SETTING TOOL FOR A BLIND FASTENER, SETTING METHOD AND SUITABLE BLIND FASTENER

Abstract

Disclosed is a blind fastener including a core bolt, a body and a blind side clamp on the core bolt insertable through an aperture, where moving the core bolt relative to the body forms an enlarged bearing surface against a back surface. The fastener includes an extension from the body with a wrenching surface and an undercut between the body and the wrenching surface that is optionally configured to break when torque equal to the sum of an application specified minimum installed seated torque and a manufacturing failure torque tolerance for the undercut is applied. Also disclosed is a method of dressing the installed fastener including machining through the top surface of the fastener along a longitudinal axis of the core bolt of the fastener and the extension that extends from a body of the fastener until intersecting the undercut between the extension to remove the extension.

Claims

1. A method for setting a blind fastener (100) comprising a rod (110) onto which an outer body (120) is fitted, the outer body (120) comprising a head (121) and a detachable portion (122) connected to said head (121) by means of a thinned portion (123) of the outer body (120), the outer body (120) comprising one or more parts, said outer body (120) comprising a deformable portion for creating a bulb under the action of the rod (110), the rod (110) comprising a rupture groove (114) which breaks from a predefined stress threshold, the setting method involving carrying out the following operations: positioning the fastener (100) in a hole (T) passing through an assembly, maintaining the fastener (100) in the hole (T), creating a bulb for fastening the assembly, rupture of the rod (110), rupture of the detachable portion (123) of the head (121) of the outer body (120), the method comprising: driving the rod (110) without jolts for creating the bulb until rupture of the rod (110) at the rupture groove (114) while retaining the detachable portion (122) of the head (121) of the outer body (120), impact driving in rotation by producing a significant dynamic stress in a very short time, by subjecting to at least one impact in a direction of rotation, the detachable portion (123) of the head (121) of the outer body (120) in order to exert a torsional stress for rupture of the thinned portion (123) of the outer body (120), the rupture resulting from a proper installation and the absence of rupture resulting from a poor installation.

2. The method according to claim 1, wherein the creation of the bulb until rupture of the rod (110) at the rupture groove (114) while retaining the detachable portion (122) of the head (121) of the outer body (120), is carried out by driving said rod (110) in rotation without jolts.

3. The method according to claim 1, wherein the significant stress is a stress corresponding to at least two times the stress necessary to break the thinned linking portion (123) connecting the detachable portion (122) to the head (121) of the outer body (120) and the very short time is a time of less than one second.

4. A setting tool (O) to implement the method according to claim 1, comprising a setting member (200) cooperating with said rod (110) and a setting-verification member (300) cooperating with said head (121) of the outer body (120), the setting member (200) having an action on the rod (110) for creating the bulb until rupture of the rod (110) at the rupture groove (114), the setting-verification member (300) retaining the detachable portion (122) of the head (121) of the outer body (120) during the action of the setting member (200) on the rod (110), the setting-verification member (300) subjecting the detachable portion (122) of the head (121) of the outer body (120) to a torsional stress by driving in rotation of the impact type which allows the production of a significant dynamic stress produced in a very short time by subjecting said detachable portion (122) of the head (121) of the outer body (120) to at least one impact in a direction of rotation for rupture of the thinned portion (123) of the outer body (120), the rupture resulting from a proper installation and the absence of rupture resulting from a poor installation.

5. The tool (O) according to claim 4, wherein the setting member (200) ensures a rotation of the rod (110) for creating the bulb by screwing until rupture of the rod (110) at the rupture groove (114).

6. The tool (O) according to claim 4, wherein the setting member (200) is moved by an electric or pneumatic motor.

7. The tool (O) according to claim 4, wherein the setting-verification member (300) is moved by an electric or pneumatic motor.

8. The tool (O) according to claim 4, further comprising a single motor driving the setting member (200) and the setting-verification member (300) in a distinct manner by means of a suitable reduction sub-assembly.

9. The tool (O) according to claim 4, wherein the setting member (200) drives the setting-verification member (300) by means of a suitable reduction assembly.

10. The tool (O) according to claim 4, wherein the setting-verification member (300) comprises an angle of free rotation that is between 60 and 240.

