US3143307A

US3143307A - Conductor wrapping bit

Info

Publication number: US3143307A
Application number: US234433A
Authority: US
Inventors: William J Baker
Original assignee: Gardner Denver Inc
Current assignee: Gardner Denver Inc
Priority date: 1962-10-31
Filing date: 1962-10-31
Publication date: 1964-08-04
Anticipated expiration: 1981-08-04
Also published as: GB950790A

Description

Aug. 4, 1964 w, J, BAKER 3,143,307

CONDUCTOR WRAPPING BIT Filed Oct. 31, 1962 2 Sheets-Sheet 1 66 4 l'ii.' mim" 58 wf//lllmx\\\\" 56 Wir..

52 )ao 41a 5/0 T nlm /1/2a 52 INVENTOR.

W/L/AM .l BAKER C F1L.4

BY w.

A 7' TOR/VE Y Aug. 4, 1964 w..1. BAKER 3,143,307

CONDUCTOR WRAPPING BIT 2 Sheets-Skaail 2 Filed Oct. 51, 1962 fabi Vwires to closely spaced terminal posts.

United States Patent O 3,143,307 CONDUCTGR WRAPPING BIT William J. Baker, Reed City, Mich., assigner to Gardner- Denver Company, a corporation of Delaware Filed Oct. 31, 1962, Ser. No. 234,433 Claims. (Cl. 242-7) The present invention generally pertains to bits for wrapping a wire or an equivalent conductor about a terminal to provide a solderless electrical connection.

Conductor wrapping tools commonly incorporate an elongated bit which is drivingly connected with a rotative power source and journaled in a surrounding stationary sleeve. For an example of a tool incorporating a wrapping bit, reference may be made to the copending United States patent application Serial No. 40,106, filed June 30, 1960, now Patent No. 3,078,052, and assigned to Gardner-Denver Company. A bit of the type disclosed in the aforementioned patent application is usually provided with a longitudinal recess for receiving an electrical terminal and a radially-offset, longitudinallyextending groove for receiving and positioning the end portion of a conductor which is to be wound in helical convolutions about the terminal upon rotation of the bit.

Many industrial applications for wrapping tools of the aforedescribed character involve connecting conductors to terminal boards which comprise component parts of electrical or electronic circuits. The present trend in most industries which utilize such terminal boards is toward increasingly closer terminal spacing in order to reduce the overall dimensions of the terminal boards without the loss of available terminal connectons. Accordingly, the diameter of the conductors being applied to these more closely spaced terminals has been substantially reduced. At the present time 30 gauge wire or smaller is often specified by terminal board fabricators; and, in the future, it can be expected that wrapping bits will be required for connecting conductors of even smaller diameters to miniaturized terminal boards.

In the use of presently available wrapping bits for applying conductors to terminals, successive convolutions are often superimposed or piled upon one another due to the forward axial thrust of the bit upon conductor convolutions as the connection is being wrapped. Thus a faulty connection is formed unless extreme caution is exercised by the tool operator to exert only sufficient forward axial thrust to insure a closely wrapped single layer connection. Experience has shown that this result is very diilicult to achieve by skilled operators even in wrapping relatively large `diameter wires. Therefore, an important object of the present invention is to overcome certain operational deficiencies of conventional wrapping bits by providing a bit face construction which effectively prevents piling up or overlaying of successive conductor convolutions one upon the other, particularly in applications requiring connection of small-diameter In the improved bit construction according to the present invention, that portion of each conductor convolution which receives the aforementioned axial thrust from the bit face is laid closely about the terminal and is securely positioned in axial alignment with the preceding convolution before axial force tending to produce pile-up is applied thereto. Moreover, the present invention contemplates provision of a bit face having means operable to maintain wrapped convolutions of small-diameter wire in intimate contact with the terminal and in axial alignment with one another even though the axial thrust applied to the convolutions might normally produce conductor pile-up. This advantageous result is generally accomplished by the prolCC radially restrains the conductor convolutions as they successively receive forward axial thrust -from the bit end face.

