GB1580773A

GB1580773A - Apparatus for inserting terminal pins into a workpiece and supply strip therefor

Info

Publication number: GB1580773A
Application number: GB621278A
Authority: GB
Original assignee: General Staple Co Inc
Current assignee: General Staple Co Inc
Priority date: 1977-03-01
Filing date: 1978-02-16
Publication date: 1980-12-03
Also published as: DE2808859A1; JPS53109284A; JPS6137052B2; DE2808859C2

Description

(54) APPARATUS FOR INSERTING TERMINAL PINS INTO A WORKPIECE, AND SUPPLY STRIP THEREFOR (71) We, GENERAL STAPLE COM PANY, INC., a corporation of the State d New York, United States of America, of 220 East 23rd Street, New York, New York 10010, United States of America do hereby declare the invention, for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to an apparatus for inserting terminal pins into a workpiece, such as a printed circuit board, and more parti- cularly relates to such an apparatus which operates from a supply strip of integrally connected preformed terminal pins. The invention also relates to a supply strip for use in such apparatus.

In the fabrication of many electrical products it is frequently necessary to establish a plurality of upstanding terminal pins on a substrate. For example, on printed circuit boards, it is necessary to establish terminal points to which external wiring can be secured.

Various types of apparatus are known which operate from a continuous supply strip to intermittently feed, sever and drive terminal pins into a workpiece. However, all such known prior art apparatus and terminal pins inserted thereby suffer from the disadvantage that the terminal pins formed and inserted in the substrate terminate in end portions which have the same planar cross-sectional area as the supply stock from which the terminal pins were formed.

Such blunt end portions of the terminal pins formed and inserted by apparatus of the prior art are particularly undesirable especially in the environment in which a wire wrapl operation is to be applied for electrically connecting an external wire to the terminal plin. In fact, many manufacturers who have to employ wire wrapping techniques to electrically connect to printed circuitboards will refuse to accept terminal pins in such boards where the terminals terminate in blunt end portions of the same planar cross-section as the pin itself. Apparently, the blunt nature of the terminal pins makes it difficult to center the wire wrapping operation which is to take place for establishing electrical connection to the printed circuits.

Another problem associated with the prior art apparatus for forming and inserting terminal pins in printed circuit boards, and somewhat related to the fact that the end portions of the inserted pins are of the same planar cross-section as the remainder of the pins, is the fact that during the shearing operation necessary to form the individual pins, an undesirable burr remains on the sheared pins. The thicker the cross-section of the supply stock, the more difficult it is to effect a shearing operation and the more pronounced is the undesirable burr which results.

According to the present invention, there is provided an apparatus for inserting terminal pins into a workpiece comprising reciprocating feeding means for sequentially advancing a supply strip of integrally connected preformed terminal pins towards the workpiece, the feeding means comprising grasping means operable only when the feeding means is moving in a first direction to ward the workpiece to grasp the supply strip at the juncture of adjacent integrally connected preformed terminal pins, shearing means for severing the leading one of the pins from the remainder of the supply strip, and driving means for inserting the leading one of said pins into the workpiece, the shearing means traveling with the grasping means and being located a predetermined distance therefrom, the predetermined distance being equal to or a mulitple of the length of said preformed terminal pins, and the preformed terminal pins terminating at both ends in pointed end portions so that the integrally connected adjacent pointed end portions of adjacent pins form notched regions in the supply strip which are grasped by the grasping means, the distance between adjacent notched regions equaling the length of one of the preformed terminal pins.

According to the present invention, there is also provided a supply strip of electrically conductive material for use in an apparatus for forming and inserting terminals in a workpiece, comprising a plurality of integrally connected preformed terminal pins, the preformed terminal pins terminating at both ends in pointed end portions, and the in- tegrally connected adjacent pointed end per- tions of adjacent pins forming notched regions in the supply strip.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a side elevational view of an embodiment of the machine of the invention which also illustrates a supply strip of the invention; Figure 2 is an enlarged front elevation of a portion of the machine and illustrates the manner in which the feeding mechanism thereof coacts with the supply strip; Figure 3 is a view similar to Figure 2 but illustrating the operation of the machine at a different portion in its cycle of operation; Figure 4 is a side view, in section, of the portion of the apparatus shown in Figure 3; Figure 5 is a front elevation of a portion of an alternative embodiment of the apparatus of the invention in which tandem operation is disclosed and with which terminal pins of differing lengths are inserted in a printed circuit board; Figure 6 is a top view of one embodiment of a terminal pin of a supply strip of the invention; Figure 7 is a top view of an alternative embodiment of a terminal pin of a supply strip of the invention; and Figure 8 is a crcrss-sectioaal view taken along the center of a terminal pin of a supply strip of a further embodiment of the invention.

