and will not be described further. The resin cartridge container 14 comprises a body 22 that is formed as a hollow cylinder with one open and one closed end. The resin cartridge container 14 also includes a cap 24 that can be removably applied to the body 22 to close the open end, so as to form an air-tight seal with the body 22. An air delivery line 26 connects the control unit 10 to an air inlet port 30 in the cap 24, and a sealant delivery line 28 connects a port 32 in the closed end of the body 22 to the application head 16.
The resin cartridge container 14 can receive a standard cylindrical resin cartridge 36 that contains the required resin locking compound. The cartridge 36 has a delivery nozzle 38 that can connect with the port 32 in the closed end whereby resin from within the cartridge 36 can be delivered to the port 32. The cartridge 36 has an open end, opposite the delivery nozzle. There is a piston 40 within the cartridge 36 that separates a body of resin 42 within the cartridge 36 from its open end, the piston facing the cap 24. Compressed air that is fed into the resin cartridge container 14 acts upon the piston 40, and therefore tends to urge the resin 42 towards the delivery nozzle 38.
The main purpose of the control unit 10 is to control flow of air from the source of compressed air to the resin cartridge container 14. The control unit 10 has an air outlet port 46 on its front panel to which the air delivery line 26 can be connected. In addition, the front panel has a pressure gauge 48, a pressure control 58, and a control panel 44. The control unit 10 is provided with an operating control 18 connected to it by a cable. A typical example of an application head 16 is shown in Figures 4 and 5.
The application head 16 is formed from a body of metal. A dome-shaped recess 50 is formed into a lower surface of the body. An inlet port 52 is formed into an upper surface of the body in communication with internal bored flow channels 54, 56. The inlet port 52 has a threaded region to allow connection of the sealant delivery line 28. The flow channels 54 extend radially from the inlet port 52 and then downwardly 56 to open into the dome-shaped recess 50. In this embodiment, there are six such flow channels 54, 56 that open into the dome-shaped recess 50 spaced equally around a centre axis of the application head 16. (Smaller or larger embodiments may have a lesser or greater number of flow channels.)
The dome-shaped recess 50 is shaped and dimensioned to fit over an installed nut 60 that is to be sealed leaving a space of substantially uniform width surrounding the nut 60. The space is sufficiently large to accommodate sufficient material to form an effective seal, while minimising excess. Typically, there will be a clearance of between 0.5mm and 2mm between the dome-shaped recess 50 and the fastener.
In use, a user places the application head 16 over a nut 60 to be sealed such that the lower surface is pressed into close contact with a surface 62 of a component that is clamped by the nut 60. Once the application head 16 is in place, the user activates the operating control 18. This instructs the control unit 10 to cause compressed air to be delivered to the resin cartridge container 14, which, in turn, causes resin to be delivered through the delivery line 28 to the application head 16. Within the head 16, the resin flows through the delivery channels 54, 56, as shown by the dashed line in Figure 4 to substantially fill the space within the dome-shaped recess 50. When sufficient resin has been delivered, the application head 16 is removed, leaving the nut completely encapsulated by resin, which is also bonded onto the surface 62.
It is important to note that the resin is both forced onto the surface 60 and forced to flow around and over the nut 60, whereby the nut is completely covered in resin. In this way, a reliable, effective seal is produced. It should also be remembered that the flow ducts cause resin to be directed against the fastener for circumferentially spaced directions, such that it flows all around the fastener. The control unit 10 is set up to deliver the correct amount of resin for each particular application. Likewise, the shape and size of the application head 16 and, in particular, the dome-shaped recess 50, is selected to accord with the shape and size of nut to be sealed. An alternative example of an application head 16 is shown in Figures 6 and 7. In some circumstances, there may be insufficient clearance above a nut to accommodate the application head 16 and the delivery line 28. This difficulty can be overcome by use of an application head 16' as shown in Figures 8 and 9. In this case, the body has a cross-section that is L-shaped, such that the dome-shaped recess 50 is formed in a short foot of the "L", and the delivery line 28 is attached to a port on the longer upright of the "L", which extends generally parallel to the surface 62 when the application head 16' is in use. In this way, the clearance required above the nut is minimised.
The control unit can be operated in several modes. In each case, the first step is for the operator to identify the fastener to be sealed, and consult application charts to select an appropriate application head 16 and to determine the amount of sealant that is required for each fastener.
In a manual mode, the operator activated the user activates the operating control 18 until sealing compound is seen to emerge from all of the flow ducts 56 into the dome- shaped recess 50. The control unit 10 is then operated in a timer mode. In this mode, the correct amount of sealing compound is entered into the control panel 44. Thereafter, each time the user activates the operating control 18, the correct amount of sealing compound is delivered to the application head 16.
To speed multiple applications, the control unit can be set to operate in a continuous mode. In this mode, the system operates in cycles in which the predetermined amount of sealing compound is delivered to the application head 16, followed by a pause of predetermined length of time, in which the operator can move the application head 16 on to the next fastener that is to be treated. It will be understood that the application head 16 could be manipulated automatically rather than manually, for example, using an industrial robot.
Since applications of the present invention typically relate to securing fasteners in safety-critical situations, it will often be desirable to implement quality control measures whereby the effectiveness of the sealing operation can be confirmed. To this end, an inspection lamp and video camera may be provided in association with the application head 16. This can help a user to directly inspect secured fasteners in locations where direct examination is difficult either due to lack of light or difficulty of access. In addition, the output from the camera can be recorded to provide a record of the securing operations that have been performed.
Note that the use of the term "resin" is not intended to impart any limitation on the form of locking compound that can be applied by embodiments of the present invention. Any locking compound that takes the form of a liquid or semi-liquid mass can be used.
An alternative form of application head 116, suitable for use with many embodiments of the invention, is shown in Figures 10 to 12. This application head comprises two components: a tubular body 118 and an insert 120. The tubular body 118 has an inlet 152 that receives resin from the sealant delivery line 28 and an outlet region 160 that is internally threaded. In this example, the inlet 152 and the outlet region 160 are at right angles to one another, but a similar construction can be used to form an application head 116 that is straight or another shape.
An insert 120 has an external thread that can be inserted into the outlet region 160 and retained there in threaded engagement. The insert 120 has a cross-sectional shape that has threaded lobes 162 that engage with the wall of the outlet region 160 between which are recesses 156 and a recess 150. When the insert 120 is within the outlet region 160, a flow channel is formed within each recess 156, being bounded by the insert 120 and the wall of the outlet region 160, and the recess 150 forms a dome into which a nut can be received. This form of construction may be advantageous because it allows the size of the flow channels to be changed by changing the insert. It also allows easier cleaning of the application head 116 by first removing the insert.