A general object is to provide an improved wrapping bit for small-diameter wire which is characterized by simplicity and eiciency in operation and by ease of manufacture and low cost.

Other objects and advantages will be apparent from the following specification and claims when read in conjunction with the accompanying drawings in which:

FIG. 1 is a partial sectional View of a rotary tool which incorporates a wrapping bit constructed in accordance with the present invention;

FIG. 2 is an enlarged end view of the bit shown in FIG. 1;

FIG. 3 is a fragmentary sectional view taken along lines 3-3 of FIG. 2;

FIG. 4 is an enlarged fragmentary sectional view taken along lines 4--4 of FIG. 1 showing a terminal and a conductor in wrapping relation with the bit;

FIG. 5 is an enlarged front elevational view of the wrapping device shown in FIG. 4;

FIG. 6 is a fragmentary sectional view taken substantially along lines 6 6 of FIG. 5;

FIG. 7 is a view similar to FIG. 5 showing the relative positions of the parts after of counterclockwise rotation of the bit member;

FIG. 8 is a fragmentary sectional view taken substantially along lines 8 8 of FIG. 7;

FIG. 9 is a view similar to FIG. 5 showing the relative positions of the parts after of counterclockwise rotation of the bit member;

FIG. 10 is a fragmentary sectional view taken substantially along lines 10-10 of FIG. 9;

FIG. 11 is a view similar to FIG. 5 showing the relative positions of the parts after 270 of counterclockwise rotation of the bit member;

FIG. 12 is a fragmentary sectional view taken substantially along lines 12-12 of FIG. 1l.

In the illustrative construction according to the invention, the numeral 10 generally indicates a rotary tool including a housing 12 for a suitable rotatable power source, such as an electric or pressure uid motor, an integrally formed handle extension 14, and a trigger element 16 for digitally actuating the tool. A guide sleeve 18 is detachably secured to a forwardly projected portion of housing 12 by a nut 20. A rotatable bit driving member 22 is coaxially carried within guide sleeve 18 and engages a mating rotatable element (not shown) which is operatively connected to the motor disposed in housing 12 and, a collet 24 extends into the forward end of guide sleeve 18 and is held therein against relative rotational and axial movement. A conductor wrapping bit 2S is insertable into a tubular bit sleeve 30 in a forwardly direction. In properly assembled relation with collet 24 and bit driving member 22, as shown in FIG. 1, the bit 28 is held against relative rotation with respect to the bit driving member 22 by the interlocking engagement of a pin 32, which is transversely carried by member 22, with a notch in an enlarged, integral shank portion 36 of bit 28. The bit sleeve 30 is held against relative rotational movement with respect to collet 24 by a collet nut 33 which compressively engages the bit sleeve 30 at its forward end and threadedly engages the forwardly extending portion of collet 24. While abutment of the extreme rear end of bit sleeve 30 and the front face of shank 36 of the bit prevents axial displacement of the bit 28 with respect to sleeve 30, the shaft 40 of the bit 28 is freely rotatable within the surrounding sleeve 30 in response to actuation of the motor.

As shown in FIG. 6, for example, a bore 44 extends into the forward end of bit 2S and has a diameter and length suiiiciently great to freely receive an electrical terminal T about which conductor C is to be wound. In the illustrative embodiment, the terminal T is shown as a generally rectangular metallic post; however, in practice, the configuration and dimensions of the terminal will vary to suit particular wiring applications. The terminal may be fixed to a terminal board (not shown) which carries a number of closely spaced terminals. To receive the stripped portion 4S of conductor C for application to the terminal T in contiguous helical convolutions upon rotation of bit 28, the bit is provided with a groove Sil' which is closed by the overlying bit sleeve 3). The groove 59 is longitudinally relieved on the peripheral. surface of the bit to open axially to the end face 46 of bit 28 and is disposed in radially offset relation to the terminal receiving bore 44. In the illustrated embodiments, a portion of bit sleeve 3i) which longitudinally projects beyond the forward end of the bit 23 is provided with a pair of radially

opposed slots

52, 52. As seen in FIG. 4, a selected one of these slots receives and retains a portion of conductor C which is first positioned in the slot and is preferably bent rearwardly along bit sleeve 3i).

