US3234776A - Crimping device - Google Patents

Description

H. c. STOLTZ CRIMPING DEVICE Feb. 15,1966

- 3 Sheets-Sheet 1 Filed Sept. 4, 1963 Feb. 15, 1966 'H. c.s1'o|.1'z

I CRIMPING DEVICE 3 Sheets-Sheet 2 Filed Sept. 4, 1963 Feb. 15, 1966 H. c. STOLTZ 3,234,776

GRIMPING DEVICE Filed Sept. 4, 1963 3 Sheets-Sheet 5 United States Patent 3,234,776 CRIMPING DEVICE Herbert C. Stoltz, Hershey, Pa, assignor to AMP Incorporated, Harrisburg, Pa. Filed Sept. 4, 1963, Ser. No. 306,522 8 Claims. (Cl. 72-402) abandoned, for Crimping Device.

This invention relates to crimping devices for crimping the tubular ferrule portions of electrical contact terminals by radial indentation. The invention is herein disclosed in an embodiment comprising a hand tool, however, it will be apparent that the principles of the invention are applicable to relatively larger bench mounted crimping presses.

An object of the invention is to provide an improved crimping device for crimping electrical contact terminals by radial indentation. A further object is to provide a crimping tool having improved dies for indenting the terminal. A further object is to provide a crimping tool having dies which move radially towards the contact ferrule and incorporating improved means for returning the crimping dies to their initial positions. A further object is to provide a crimping tool which can be manufactured without recourse to expensive machining operations. Further objects of the invention include the achievement of an improved crimp and an improved method of crimping electrical connectors.

These and other objects of the invention are achieved in a preferred embodiment comprising a cylindrical collet having an axial bore therein and a counterbore at one end. A cylindrical insert of a toughly resilient polymeric material is contained in the counterbore, this insert having an axial opening extending therethrough so that the uncrimped connector can be positioned coaxially within the insert and in the bore of the collet. The collet has a plurality of circumferentially spaced-apart slots opening into the counterbore and discs are disposed in the slots which function as indentors for the connector. These discs have a diameter which is greater than the wall thickness of the collet at the counterbore so that a segmental portion of each disc projects beyond the external surface of the collet and another segmental portion extends into the counterbore and the insert. A cylindrical cam is telescopically movable over the collet and has an internal conical camming surface for engagement with the externally projecting portions of the discs so that as the cam moves axially relative to the collet, the discs are moved relatively radially inwardly of the collet and the insert.

. In this manner, the inwardly projecting segmental portions of the discs indent the contact terminal to crimp it onto the end of a wire. During such radial inward movement of the discs, the resilient insert is elastically deformed so that upon movement of the cam out of engagement with the discs, this insert returns the discs to their normal positions thereby permitting removal of the now crimped contact terminal.

The invention provides several advantages among which are the use of disc-type indenting dies which can be manufactured to extremely close dimensional tolerances thereby to permit formation of an accurately proportioned crimp. Additionally, the use of the toughly resilient insert in the collet provides a simple and eifective means for returning the discs to their normal positions. An additional advantage is that virtually all of the critical and important metal parts of the preferred embodiment, such as the collet, the cam, and the discs, can be manufactured to close dimensional tolerances on a turret lathe.

In the drawing:

FIGURE 1 is a perspective view of a preferred embodiment of a hand tool in accordance with the invention.

FIGURE 2 is a perspective exploded view showing the parts of the tool head in section.

FIGURE 3 is a perspective view of an electrical contact terminal crimped onto the end of a wire.

FIGURE 4 is a view taken along the lines 4-4 of FIGURE 3 and showing the cross section of the crimped connection.

FIGURE 4A is an enlarged plan view showing a single indentation of the crimp.

FIGURE 5 is a sectional view of the tool head showing the parts in their normal positions.

FIGURE 6 is a view similar to FIGURE- 5 but showing the relative positions of the parts at the end of the crimping stroke.

FIGURES 7 and 8 are views taken along the lines 77 of FIGURE 5 and 8-8 of FIGURE 6.

FIGURE 9 is a cross sectional view of the head of a modified form of tool in accordance with the invention.

FIGURE 10 is a perspective view of an indentor of the type used in the embodiment of FIGURE 9.