11. A blind fastener (100) comprising a rod (110) onto which an outer body (120) is fitted, the outer body (120) comprising a head (121) and a detachable portion (122) connected to said head (121) by means of a thinned portion (123) of the outer body (120), the outer body (120) comprising one or more parts, said outer body (120) comprising a deformable portion for creating a bulb under the action of the rod (110), the rod (110) comprising a head (112) and a detachable portion (113) of the rod head connected to said head (112) by a rupture groove (114) which breaks from a predefined stress threshold, said thinned portion (123) of the outer body (120) connecting the detachable portion (122) to said head (121) being dimensioned in such a way as to resist the counter-torque that it undergoes during the creation of the bulb by rotation of the rod (110) until the rupture of the rupture groove (114) of the rod (110), and break during an impact driving if the fastener (100) is properly installed, wherein the detachable portion (113) of the head (112) of the rod (110) is preformed in such a way as to form an axial support so that a movement in translation applied to the detachable portion (113) detached from the rod (110) head (112) for ejection, causes a contact with the detachable portion (122) detached from the head (121) of the outer body (120) and its own ejection.

12. The method according to claim 2, wherein the significant stress is a stress corresponding to at least two times the stress necessary to break the thinned linking portion (123) connecting the detachable portion (122) to the head (121) of the outer body (120) and the very short time is a time of less than one second.

13. A setting tool (O) implement the method according to claim 2, comprising a setting member (200) cooperating with said rod (110) and a setting-verification member (300) cooperating with said head (121) of the outer body (120), the setting member (200) having an action on the rod (110) for creating the bulb until rupture of the rod (110) at the rupture groove (114), the setting-verification member (300) retaining the detachable portion (122) of the head (121) of the outer body (120) during the action of the setting member (200) on the rod (110), the setting-verification member (300) subjecting the detachable portion (122) of the head (121) of the outer body (120) to a torsional stress by driving in rotation of the impact type which allows the production of a significant dynamic stress produced in a very short time by subjecting said detachable portion (122) of the head (121) of the outer body (120) to at least one impact in a direction of rotation for rupture of the thinned portion (123) of the outer body (120), the rupture resulting from a proper installation and the absence of rupture resulting from a poor installation.

14. A setting tool (O) implement the method according to claim 3, comprising a setting member (200) cooperating with said rod (110) and a setting-verification member (300) cooperating with said head (121) of the outer body (120), the setting member (200) having an action on the rod (110) for creating the bulb until rupture of the rod (110) at the rupture groove (114), the setting-verification member (300) retaining the detachable portion (122) of the head (121) of the outer body (120) during the action of the setting member (200) on the rod (110), the setting-verification member (300) subjecting the detachable portion (122) of the head (121) of the outer body (120) to a torsional stress by driving in rotation of the impact type which allows the production of a significant dynamic stress produced in a very short time by subjecting said detachable portion (122) of the head (121) of the outer body (120) to at least one impact in a direction of rotation for rupture of the thinned portion (123) of the outer body (120), the rupture resulting from a proper installation and the absence of rupture resulting from a poor installation.

15. The tool (O) according to claim 5, wherein the setting member (200) is moved by an electric or pneumatic motor.

16. The tool (O) according to claim 5, wherein the setting-verification member (300) is moved by an electric or pneumatic motor.

17. The tool (O) according to claim 5, further comprising a single motor driving the setting member (200) and the setting-verification member (300) in a distinct manner by means of a suitable reduction sub-assembly.

18. The tool (O) according to claim 5, wherein the setting member (200) drives the setting-verification member (300) by means of a suitable reduction assembly.

19. The tool (O) according to claim 5, wherein the setting-verification member (300) comprises an angle of free rotation that is between 60 and 240.

20. A setting tool (O) implement the method according to claim 1, comprising a setting member (200) cooperating with said rod (110) and a setting-verification member (300) cooperating with said head (121) of the outer body (120), the setting member (200) having an action on the rod (110) for creating the bulb until rupture of the rod (110) at the rupture groove (114), the setting-verification member (300) retaining the detachable portion (122) of the head (121) of the outer body (120) during the action of the setting member (200) on the rod (110), the setting-verification member (300) subjecting the detachable portion (122) of the head (121) of the outer body (120) to a torsional stress by driving in rotation of the impact type which allows the production of a significant dynamic stress produced in a very short time by subjecting said detachable portion (122) of the head (121) of the outer body (120) to at least one impact in a direction of rotation for rupture of the thinned portion (123) of the outer body (120), the rupture resulting from a proper installation and the absence of rupture resulting from a poor installation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0114] FIG. 1a is a diagram of a cross-sectional side view of a first embodiment of a blind fastener according to the invention;

[0115] FIG. 1b is a diagram of a front outside view of the fastener of FIG. 1a;

[0116] FIG. 1c is a diagram of a perspective outside view of the fastener of FIG. 1a;

[0117] FIGS. 2a to 2f are diagrams of cross-sectional side views of the tool and of the fastener of FIG. 1a installed in an assembly and illustrating the steps of the setting operation implemented by the tool of the invention;