Turning to the drawings, wherein like num erals are used to designate like elements, the machine 10 of the invention is seen to include a frame generally indicated 12 within which is located motor 14. The output shaft 16 car ries pulley 18, the rotation of which is com municated by V-belt 20 to main shaft 22 through the intermediate and selective opera tion of a conventional solenoid actuated, single revolution clutch, broadly designated 24. Main shaft 22 is journalled for rotation in bearings 25 and 26 carried on the main frame 12.

At the left-most end of shaft 22 there is carried a crank 28 having an upstanding pin 30 thereon. A line 32 is connected be tween pin 30 and a pin 34 carried on the rear of a longitudinally reciprocating slide member 36. Secured to the slide member 36 and mov able therewith is a block 38 which carries the feed mechanism broadly designated 40, the shearing mechanism broadly designated 42, and the driving mechanism broadly desig nated 44, the details of all of which will he presented below.

Keyed for rotation with main shaft 22 is an eccentric cam 46, the cam surface of which controls the downward stroke of a follower 48, the lower end 50 of which projects through the frame 12 and is engaged with the rightmost end 52 of a bell crank lever 54 pivoted to the frame at 56. The bell crank lever 54 is normally biased counterclockwise around its pivot point 56. However, when the follower 48 is depressed by the eccentric cam 46, the bell crank lever 54 rotates clockwise to drive the cutter actuator plunger 58 to the left as viewed in Figure 1, to actuate the shearing plunger 60 to sever the leading terminal pin LP (see Figure 4) from the remaining supply strip SS (Figure 4) of terminal pins. A compression spring 62 normally maintains the shearing plunger 60 in its rightmost, nonshearing position.

As can be seen in the Figures, the supply strip SS is in the form of a continuous length of electrically conductive material formed of integrally connected preformed terminal pins 64, the supply strip being stored in coil form, shown at 65 in Figure 1, and sequentially advanced by the reciprocating feeding means 40 in a manner as described with respect to Figures 2--4. As seen in the Figures, each of the integrally connected terminal pins 64 terminate in pointed end portions 66; integrally connected adjacent pointed end portions 66 of adjacent pins 64 forming notched regions in the supply strip SS.

In one embodiment of the invention, the terminal pins 64 are of rectangular or square cross-section such that the pointed end per- tions are of prismatic configuration, as illu strated in Figure 6. In the embodiment wherein the cross-section of the terminal pins is square or rectangular, the maximum dimension illustrated at 68 in Figure 6, is greater than the diameter of the aperture 70 (Figure 2) in the workpiece 72 into which the pins 64 are to be inserted whereby a tight press fit can be obtained.

In an alternative embodiment of the invention, the supply strip is formed of integrally connected preformed terminal pins of circular cross-section such that the pointed end per- tions are of frustoconical configuration, as illustrated in Figure 7. In this embodiment, the diameter of the terminal pins, indicated as 74 in Figure 7, is less than the diameter of the aperture 70 in the workpiece 72 into which the pin is to be inserted. Therefore, with this embodiment a region along the length of each of the terminal pins may be enlarged, as illustrated at 76 in Figure 8, whereby the enlarged region will have a dimension 78 larger that the diameter of the aperture 70 in the workpiece 72 into which the pin will be inserted.

In the preferred method of manufacture of the supply strip o the present invention a continuous ribbon of electrically conductive material (of rectangular, square, or circular cross-section) is passed through notching dies od appropriate configuration which intermittently operate to notch the stock material so as to form the pointed end portions on adjacent terminal pins integrally connected to one another. In the case ob stock material of circular configuration, an additional swaging step is performed on each terminal pin to form the enlarged region, illustrated. at 76 in Figure 8.

Turning to Figure 2, it will be seen that the feeding means 40 includes grasping means in the form of a pivoting feed finger 80 pivoted for rotation about a pivot pin 82 carried by a guide block 84. Guide block 84 is slotted, as at 86, and connected to block 38 by screw 88 whereupon by loosening screw 88 the position of guide block 84, and hence the position of feed finger 80, may be varied along the length of block 38.