Referring first to FIGURES 3 and 4, the reference numeral 2 denotes a common type of contact terminal which is used in multi-contact connecting devices. The contact shown is a pin contact which is adapted to be received within a complementary socket and has at its rearward end a tubular ferrule portion for reception of the stripped end of a wire 4. The tubular ferrule portion of the contact is crimped onto the end of the wire by means of four indentations 6 which are generally arcuate in both transverse and longitudinal cross section; that is, each indentation slopes inwardly from its ends along the axis of the contact terminal and inwardly from its sides. It will be noted that the individual indentations are not symmetrical about their major and minor axes but are substantially egg-shaped, i.e. the deepest and widest portion of each indentation occurs near one end rather than mid-way between the ends. The reasons for this configuration are explained fully below.

A preferred embodiment of a tool in accordance with the present invention comprises a cylindrical housing or head formed in two sections 10, 12. The lower section 10 has an internally threaded counterbore 14 at its upper end, an intermediate conical bore portion 16 and a lower reduced diameter bore 18. A cylindrical camming member 20 is contained within this housing and has an outside diameter such that it has a relatively close sliding fit within the upper housing section 12. A reduced diameter projection 22 on the lower end of the carnming member extends through the bore 18 of housing section 10 and a conical surface between the portions 20 and 22 of the camming member which conforms to the surface 16. The lower end of the projection 22 has a relatively wide transverse slot 24 in which the ends of a pair of links 30 are pivotally mounted on a common axis by means of a pin 26. The opposite ends of the links are pivotally connected at 29 to handles 28. These handles 28 each have spaced-apart cars 32 at their upper ends by means of which they are pivotally mounted on parallel spaced-apart axes 34 on opposite sides of the housing section 10. Advantageously, stops 36 are provided on the links which engage each other when the handles are fully closed. It will be obvious that upon closure of the handles, the camming member 20 is moved upwardly by the links 30.

Camming member 20 is axially bored as shown at 45 and counterbored at 42 and 40. The larger diameter counterbore 40 adjoins a conical carnming surface 38 which diverges from the axis of the bore. A generally cylindrical collet 46 is slidably contained within the hollow interior of the camming member 20 and has a diameter at its upper end such that it has a relatively snug sliding fit within the bore diameter 40 of the camming member. The lower end of the collet is of a reduced diameter which is substantially equal to the bore 45 of the camming member. A coil spring 48 is interposed between a recess 50 and the collet and a shoulder 44 in the camming member normally to bias the collet upwardly in the drawing and at the same time to bias the handles to their open positions.

Colle-t 46 has an axial bore 51 and an enlarged counterbore 54 at its upper end. A plurality of axial slots 56 are provided in the upper end of the collet which extend through the collet walls and open into the counterbore 54. Indentors in the form of flat discs 58 are mounted in the slots, the slots being of a width only slightly greater than the thickness of the indentors. These indentors have arcuate edges or sides 60 so that when they are pressed into engagement with the contact they will produce a crimp having the arcuate transverse cross section of FIGURE 4. It will be noted that these indentors have central openings, these openings being provided only for convenience during manufacturing of the indentors and serving no function in the finished tool.

The diameter of the indentors is such that segmental portions of each indentor extend beyond the slots 56 and into the counterbore 54 on one side and externally of the surface of the collet on the other side. The projecting ends or segments can thus be contacted by the conical camming surface 38 of the camming member to urge the indentors inwardly of the counterbore as is described below. A cylindrical contact support 53 is slidably mounted in the bore 51 of the collet and resiliently biased upwardly by means of a coil spring 55. This contact support is axially bored to receive the leading end portion of the pin and counterbored at its upper end to provide a seat for the collar of the contact terminal. Since the contact support moves downwardly relative to the collet it is desirable to provide a vent hole as shown at the end of the bore 51.

A cylindrical insert 62 is contained within counterbore 54 and has an axial opening 64 in alignment with the bore 51 which has a diameter slightly greater than that of the contact. This insert has a plurality of axially extending arcuate openings 66 at evenly spaced locations around its periphery corresponding to the locations of the slots 56 so that the inwardly projecting segmental portions of the discs are received within these openings. The insert 62 is of a toughly resilient polymeric material capable of undergoing substantial elastic deformation and subsequently returning to its initial shape. It should also be capable of repeated deformation without change in its elastic properties or its shape. A preferred material for this insert is a solid polyurethane having a hardness of about 80 as measured on the durometer A scale. This insert can be formed by injection molding in which case the openings 66 will not extend entirely through the walls of the insert to the axial opening 64 but a relatively thin film of polymer will close off the bottoms of these openings. When the discs 58 are first forced into the axial opening against an inserted terminal as described below. these thin films will be ruptured and the discs will be forced through the resulting opening and into engagement with the ferrule portion of the contact.

