MXPA99005921A - Terminal system with deform screw - Google Patents

Abstract

The present invention relates to a terminal assembly, which comprises: a terminal base, having a bore with an internal thread, a screw, having a pin with first and second opposite ends and with an external thread, and has a head on the first end of the pin, and a deformation in a portion of the external thread, adjacent to the second end of the pin, so this deformation limits the removal of the screw from the bar

Description

TERMINAL SYSTEM WITH DEFORMED SCREW Field of the Invention The present invention relates to a terminal assembly having an externally threaded screw, engaged within an internally threaded bore of a terminal, with this threaded screw being deformed adjacent a remote end of the screw head. This deformation acts as a stop to limit the removal of the screw from the terminal bore. Additionally, the present invention relates to a method for forming this terminal assembly.

BACKGROUND OF THE INVENTION Wiring for industrial, residential, commercial and other applications, to provide access to and control the provision of electric power, includes such wiring devices as plugs, receptacles and switches. The various wiring devices are connected by insulated copper wires. The wires are connected to the wiring devices by screw terminals mounted on the wiring devices. Each screw terminal includes a terminal base having an internally threaded bore and a screw, which has a pin with an external thread and a head at one end of the pin. The screw pin is screwed into the borehole, with a portion of the threaded screw pin extending beyond the end of the bore, remote from the screw head. The ends of the copper wire are secured to the terminal by this placed between the terminal base and the underside of the screw head, and then secured in place by tightening the screw head against the conductor to trap this conductor between the base terminal and screw head. To improve this connection, a support plate is often provided between the screw head and the terminal base. This support plate has an opening, through which the screw shank extends, and has dependent tabs which engage slidably within the openings in the terminal base. When the supporting plates are used, the conductors are placed between the support plates and the terminal bases. With the rotation of the support plates being prevented by the coupling of the tabs of the support plate and the openings of the terminal base, the conductors are compressed without the application of twisting resulting from the screwing of the screw in the base hole. terminal.

When the wiring devices are sold or supplied for installation, the screws are removed or unscrewed to a predetermined degree in the basic terminal bores, to provide adequate space between the screw head and the terminal base or between the support plate and the terminal base, to easily receive the driver without having to unscrew the screws. The installer then only needs to tighten the screws, after placing the conductor, in the proper location, to secure the conductor in place to the wiring device. However, conventional terminal assemblies for wiring devices do not have the resources to set the amount of output or unscrewing of the screws. Without a means to fix this amount, the screws can be screwed too much in or out of the borehole of the terminal base. If the screws are screwed too far into the terminal base hole, inadequate space is provided for the conduit, which requires the installer to again remove the screw from the terminal base. This action requires an additional effort by the installer and increases the possibility that the screw becomes removed from the wiring device and becomes lost. Additionally, if the screw is not properly screwed into the terminal base, the screw may become disconnected from the wiring device and be lost.

