US 3541661 A
Description (OCR text may contain errors)
NOV. 24, 1970 J, A, NAVA 3,541,661"
CONTACT EXTRACTION TOOL Filed March e, 1968 v 2 sheets-shewv 1 Nov. 24, 1970 J. A. NAVA CONTACT` EXTR'ACTION TOOL 2 Sheets-Sheet 2 Filed March 6, 1968 1N MN QM. R, N N KN United States Patent O 3,541,661 CONTACT EXTRACTION TOOL Joseph A. Nava, Villa Park, Ill., assignor to The Pyle National Company, Chicago, Ill., a corporation of New Jersey Filed Mar. 6, 1968, Ser. No. 711,062 Int. Cl. BZSb 27/00; H05k 13/00 U.S. Cl. 29-203 6 Claims ABSTRACT OF THE DISCLOSURE audible signal when the axial force imposed on the body exceeds a predetermined level.
BACKGROUND `OF THE INVENTION This invention relates generally to the field of electrical connectors and more particularly to an extraction tool for removing from a collet mounted in the bore of an electrical connector a contact secured within the bore by the collet.
The pin-type contact members of electrical connectors, particularly of the multiple-contact type, are generally retained within bores of the connectors by mechanical latches commonly referred to as collets. Each of the collets is held in its respective bore of the connector by means of cooperating ridges and grooves formed on the outer surface of the collet and on the bore wall. The contact generally has a circumferentially continuous radial shoulder formed thereon and the collet comprises a plurality of spreadable fingers which have corresponding radial shoulders formed thereon for abutting engagement with the shoulders of the contact. When the Contact is inserted into the collet, the collet fingers spread radially to receive the contact and then contract due to the inherent resilient properties of the fingers when the shoulders of the contact align axially with the shoulders of the collet fingers to hold the contact against removal.
To remove the Contact from the collet, and thus from the bore, the tubular tip of an extraction tool is inserted telescopically over the end of the contact to spread the collet fingers and to move the radial shoulders of the fingers away from the contact shoulder. A plunger is then pushed through the tubular tip and against the end of the contact to force the contact axially out of the collet.
In spreading the collet fingers and in pushing the contact, the extraction tool must exert both an axial and radial force on the collet and an axial force on the contact. Moreover, unless the tip of the extraction tool is Very accurately axially aligned with the contact, the tip of the tool will also exert a bending moment on the contact. The body of the electrical connector is usually made of rigid insulation material. The ridge formed on the bore wall of the connector will withstand only limited axial forces without shearing off. The contacts are made of metal and are generally quite slender. The contacts will Patented Nov. 24, 1970 ICC withstand only very limited bending moments without acquiring a permanent deformation.
The extraction tools that were heretofore known in the art are made of substantially rigid material capable of withstanding axial forces and bending moments greatly in excess of the axial forces and bending moments to which the connector body-collet-contact assembly is capable of withstanding without permanent damage. Damage to the connector body or to the collet or to the contact, or to the entire assembly often occurs in the use of such rigid prior art devices. In situations in which the use of less rigid plastic extraction tools has been attempted, the durability of the tools in terms of removal capability has been completely unacceptable.
SUMMARY OF THE INVENTION With these deiiciencies of the prior art in mind, the present invention may be summarized as comprising an extraction tool which comprises a tubular tip which is constructed and arranged to collapse when it is subjected to an axial force or to a bending moment which approaches the maximum axial force or bending moment to which the connector body-collet-contact assembly can be subjected without being subject to damage. To this end, a plurality of ribs are formed in the tubular tip to provide a column strength in the tip which is less than the maximum permissible axial force to which the connector bodycollet-contact assembly can be subjected. Furthermore, a series of windows or spaces are provided between the ribs to reduce the maximum bending moment which the tip is capable of withstanding without collapse to a level below the maximum permissible bending moment of the contact.
The body of the extraction tool is also provided with windows to reduce the maximum bending moment, but the body is constructed and arranged with respect to the tip such that the collapse will occur in the tubular tip before it will occur in the body portion of the tool.
In addition, an audible signal mechanism such as a clicker is mounted under a movable cap at the end of the tool and is adapted to provide a signal when the axial force acting on the end of the tool approaches the collapse force of the tubular tip. Thus the tool operator is warned in advance that the force being applied to remove the contact may well exceed the maximum allowable force of the connector collet-contact assembly.
In view of the foregoing, it is an object of the present invention to provide an extraction tool for removing contacts from the collets of electrical connectors which will prevent serious damage to the connector body-colletcontact assembly.
