US3491451A

US3491451A - Inspection station

Info

Publication number: US3491451A
Application number: US662324A
Authority: US
Inventors: Willard Emanuel Rapp
Original assignee: Western Electric Co Inc
Current assignee: AT&T Corp
Priority date: 1967-08-22
Filing date: 1967-08-22
Publication date: 1970-01-27
Anticipated expiration: 1987-01-27

Description

Jan. 27, 19701 v w. E. RAPP 3,491,451

INSPECTION STATION l v Filed Aug. 22, 1967 5 Sheets-Sheet l j; ELL/MQ@ QT TUE/veg:

Jan. 27, 1970 w. E. RA'PP INSPECTION STATION 5 Sheets-Sheet 2' Filed Aug. 22. 1967 INSPECTION STATION Filed Aug. 22. 1967 5 Sheets-Sheet 5 Jan. 27, 1970 w. E'. RAPP 3,491,451 I INSPECTION STATION Filed Aug. 22, 1 967 5 Sheets-Sheet 4 lill J*. L

mi t ll I i9 7/ l l78 j; J- Cl'; E- ":2 '-7 A Jan- 27, 1970 w. E. RAPP INSPECTION STATION Filed Aug. 22. 1967 5 Sheets-Sheet 5 United States Patent ON 3,491,451 INSPECTION STATION Willard Emanuel Rapp, North Brunswick, NJ., asslgnor to Western Electric Company, Incorporated, New York, N.Y., a corporation of New York Filed Aug. 22, 1967, Ser. No. 662,324 Int. Cl. Gtllb /02 U.S. Cl. 33-174 8 Claims ABSTRACT 0F THE DISCLOSURE An automatic contact spring inspection station simul taneously gages the location of a protuberance on the spring and the location of a gold overlay on the protuberance. The engagement of mating camming surfaces on a slotted mask in the station and on an incoming spring displaces the mask by an amount indicative of the distance of the protuberance from a reference surface on the spring. The slot in the mask is aligned with the overlay when the mask is in its displaced position if the location ofthe overlay on the protuberance is proper.

BACKGROUND OF THE INVENTION lContact springs are frequently employed in conjunction with printed circuit boards and the like. Typically, the springs are mounted within suitable connector blocks into which the boards are inserted. As a result of the insertion, the protuberant portion of the spring is forced into intimate engagement with the board. In particular, the area of the protuberant portion which engages the inserted board is provided with a precious metal overlay, usually of gold, to improve the electrical contact between the spring and the board.

The proper location of the protuberance on the spring and the proper position of the gold overlay on the protuberance are both critical in obtaining the desired electrical contact at assembly. At present, the determination of whether each of these locations is within the required tolerances is ascertained by manual gaging techniques. Since a great number of such contact springs are produced annually, such manual operations are time consuming, fatiguing and inefficient even on a spot-check basis.

SUMMARY OF THE INVENTION These disadvantages are alleviated by a Contact spring inspection apparatus constructed in accordance with the invention. This apparatus is capable of automatically and simultaneously determining whether the location of the protuberance on the spring and the location of the gold overlay on the protuberance are proper. In a preferred embodiment, the contact springs to be tested are fixedly supported in a rotary turret and are successively indexed into a mask having a slot whose width is slightly smaller than the desired width of the gold contact on the protuberance. The mask is mounted for translational movement in a radial direction with respect to the turret. A pivoted lever normally biases the mask in a direction away from the turret center against a first reference surface with the slot out of alignment with the gold overlay on the protuberance. The indexing of the spring into the mask causes an essentially linear side of the spring protuerance to engage a depending camming surface on the mask. The continual movement of the spring against the camming surface displaces the mask toward the turret center by an amount indicative of the distance of the protuberance from a reference surface on the spring. The correct positioning and width of the overlay is indicated by the overlapping of the latter beyond both sides of the slot when the mask is in its displaced position,

ice

BRIEF DESCRIPTION OF THE DRAWING The nature of the present invention and its advantages will become more apparent from the following detailed description when taken in connection with the appended drawing in which:

FIG. l is a plan view, partially broken away and partially in diagrammatic form, of a spring inspection apparatus constructed in accordance with the invention;

FIG. 2 is an elevational fragmentary section, taken on line 2-2 of FIG. l, illustrating details of the spring and the relative vertical orientation of the spring and a mask;

FIG. 3 is a perspective view of a mask suitable for use in the apparatus of FIG. 1;

FIGS. 4A-4C are perspective Views, taken at successively later points in time, illustrating a camming action between the mask and the spring under test in the apparatus of FIG. 1;

FIG. 5 is an elevational View of a more detailed version of the apparatus of FIG. l;

FIG. 6 is a sectional plan view taken along line 6 6 of FIG. 5; and

FIG. 7 is a sectional elevation view taken along line 7 7 of FIG. 5.

