US3456480A - Method and apparatus for crimping electrical connectors - Google Patents

Description

July 22, 1969 J. w. BALDYGA METHOD AND APPARATUS FOR CRIMPING ELECTRICAL CONNECTORS 3 Sheets-Sheet 1 Filed Nov. 21, 1966 INVLNTOR. JO EPH w. BALDYGA BY 1 M25 '4 4/ "'fia ATToRNEv/s y 1969 J. w. BALDYGA 3,456,480

METHOD AND APPARATUS FOR CRIMPING ELECTRICAL CONNECTORS Filed Nov. 21, 1966 s Sheets-Shet :1

FIG.3 FIG-4 INVENTOR. JQSEP W. BALD GA BY a n w 4 MAM L ATTORNEYS July 22, 1969 J. w. BALDYGA 3,456,480

METHOD AND APPARATUS FOR CRIMPlNG ELECTRICAL CONNECTORS Filed Nov. 21, 1966 v5 Sheets-Sheet 5 INVENTOR.

[17PM W. BALDYGA BY x 61/4 ATTORNEZ United States Patent F U.S. Cl. 72--362 2 Claims ABSTRACT OF THE DISCLOSURE The present disclosure relates to a method and apparatus for crimping electrical connectors in which crimping pressure is applied by a plurality of interconnected toggle devices, the final toggle preferably being operated slightly over-center to produce a re-striking operation.

This is a continuation-in-part of application Ser. No. 458,141, filed May 24, 1965, and now Patent No. 3,374,657, issued Mar. 26, 1968.

At the present time electrical connectors are crimped to the end of insulated wire by an operation in which one or more pairs of tabs formed on the electrical connector are crimped over into engagement with the electrical conductor or the insulation surrounding the electrical conductor, or preferably both. The lectrical connectors are ordinarily formed of brass and it has been found that best results are obtained when the crimping force is applied in such a way that substantially the maximum crimping force is maintained for a sensible time interval. In other words, crimping by impact is not satisfactory.

It is an object of the present invention to provide a method and apparatus for crimping electrical connectors to insulated conductors characterized in the provision of maintaining crimping pressure for a sensible interval as for example about onetenth of a second.

More specifically, it is an object of the present invention to provide a method and apparatus for crimping electrical connectors to conductors employing double toggle mechanism with the result that movement of the crimping ram or press into final position is relatively slow and results in maintaining substantially maximum crimping pressure for a sensible interval.

It is a further object of the present invention to provide crimping mechanism of the character described comprising a rotatable driver, toggle actuating mechanism, selectively operable means for connecting the toggle actuating mechanism to the driver, and means for automatically disengaging the toggle actuating mechanism from the rotating driver after one actuation of the toggle mechanlsm.

It is a further object of the present invention to provide apparatus of the character described comprising a crimping ram, a toggle connected to said crimping ram, a second toggle connected to the first mentioned toggle, and means for actuating the second toggle to produce movement of the crimping ram characterized in extremely slow movement of the final crimping position, and extremely slow movement out of crimping position so that in effect, substantially maximum crlmplng pressure 1s maintained for a sensible interval.

It is a further object of the present invention to provide crimping mechanism comprising a rotary member adapted to move through approximately 360 degrees to effect a single crimping operation, a crlmplng ram, toggle mechanism connected between said ram and said rotary member, a cam connected to said rotary member, and work feed mechanism actuated by said cam.

3,456,480 Patented July 22, 1969 It is a further object of the present invention to provide apparatus as described in the preceding paragraph in which the cam for actuating the work feed mechanism is provided with an abrupt fall-off positioned to register with a cam follower when the toggle mechanism is in substantially collapsed position.

Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawings, illustrating preferred embodiments of the invention, wherein:

FIGURE 1 is an elevational view of the crimping apparatus.

FIGURE 2 is a plan view of the apparatus shown in FIGURE 1, partly sectioned on line 22, FIGURE 1.

FIGURE 3 is an elevational view of the apparatus shown in FIGURE 1, viewed from the right.

FIGURE 4 is a sectional view on the line 44, FIG- URE 1.

FIGURE 5 is a sectional view on the line 5-5, FIG- URE 1.

FIGURE 6 is a fragmentary sectional view on the line 6- 6, FIGURE 4.

FIGURE 7 is a fragmentary perspective view showing an electrical connecter crimped to an insulated electrical conductor.

Referring first to FIGURE 7 there is illustrated a typical application of the crimping operation to connect an electrical connector to an insulated electrical conductor. As seen in this figure, the insulated electrical conductor comprises an elongated electrical conducting element such for example as a copper wire or assembly of copper filaments indicated at 10. Insulation 12 surrounds the electrical conductor. The electrical connector, which may be of brass or the like, may be in the form of a plate 14 having a pair of ears or tabs 16 adapted to be bent around and crimped into clinched engagement with the insulated conductor, and more specifically, with the insulating cover 12 thereof. At the same time, a pair of smaller ears or tabs 18 are provided which are crimped around and firmly clinched to the bared end of the electrical conductor. The plate 14 may be provided with suitable formations for cooperation with elements of an electrical circuit and in the present instance this is illustrated simply as comprising a circular opening 20 formed in the end portion of the connector.