The upper housing section 12 has an inwardly turned flange 68 and a central opening 70 in alignment with the opening 64 and the bore 51. Preferably, the outer surface of this flange i-s conical so that it can function as a guiding surface when the wire or contact terminal is inserted into the tool. The underside of flange 68 has a shoulder 72 which normally bears against a complementary shoulder 74 on the upper end of the collet 46 to keep this member centered with respect to the tool axis and the opening 70.

In use, a contact terminal, either a pin contact as shown in FIGURE 3 or a socket contact, is inserted through the opening 70, through the insert 62 until the end portion is disposed within the contact support 53. Thereafter the wire is inserted into the ferrule of the contact and the handles 28 are closed to move the camming member 20 relatively upwardly. The camming surface 38 engages the projecting segmental portions of the discs and moves them uniformly inwardly from their normal positions (FIGURE 3) through the insert 62 whereby indentations of arcuate cross section are formed on the external surface of the contact to crimp the contact to the wire as shown in FIG- URE 8. Upward movement of the camming member 20 results in compression of the spring 48 so that when the handle force is relieved, the camming member is driven downwardly and the handles are biased away from each other.

It will be apparent from FIGURE 5 that the discs are not in engagement with the ferrule prior to upward movement of the camming member and that the discs will elastically deform the insert before they engage the ferrule. If the ferrule is not centered with respect to the discs at the start of the crimping operation, the initial movement of the discs will thus center the ferrule before indentation stants so that the indentations will all be of substantially the same depth. An additional reason for the fact that indentations of uniform depth can be obtained is that the camming surface 38 and the discs 58 can be manufactured by turning operations so that they can be made to close dimensional tolerances.

During movement of the camming surface 38 relative to the discs 58, the discs are rotated about their own axis while they are driven laterally inwardly towards the contact terminal. The rotation of the discs, in turn, causes the contact terminal to move axially inwardly of the collet 46 (downwardly as shown in FIGURE 6) so that the indentations are rolled into the ferrule of the terminals.

The rotation of the discs has some advantages; for example, the losses due to friction are reduced since rolling friction (rather than sliding friction) is developed between the cam surface 38 and the discs. Furthermore, the entire periphery of each disc is utilized as a bearing surface against camming surface 38 so that the wear is evenly distributed around the entire periphery during the life of the tool.

Under some circumstances it may prove advantageous to prevent the discs from rotating during indentation. In the embodiment of the invention shown in FIGURES 9 and 10, such rotation of the discs 58 is prevented by merely grinding flats as shown at 73 in a manner such that one of these flats faces upwardly as viewed in FIGURE 9 and the other is engaged by the camming surface 38'. It will be understood that the discs are first formed by conventional turning operations on a lathe and that the flats are subsequently ground. The term disc as used in appended claims is intended to be generic to the discs 58 and the discs 58 which are provided with flats.

The embodiments shown in FIGURES 9 and 10 are substantially similar to the embodiment of FIGURE 1 and need not be described in detail. Some minor differences do exist, however. For example, a spacer plate 71 is provided against the underside of the flange 68' and that the discs bear against the underside of this spacer plate. The provision of such a plate is advantageous in that precise adjustment of the depth of penetration of the indentors can be achieved normally by grinding the lower surface of this plate.

The depth to which the disc-type indentors 58 penetrate the ferrule portion of the contact is dependent upon the stroke of the camming member 20 so that this depth can be reduced by merely partially unscrewing the housing 12 from the housing 10. For purposes of calibration and adjustment, indicia 76 may be provided on the surface of the housing member 12 around the periphery thereof to indicate the relative positions of housing members 10, 12 and a set screw 78 provided in the housing member to lock the two housing members in a given position.

