IL34883A

IL34883A - Locking device for a fastener

Info

Publication number: IL34883A
Application number: IL34883A
Authority: IL
Original assignee: Motorola Inc
Priority date: 1969-07-15
Filing date: 1970-07-09
Publication date: 1973-07-30
Also published as: US3561075A; DE7026303U; BR7020415D0; ZA704645B; DE2034680A1; IL34883A0

Description

LOCKING DEVICE FOR A FASTENER This invention relates to a locking device for captivating a fastener having a body and a head use to secure sheet material to a base, In the mounting of sheet material such as a printed circuit board to a frame or base, it often is desired to secure the material by means of a threaded fastener in the form of a screw passing through a hole In the material, Xn some environments in which the printed circuit board may be mounted, vibrations or the like cause loosening of the screws to t?he poin ere the printed circuit board no longer is securely mounted or the screws fall out, and get lost, or at disassembly the screw may be lost. Thus, it is desirable to provide a means for captivating the screws once they are in place to prevent this In addition, it often is desirable to mount additional components at a predetermined spacing relative to the circuit board, so that it generally is necessary to provide a separate fastening means mounted on the circuit board in order to support these additional components.

Accordingly it is an object of this invention to provide a new and improved fastener captivating device.

The present invention, therefore, provides a locking device for a fastener having a body and a head used to secure sheet material to a base, wherein the body portion of the fastener passes through a hole in the sheet material, said device including a hollow resilient member having walls defining a shank portion of a dimension substantially conforming to the width of the hole in he shee material and a fastener head receiving portion of a substantially greater dimension than the dimension of the shank portion, with a common opening between the head receiving portion and the shank portion of the member, the walla of the head receiving portion remote from the shank portion extending inwardly toward a central axis of the member and extending downwardly at an acute angle toward the shank portion of the member to form a ledge, the width of the opening defined by the edges of the ledge being lees than the width of the head of the fastener, with the width of the head receivin portion bein at least as great as the width of the head of the fastener, whereupon insertion of the fastener into the head receiving portion causes the walls of the head receiving portion to be cammed outwardly to allow the head of the fastener to pass therethrough, whereupon the head receiving portion tends to resume its original configuration thereby captivating the fastener within the head receiving portion.

Th invention also, provides a combination fastener captivating device and a snap receptacle for a mounting button.

More specifically, the invention further provides a combined locking device and snap receptacle for captivating a fastener having a shank and a relatively wider head and for providing a snap receptacle for a button having a shank and a relatively wider base in which the fastener is used to secure a sheet material to a base, with the fastener passing through a hole in the sheet ma- terial, said device and receptacle including a hollow, cylindrical member having a firat portion of a predeter-mined outside diameter and an Inside diameter sufficient to accommodate the shank of the fastener, and with a fastener head and button base receiving chamber of a greater predetermined diameter formed of resilient a-terial and having a slot extending axially therethrough, the axial length of the first portion being such as to permit insertion of the first portion through the sheet material, the end of the receiving chamber remote the first portion including an inwardly and downwardly ex-tending portion forming a ledge causing the opening in the chamber to be of less diameter than the width of the head of a fastener and less than the width of the base of a button adapted to be inserted Into the chamber, the spacing from the inner edge of the ledge to the bottom of the chamber adjacent the first portion of the member being sufficient to accommodate the head of the fastener and the base portion of the snap button, so that the device captivates a fastener and button once they have been inserted therein.

In the accompanying drawings: Figure 1 is a perspective view of a captivating device formed in accordance with a preferred embodiment of this invention; Figure 2 is a cut-away side view of the device shown in Figure 1, with a fastener located therein Figure 3 is a top view of the device shown in figure Ij Figure la a side view o a snap button to be used in conjunction wi h an embodiment of the device shown In Figur s I, s and 3; and Figure 5 is a partially cu -away side v ew of another embodiment of the device shown in Figures X, 2 and 3 showing the use of the device to captivat a fastener and to hold the snap button shown in Figure 5· Hef e i g now to the drawings e wherein like reference numerals are used throughout the several views to designate the same elements , there Is shown a a nap-in screw captivating device formed of resilient material such as relatively rigid plastic, metal or the like in the form of a member 10. The member 10 includes a cylindrical shank portion defined by the wall 11 and an upper fastener head receiving portion or chamber defined by the wall 12.. . A vertical slot 13 is ormed in the member 10, so that the member may be compressed for insertion into a hole in a sheet to be fastened by the threaded fastener which the member is to captivate.

