FR3058193A1 - METHOD OF RADIALLY EXPANSIONING A HOLE COMBINED WITH A MOUNTING WITH INTERFERENCE OF A FASTENING IN THIS HOLE AND TOOLING FOR ITS IMPLEMENTATION - Google Patents

Abstract

The invention relates to a method of radially expanding a hole (16) in at least one piece (10) and interfering mounting a fastener (20) in the hole (16), the method comprising passing an expanding tool (32) through the hole (16) to radially expand and inserting the fastener (20) into the hole (16) adjacent to the expansion tool (32). ).

Description

® FRENCH REPUBLIC

NATIONAL INSTITUTE OF INDUSTRIAL PROPERTY © Publication number:

(only to be used for reproduction orders) © National registration number

058 193

60480

COURBEVOIE © IntCI ⁸ : F16 B 13/02 (2017.01)

PATENT INVENTION APPLICATION

A1

©) Date of filing: 28.10.16. (© Applicant (s): AIRBUS OPERATIONS Company by (© Priority: simplified actions - FR. @ Inventor (s): TUERY JEAN-BAPTISTE and CHIROL CLEMENT. (43) Date of public availability of the request: 04.05.18 Bulletin 18/18. ©) List of documents cited in the report preliminary research: Refer to end of present booklet (© References to other national documents ® Holder (s): AIRBUS OPERATIONS Company by related: simplified actions. ©) Extension request (s): © Agent (s): CABINET ALLICI.

04) METHOD OF RADIAL EXPANSION OF A HOLE COMBINED WITH A MOUNTING WITH INTERFERENCE OF A FIXING IN THE SAME HOLE AND TOOLS FOR ITS IMPLEMENTATION.

(© The subject of the invention is a method of radially expanding a hole (16) produced in at least one part (10) and mounting with interference a fixing (20) in the hole (16), the method of passing an expansion tool (32) through the hole (16) to obtain radial expansion and inserting the fastener (20) into the hole (16) while being attached to the expansion tool (32).

FR 3 058 193 - A1

i

METHOD FOR RADIAL EXPANSION OF A HOLE COMBINED WITH MOUNTING WITH

INTERFERENCE OF A FIXATION IN SAID HOLE AND TOOLS FOR ITS IMPLEMENTATION

ARTWORK

The present application relates to a method of radial expansion of a hole combined with mounting with interference of a fixing in said hole as well as a tool for its implementation.

A method of cold expansion of a part hole aims to generate a radial compressive field around the hole, using an expansion ring and an expansion tool to strengthen the mechanical characteristics of the part around the hole.

According to one embodiment, the expansion ring comprises a tube-shaped body with an outside diameter substantially equal to that of the hole and a collar configured to bear against a face of the part, around the hole.

The expansion tool has an outside diameter greater than the inside diameter of the expansion ring.

When the expansion tool passes through the expansion ring previously positioned in the hole, it generates a radial expansion of the expansion ring which in turn produces a radial compressive field and a plastic deformation of the part around the hole, over its entire height. After the cold expansion process, a stress relaxation phenomenon appears, causing a slight reduction in the diameter of the hole due to elastic return.

To improve the mechanical performance of an assembly, a fastener is mounted in a hole with interference. In this case, the outside diameter of the fixing is greater than that of the hole and the fixing is forced into the hole.

When the hole has already been subjected to a cold radial expansion, it becomes more difficult to forcely introduce a fastener to obtain an assembly with interference, taking into account the improvement of the mechanical characteristics around the hole by the expansion process. cold. Consequently, cold expansion techniques and assembly with interference are difficult to combine.

The present invention aims to remedy the drawbacks of the prior art.

To this end, the subject of the invention is a method of radially expanding a hole produced in at least one part and of mounting with interference a fixing in the hole, the fixing comprising at a first end a head, with a second end an end face, a first smooth part adjoining the head and a second threaded part adjoining the end face. According to the invention, the method consists in passing an expansion tool through the hole to obtain a radial expansion and is characterized in that the fixing is introduced into the hole while being attached to the expansion tool.

This solution makes it possible to mount with interference a fixing in a hole having undergone a radial expansion. Thus, the effects provided by a mounting with interference are combined with those provided by the radial expansion of the hole and avoid elastic return.

According to another characteristic, the second threaded part of the fastener is housed in an enlarged section of a through hole of the expansion tool, the fastener is connected to a first end of a pull rod which crosses the the part and the through hole of the expansion tool and the pull rod exerts a tensile force on the fastener to pass the expansion tool through the hole of the part and to introduce the fastener into the hole of the room.

According to another characteristic, the expansion tool and the fixing are introduced from a first face of the part, and a stop configured to immobilize the part during the tensile force of the traction rod is in abutment against a second face of the room.