DETAILED DESCRIPTION Referring now in more detail to the drawing and more particularly to FIG. l, a plain View of an illustrative inspection station for automatically testing a plurality of contact springs 11 is depicted. The springs to be tested are received in a plurality of slot-like nests 12-12 disposed at equally spaced angular intervals around the periphery of a turntable 13, which is rotatable in a horizontal plane. Each received spring is supported against movement relative to the turntable in both horizontal and vertical planes (such as by spring-loaded means not illustrated).

As best shown in FIG. 2, each spring 11 consists, for purposes of this description, of (l) a planar terminal 14 received in the associated nest 12 0f the turntable, 'and (2) a generally elliptical head 16 projecting outward from and joined to a left end 17 of the terminal 14 by means of an upwardly extending portion 18. The top of the head 16 has an arcuate protuberance 19, a portion of which is overlaid with a bonded gold contact 21. For simplicity, and without limiting the generality of the following description, it will be assumed that (1) the gold contact 21 is symmetrically disposed about a centerline 22 of the protuberance 19, and that (2) the centerline 22 is vertical.

The side of the protuberance nearer the terminal 14 has an oblique linear portion 23 which forms an acute angle with the terminal 14. The portion 23 terminates at a horizontal end region 24 disposed below and adjacent the left end 17 of the terminal 14. The left end 17 and the end region 24 form a pair of selectively closable contacts of the spring 11.

A surface 26 of the upwardly extending portion 18 on the elliptical spring head serves as a reference surface for the inspection of the protuberance 19 in the manner described below. As shown, each spring is received within the asociated nest 12 of the turntable 13 with its reference surface 26 abutting the periphery of the turntable 13.

Referring to FIG. l, the turntable 13 is provided with an indexing mechanism 27 for successively moving the nested springs 11 into an inspection apparatus 28, constructed in accordance with the invention and shown in block and schematic form for immediate discussion purposes. While the indexing mechanism for the turntable 13 may take any suitable form, the particular arrangement shown in FIG. l includes a turntable drive shaft 29 which is driven counter-clockwise about a vertical axis 3,491,451` Patented Jan. 27, 1970` 30 by a continuously energized torque motor (not shown) through a suitable worm and wheel drive (not shown). A ratchet wheel 31 is rigidly connected to the shaft 29 for rotation therewith. The periphery of the ratchet wheel 31 is provided with a plurality of equally spaced teeth 32--32 selectively engageable by a pair of spaced, pivotally mounted

pawls

33 and 34. The movement of the

pawls

33 and 34 is controlled by a pair of

solenoids

36 and 37 acting through an associated pair of

links

38 and 39. The motion of the ratchet wheel is arrested each time a pawl engages a tooth 32, thereby providing an effect which is exactly opposite to a pawl` and ratchet drive. The

pawls

33 and 34 are so associated with the periphery of the ratchet wheel that When one of the pawls (illustratively the pawl 33) engages an adjacent tooth 32 as shown to stop the counterclockwise movement of the ratchet wheel (and thus of the drive shaft 29), the other pawl 34 rests on an inclined portion of the ratchet wheel periphery intermediate a pair of successive teeth 32.

In order to rotate the turntable from the index position Shown in FIG. 1 (i.e., with the pawl 33 contacting the adjacent tooth 32 of the ratchet wheel), the solenoid 36 is energized to retract the pawl 33 from the engaged tooth 32. This permits the torque motor to rotate the turntable one half of the angular distance between successive teeth, whereupon the other pawl 34 engages the adjacent tooth 32 to stop the motion of the turntable. Upon the de-energization of the solenoid 36, the pawl 33 is reextended and engages a portion of the periphery of the ratchet wheel 29 intermediate successive teeth. The next movement of the turntable is accomplished by energizing the other solenoid 37 to retract the pawl 34. When the turntable again rotates half the distance between successive teeth, the pawl 33 engages the adjacent tooth to stop the rotation. Subsequent movement of the turntable between adjacent index positions is accomplished in a like manner by alternately retracting the

pawls

33 and 34. The solenoids may be controlled by a suitable timing circuit (not shown).