Since the electrical connector has two pairs of tabs which are respectively firmly clinched to the insulating cover of the electrical conductor and to the conducting core or element thereof, the connector is firmly and permanently attached to the conductor.

It has been found that the clinching of the tabs to the conductor as above described is best accomplished when crimping pressure is applied in such a way that substantially maximum pressure is maintained for a sensible interval. This is to be contrasted with a clinching operation in which tabs are clinched by extremely brief application of pressure such for example as by impact.

The method suggested in the foregoing is adapted to be carried out by the apparatus illustrated herein.

Referring now to FIGURES 1-6, the apparatus comprises a frame 22 to which a motor 24 is connected, the motor driving a pinion 26 which is in mesh with a gear 28 mounted for free rotation on a shaft 30. Securely fixed to the shaft 30 is a collar 32 the connection to the shaft being illustrated in FIGURE 4 as including a pointed set screw 34, the pointed end of which is received in a recess in the shaft 30. Slidably carried by the collar 32 in a channel 36 is a pin 38 having a radially projecting dog 40. The pin 38 is provided with an elongated recess 42 in which is received a compression spring 44 the outer end of which seats against a disc 46. With this arrangement the spring 44 biases the pin 38 to the right as seen in FIGURE 4. Movement of the pin 38 to the right is normally prevented by engagement between the dog 40 on the pin 38 with a depending flange 48 formed on a lever 50 which is pivoted as indicated at 52 and is adapted to be moved upwardly by momentary energization of the windings of a solenoid 54. The gear 28 is provided with a plurality, as for example six, openings in circumferential alignment with the pin 38 and when the pin is freed for movement under the action of the spring 44 the pin moves into the next opening in the gear, and thus, directly mechanically couples the gear 28 to the collar 32. As a single rotation of the collar 32 nears completion, the dog 40 on the pin 38 engages a camming surface on the flange 48 so that the pin is retracted from the opening in the gear 28. The lever 50 carries a dog 56 which is engaged by the dog 40 on the pin, thus arresting rotation of the collar 32 after 360 degrees of rotation.

The collar 32 of course, during its rotation imparts rotation to the shaft and this shaft in turn rotates a combined cam and crank arm 58 having a crank pin 60 thereon.

Mounted on the exterior of the frame 22 is a pivot mounting pin 62, the pin being rigidly mounted in a boss 64 as best seen in FIGURE 2. Connected to the pin 62 are a pair of links 66 which are connected by a pivot pin 68 to a pair of links 70 and a second pair of links 72. The links 72 have the opposite end connected to crank pin 60. Links 70 are connected to a pin 74 and to this pin are also connected the links 76 and 78. The opposite end of the links 76 are connected to a pin 80 which in turn is supported in openings in a plurality of leaves 82 formed on a support member 84 having the circular flange 86 engaged against a threaded abutment member 88. Support 84 is retained in assembled relation against the adjustable member 88 by a screw 90 carried by a cap 92.

The other ends of the links 78 are connected to a pin 94, the pin being carried by a driver 96, the driver having a circular base portion 98 and vertically extending leaves 100, and a central relatively thick leaf 102. The circular base of the driver 98 is received in a similarly shaped recess 104 in the ram 106 which is vertically slidable in a guide housing 108, as best seen in FIGURE 2. In this figure it will be observed that the ram 106 has four corner portions 110 each of which is guidingly re ceived in a correspondingly shaped corner 112 of the guide and housing member 108. Thus, the ram 106 is firmly supported for rectilinear movement upon actuation of the toggle mechanism. It will further be apparent that the downward limiting position of the ram 106 may be accurately predetermined by adjustment of the adjustable abutment member 88.

Referring now to FIGURE 1 it will be observed that the links 66 and 70 form a first toggle in which the toggle elements are moved into substantial alignment when the actuating links 72 are in the position shown in this figure. The first toggle mechanism comprising the links 66 and 70 is connected to the second toggle mechanism comprising the links 76 and 78 and the relationship is such that when the links of the first toggle mechanism approach substantial alignment the links 76 and 78 of the second toggle mechanism also approach alignment. Thus, it is apparent that as the ram 106 approaches its lowermost position, it is moving extremely slowly and also it is capable of applying forces of relatively great magnitude with only moderate power being supplied to the drive pinion 26.