In accordance with the invention disclosed in the above identified copending application, the illustrative wrapping bit 28 is provided with a bit face 46 which facilitates production of wrapped connections characterized by increased compression between conductor C and terminal T. Such improved connections are made possible by a continuous camming action exerted upon the conductor C to successively urge each convolution into tight engagernent with the terminal T and with the next preceding completed convolution. As will be hereinafter described in connection with the improved features of the present invention, this camming action is provided by a generally U-shaped cam surface which during the entire winding operation, continuously urges successive portions of conductor C radially inwardly toward terminal T and axially forwardly from the end face 46 of the bit.

Referring to a preferred embodiment of the present invention shown in FIGS. 2 and 3, the bit face 46 includes a flat inner surface 54 which is parallel with a forwardly disposed at outer surface 56. A forwardly projecting, generally U-shaped conductor-camming surface, indicated in its entirety by numeral 58, slopingly intersects the plane of the inner surface 54; and, the interior wall 60 of a forwardly-opening, U-shaped recess 62 joins the outer sur-face 56 and the camming surface 5S. The conductor-receiving groove S0 and the terminal receiving bore 44 open to the bit end face 46 and terminate in the plane of the inner surface 54. The curved portion 64 of the Ll-shaped camming surface 58 intersects the opening of the terminal receiving bore 44 and connects the

spaced surfaces

6,6 and 68 of U-shaped cam 58 which respectively intersect the inner surface 544 and the wall 60. The curved portions of the camming surface 58 and the recess wall 60 are coaxial with the terminal-receiving bore 44.

The cam 58 is uniformly sloped with respect to the plane of the inner surface 54 and with respect to the wall 6,0 which is normal to the inner and

outer surfaces

54 and 56. Preferably, but not necessarily, both the cam 58 and the recess 62 are symmetrical about a prolonged diameter of the terminal-receiving bore 44.

The advantages afforded by the present invention will be better understood from the following description of a preferred mode of operation of the tool 10. In the usual manner, the end portion 48 of conductor C is prepared and inserted a predetermined distance into groove 50 while an insulated portion of the conductor is bent into anchored position within a selected slot 52 and is manually held against the exterior surface of the bit sleeve Sil. The tool is then moved forwardly to insert the end of terminal T into bore 44; and, the rotative power source disposed in housing 12 is energized by depressing trigger 16. From the foregoing description of the parts of tool 10 and their operational relationships, it will be understood that the bit 28 and its end face 46 will then revolve within the bit sleeve 30 and about the stationary terminal T. The stripped portion 48 of conductor C will be withdrawn from groove 50; and, successive convolutions thereof will be wrapped around terminal T until the extreme end of the conductor C is withdrawn and wiped down. As thus far described, the winding operation is somewhat similar to the operation of prior art devices for applying a conductor to a terminal; however, the following detailed description of the action of the improved bit face 46 will point out certain essential features of the invention unattainable in prior art devices.