As best shown in FIGS. 2 and 3, the inspection apparatus includes a horizontally disposed planar mask 41 having a slot 42 and a sloped camming surface 43 displaced from the slot in the direction toward the axis 30 of the turntable 13. The camming surfaces 43 projects from a lower surface 44 of the mask. The width of the slot is made slightly less than the desired linear width of the gold contact 21 (FIG. 2) on the spring protuberance 19. The top portion of the slot periphery is beveled for ease of illumination, as described below.

The plane of the lower surface 44 of the mask 41 is disposed vertically adjacent to the plane of the uppermost portion (i.e., the gold-overlaid portion) of the spring 11. The mask is arranged so that the plane of the camming surface 43 forms an acute angle with the lower surface 44 and so that an intersection 45 (FIG. 3) of the

surfaces

43 and 44 also forms an acute angle, when extended, with a longitudinal `axis 46 of the slot 42. The angle between the

surfaces

43 and 44 preferably corresponds to the angle between the linear side 23 (FIG. 2) on the spring protuberance 19 and the spring terminal 14.

The mask 41 is constrained by suitable means, shown schematically as a pair of guide blocks 47-47, for radial movement toward and away from the centerline 30 of the turntable 13 along an axis 48. The axis 48 is aligned with one of the index positions of the turntable 13. The mask 41 is so oriented that the longitudinal axis 46 (FIG. 3) of the slot 42 is perpendicular to the axis 48.

'I'he mask 41 is biased in the radially outward direction by suitable means (diagrammatically shown in FIG. 1 as a spring 49) such that the mask is normally urged against a second surface 50. The surface 50 is so positioned that when the mask 41 is biased against it, the slot 42 of the mask is out of alignment with the goldoverlaid portion 21 of an adjacent spring 11, and the camming surface 43 is disposed in engageable relation with the sloping side 23 (FIG. 2) of the protuberance 19.

The mask 41 (FIG. l) is mechanically coupled to a suitable optical sensing device 51. This device 51 is provided With a pair of output leads 52-52 for transmitting a signal having a first state when the displacement of the mask from the reference surface 5()` is Within predetermined -limits and a second state when the displacement is outside the limits. As indicated in more detail below in connection with FIG. 5, the device 51 may be normally illuminated by a light source 53 to yield the second state. An interruption of the illumination occurs only during a correct displacement of the mask. The output state of the signal on the leads 52-52 is switched from the second state to the first state When the illumination is interrupted.

The operation of the portion of the arrangement of FIGS. 1-3 thus far considered will be described in connection with FIGS. lA-4C. The latter illustrate the relative positions, at successively later points in time, of an incoming contact spring 11 and the mask 41. At the point in time shown in FIG. 4A, the spring 11 has just come into contact with the mask 41 so that the camming surface 43 of the mask is engaged by the linear side 23 of the spring protuberance 19. The further motion of the turntable 13 in the counterclockwise direction will continually move the side 23 along the camming surface 43 through intermediate positions such as that shown in FIG. 4B until the turntable has reached its index position in line with the axis of movement 48 (FIG. 4C) of the mask. Since the spring 11 is xedly held during this indexing movement, and the mask 41 is free to move in the direction to the right as shown in the figure, the movement of the side 23 along the camming surface 43 will cause the mask 41 to be displaced a corresponding distance to the right from the reference surface 50. When the turntable has reached its fully indexed position (FIG. 4C), the mask has been displaced to the right by a total distance L under the camming action of the side 23 and the surface 43.