Feed finger 80 is normally biased by a small compression spring 90 to rotate in a clockwise direction around its axis 82. The end 92 of feed finger 80 is so configured as to enter the notched regions 94 formed between adjacent pointed end portions 66 of adjacent terminal pins 64. Thus when slide member 36 and block 38 are reciprocated in a downward direction, as viewed in Figure 1 and Figure 2, the end portion 92 of feed finger 80 (being biased into the notched region 94) causes the supply strip SS to be advanced toward the workpiece 72. On the return upward stroke, the feed finger 80 slides freely along the now stationary supply strip SS held in a stationary position by an antireverse motion calming means, broadly designated 96 in Figure 2.

Anti-reverse motion camming means 96 includes a check-finger 98 mounted for pivotal rotation on pivot pin 100, carried by another guide block 102 fixed to the front face 104 of the frame 12. The second guide block 102 likewise includes an elongated slot 106 through which a screw 108 passes in securing the guide block 102 to the front face 104.

Thus by loosening screw 108, the guide block 102 and hence the check-finger 98 may be adjusted along the length of the face 104.

Check-finger 98 is biased in a clockwise direction by a small compression spring 110 housed in the guide block 102. The pointed end 112 of check-finger 98 engages the notched regions 94 to prevent the supply strip from moving upwardly back toward the supply coil 65 when the block 38 and the feed finger 80 are reciprocating in their upward path of travel.

The timing of the machine, prearranged by the eccentric cam 46, is such that when the downwardly traveling feeding finger 80 has advanced the supply strip the length of one terminal pin 64, the cutter plunger 60 will be actuated toward the left, as viewed in Figure 4 (by the previously described action od the bell crank lever 54) to cause the shearing edge 114 to sever the leading pin LP from the remaining supply strip SS. During the shearing operation the leading pin LP is displaced laterally to the left, as viewed in Figure 4, so as to be placed under the driving shoulder 116 which then continues to drive the pin into the workpiece 72. During the remainder of the downward travel, the leading pin LP is maintained in its proper position under the driving shoulder 116 by a spring-biased keeper plunger designated 118 carried in the block 38 beneath the cutting plunger 60.

As will be appreciated from the above description, certain spatial relationships must be maintained between the various described elements. For example, the distance between the end 92 of the feeding finger 80 and the shearing edge 114 must be either the exact length of one of the terminal pins 64 or a multiple thereof. Only in this manner will it be assured that the shearing edge severs the leading pin LP from the supply strip SS at the juncture of the integrally connected pointed end portions 66 of adjacent pins. 64 forming the notched regions 94 in the supply strip. This is extremely critical since it guarantees that the end portion of the finally inserted pin will indeed have the pointed end portion which is highly desirable in situations where a wire wrap application is to be applied. Likewise, by severing at the mid-point of the notched regions 94, the sharpest pointed end portion on the terminal pin is formed thereby eliminating any possibility of an undesirable burr remaining.

It will be appreciated that supply strips formed of integrally connected preformed terminal pins of a different length may be employed simply by adjusting the position of guide block 84 to always make sure that the distance between the driving edge 92 of the feed finger 80 and the shearing edge 114 of the shearing plunger 60 is equal to or a multiple of the length of the pins 64. Similarly, when the pins 64 are of a different length, the spacing of the guide block 102 will also be changed relative to the spacing of the guide block 84 so that the distance between the end 112 of the check-finger 98 and the end 92 of the feed finger 80 will be a multiple of the length od the terminal pins 64.

Turning to Figure 5, there is illustrated in somewhat schematic form an alternative embodiment ob the invention by which two terminal pins may be simultaneously inserted into a workpiece such as a printed circuit board. In such an embodiment, a duplicate set od tooling is employed, i.e., guide block 102' is also fixed to the front face 104; duplicate feeding means 40' is carried by an enlarged block 38; and duplicate shearing means 42' is likewise carried by guide block 38. Slide member 36 drives block 38 in the manner previously described and an enlarged bar 120 is carried on the face of the cutter actuator plunger 58 to actuate the shearing plunger 60 and 60' associated with each of the shearing mechanisms 40 and 42'. The apparatus is provided with an operating mechanism for controlling the operation of both feeding means and both shearing means.

Figure 5 also illustrates the manner in which the tandem arrangement shown therein may be employed to simultaneously insert terminal pins which are of a different length.