According to one embodiment, the enlarged section of the through hole of the expansion tool is tapped and the second threaded part of the fixing is screwed into the enlarged tapped section of the expansion tool.

According to one embodiment, the end face of the binding comprises a tapped hole and the first end of the pull rod is screwed into the tapped hole of the binding. The invention also relates to a tool for implementing the method according to the invention, characterized in that it comprises on the one hand an expansion tool which extends from a first end to a second end and which has a first covering section adjoining the first end and a second section adjoining the second end and configured to achieve radial expansion, and on the other hand, a through hole opening at the first and second ends and which has a section enlarged which opens at the first end and which is configured to accommodate the second threaded part of the fixing.

According to another characteristic, the enlarged section comprises at least one thread configured to allow the second threaded part of the binding to be screwed.

According to another characteristic, the tool comprises a traction tool which comprises:

a draw rod which has a first end configured to be connected by means of a removable connection to the fastener and a second end, an actuator connected to the second end of the draw rod and configured to move the draw rod in a direction of traction, between a first extended position in which the expansion tool and the fastener are outside the hole and a retracted position in which the fastener is mounted in the hole, a stop configured to immobilize the part when the rod is moved traction.

According to another characteristic, the actuator comprises a tubular extension, one end of which forms the stop.

According to another characteristic, the first end of the pull rod is threaded and configured to be screwed into a tapped hole provided at the end face of the binding.

Other characteristics and advantages will emerge from the description of the invention which follows, description given by way of example only, with reference to the appended drawings in which:

FIG. 1 is a sectional view of a part comprising a hole and of a fixing to be mounted in the hole of the part with interference, after a radial expansion,

FIG. 2 is a section of an expansion tool which illustrates an embodiment of the invention,

FIG. 3 is a section of a tool for radial expansion and assembly combined with interference which illustrates an embodiment of the invention after an assembly step,

FIG. 4A is a section of an expansion tool connected to a fixing,

FIG. 4B is a section illustrating a detail of FIG. 4A,

FIG. 5 is a section which illustrates a step of expanding the hole using the tool visible in FIG. 3,

FIG. 6 is a section which illustrates a step of approaching the fixing in the hole using the tool visible in FIG. 3,

Figure 7 is a section illustrating a step of dismantling the tool visible in Figure 3 after mounting the fastener in the hole.

FIG. 1 shows a part 10 comprising a first face 12, a second face 14 and a hole 16 passing through and opening out on the first and second faces 12, 14.

The hole 16 has an initial diameter D16i and a longitudinal axis A16 substantially perpendicular to the first and second faces 12,14.

For the present application, the term piece designates both a piece and a stack of several pieces 10. Thus the hole 16 passes through at least one piece 10.

According to one embodiment, a binding 20 comprises a cylindrical body 22 which comprises at a first end a head 24 and at a second end a terminal face 26. The binding 20 has a shape of revolution and an axis A20.

The body 22 comprises a first smooth part 28 adjoining the head 24 and a second threaded part 30 adjoining the end face 26.

The first smooth part 28 is coaxial with the axis A20 of the binding and has a diameter D28 greater than the initial diameter D16i of the hole 16, in order to obtain a mounting with interference.

The second threaded part 30 is coaxial with the axis A20 of the binding and has a diameter D30 less than the diameter D28 of the first smooth portion 28.

The end face 26 is substantially perpendicular to the axis A20 of the binding.

The head 24 is configured to be pressed against the first face 12 of the part after assembly (as illustrated in FIG. 7) and comprises a diameter greater than that of the first smooth portion 28.

A tool for carrying out in a combined manner a radial expansion and an interference mounting of the fastener 20 in the hole 16 comprises a first tool called the expansion tool 32 and a second tool 34 configured to pass the expansion tool 32 to through hole 16.

The expansion tool 32 comprises an expansion ring 36 which extends from a first end 38 to a second end 40 and which has a first overlapping section 42 attached to the first end 38, a second adjoining section 44 at the second end 40 and configured to produce a radial expansion as well as a through hole 46 opening at the first and second ends 38, 40.

The expansion tool 32 has a shape of revolution with an axis A32.

The first and second sections 42 and 44 are coaxial with the axis of the ring A32 and have the same outside diameter D32 greater than the initial diameter D16i of the hole 16, determined to obtain the desired radial expansion.

The outside diameter D32 of the expansion tool is greater than or equal to the diameter D28 of the first smooth part 28 of the fastener 20 which is itself greater than the initial diameter D16i of the hole 16.

To give an order of magnitude, the outside diameter D32 of the expansion tool is 0.2 mm larger than the initial diameter D16i of the hole 16. The diameter D28 of the first smooth part 28 of the fastener 20 is 0, 03 mm larger than the initial diameter D16i of hole 16.