SUMMARY OF THE INVENTION An object of the present invention is to provide a terminal assembly for a wiring device that makes it possible for the screw to be pulled out by a predetermined amount, according to a relatively narrow tolerance. Another object of the present invention is to provide a screw terminal that allows the screw to be removed from the terminal base to its maximum capacity, without becoming uncoupled, and that is cheap and of robust construction. A further object of the present invention is to provide a method for obtaining a terminal assembly, which is easy to manufacture and provides a terminal assembly, which is cheap and robust in construction. The above objects are obtained by a terminal assembly comprising a terminal base and a screw. The terminal base has a hole with an internal thread. The screw has a pin with first and second opposite ends and with an external thread, and has a head at the first end of the pin. A deformation is provided in a portion of the external thread, adjacent the second end of the pin. By forming the terminal assembly in this manner, the deformation acts as a stop to limit the degree of removal of the screw from the hole in the terminal base. This allows adjusting the output of the screw to a certain predetermined amount, with a relatively high tolerance. Additionally, the screw can exit to its maximum extension without becoming uncoupled from the terminal base, since the deformation prevents it from unscrewing beyond the deformation. In a particularly advantageous embodiment of the invention, the deformation is obtained by a limitation at the second end of the pin. The limitation forms the deformation and can be easily formed after the screw is placed inside the terminal basic bore. The above objects are also obtained basically by a method for forming a terminal assembly, comprising the steps of screwing an eternal thread of a pin of a screw into a bore threaded internally into a terminal base. The spike has a first and second opposite ends, with a head at its first end. A portion of the external thread is deformed adjacent the second end of the spigot, to limit the amount of the screw to be removed from the hole, after the screw has been screwed into the hole. Other objects, advantages and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the accompanying drawings, disclose the preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS With reference to the drawings, which form a part of this description: Figure 1 is a top plan view of a terminal assembly, according to the first embodiment of the present invention; Figure 2 is a side elevation view of the terminal assembly of Figure 1; Figure 3 is a bottom plan view of the terminal assembly of Figure 1; Figure 4 is a side elevation view, enlarged, partially in section, of the terminal assembly of Figure 1; and Figure 5 is a side elevational view of a terminal assembly, according to a second embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring initially to the first embodiment of the present invention, illustrated in Figures 1 to 4, the terminal assembly 10 comprises a terminal base 12, a screw 14 and a support plate 16. The screw 14 is it engages by thread with the terminal base 12. The support plate 16 is mounted on the screw and can be forced by the screw in the direction of the terminal base, to compress a conductor between them. A deformation 18 in a portion of the screw thread, adjacent to its remote end from the screw head, limits the removal of the screw from the terminal base. This terminal base 12 is conventional and comprises a base plate 20, substantially planar, which is generally rectangular in configuration. The terminal base is formed of an electrically conductive metal. Dependent flanges, 22 and 24, extend from the opposite side edges of the base plate 20. The flange 22 extends at an obtuse angle relative to the base plate and has a cut-out 26. The flange 24 has cut-outs 28 and 30 Each of the flanges has a projection, 32 or 34, which extends parallel and in the same direction from the respective flange. The flanges, 22 and 24, secure the terminal base to a wiring device and provide the electrical connection to the electrically conductive inner portions of the wiring device. The central portion of the base plate 20 has a cylindrical dependent portion 36, which defines a bore 38. This bore 38 has an internal thread 39. Adjacent to the opposite sides of the base plate 20, the elongated openings 40 and 30 are provided. 42. The screw 14 comprises a spigot 44 with a head 46 at one end of the spike. The head is of conventional design with a slit 48, which receives a screwdriver. This pin 44 has an external thread 50, which extends substantially over its entire length from its head 46 adjacent the end at its opposite end 52. The thread 50 coincides with the internal thread 39 in the hole 36. The axial length of the The external thread 50 is substantially larger than the axial length of the internal thread 39 in the hole 38, to allow the head to be placed at various desired distances from the base plate 20, while the two threads engage. The end 52 of the spigot 44 is circular. A stake or limitation 54 is formed at the shank end 52, extends along the cord of that circular end, and is laterally spaced or offset from the longitudinal axis of the screw. This stake creates a deformed portion or deformation 56 in the external thread, which has a reduced width between the adjacent crests of the external thread, relative to the other portions of the external thread. This deformed portion or deformation in the external thread of the screw forms a stop that does not threadably coincide with the internal thread 39 in the bore 38. In this way, the deformed portion limits the removal of the screw from the borehole. The support plate 16, like the terminal base 12, is of conventional construction and thus, is only generally described. The support plate 16 comprises a plate member 58 of generally rectangular configuration. The tabs 60 and 62 depend on the opposite side edges of the plate member 58, and they coincide with and are received within the basic terminal openings 40 and 42. The coupling of the basic terminal openings with the tabs, restricts the rotation of the support plate. An edge of the support plate includes flared potions 64, which facilitate the introduction of the electrical conductors between the base plate 20 and the plate member 58. Additionally, the plate member 58 has a central opening 66. This opening 66 is circular and has a diameter somewhat larger than the crest diameter of the external thread 50 in the stem of the screw 44 to allow the screw to easily pass through and rotate relative to it.