For example, it will be seen that the terminal pins 64' are substantially longer than the terminal pins 64 being processed by the tooling shown on the right-hand side of the apparatus of Figure 5. However, and as described previously, this greater length may be easily accommodated simply by raising the guide block 84' to make sure that the distance between the end 92' of the feed finger 80' remains either the same length as, or a mul title of, the length of the terminal pins 64'.

while embodiments of the invention have been described with a certain degree of particularity, it will be understood that the description was by way of example only and that numerous variations and modifications, as may become apparent to those ob ordinary skill in the art, can be made without departing from the scope od the invention as herein

Claims

after claimed. WHAT WE CLAIM IS:-

1. Apparatus for inserting terminal pins into a workpiece, comprising reciprocating feeding means for sequentially advancing a supply stripl of integrally connected preformed terminal pins towards said workpiece, said feeding means comprising grasping means operable only when said feeding means is moving in a first direction toward said work piece to grasp said supply strip at the junc ture of adjacent integrally connected pre formed terminal pins, shearing means for severing the leading one of said pins from the remainder of said supply strip, and driv ing means for inserting said leading one of said pins into said workpiece, wherein said shearing means travels with said grasping means and is located a predetermined dis tance therefrom, said predetermined distance is equal to or a multiple of the length of said preformed terminal pins, and said pre formed terminal pins terminate at both ends in pointed end portions so that said integrally connected adjacent pointed end portions of adjacent pins form notched regions in said supply strip which are grasped by said graspS ing means, the distance between adjacent notched regions equaling the length of one of said preformed terminal pins.

2. Apparatus according to Claim 1, wherein said grasping means includes a pivotally mounted feed finger, one end of which is biased towards engagement with said supply strip, said one end pivoting to permit relative motion of said feed finger with respect to said supply strip when said feeding means is moving in a direction opposite to said first direction.

3. Apparatus according to Claim 1 or 2, further comprising adjusting means for adjusting said grasping means relative to said shearing means whereby said predetermined distance may be varied.

4. Apparatus according to any one of the preceding claims, wherein said shearing means displaces said leading one af said pins under said driving means during shearing, said shearing means includes a reciprocating plunger which travels in a path of motion transverse to the path of travel of said supply strip, and spring biased keeper means maintains said severed leading one of said pins under said driving means when said reciprocating plunger travels in a direction opposite to its shearing direction.

5. Apparatus according to any one of the preceding claims, further comprising second reciprocating feeding means for sequentially advancing a second supply strip of integrally connected preformed terminal pins toward said workpiece, said second feeding means comprising second grasping means operable only when said second feeding means is moving in a first direction toward said workpiece to grasp said second supply strip at the junction of adjacent integrally connected terminal pins, second shearing means for severing the leading one of said pins from the remainder of said second supply strip, second driving means for inserting said leading one of said pins of said second supply strip into said workpiece, and an operating mechanism for controlling the operation of both the feeding means and the second feeding means and of both the shearing means and the second shearing means, and wherein said second grasiping means is adjustable relative to said second shearing means whereby a plurality of supply strips having integrally connected preformed terminal pins of different lengths may be accommodated.

6. A supply strip of electrically conductive material for use in an apparatus for forming and inserting terminals in a workpiece, said supply strip comprising a plurality of integrally connected preformed terminals pins, and wherein said preformed terminal pins terminate at both ends in pointed end portions and connected adjacent pointed end portions of adjacent pins form notched regions in said supply strip.

7. A supply strip according to Claim 6, wherein said terminal pins are of rectangular cross-section, and said pointed end portions are of prismatic configuration.

8. A supply strip according to Claim 6, wherein said terminal pins are of square crosssection, and said pointed end portions are of prismatic configuration.

9. A supply strip according to Claim 6, wherein said terminal pins are of circular cross-section and said pointed end portions are of frustoconical configuration.

10. A supply strip according to Claim 9, wherien a region along the length of each of said terminal pins is enlarged relative to the diameter of the remaining length of said terminal pins.

11. Apparatus for inserting terminal pins into a workpiece, substantially as described and shown in Figures 1 to 4, or Figures 1 to 4 as modified by Figure 5, of the accompanying drawings.

12. A supply strip of electrically conductive material, substantially as described and shown in Figure 6 or Figure 7, or Figure 7 as modified by Figure 8, of the accompanying drawings.