A salient overall advantage of the invention is that all of the dimensionally critical parts of the tool including the housing 10-12, the camming member 20, the collet 26, and the discs 58 can be manufactured by conventional turning operations, for example, on a turret lathe and, where necessary, ground to final dimensions within very precise limits. From a manufacturing standpoint, this is a distinct advantage since turning operations can be very closely controlled and a high degree of symmetry is always obtained. Thus, the outside diameter of the upper portion of the collet 46 will have a snug sliding fit within the counterbore 40 of the camming member and the movement of the camming member relative to the collet will be along the common axis of these two members. The camming surface 38 can be formed in a turning operation with an extremely high degree of symmetry with respect to the tool axis so that all of the indentors will be moved inwardly by almost precisely the same amount. The indentors themselves can be made by turning and grinding to very close dimensional tolerances so that the indentations in the ferrule will be of uniform depth. The specific embodiments of the invention shown thus utilizes the inherent advantages of parts having a circular and symmetrical cross section as opposed to parts non-circular and non-symmetrical parts. The insert 62 as mentioned above can be formed by injection molding, again an extremely low cost manufacturing process in which a high degree of reproducibility is commonly obtained. The handles 28 and the links 30 must, of course, be formed by some method other than by turning but these members are not critical and precise and exacting forming operations are not essential.

A significant feature of the invention is the use of a resilient polymeric insert 62 for returning the indentors to their initial positions after the completion of the crimping operation and for maintaining these indentors in their proper locations during crimping. The use of the insert completely obviates the need for conventional springs on the indentors as has been common in prior art crimping devices. It is also noteworthy that a single insert functions as a resilient biasing means for all four indentors 59 so that the need for a separate returning means such as a spring for each indentor is also avoided.

The foregoing advantages of the invention permit the manufacture of a relatively low cost crimping tool for extremely small contact terminals, for example, contact terminals adapted to receive AWG #24 wires. The use of contact terminals of the type shown in FIGURE 3 for these extremely small wires has not been common in the past, most contact terminals of this type having been intended for usage with wires of AWG size 20 or 18 and larger. Prior art crimping tools for these larger contact terminals have been satisfactory, however their construction involving springs for returning the indentors to their initial positions and rotating cams for driving the indentors inwardly, did not readily limit of the design of a smaller tool for the extremely small contact terminals intended for AWG #24 wires. In the practice of the present invention however, a tool for this size can easily be achieved because of the simplicity of the parts, the small number of parts required, and the use of this type indentors in combination with the resilient insert 62. The principles of the invention are, of course, equally applicable to crimping tools for larger sized contacts and to the crimping of connectors and terminals of types other than the contact terminal shown.

While the disclosed embodiments of the invention have a unitary resilient insert 62 for returning the indentors to their initial positions, it will be apparent that this insert might be formed in two separable sections. For example, the die blocks shown in US. Patent 2,921,618 might be formed of resilient polymeric material adapted to be elastically deformed as the indentors are driven inwardly. This arrangement would avoid the need for springs in the above-mentioned patent for returning the indentors to their initial positions after completion of the crimping operation. It should also be pointed out that while disc type indentors are disclosed in the embodiments of the invention shown, it would be practical to utilize indentors of other shapes in combination with the resilient insert 62.

Changes in construction will occur to those skilled in the art and various apparently different modifications and embodiments may be made without departing from the scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only. The actual scope of the invention is intended to be defined in the following claims when viewed in their proper perspective against the prior art.

I claim:

1. A crimping device for indenting a tubular ferrule comprising holding means having a central opening there in for reception of said ferrule, a plurality of discs in surrounding relationship to said holding means with their medial planes in substantial parallelism with the axis of said opening, said discs having normal positions in which edge portions of said discs are adjacent to said opening, means operatively engageable With said dis-cs for moving said discs in their own planes from said normal positions through said holding means and into said opening to indent a ferrule positioned in said opening, said holding means including resilient means acting on said discs, said resilient means being elastically deformable upon movement of said discs into said opening whereby, said resilient means returns said discs to their normal positions after indentation of said ferrule.

2. A crimping device for indenting a tubular ferrule comprising, a generally cylindrical collet having an axial opening therein for reception of said ferrule, a plura ity of radial slots in said collet opening into said axial opening, a disc disposed in each of said slots, said discs having their planes in substantial parallelism with said axial openings, means operatively engageable with said discs for moving said discs at least partially through. said slots and into said axial opening thereby to indent a ferrule disposed in said opening, and resilient means for returning said discs to their normal positions after indentation of said ferrule, said resilient means comprising a resilient organic material which is elastically deformed upon radial inward movement of said discs relative to said axial opening.