Another object is to provide an extraction tool which will collapse either in an axial direction or by merely bending over when the axial force or bending moment to which it is subject exceeds a critical level which is related to the maximum allowable axial force and bending moment of the connector body-collet-contact assembly.
Another object is to provide an extraction tool in which the tubular tip will collapse when subjected to an axial force or bending moment considerably less than the axial force or bending moment required to collapse the body portion of the tool.
Another object is to provide an extraction tool having a signal mechanism to warn the tool operator when the force being applied by the tool exceeds a safe limit for the connector body-collet-contact assembly.
Many other features, advantages and additional objects of the present invention will become manifest to those versed in the art upon making reference to the detailed description which follows and the accompanying sheets of drawings, in which a preferred structural embodiment incorporating the principles of the present invention is shown by way of illustrative example only.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a connector bodycollet-contact assembly and the tip portion of a contact extraction tool.
FIG. 2 is an elevational view of a contact extraction tool cnstructed in accordance with the principles of the present invention.
FIG. 3 is an enlarged cross-sectional view of the extraction tool shown in FIG. 2.
FIG. 4 is a sectional view taken along the lines IV--IV of FIG. 3.
FIG. 5 is a sectional view taken along line V-V of FIG. 3 with a knob portion of the tool removed.
DESCRIPTION OF THE PREFERRED EMBODIMENT By way of further explanatory and background information, electrical connector manufacturers have experienced continuing problems with respect to extraction tools lwhich are utilized to expand or spread the iingers of the collets to remove the contacts. These problems may be generally characterized as (a) damage to the connector insulator body, (b) damage to the contact, (c) breakage or chipping of the mouth of the bore, and (d) durability of the extraction tool.
The foregoing problems may be understood more readily by making reference to FIG. 1 in which is disclosed an electrical connector comprising a connector body indicated generally at reference numeral having a bore 11 formed therein which houses a collet 12. A contact 13 is shown mounted in the bore 11 and held in place against removal by the collet 12. The connector body-collet-contact assembly is indicated generally by reference numeral 10a.
The collet 12 is split axially for radial contractability, and is held in place in the bore 11 by means of a ridge 14 formed on the bore wall and a cooperating groove 16 formed on the outer surface of the collet 12. When the collet 12 is initially inserted in the bore 11, it is contracted radially until the groove 16 aligns with the ridge 14 and is then released to expand into snap in assembly with the ridge 14.
The collet 12 further comprises a plurality of axially extending lingers as shown, for example, at reference numerals 12a and 12b. 'I'he lingers 12a and 12b are spreadable radially and have formed thereon radial shoulders as at 17 which cooperate with a corresponding circumferentially continuous radial shoulder 18 formed on the contact 13 for holding the contact 13 against removal from the collet after the contact has been inserted axially thereinto.
A contact extraction tool is indicated generally at reference numeral 19 and comprises a tubular tip portion 20. The outer end of the tip 20 is tapered as at 21 and when the contact 13 is to be removed from the collet 12, the tip 20 is urged axially into abutting engagement with an inclined surface 22 of the collet fingers 12a and 12b to spread the ngers radially so that the shoulders 17 of the fingers are moved out of abutting engagement with the shoulder 18 of the contact 13. Then a plunger 23 is moved axially into abutting engagement with an end portion 24 of the contact 13 to push the contact axially out of the collet 12. Generally, only a slight axial force should be required to position the tool 20 against the collet lingers 12a! and 12b to expand the fingers. This force is applied in an area indicated in FIG. 1 as Area A. Typically, this force should not generally exceed about 3 to 5 pounds. The collet 12, however, in respect of the connector body 10, which is usually constructed of rigid insulation material, has a nite holding or axial retention force capability in the order of about 30 to 40 pounds in the area indicated as Area B. Thus, if an axial force which exceeds the collet retention force is imposed on the collet by the contact extraction tool 19, due to an insuicient spreading of the collet fingers 12a and 12b, the collet 12 will break off the connector body ridge 14, thus destructively dislodging the collet from the insulator body and rendering the entire connector useless.
If the fingers 12a and 12b have been properly spread, an axial force of only about 1 to 3 pounds should be required to remove the contact from the collet. However, if the lingers 12a and 12b have not been completely opened, the contact may be retained within the collet by a force capability of between 2() to 30 pounds. This force capability is exerted between shoulders 17 and 18 as indicated at Area E. Now if a force in excess of this 20 to 30 pound capability is applied to the contact 13 by the plunger 23 as, for example, at Area D, due to failure of the lingers 12a and 12b to open completely, the contact will be destructively dislodged from the collet, rendering at least this one Contact position useless.