More important than the relatively great magnitude of the pressure capable of being applied by the ram is the fact that the described arrangement in effect operates to maintain the pressure applied to a workpiece such as an electrical connector, at approximately the same peak value for a sensible interval. In practice, the apparatus is semiautomatic in that the uncrimped connectors are automatically fed to crimping position while the ram is at the top of its stroke and the operator inserts the prepared conductor end so that the bared conductor is positioned between one pair of tabs, and the insulating cover adjacent the bared ends is positioned between the other pair of tabs on the connector. At this time the operator energizes the solenoid 54 momentarily. In practice, 'the solenoid may be energized by discharge from a condenser. Energization of the solenoid raises the lever 50 and releases the pin 38 for movement into coupling engagement with the gear 28. The collar 32 is given 360 degrees of rotation and as it completes such rotation the pin is retracted so as to disconnect the collar from the gear and rotation of the collar and associated mechanism is r terminated in precise position by engagement between dogs 40 and 56.

Referring to FIGURE 1, there is illustrated a cam surface engageable by a roller 122 on a lever 124 pivoted to the frame 22 as indicated at 126. The lever 124 is biased to the left as seen in this figure by a tension spring 128 and is adapted to connect with mechanism (not shown) for effecting feed of an uncrimped connector into position beneath the ram 106. Details of the crimping head and the base which receives the uncrimped connector are omitted since these elements are of course designed in accordance with each particular crimping operation to be performed. It will be observed however, that the cam surface 120 includes the abrupt fall-off portion 130 which is adapted to move into position adjacent the roller 122 when the two toggles are substantially completely collapsed. Thus, feed of the connector is accomplished very quickly when the ram is in its uppermost position, thus affording maximum clearance and at the same time, the arrangement provides for a minimum of delay in conditioning the apparatus for the succeeding crimping operation.

While the force supplied in the crimping operation is of course variable in accordane with the particular connector, it has been observed that a pressure of 23,400 pounds has been developed when the press is .001 displaced from its maximum downward movement, using a /2 horsepower motor operating at 1750 rpm. The gear ratio between the pinion 26 and the gear 28 is such that shaft rotation is at the rate of rpm. This of course means that only .333 second is required for complete rotation of the shaft or for a complete downward and upward reciprocation of the ram. However, with the arrangement of the crank and double toggle, about half of this time or aproximately one-sixth of a second, is taken up by the last .015" of movement of the ram. Thus, the cycle involves a crimping operation in which the pressure is increased at a controlled but increasing rate and is maintained at relatively high values for a sensible interval. While variations are possible and are in accordance with the material and shape of the connectors, it may be stated that the application of pressure adequate to crimp the connector tabs into required position should be maintained for an interval of at least .100 second.

In the foregoing the toggle links 76 and 78 are disclosed as in alignment, the axes of the pivot connections 74, 80 and 94 occupying a vertical plane. However, it is preferred to dimension and adjust the parts so that in the operating stroke of the press, the pivot pin 74 moves slightly beyond the vertical plane containing the axes of the pins 80 and 94, or in other words, moves to a slightly over-center position with respect to the toggle.

As a result of this the final down stroke of the press involves a very slight upward movement of the ram followed by a correspondingly slight downward movement before it moves upwardly into retracted position. This results in an operation which is known in the industry as restriking and materially improves the operation in that the crimped piece due to the re-striking operation, tends to retain its fully crimped condition without any relaxation.

It will of course be appreciated that in addition to restriking resulting from the slightly over-center movement of the pivot pin 74, the operation results in effectively holding the crimped element in crimped position for a substantially longer period than is the case where the pivot pin 74 merely reaches the center position and is then retracted.

Excellent results are obtained when the parts are dimensioned and adjusted so that the axis of the pivot pin 74 moves approximately .040" beyond center. It is preferred to limt the over-center movement of the pivot pin 74 to between .010" and .080".

The drawings and the foregoing specification constitute a description of the improved method and apparatus for crimping electrical connectors in such full, clear, concise and exact terms as to enable any person skilled in the art to practice the invention, the scope of which is indicated by the appended claims.

What I claim as my invention is:

1. The method of crimping electrical connectors to electrical conductors in which tabs on the connectors are bent around and crimped against the conductors, comprising the step of applying crimping pressure to the tabs, and maintaining the crimping pressure for a sensible interval of at least 0.100 second.

2. The method of crimping electrical connectors to electrical conductors in which tabs on the connectors are bent around and crimped against the conductors, comprising the step of applying crimping pressure to the tabs rapidly until crimping pressure is approached, thereafter continuously decreasing the rate of increase in pressure until maximum pressure is reached, thereafter slightly decreasing pressure, thereafter slightly increasing pressure to re-strike the connector, and finally reducing pressure at an increasing rate, whereby pressure is maintained for a sensible interval with only slight change in magnitude.

References Cited UNITED STATES PATENTS 337,297 3/1886 Berry 72--451 3,064,706 11/1962 Ehmann 72451 RONALD D. CREPE, Primary Examiner U.S. Cl. X.R. 72-372, 416, 451

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