FIGS. 5 through 12 show progressive angular positions of cam 58 and the recess wall 60 with respect to conductor C at degree increments of counterclockwise movement of the bit face 46. Spaced points X, Y, and Z which are respectively located centrally and at opposite ends of the curved camming surface 64 are included in the drawings to indicate the position of an operative camming point of cam 58 at each illustrated angular position of the bit face 46. In FIGS. 5 and 6, the stripped portion 48 of conductor C is being drawn from groove 5t) around the right-hand side of terminal T. As shown in FIG. 6, the stripped portion 48 engages the sloped cam surface 64 substantially at point X. At this particular rotative position of the bit face 46, the bottom portion 7f3 of the engaged convolution is being urged radially inwardly toward the bottom surface of terminal T. At the same time, cam surface 64 is urging the. bottom portion 70 of the convolution axially outwardly against the corresponding bottom portion 72 of the next preceding convolution. As the cam 58 moves counterclockwise from the position illustrated in FIGS. 5 and 6 toward the position illustrated in FIGS. 7 and 8, the operative camming point on the curved cam portion 64 moves in a clockwise direction from point X toward point Y. Such counterclockvvise rotation of the bit face 46 causes withdrawal of conductor C from groove 50 and, as shown in FIGS. 7 and 8, places camming point Z in contact with the upper portion 74 of the instant convolution just as the bottom portion 70 thereof moves axially away from point Y. The upper portion 74 of the convolution is continuously cammed radially inwardly and axially outwardly in the manner hereinbefore described with reference to the action of the curved cam surface 64 against the lower portion 70 during the preceding 90 degree increment of revolution. After the curved carn surface 64 has rotated from the angular position illustrated in FIGS. 7 and 8 to the position shown in FIGS. 9 and l0, the operative camming point once again becomes point X. During the next 90 degrees of rotation of bit 28, the operative camming point will move progressively around curved cam surface 64 from point X to point Y and will continuously cam the upper portion 74 of the convolution against the upper surface of terminal T, as indicated in FIGS. 9 and 10. As point Y becomes inoperative for camming conductor portion 74, as shown in FIGS. 11 and l2, the operative camming point shifts from point Y to point Z. Point Z then engages the last formed bottom conductor portion 76 camming the same radially inwardly toward the lower surface of terminal T and, axially outwardly into intimate contact with portion 70 of the next preceding convolution. As the cam 58 rotates 90 degrees in a counterclockwise direction from the position shown in FIGS. l1 and 12 to that shown in FIGS. 5 and 6, the camming point operating upon lower conductor portion 76 will travel clockwise from point Z to point X to complete one wrapped convolution.

From the above described Wrapping operation of the

bit

2,8 it will be appreciated that the described bit has a i, l i

wrapping face 46 which continuously and uniformly cams the conductor radially inwardly into high pressure contact with terminal T at the upper and lower portions of each Wrap. The contacting surfaces which prow'de electrical conductivity and mechanical stability between conductor C and the rectangular terminal T occur generally at upper and lower portions of each convolution of the conductor. These contacting surfaces comprise mating indentations occurring at the sharp corners of terminal T and at spaced intervals along conductor C. Such mutual deformation is created by tensile and compressive forces operating upon conductor C as it is drawn around and forcibly compressed against terminal T by the improved bit face 46. As previously shown, the curved cam surface 64 provides an operative camming point which is continuously in contact with conductor C as it is drawn around the top and bottom surfaces of terminal T. Thus the contacting areas between the conductor and the terminal are compressively formed by the rotating cam surface 64 as the latter alternately operates on the upper and lower portions of each convolution of a wrapped connection. From the foregoing, it will be appreciated that the instant bit provides connections between electrical conductors and terminals having a higher contacting pressure and larger total contacting area than can be obtained from bits which are constructed to provide intermittent or irregular camming action or from noncamming bits which depend solely upon tensile forces created by drawing the conductor around the terminal to provide contact pressure.