Since the tool tip 20 is generally made of metal, which is stronger than the rigid or plastic or rubber insulation used in the construction of the connector body 10, the tip 20 will break or chip the rigid insulation at the mouth of the bore 11 as indicated at Area C unless the tip is very carefully guided into the bore 11.
The problem of contact removal is also complicated by the fact that unless the tubular tip 20 is very accurately axially aligned with the end portion 24 of the contact 13, a bending moment may be applied to the end portion 24 which is beyond the maximum bending moment capability of the contact, which in a typical construction may be in the order of about 5 inch-pounds. Thus the contact may be bent and permanently deformed and rendered completely useless.
The durability of the extraction tools has also caused serious problems. Users of electrical connectors who have need for continuing service require extraction tools with satisfactory durability. Extraction tools which are constructed with a metal tip can often extract about 5,000 contacts, but steel tips are so strong 4that often the connector body 10, or the collet 12, or the contact 13 is permanently damaged during extraction. Some extraction tools have been constructed with plastic tips, but such tips have a contact removal capability of only about 200.
The extraction tool of the present invention combines the advantages of increased durability of a metal tip with the advantages resulting from the reduced axial force and bending moment capabilities of a plastic tip. Thus, if the axial force or bending moment to which the tool tip, and thus the connector-collet-contact assembly, is subject exceeds the permissible axial force or bending moment of the assembly, the tip will collapse. Nevertheless, the tip is made of metal, and thus is capable of maximum durability.
Referring now to FIGS. 2-5, wherein like reference numerals are used to denote like parts shown in FIG. l, the contact extraction tool 19, which is constructed in accordance with the principles of the present invention, comprises a tubular body 26 from one end of which the tip 20 projects. The tip 20` may be further characterized as comprising a tip end 27 and an increased diameter portion 28. The tip 20 is tubularly shaped and made of metal and comprises a circumferentially continuous shoulder 29 which is seated on a complementarily shaped notch 30 formed at one end 31 of the tool body 26. The tip 20 is maintained on the body 26 by means of a tubular sleeve 32 which surrounds a portion of the body 26 and which comprises a radially inturned flange 33 wrapped around the shoulder 29 of the tip 20. The sleeve 32 is threaded to the body 26 as at 34 so that it can be removed of the end of the body 26 to remove the tip 20.
The plunger 23 comprises a long, slender column having a radial shoulder 36 situated adjacent a back end 37 of the plunger opposite a nose end 38. The back end 37 projects through a bore 39 centrally formed in a knob 40 mounted on the tool body 26 for axial movement. The knob 40 comprises a radial spider 41 having three legs which extend through an equal number of slots 42 formed axially in the body 26 so that the knob 40 is restrained against rotatable movement but is arranged for limited axial movement on the body 26. The spider 41 engages the shoulder 36 of the plunger 23 to move the nose 38 of the plunger out the forward end 27 of the tip 20 when finger pressure is applied to the knob 40 in the direction of the tip 20v,
A helical spring 43 disposed in the body 26 around the plunger 23 is bottomed at one end 44 and the tool tip 20, and is bottomed at an opposite end 46 against the spider 41 of the knob 40. The plunger 23 is thus normally biased into the retracted position shown in FIG. 3.
In accordance with the principles of the present invention, the increased diameter portion 28 of the tool tip 20 has a plurality of ribs 47 formed therein as seen, for
example, in FIG. 4. The ribs 47 extend in an axial direction and provide an axial force capability of the thin- Walled tip 20 of about 15 pounds. The tip 20 will collapse if it is subjected to an axial force in excess of about pounds, thus precluding the buildup of an axial force sufficient to damage the connector body-collet-contact assembly.
Another safety feature, however, involves the shoulder 29 of the tip portion 20 which is constructed and arranged so that it will shear off if the axial force imposed thereon by the body 26 at the notch 30l exceeds about 20 pounds. It will be appreciated, of course, that this -pound shear strength is still substantially less than the maximum permissible axial force capability of the connector body-collet-contact assembly 10a.
To reduce the bending moment capability of the tip 20, a plurality of Windows or openings as indicated at 48 are formed between the ribs 47. The maximum bending moment of the tip 20 is thus reduced in the exemplary embodiment to about 4 inch-pounds, or about 20 percent less than the maximum bending moment capability of the contact 13. The windows 48 are configured as axially extending slots,
Also in accordance with the principles of the present invention, the nose 38 of the plunger 23 is made of metal for increased durability, but the remaining portion of the plunger 23 is made of plastic or the like flexible material capable of transmitting a sufficient axial force to remove the contact from the collet while having a low bending moment capability such that it cannot substantially reinforce the tip 20 or the tool body 26 and prevent these portions from collapsing under excessive stress.