The terminal assembly is formed by initially joining the conventional terminal base 12 and the support plate 14 with the tabs 60 and 62 received in the openings 40 and 42. A screw, without the stake 56, is then received in the hole 38 to a point of its maximum output dimension. Such exit dimension corresponds to a spacing between the head 46 and the base plate 20, which allows the tabs 60 and 62 to be received, at least partially, within the openings 40 and 42, to restrict the rotation of the support plate in relation to the terminal base. In this position, the stake 56 is then formed by piercing at the end 52 of the spigot 44. The formation of the stake 54 creates the deformation or deformed portion 56 on the external thread 50, to limit the amount that the screw can exit from. terminal base hole. Figure 5 illustrates a terminal assembly 110, according to a second embodiment of the present invention. The terminal assembly 110 comprises a terminal base 112, a screw 114 and a support plate 116. The screw 114 and the support plate 116 are identical in configuration to the screw 14 and the support plate 16 of the first embodiment, respectively, and thus, they do not need to be described in additional form.

The terminal base 112 is of conventional configuration, suitable for use in an electrical receptacle. Since the shape of this terminal assembly is conventional, it will not be described further here. Figure 5 illustrates the screw in the fully inserted position within the terminal basic bore. In contrast, Figure 2 illustrates the screw at its maximum exit position. While various embodiments have been selected to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the invention, as defined in the appended claims.

Claims (18)

1. CLAIMS 1. A terminal assembly, which comprises: a terminal base, having a hole with an internal thread; a screw, having a pin with first and second opposite ends and with an external thread, and having a head on the first end of the pin; and a deformation in a portion of the external thread, adjacent the second end of the spigot; therefore, this deformation limits the removal of the screw from the hole.
2. 2. A terminal assembly, according to claim 1, wherein the deformation comprises a stake or boundary at the second end of the peg.
3. 3. A terminal assembly, according to claim 2, wherein the second end of the spike is circular; and the spike extends along a rope of the second end.
4. 4. A terminal assembly, according to claim 2, wherein the pin is offset from a longitudinal axis thereof.
5. 5. A terminal assembly, according to claim 1, wherein the portion of the external thread, which forms the deformation, has a reduced width between its ridges, relative to other portions of the external thread.
6. 6. A terminal assembly, according to claim 1, in which a support plate has a central opening, which receives the pin and is placed between the head and the terminal.
7. 7. A terminal assembly, according to claim 6, wherein the support plate comprises a dependent tab; and the terminal base comprises an opening, which slidably receives this tongue.
8. 8. A terminal assembly, according to claim 6, wherein the support plate comprises a first and second tabs depending on their opposite lateral edges; And the terminal base comprises first and second openings, which slidably receive the first and second tabs.
9. 9. A terminal assembly, according to claim 1, wherein the terminal base comprises a contact, extending therefrom.
10. 10. A terminal assembly, according to claim 1, wherein the external thread has an axial length substantially greater than the axial length of the internal thread.
11. 11. A terminal assembly, comprising: a terminal, having a base plate, including a bore with an internal thread of a first axial length; a screw, having a pin, with a first and second ends and with an external thread of a second axial length, which coincide in their threads with the internal thread, and which has a head at the first end of the pin, this second The end of the pin is circular, the second axial length is substantially greater than the first axial length; and a stake or boundary, formed in and extending along a rope of the second end of the peg, this peg creates a deformed portion of the eternal thread, which has a reduced width between its ridges, relative to other portions of the external thread, the deformed portion of the external thread forms a stop that does not coincide in a threaded manner with the internal thread.
12. 12. A terminal assembly, according to claim 11, in which a support piece, having a central opening, receives the pin and is placed between the head and the terminal.
13. 13. A terminal assembly, according to claim 12, in which the support plate comprises a dependent tab; and the terminal base comprises an opening, which slidably receives the tongue.
14. 14. A terminal assembly, according to claim 12, wherein the support plate comprises a first and second tabs depending on their opposite lateral edges; and the terminal base comprises first and second openings, which receive, in slidable form, the first and second tabs, respectively.
15. 15. A terminal assembly, according to claim 11, wherein the terminal comprises a contact, extending from the base plate.
16. 16. A method for forming a terminal assembly, comprising the steps of: screwing an eternal thread of a pin of a screw into a hole in a terminal, with an internal thread, the pin has a first and second opposite ends, with a head at the first end; and deforming a portion of the external thread, adjacent the second end of the pin, to limit the amount that the screw can exit the hole.
17. 17. A method, according to claim 16, wherein the second end is staked along a line extending through the second end and offset from the longitudinal axis of the spike.
18. 18. One method, according to the claim 16, in which the pin is placed inside a central opening of the support plate, before being screwed into the hole.