The through hole 46 is substantially coaxial with the axis A32 and comprises an enlarged section 48 which opens at the first end 38 and which forms a housing with a bottom 50 substantially perpendicular to the axis A32. The enlarged section 48 is configured to accommodate the second threaded part 30 of the fixing 20. Thus, the enlarged section 48 has a diameter greater than or equal to that of the second threaded part 30 of the fixing 20 and a length (dimension taken according to a direction parallel to the axis A32 of the expansion tool) greater than or equal to the length of the second threaded part 30 of the fastener 20 so that the second threaded part 30 of the fastener 20 is covered and protected by the first section 42 of the expansion tool 32 during the expansion of the hole 16 and of the fastening of the fastener 20 in the hole 16.

Thus, the enlarged section 48 has a length such that when the end face 26 of the fastener 20 abuts against the bottom 50, almost the entire second threaded portion 30 of the fastener 20 is covered by the first section 42. Thus, the end face 26 and the bottom 50 ensure the transmission of the thrust forces between the attachment 20 and the expansion tool 32. According to one embodiment, the enlarged section 48 is tapped and comprises at least one thread 52 configured to allow the screwing of the second threaded part 30 of the fastener 20, as illustrated in detail in FIG. 4B. This embodiment makes it possible to reinforce the protection of the second threaded part 30 and contributes to the transmission of the thrust forces between the fixing 20 and the expansion tool 32 during the radial expansion.

In operation, when the expansion tool 32 is connected to the attachment 20, the first smooth part 28 is attached to the first section 42 of the expansion tool 32 and the diameter of the first smooth part 28 of the attachment 20 is equal to or less than the diameter of the second section 44 of the expansion tool 32.

According to one configuration, the second tool 34 configured to pass the expansion tool 32 through the hole 16 is a traction tool. Of course, the invention is not limited to this configuration. Thus, as a variant, the second tool 34 can be a tool configured to push the attachment 16 and the expansion tool 32 into the hole.

The second tool 34 comprises a pull rod 54 which has a first end 56 connected by a removable link 58 to the binding 20 and a second end 60 connected to an actuator 62 configured to move the pull rod 54 in a direction of traction, between a first extended position (visible in FIG. 3) in which the expansion tool 32 and the fastener 20 are outside the hole 16 and a retracted position (visible in FIG. 6) in which the fastener 20 is mounted in hole 16.

The traction rod 54 is cylindrical and comprises an axis A54 coincident with the direction of traction.

According to one configuration, the removable link 58 comprises a threaded portion 64 provided at the second end 60 of the pull rod 54 and which is configured to cooperate with a tapped hole 66 provided at the end face 26 of the attachment 20. This threaded hole 66 is coaxial with the axis A20 of the fastener 20.

In addition, the traction tool 34 includes an anti-rotation system to prevent the unscrewing of the traction rod 54 from the tapped hole 66 during traction.

According to one embodiment, the actuator 62 is a jack which comprises a body 68 in which a piston 70 can slide slidingly connected to the traction rod 54.

The traction tool 34 also includes a stop 72 configured to immobilize the part 10 when the traction rod 54 is moved from the extended position to the retracted position.

According to one embodiment, the actuator 62 comprises a tubular extension 74, one end of which corresponds to the stop 72. This tubular extension 74 has an inside diameter greater than the outside diameter of the expansion ring 36 and the initial diameter of the hole 16 and a length greater than the length of the expansion ring 36 for accommodating the expansion ring in the retracted position.

The actuator 62 and the tubular extension 74 are dimensioned so that the head 24 of the binding 20 is pressed against the first face 12 of the part 10 when the traction rod 54 is in the retracted position.

The process of radial expansion of a hole combined with the interference mounting of a fixing in the hole is now described with reference to FIGS. 3, 5, 6 and 7.

A first assembly step includes:

an assembly phase of the fastener 20 and the expansion tool 32 by screwing the second threaded portion 30 of the fastener 20 into the enlarged section 48 threaded of the expansion tool 32 until the face end 26 of the fastening 20 is in abutment against the bottom 50, an exit phase of the pull rod 54, a phase of pressing the abutment 72 against the second face 14 of the part 10, around the hole 16, and a phase of assembling the first end 56 of the traction rod 54 and the fastening 20, said rod 54 passing through the hole 16 of the part 10 and the through hole 46 of the expansion tool 32.

At the end of this first assembly step illustrated in FIG. 3, the actuator 62 and the stop 72 are arranged on one side of the part 10, the expansion tool 32 and the fixing 20 are positioned the other side of the part, the pull rod 54 connecting the fastener 20 to the actuator 62. The axis A54 of the pull rod 54 coincides with the axis A16 of the hole 16 and the axis A20 of the fixation.