Claims

Claims
1. A system for application of locking compound to a fastener comprising a delivery unit connected to an application head, the delivery unit being operable to deliver a quantity of sealing compound to the application head, characterised in that the delivery head has a recess into which the sealing compound is delivered, the recess being shaped and dimensioned to surround the fastener and a surface of a component that is secured by the fastener, whereby sealing compound delivered to the sealing head forms a body within the recess that surrounds the fastener and makes contact with the surface of the component surrounding the fastener.
2. A system according to claim 1 comprising a plurality of application heads of a range of sizes or shapes, any one of which can be connected to the delivery unit.
3. A system according to claim 1 or claim 2 in which the delivery unit can be programmed to deliver a required amount of sealing compound to the application head.
4. A system according to any preceding claim in which the delivery unit can operate to deliver a quantity of sealing compound to the application head in response to operation of a user control.
5. A system according to any preceding claim in which the delivery unit can operate to deliver a quantity of sealing compound to the application head periodically.
6. A system according to any preceding claim in which the delivery unit comprises an enclosure within which a cartridge containing sealing compound can be retained.
7. A system according to claim 6 in which the delivery unit includes a source of compressed air that can be delivered to the enclosure to drive sealing compound from the cartridge to the application head.
8. A system according to any preceding claim in which the application head is connected to the delivery unit by a flexible pipe.
9. A system according to any preceding claim in which the application head comprises a body and an insert that can be inserted and retained in a space within the body, one or more flow channels being defined between the insert and a wall of the space.
10. A system according to claim 9 in which the insert is a screw fit within the body.
11. A system for application of locking compound to a fastener substantially as described herein with reference to the accompanying drawings.
PCT/GB2012/050484 2011-03-03 2012-03-05 Locking of threaded fasteners WO2012117259A2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB1317128.5A GB2502756A (en) 2011-03-03 2012-03-05 Locking of threaded fasteners

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB1103650.6A GB2491799A (en) 2011-03-03 2011-03-03 Locking of threaded fasteners
GB1103650.6 2011-03-03

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WO2012117259A2 true WO2012117259A2 (en) 2012-09-07
WO2012117259A3 WO2012117259A3 (en) 2012-11-08

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Also Published As

Publication number Publication date
GB201317128D0 (en) 2013-11-06
WO2012117259A3 (en) 2012-11-08
GB201103650D0 (en) 2011-04-13
GB2491799A (en) 2012-12-19
GB2502756A (en) 2013-12-04

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