At the lower edge of the shank portion, the wall 11 flares outwardly. o form a rib 14, the upper surface o which forms a shoulder 15 for engaging the lower surface of the sheet material into which the member 10 is to be inserted. The lower surface 17 of the wall forming the bottom of the chamber defined by the wall 12 rests on the upper surface of the sheet material into which the member is inserted, so that the distance A between the surface 17 and the shoulder 15 Is equal to the thickness of the sheet material. When the member 10 is inserted into the sheet material, the resiliency of the member causes the member to attempt to expand to its original shape. This causes the member to securely engage the edges of the hole in the sheet material, since the hole -is chosen to be of a slightly smaller diameter than the outside diameter of the shank portion of the member defined by the wall 11 when the member is in its unrestrained configuration. If the member 10 is made of metal, it may be preferable to use a metal cup eyeleted to the hole in place of the one-piece snap-in device shown.

A top ledge 18 extending over and into the chamr-ber defined by the side wall 12 is formed by extending the-side wall 12 Inwardly toward the center of the chamber at an angle of approximately 50 from the vertical surface of the side wall 12. This top ledge 18 is provided with additional slots 19 and 20, and the diameter C of the circle formed by the edge of the top ledge is chosen to be less than the width of the screw head with which the captivating member 10 is to be used. The distance B extending from the innermost edge of the ledge 18 to the bottom of the cavity defined by the side wall 12 is chosen to be such that, with the screw head in place and with the addition of a suitable washer if desired, the innermost edge of the ledge 18 extends over the head of the screw as shown in Figure 2, thereby captivating the screw and preventing its loss, while providing sufficient clearance to ■diseng ge the threads of the screw from the material to which the sheet is mounted.

After the captivating member 10 la installed in the sheet material, the screw is pushed past the slotted edge 18, with the downward sloped cammin surface of the ledge 18 being acted upon by the outermost edges of the head o the scre to expand the opening C to permit passage of the screw head therethrough. Once the head has passed through the opening, the resiliency of the material out of which the member 10 is formed causes it to tend to return to its original shape, thereby closing the opening over the screw head, with the edges of the ledge 18 engaging over the pper surface of the screw head to captivate the screw in place. The opening C is of sufficient width to permit insertion of a screwdriver, or the like, for turning the screw in order to secure the screw to the material to which the sheet material is to be mounted .

Referring now to Figure 4 there is shown a side vie of a cylindrleally shaped stud or snap button 21 which is utilized with a snap receptacle of the type provided by the member 10 shown in Figures 1, 2 and 3, and capable of being anchored by the member 10, so that components may be attached to. the button as desired. The shank of the snap button 21 flares outwardly at its lower end and has the lower surface thereof In a concave shape having a configuration generally conforming to the head of a screw with which the button 21 may be used. The flared but portion includes a camming surface 22 and an upper shoulder surface 23, with the ngle of the camming s rface 21 being such as to cooperate with the angle of the ledge 18 on the member 10 to spread the upper portion of the chamber of the captivating device outwardly as the snap button ia inserted into the chamber.

If the member 10 is to be utilized to both captivate a s crew in the manner shown in Figure 2 and further to provide a mounting base for the snap button 21, the chamber defined by the wall 12 may be enlarged in a ver <» tlcal direct ion in order to accommodate the snap button 21 , A member 10 having such an enlarged chamber ia shown in Figure 5 which als o s hows the relative pos itions occupied by a s crew 16 and the snap button 21 when both the screw and the button are inserted into the member 10.

When the components are inserted as show n in Figure 6, the member 10 performs the dual, function of captivating the s crew 16 in it s f ully Inserted pos ition and additionally provid ing an anchoring base for the snap button 21.

In Figure 5 the member 10 further is shown inserted into a circuit board 25, illustrating the manner in which the flange 14 and the s urface 17 cooperate with the printed circuit board 25 to secure the member 10 in position within the hole in t he printed circuit board 25. With the member 10 secured to the printed circuit board 5, the snap button 21 also is secured relative to the board and provides a mounting shoulder 26 formed by re d ucing the diameter of the shank or the body of the snap but ton 21 at its upper end .

The reduced s ank 27 of the snap button 21 is Inserted through a hole In a component, such as an electromagnetic shield , with the shield resting on e shoulder 26. The shield 29 then ma be secured to the sn¾p button gi b means of a bow washer 31 which is locked into place to hold the shield 29 against the shpuld^r 26 t ereby flrmiy anchoring the shield to the s a button 24, , A locking ring or- threaded washer 32 is provided to retain the b©w washer 31 i place relative to the snap button 2X and is mounted on a second reduced portion 33 of the body 21, which provides a mounting shoulder 3 for the locking ring 32, If a shield 29 Is to be secured at a predetermined distance from the surface of a printed circuit board 25, three or more of the assemblies of the type shown in Figure 5 may be utilized in order to provide the necessary mounting points for the shield. The same captivating members 10 which are utilized to captivate the scre 16 used to mount the board also perform the additional function of providing a snaprin base for the snap buttons 21 used to support the shield 29 over the printed circuit board 25.