3. A crimping device for indenting a tubular ferrule comprising, a generally cylindrical collet having an axial opening therein for reception of said ferrule, a plurality of radial slots in said collet opening into said axial opening, a disc disposed in each of said slots, said discs having their planes in substantial parallelism with said axial opening, a resilient, rubber-like body in said axial opening in alignment with said slots and said discs, said rubber-like body having radial openings extending therethrough for reception of portions of said discs, and means operatively engageable with said discs for moving said discs radially with respect to said collet towards said axial opening whereby, said rubber-like body is elastically deformed and said discs indent a ferrule disposed in said opening, and after indentation, said rubber-like body returns said discs to their initial positions.

4. A crimping device for indenting a tubular ferrule comprising, a generally cylindrical collet having an axial bore therein for reception of said ferrule, a counterbore at one end of said collet, a plurality of radially extending slots in said one end opening into said counterbore, a cylindrical biasing means in said counterbore, said biasing means being of a resilient organic material and having an axial opening in alignment with said axial opening in said collet and having radial openings in alignment with said radial slots, a disc in each of said slots, each of said discs having a segmental portion extending into one of said radial openings in said biasing means, and camming means operatively engageable With said discs for camming said discs radially inwardly towards said opening in said collet whereby, said biasing means is elastically deformed and a ferrule disposed in said axial opening is indented, and said indentors are returned to their initial positions after indentation by said biasing means.

5. An indenting device for indenting the tubular ferrule of an electrical connector, said device comprising indentor biasing means having a recess for reception of said ferrule, said biasing means being of a tough resilient polymeric material, confining means for confining said biasing means, an opening extending through said biasing means towards said recess, said opening having convergent sidewalls, an indentor disposed in said opening and having a configuration conforming to the shape of said opening, and means operatively engageable with said indentor for moving said indentor through said opening and towards said recess whereby, a ferrule disposed in said recess is indented and said biasing means is elastically deformed, and after indentation of said ferrule, said indentor is returned to its initial position by said biasing means.

6. An indenting device for indenting the tubular ferrule of an electrical connector, said device comprising, a toughly resilient polymeric body having a cylindrical opening for said ferrule, a plurality of recesses extending radially towards said opening, indentors in said recesses, said recesses and said indentors being tapered towards said opening, and means operatively engageable with said indentors for driving said indentors radially towards said opening thereby to elastically deform said polymeric body while driving said indentors radially into a ferrule disposed in said opening, said polymeric body functioning to retract said indentors from said ferrule after indentation upon return of said body to its normal undeformed condition.

7. A device as set forth in claim 6 wherein each of said indentors comprises a disc, said discs lying in planes extending radially from the axis of said opening, said camming means comprising a conical camming surface disposed in surrounding relationship to said discs and movable axially with respect to said opening in said polymeric body thereby to drive said disc into said opening.

8. A device as set forth in claim 7 wherein each of said discs has a flat on one side thereof for engagement with said camming surface thereby to prevent rotation of said discs.

References Cited by the Examiner UNITED STATES PATENTS 2,182,663 12/1939 Eby et al 153--1 2,311,662 2/ 1943 HunZike-r 153--1 2,467,012 4/1949 Deuschle 1531 2,921,618 1/1960 Fuller 153-1 CHARLES W. LANHAM, Primary Examiner.

Claims (1)

1. A CRIMPING DEVICE FOR INDENTING A TUBULAR FERRULE COMPRISING HOLDING MEANS HAVING A CENTRAL OPENING THEREIN FOR RECEPTION OF SAID FERRULE, A PLURALITY OF DISCS IN SURROUNDING RELATIONSHIP TO SAID HOLDING MEANS WITH THEIR MEDIAL PLANES IN SUBSTANTIAL PARALLELISM WITH THE AXIS OF SAID OPENING, SAID DISCS HAVING NORMAL POSITIONS IN WHICH EDGE PORTIONS OF SAID DISCS ARE ADJACENT TO SAID OPENING, MEANS OPERATIVELY ENGAGEABLE WITH SAID DISCS FOR MOVING SAID DISCS IN THEIR OWN PLANES FROM SAID NORMAL POSITIONS THROUGH SAID HOLDING MEANS AND INTO SAID OPENING TO INDENT A FERRULE POSITIONED IN SAID OPENING, SAID HOLDING MEANS INCLUDING RESILIENT MEANS ACTING ON SAID DISCS, SAID RESILIENT MEANS BEING ELASTICALLY DEFORMABLE UPON MOVEMENT OF SAID DISCS INTO SAID OPENING WHEREBY, SAID RESILIENT MEANS RETURNS SAID DISCS TO THEIR NORMAL POSITIONS AFTER INDENTATION OF SAID FERRULE.

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