ln carrying out another important aspect of the invention; namely, prevention of conductor pile-up during the wrapping operation, the axial thrust of the bit 28 against the conductor convolution being formed is imparted to a portion of the conductor C only after the latter is drawn against the terminal T into axial alignment with a corresponding portion of the next preceding convolution. This objective is achieved by providing a space along terminal T to receive a stripped wire portion, such as portion 74 in FlG. 6, as it emerges from groove Sil but before it is contacted by the camming surface 64. The space along the upper edge of terminal T into which conductor portion 74 is received, as seen in FIG. 6, is provided in the following manner: ln response to rotation of the bit, the conductor portion 7G at the bottom edge of terminal T coacts with the inclined plane of cam surface 64 to axially move the bit toward the free end of terminal T. Preferably the slope of cam surface 64 and the diameter of the stripped conductor portion 48 are so related that the axial displacement of terminal T outwardly from bore 44 per revolution of the bit at least one wire diameter. As the bit rotates from the position illustrated in FIG. 5 to that shown in FIG. 7, the above described space will receive conductor portion 74 in intimate contact with the upper edge of terminal T. It will be apparent that conductor portion 74 is positioned about terminal T, as shown in FIG. 7, before it is acted upon by the operating camming point Z of cam surface 64. Therefore, no axial camming of portion 74 occurs until that portion is Wrapped closely about terminal T in direct alignment with the corresponding portion 78 of the next preceding wrapped convolution. FGS. 5 through 12 illustrate that the axial thrust against the conductor convolution being wrapped is imparted by the curved camming surface 64 at a point along the convolution which is remote from the opening of groove 50. lt will be seen that the inner surface 54 of the face of bit 2S does not produce axial camming of the stripped conductor portion 4S; instead, the axial camming action is delayed until the cam surface 64 overrides the conductor at a point angularly remote from the opening of groove 5t?, such as point Z in FTGS. 7 and 8. Such delay -in application of the full axial thrust of the bit 28 against conductor C allows that portion of the convolution which later receives the axial thrust to be laid tightly against terminal T and in axial alignment with previously completed convolutions. It will also be apparent that the camming surface 64 tends to prevent pile-up since the radially directed thrust component created by this sloping surface tends to hold the convolution tightly against terminal T in opposition to axially directed forces tending to lift the convolution from terminal T or `to otherwise cause the cammed convolution to override previously formed convolutions.

While the hereinbefore disclosed operation of the bit face 46 eectively prevents conductor pile-up in most instances, the present invention contemplates provision of additional means for preventing pile-up, particularly where small-diameter wire is to be wrapped. This object is generally accomplished by providing the bit face 46 with the aforementioned recess 62 which has a U-shaped Wall 6i) disposed about the terminal-receiving recess 44 that is operable to restrain the conductor convolutions from separating radially from the terminal as axial thrust is applied threto by the camming surface 64. As shown in FIGS. 5-12, the curved portion of the recess wall 60 engages a given conductor `convolution at the same time the camming surface 64 applies forward axial thrust to that convolution. This coaotion of wall surface 60 with conductor 4S is shown in FIG. 6, for example, where the convolution portion 7? is contacted simultaneously by camming point X and by the wall surface 6i). Thus the wall surface 6u engages the convolution being formed to prevent that convolution from lifting radially away from the terminal as the camming surface 64 exerts an axial thrust thereupon which tends to produce such radial lifting. In order to attain this advantageous mode of operation, the dimension of the radial space between the curved surface of wall 6i) and the terminal should substantially correspond to the diameter of the conductor. Preferably the aforementioned radial space is sized so that the Wall 60 will engage the conductor and smoothly override the same without excessive binding or dragging against the conductor.

As shown in FIG. l2, the axial dimension of the recess wall 6) may be made sufficiently great to afford restraining radial contact between the wall 60 and fully formed conductor convolutions, such as the convolution having top and bottom portions indicated respectively at

numerals

74 and 70. The recess wall 60 could be extended forwardly beyond the position shown in FIG. 12 for engaging and radially restraining the next preceding fully formed convolution having top and bottom portions indicated respectively at numerals 7S and 72.

Another aspect of the invention is the provision of a bit productive of the aforedescribed advantageous operational characteristics which may be rotated in either direction to wrap a conductor about a terminal. Advanced wrapping tools equipped with reversible motor means and intended for industrial applications requiring wrapping in either direction are becoming more common. Therefore, a reversible wrapping bit which performs the wrapping operation equally well in either rotational direction is obviously more desirable than a conventional unidirectional bit which must be replaced when reverse rotation is required. This object is accomplished by providing a bit face 'which is symmetrical about a rectilinear prolongation of a diameter of the terminal receiving bore 44. The symmetry of the bit face is c.early shown in FIG. 2 for example. While the foregoing operational description of the bit has assumed counterclockwise roltaton of the bit, it will be apparent that the action of the bit face 46 with respect to conductor C would be identical in principle if the bit were'rotated in a clockwise direction.