Claims

1. A looking device for a fastener having a body and a head used to secure sheet material to a base, wherein the body portion of the fastener paeses through a hole in the sheet material, said device includingt a hollow resilient member having walls defining a shank portion of a dimension substantially conforming to the width of the hole in the sheet material and a fastener head receiving portion of a substantially greater dimension than passage the dimension of the shank portion* with a common-opening--between the head receiving portion and the shank portion of the member, the walls of the head receiving portion remote from the shank portion extending Inwardly toward a central axis of the member and extending downwardly at an acute angle toward the shank portion of the member to form a ledge, the width of the opening defined by the edges of the ledge being less than the width of the head of the fastener, with the width of the head receiving portion being at least as great as the width of the head of the fastener, whereupon insertion of the fastener into the head receiving portion causes the walls of the head receiving portion to be cammed outwardly to allow the head of the fastener to pass therethrough, whereupon the head receiving portion tends to resume its original configuration thereby captivating the fastener within the head receiving portion.

2. A device according to claim 1, wherein the ledge and the walls defining the fastener head receiving portion include at least one slot therein to facilitate the expansion of the ledge under the camming action caused by the insertion of a fastener therein.

3. A device according to claim 1 or 2, wherein the hollow member has at least one slot extending substantially parallel to the axis thereof* the slot formed therethrough to enable deformation of the shank portion to permit insertion of the member into the hole in the sheet material and to more readily permit the outward camming of the ledge of the head receiving portion upon insertion of the fastening device therein.

4. A device according to claim 3, wherein the hollow member is of a substantially cylindrical configuration and the outside diameter of the shank portion is slightly greater than the inside diameter of the hole in the sheet material, so that upon insertion of the member into the hole the tendency of the hollow member to retain its original shape causes the outer sides of the shank portion to firmly engage the edges of the hole.

5. A device according to claim 3 or 4, wherein the shank portion is of sufficient length to extend through the hole in the sheet material and carries at the end remote from the head receiving portion a rib portion flaring outwardly from the axis of the member so that when the member is inserted into the hole* the rib portion extends outwardly over the sheet portion at the edges of the hole to impede removal of the member from the hole.

6. A combined locking device and snap receptacle wider head and for providing a snap receptacle for a button having a shank and a relatively wider base in which the fastener is used to secure a sheet material to a base* with the fastener passing through a hole in the sheet material, said device and receptacle including: a hollow, cylindrical member having a first portion of a predetermined outside diameter and an inside diameter sufficient to accommodate the shank of the fastener* and with a fastener head and button base receiving chamber of a greater predetermined diameter formed of resilient material and having a slot extending axially therethrough, the axial length of the first portion being such as to permit insertion of the first portion through the sheet material, the end of the receiving chamber remote the first portion including an inwardly and downwardly extending portion forming a ledge causing the opening in the chamber to be of less diameter than the width of the head of a fastener and less than the width of the base of a button adapted to be inserted into the chamber, the spacing from the inner edge of the ledge to the bottom of the chamber adjacent the first portion of the member being sufficient to accommodate the head of the fastener and the base portion of the snap button, so that the device captivates a fastener and button once they have been inserted therein.

7. A combined device and receptacle according to claim 6, wherein the outside diameter of the first portion in an undistorted configuration is greater than the inside being of sufficient width to permit compression of the f irst portion by an amount to permit insertion of the first portion into the hole , so that upon release, the member tends to revert to its undistorted configuration, firmly engaging the edge of the hole .

8. A combined device and receptacle according to claim 6 or 7, Wherein the base of the button is adapted to be inserted into the chenber after the fastener is inserted therein.

9. A combined device and receptacle according to claim 6 , 7 , or 8« wherein the chamber includes at least one additional slot therein to facilitate expansion of the ledge under the camming action of the fastener head and button base upon insertion thereof into the chamber .

10. A locking device for a fastener constructed substantially as herein described with reference to the accompanying drawings .

11. A combined locking device and snap receptacle constructed substantially as herein described with reference to the accompanying drawings . S. HOROWITZ & CO. AGENTS FOR APPLICANTS