The shoulder 36 of the plunger 23 is also adapted to perform a shearing function. To this end, the shoulder 36 will shear if the axial force applied thereto by the knob 40 exceeds about l0 pounds, thus ensuring that a destructive force greater than l0 pounds cannot be applied to the end of the contact 13. A handle portion 49 of the body 26 is provided with a plurality of circumferentially spaced, axially elongated windows or openings as at 50l similar to the windows 48 formed in the tip 20 for performing the same function, that, is to collapse in the event eX- cessive axial force is applied thereto.
Another safety feature of the extraction tool 19 resides in the provision of a signal mechanism for warning the tool operator against the use of excessive and damaging removal forces. To this end, a cap 51 is mounted on an outer end 52 of the body 26 for limited axial movement. The cap 51 is hollow, and mounted therein against the end 52 of the body 26 is a signal mechanism such as a Clicker 53 which is adapted to provide an audible signal when an axial force above a predetermined level is applied to the cap 51. In the embodiment illustrated, the elicker 53 will produce a clicking sound when a force of about 5 to 7 pounds is applied to the cap 51. Thus, the Clicker 53 is adapted to announce attainment of the maximum force that should be applied to the connector body-collet-contact assembly and operates before the force is sufiicient to collapse the tip 20 or body 26 of the extraction tool 19.
It should be understood that the axial force and bending moment values discussed herein are merely typical for exemplary electrical connectors of typical connector body-collet-contact design, and will vary as the electrical connector design varies. In accordance with the principles of this invention, however, the various safety features are constructed and arranged such that axial forces and bending moments which are applied to the connector bodycollet-contact assembly cannot exceed maximum permissible values.
Although minor modifications might be suggested by those versed in the art, it should be understood that I wish to embody within the scope of the patent warranted herein all such modifications as reasonably come within the scope of my contribution to the art.
l claim as my invention:
1. An extraction tool for removing a contact from a collet having radially-spreadable fingers which is mounted in a bore of an electrical connector and which is held in place against axial movement by means of complemental radial abutment surfaces formed on the collet and on the wall of the bore, the contact and collet including complemental abutting radial shoulders for preventing removal of the contact unless the collet lingers are spread, said tool comprising:
a body having a hollow tubular tip extending therefrom for telescoping axially over the end of the contact to spread the collet fingers, and a plunger slidable in the body and projectable from the end of the tip for pushing the contact axially from the spread collet,
shear means interconnecting said body and said tip and constructed and arranged so as to shear the tip from the body when the tip is subjected to an axial force approaching the maximum axial force to which the abutment surface on the connector bore wall can be subjected without breakage.
2. The extraction tool as dened in claim 1 and including an axially shiftable member mounted on said body for moving said plunger axially against the contact, and shear means interconnecting said plunger and said member and constructed and arranged so as to shear the plunger from the member when the member exerts an axial force on the plunger which approaches the maximum axial force to which the abutment surface on the connector bore wall can be subjected Without breakage.
3. The extraction tool as defined in claim 1 wherein said body is tubularly shaped and including means forming windows in said body for reducing the bending moment which said body can withstand without collapse.
4. The extraction tool as defined in claim 1 and including signal means mounted on said body for providing a signal when a force acting thereon in the axial direction of said tip to urge the tip into the collect exceeds a predetermined level.
5. An extraction tool for removing a contact from a collet having radially-spreadable fingers which is mounted in a bore of an electrical connector and which is held in place against axial movement by means of complemental radial abutment surfaces formed on the collet and on the wall of the bore, the contact and collet including complemental abutting radial shoulders for preventing removal of the contact unless the collet lingers are spread, said tool comprising a body having a hollow circumferentially 8 Y continuous cylindrical wall forming a tubular tip for tele- 6. The extraction tool as dened in claim 5 wherein the scoping axially over the end of the contact to spread the nose of the plunger is made of metal and the portion of collet fingers, the plunger immediately adjacent the nose is made of said tip wall having means forming a plurality of radiexible plastic.
ally angularly spaced axially extending ribs on the 5 References Cited inner surface thereof for increasing the olumn UNITED STATES PATENTS strength of the ti in an axial direction and a urality 3,451,117 6/1969 Cameron 29-203 a plunger slidable in said body and projectible from the end of the tip for pushing the contact axially from the spread collet, the radially innermost surfaces of said THOMAS H' EAGER Primary Exammer ribs being spaced in a radial direction to provide a U.S. Cl. X.R. slidable bearing surface for said plunger. 15 29-206