[0118] FIG. 2g is a diagram of a cross-sectional side view of a blind fastener installed by the tool of the invention;

[0119] FIG. 2h is a diagram of a front outside view of the accessible side of the fastener once installed;

[0120] FIG. 3 is a diagram of a cross-sectional side view of another embodiment of a blind fastener according to the invention;

[0121] FIG. 4 illustrates the monitoring curves of the installation parameters in the case of an effective clamping lower than the installation torque S1calibration in the 30-70% rangecounter-torque;

[0122] FIG. 5 illustrates the monitoring curves of the installation parameters in the case of an effective clamping lower than the installation torque S1calibration outside of 30-70% rangeslippage;

[0123] FIG. 6 illustrates the monitoring curves of the installation parameters in the case of an effective clamping lower than the installation torque S1impact ruptureno slippage;

[0124] FIG. 7 illustrates the monitoring curves of the installation parameters in the case of an effective clamping greater than the installation torque S1impact ruptureno slippage.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0125] As illustrated in the drawings of FIGS. 1a, 1b and 1c, the blind fastener labelled 100 as a whole comprises a rod 110 onto which an outer body 120 is fitted.

[0126] The outer body 120 is thus hollow and comprises a head 121 countersunk and equipped with a detachable portion 122. This outer body 120 comprises a plurality of parts: [0127] a fixed portion 130 equipped with said head 121 and bearing on the accessible face of the assembly to be carried out, [0128] a mobile and deformable portion 140 for creating a bulb under the action of the rod 110.

[0129] To do this, this mobile and deformable portion 140 is preformed with a hollow core 141 that passes all the way through, a portion 142 of which has an inner thread. An end of the rod 110 is preformed with a threaded portion 111 and is screwed into the portion 142 with an inner thread of the mobile and deformable portion 140.

[0130] A thinned annular linking portion defined by a rupture groove 123 connects the detachable portion 122 to the head 121 of the outer body 120. This thinned rupture portion 123 of the outer body 120 breaks from a predefined stress threshold S2.

[0131] The rod 110 is positioned in the hollow core of the outer body 120 and comprises a rod 110 head 112 countersunk and equipped with detachable portion 113, a thinned portion defined by a rupture groove 114 connects said detachable portion 113 to the rod 110 head 112. This thinned portion 114 of the rod breaks starting from another predefined stress threshold S1 lower or greater than that S2 defined for the rupture of the thinned portion 123.

[0132] The detachable portion 113 of the head 112 of the rod 110 has a smaller diameter than and protrudes with respect to the detachable portion 122 of the head 121 of the outer body 120.

[0133] These two detachable portions 122 and 113 have according to the non-limiting embodiment illustrated, a hexagonal outer profile facilitating their association with tools having a suitable recess. Of course, other profiles, mismatched or not, are possible.

[0134] As illustrated in the drawing of FIG. 2a, in order to carry out the proper setting and make sure of the latter, a tool O cooperates with the fastener 100 installed in a through-hole T with a countersunk rim arranged in an assembly A represented according to the non-limiting embodiment illustrated by the stack of two sheets. The fastener 100 is positioned in the hole T with the countersunk head 121 of the outer body 120 bearing on the countersunk rim of the hole T.

[0135] For greater clarity, only the end of the tool O is illustrated. The latter is engaged on the protruding end of the fastener 100 on the accessible side of the assembly A.

[0136] The end of the tool O combines a setting member 200 cooperating with the detachable portion 113 of the head 112 of said rod 110 and a setting-verification member 300 cooperating with the detachable portion 122 of the head 121 of the outer body 120.

[0137] The setting-verification member 300 comprises a body adopting a cylindrical outer shape with a hollow core 310 is also cylindrical and receives via a pivot link a portion of the setting member 200.

[0138] The hollow core 310 opens at the end of the body of the verification member 300 oriented towards the fastener 100. This end is preformed with a recess 311 with which the detachable portion 122 of the head 121 of the outer body 120 cooperates for retaining during the setting and for driving during the setting verification.

[0139] This recess 311 is preformed in the central rear part with a hollow 312 allowing the detachable portion 113 of the rod to cooperate with the distal portion of the setting member 200 which is itself preformed with a recess 210 set back with respect to the recess 311 of the verification member 300.

[0140] According to the preferred but non-limiting embodiment illustrated, said setting member 200 comprises an ejector punch 320 that exerts by means of a spring 321, an axial thrust against the detachable portion 113 during the ejection phase. During the phases of setting and of setting-verification, the punch remains in a retracted position.