After the assembly step, a radial expansion step (visible in FIG. 5) consists in moving the pull rod 54 towards the retracted position so that it exerts a pull force on the fastener 20 which then pushes the expansion tool 32 through the hole 16. The outside diameter of the expansion tool 32 being greater than the initial diameter of the hole 16, radial compressive fields are generated all around the hole 16, over the entire length of the hole 16.

The fastener 20 being connected to the expansion tool 32, continuing the movement of the pull rod 54 towards the retracted position, the first smooth part 28 is inserted in the hole 16 before the relaxation of the material of the part 10 around hole 16.

The traction rod 54 is moved to the retracted position (visible in FIG. 6) so that the head 24 of the binding 16 is pressed against the first face 12 of the part 10. The diameter of the first smooth part 28 of the fastener 20 is greater than the diameter of the hole 16 after the relaxation of the material to obtain a mounting with interference. The diameter of the first smooth part 28 of the fastener 20 has a diameter substantially equal to that of the expansion tool 32 to facilitate its mounting in the hole 16.

According to a feature of the invention, the fixing 20 is introduced into the hole 16 while being attached to the expansion tool 32. According to another feature, the relaxation phenomenon will gradually increase the interference.

Finally, during a last disassembly step, the traction tool 34 is detached from the attachment 20 and the expansion tool 32 is unscrewed from the attachment 20.

Claims (10)

1. A method of radially expanding a hole (16) produced in at least one part (10) and mounting with interference a fixing (20) in the hole (16), the fixing (16) comprising at one first end a head (24), at a second end an end face (26), a first smooth part (28) adjoining the head (24) and a second threaded part (30) adjoining the end face (26), the method of passing an expansion tool (32) through the hole (16) to obtain radial expansion and being characterized in that the fastener (20) is introduced into the hole (16) being attached to the 'expansion tool (32). 2. Method according to claim 1, characterized in that the second threaded part (30) of the fixing (20) is housed in an enlarged section (48) of a through hole (36) of the expansion tool ( 32), in that the fixing (20) is connected to a first end (56) of a pull rod (54) which passes through the hole (16) of the part (10) and the through hole (46) of the expansion tool (32) and in that the traction rod (54) exerts a traction force on the fastener (20) to pass the expansion tool (32) through the hole (16) of the part (10) and to introduce the fixing (20) into the hole (16) of the part (10). 3. Method according to claim 2, characterized in that the expansion tool (32) and the fixing (20) are introduced from a first face (12) of the part (10) and in that a stop ( 72) configured to immobilize the part (10) during the tensile force of the traction rod (54) bears against a second face (14) of the part (10). 4. Method according to claim 2 or 3, characterized in that the enlarged section (48) of the through hole (36) of the expansion tool (32) is tapped and in that the second threaded part (30) of the fastener (20) is screwed into the enlarged section (48) of the expansion tool (32). 5. Method according to one of claims 2 to 4, characterized in that the end face (26) of the fixing (20) comprises a threaded hole (66) and in that the first end (56) of the rod traction (54) is screwed into the threaded hole (66) of the fixing (20). 6. Tool for implementing the method according to one of the preceding claims, characterized in that it comprises an expansion tool (32) which extends from a first end (38) to a second end ( 40) and which has a first covering section (42) attached to the first end (38) and a second section (44) attached to the second end (40) and configured to produce a radial expansion, and a through hole ( 46) opening at the first and second ends (38, 40) and which has an enlarged section (48) which opens at the first end (38) and which is configured to accommodate the second threaded part (30) of the fixing ( 20). 7. Tool according to the preceding claim, characterized in that the enlarged section 5 (48) comprises at least one thread (52) configured to allow the second threaded part (30) of the fastener (20) to be screwed. 8. Tool according to one of claims 6 to 7, characterized in that it comprises a traction tool (34) which comprises: a pull rod (54) which has a first end (56) configured to be connected by a removable link (58) to the fixing (20) and a second end (60), an actuator (62) connected to the second end (60) of the pull rod (54) and configured to move the pull rod (54) in a pull direction, between a first extended position in which the expansion tool (32) and the fastener ( 20) 15 are outside the hole (16) and a retracted position in which the fixing (20) is mounted in the hole (16), a stop (72) configured to immobilize the part (10) when the traction rod is moved (54). 9. Tool according to the preceding claim, characterized in that the actuator (62) 20 comprises a tubular extension (74), one end of which forms the stop (72). 10. Tool according to claim 8 or 9, characterized in that the first end (56) of the pull rod (54) is threaded and configured to be screwed into a tapped hole (66) provided at the end face ( 26) of the fixing (20). 1/1