From the foregoing description of the novel bit face construction, it will be apparent to bit users that the instant bit provides improved wrapping features; and, it will also be appreciated by bit fabricators that such bits may be manufactured entirely by simple machining operations.

While the bit device has been shown and described as having particular utility when employed in hand-held, motor-actuated tools, it will be appreciated that the invention is not limited to any particular type of wiring device. Wrapping bits of the described type are Well suited for use in automatic multi-bit wiring machines as well as in manually rotated tools. Since the invention resides primarily in the novel bit face configuration, many different types of special wrapping bits may be constructed in accordance with this invention without interfering with such known special features as lateral loading of the conduotor into the bit, combined insulation stripping and wire Wrapping operations, et cetera. Moreover, it will be understood that the above description and accompanying drawings comprehend only the general and preferred embodiment of the bit face and that various changes in the construction, proportion and arrangement of the various bit face surfaces may be made without sacrificing any of the enumerated advantages o-f the invention.

Having fully described the invention, I claim:

1. In a device for wrapping a conductor around a terminal in successive convolutions:

a. a rotatable wrapping bit having an end face;

b. said bit defining terminal-receiving means and conductor receiving means opening to said end face;

c. first surface means defined by said end face and sloping with respect to the plane of the terminalreceiving opening for camming a conductor convolution radially toward a terminal disposed in said terminal-receiving means and axially forwardly into engagement with a next preceding convolution wrapped around said terminal; and,

d. second surface means defined by said end face and extending forwardly from said first surface means in contacting relation with said conductor convolution to restrain the latter from radial separation from said terminal due to the forward axial thrust of said first surface means.

2. The invention according to claim 1 wherein said second surface means extends forwardly from said first surface means in contacting relation with said next preceding convolution.

3. A bit for wrapping a wire about a terminal having:

a. an end face providing axially spaced inner and outer surfaces; b. terminal-receiving means and Wire-receiving means opening to said end face;

c. wire-contacting surfaces defined by said end face and comprising:

(1) surface means intersecting said outer surface; and

(2) surface means slopingly intersecting and connecting the first-mentioned surface means and the plane of said inner surface.

4. The invention defined in claim 3, wherein the secondmentioned surface means slopingly intersects said terminal-receiving means.

5. The invention defined in claim 4, wherein said wirecontacting surfaces include intersecting curved surfaces which are coaxial with said terminal-receiving means.

References Cited in the file of this patent UNITED STATES PATENTS 2,585,010 Hickman et al. Feb. 12, 1952 Q 2,743,502 Reck May 1, 1956 u 2,758,797 Miklau Aug. 14, 1956 3,077,211 Brooks Feb. 12, 1963 FOREIGN PATENTS 611,962 Canada Ian. 3, 1961

Claims

1. IN A DEVICE FOR WRAPPING A CONDUCTOR AROUND A TERMINAL IN SUCCESSIVE CONVOLUTIONS: A. A ROTATABLE WRAPPING BIT HAVING AN END FACE; B. SAID BIT DEFINING TERMINAL-RECEIVING MEANS AND CONDUCTOR RECEIVING MEANS OPENING TO SAID END FACE; C. FIRST SURFACE MEANS DEFINED BY SAID END FACE AND SLOPING WITH RESPECT TO THE PLANE OF THE TERMINALRECEIVING OPENING FOR CAMMING A CONDUCTOR CONVOLUTION RADIALLY TOWARD A TERMINAL DISPOSED IN SAID TERMINAL-RECEIVING MEANS AND AXIALLY FORWARDLY INTO ENGAGEMENT WITH A NEXT PRECEDING CONVOLUTION WRAPPED AROUND SAID TERMINAL; AND, D. SECOND SURFACE MEANS DEFINED BY SAID END FACE AND EXTENDING FORWARDLY FROM SAID FIRST SURFACE MEANS IN CONTACTING RELATION WITH SAID CONDUCTOR CONVOLUTION TO RESTRAIN THE LATTER FROM RADIAL SEPARATION FROM SAID TERMINAL DUE TO THE FORWARD AXIAL THRUST OF SAID FIRST SURFACE MEANS.