[0141] According to a preferred but non-limiting embodiment, the setting method involves carrying out the following operations: [0142] positioning the fastener 100 at the end of the tool O then positioning the fastener 100 in a hole T passing through an assembly A by means of said tool O, [0143] maintaining the outer body 120 in position by the tool O, [0144] creating a bulb for fastening the assembly by rotation of the rod 110, a rotation implemented by the tool O, [0145] breaking the detachable portion 113 of the head 112 of the rod 110, [0146] breaking the detachable portion 122 of the head 121 of the outer body 120 for verification of the proper setting, [0147] evacuation of the detachable parts 113 and 122.

[0148] This setting is described below in association with the succession of FIGS. 2a to 2g.

[0149] According to another embodiment, the fastener 100 is installed in the hole T before the end of the tool O cooperates with it.

[0150] As illustrated in the drawing of FIG. 2a, the setting tool O cooperates with the protruding end of the fastener 100 so that its setting member 200 cooperates with the detachable portion 113 of the rod 110 and the verification member 300 cooperates with the detachable portion 122 of the outer body 120.

[0151] As illustrated in the drawing of FIG. 2b, a movement of rotation F1 is imparted on the setting member 200 which drives the rod 110 in rotation. The verification member 300 remains stationary during this rotation in order to propose a counter-torque. Due to the helical link between the end 111 of the rod 110 and the portion 142 with an inner thread of the mobile portion 140, the rotation of the rod 110 drives the mobile part 140 of the outer body 120 in translation F2 towards the fixed part 130. The interactions of the friction type between said rod 110 and said head 121 of the outer body also engender a resistant torque opposed to the motor torque of installation on said rod 110. Thus, the counter-torque undergone by the detachable portion 122 of said head 121 can vary in a wide range.

[0152] As illustrated in the drawings of FIGS. 2c and 2d, the continuation of the movement of rotation according to the arrow F1 leads the mobile part 140 to be deformed by progressively forming a bulb 143 that comes in contact with the blind side of the assembly A as illustrated in the drawing of FIG. 2e. As illustrated, this bulb forms completely in the air before clamping the parts to be assembled. The torque necessary to deform the bulb is transmitted largely to the body. The counter-torque is thus high from the beginning of the setting which constitutes an additional difficulty.

[0153] At this stage, the bearing of the bulb 143 leads the rotation to exert a clamping creating a torsional stress at the rupture groove 114 which, after a predefined threshold S1 is exceeded, breaks. The detachable portion 113 thus detaches from the head 112 of the rod 110. The rotation according to the arrow F1 of the rod 110 stops. The detachable part 113 remains in the tool O.

[0154] A movement of impact rotation (arrow F3) is then transmitted to the verification member 300 which transmits it to the outer body 120 via the detachable part 122 according to a movement of rotation arrow F3. The thinned part or rupture groove 123 breaks starting when a stress threshold S2 is exceeded. If this rotation has the consequence illustrated namely a rupture of the thinned part 123, the fastener 100 is considered to be properly installed since the tension installed in the assembly is judged to be sufficient and a smooth surface state is obtained.

[0155] If this rotation has the non-illustrated consequence of a rotation of the fastener 100 in the hole T, the fastener 100 is considered to be poorly set since the tension installed in the assembly is not sufficient to lead to the rupture of the groove 123. The poorly set fastener is thus removed.

[0156] To do this, the fastener can be destroyed by piercing. The non-broken part of the outer body can then be used as a guide for centering and/or obtaining a reference for the piercing tool.

[0157] As illustrated in the drawing of FIG. 2f, the detachable parts 113 and 122 are ejected from the tool O by the ejector 320. In order to facilitate this ejection, a different embodiment of a blind fastener 100 is proposed and illustrated by the drawing of FIG. 3. To do this, in this new embodiment, the blind fastener labelled 100 adopts the following differences with regard to the blind fastener 100 described above: [0158] the detachable portion 113 of the head 112 of the rod 110 is preformed in such a way as to form an axial support so that the movement in translation of the ejector imparted on the detached portion 113 causes a contact with the detachable portion 122 of the head 121 of the outer body 120.

[0159] According to the embodiment illustrated, the detachable portion 113 has a dimension greater than that of the hollow core passing through the outer body 120 in such a way as to guarantee said contact.

[0160] As illustrated in the drawings of FIGS. 2g and 2h, the fastener 100 has a clean rupture once set. The aerodynamic fingerprint is small and a cosmetic appearance is substantially smooth. Indeed, the remainder of the broken parts does not exceed 150 microns with respect to the surface of the assembly A in accordance with the goals of the invention.

[0161] It is understood that the tool and the blind fastener, which have just been described and shown above, were described and shown with a view to a disclosure rather than a limitation. Of course, various arrangements, modifications and improvements can be made to the examples above, without going beyond the context of the invention.