It will be appreciated that the distance L will vary with changes of the point in initial contact (FIG. 4A) of the side 23 on the camming surface 43. This point of initial contact, in turn, is determined by the position of the protuberance 19 on the spring 'with respect to the spring reference surface 26 abutting the periphery of the turntable 13. Thus, since variations in the dimension L (FIG. 4C) correspond to variations in the location of the protuberance 19, the optical sensing device 51 (FIG. 1) may be set, in a well-known manner, so that its output signal on the leads 52-52 has the first state when the total displacement L (FIG. 4C) of the mask is within a desired range of values and the second state when the displacement is outside this range. The desired range, of course, will correspond to a correct location of the protuberance 19 within specified tolerances.

The spacing between the slot 42 and the camming surface 43 on the mask is so chosen with respect to the nominal dimensions of the spring that the displacement of the mask by its full extent to the right, as in FIG. 4C, under the camming action of the spring and the mask will generally align the slot 42 with the underlying gold contact 21 of the protuberance. Since the width of the slot 42 is somewhat less than the width of the gold contact 21, the failure of the contact to overlap both sides of the slot is indicative .of either (a) an incorrect position of the contact 21 on the protuberance, or (b) an insufficient contact width.

In general, since the gold contact 21 optically contrasts with the ibase metal of the spring, it is convenient for an operator to visually ascertain whether the desired overlap of the gold contact 21 with respect to the slot 42 has occurred. For this purpose, the testing apparatus 28 (FIG. 1) may be further provided with a stationary optical projection system 54 for projecting an enlarged image of the region of the slot 42 on the mask onto a suitable screen 54A. If the base metal of the spring is anywhere visible within the projected image of the slot where the gold contact should be, the operator may reject the piece part.

The inspection apparatus is shown in more detail in FIGS 5-7. The apparatus is shown as being mounted in a housing 55 (FIG. 5) having a first elongated horizontal bore 56 whose axis is parallel to the axis of motion 48 of the mask 41. The mask is slidably mounted for movement to the right with respect to the housing 55 by means of a rod 57 afiixed to a rear portion 58 of the mask; The rod 57 is carried in a pair of sleeve bearings 59-59 disposed in the first bore 56.

The mask 41 is normally urged to the left against a vertical surface 61 of the housing 55 by means of a lever 62 pivotally mounted by a pin 63 on a bracket 64 that is affixed to the surface 61. In the position shown in FIG. 5, which functionally corresponds to the situation depicted in FIG. 4C, the mask is displaced away from the reference surface 61 (FIG. 5).

The pin 63 divides the lever into a shorter arm 66 and a longer` arm I67. The shorter arm 66 engages a depending portion `68 of the mask to exert the required biasing force to the left. The longer arm 67 extends through a second bore 69 disposed in the housing 55 and situated below and parallel to the first bore 56. The lower arm 67 terminates in a shutter plate 71. A pair of vertically aligned schematically depicted photocells 72-72 are carried in a circular housing 73 located adjacent to one side of the shutter plate 71. The housing 73 is mounted on a bracket 74 ('FIG. 6) affixed to a second vertical side 76 of the housing 55. A stationary source of illumination, such as a projection lamp 77, is provided for normally illuminating both photocells from a location adjacent to the opposite side of the shutter plate 71. The lamp 77 is sup ported on a bracket 7 8 afiixed to the side 76.

The relative lengths of the longer and shorter arms 66 and 67 (FIG. 5) of the lever 62 are so chosen with respect to the width of the shutter plate 71 and the vertical spacing of the photocells 72-72 that when the mask 41 is biased against the vertical surface 61, the shutter plate 71 is in a position below the path of illumination of at least one of the photocells by the lamp 77 (i.e., in a position below that shown in FIG. 5). As the mask is displaced to the right under the camming action between the spring and the mask in the manner described above, the longer arm 67 of the lever, and thus the shutter plate 71, will be pivoted clockwise. If the displacement of the mask is within predetermined limits as described above, the shutter plate will rotate to the position shown in FIG. 5 and will block illumination from both of the photocells 72-72. If the displacement ofthe mask 41 is either too small or too large corresponding to an improper location of the protuberance on the spring, the shutter plate will rotate to a position either above or below the position shown in FIG. 5 and will permit some illumination to fall on at least one of the photocells. The latter may be arranged in any well-known manner to yield an output signal having the desired first state only when the blocked condition shown in FIG. 5 exists.

The arrangement of FIG. 5 further includes an optical fixture 79 mounted on the housing 55. The fixture includes a pair of obliquely disposed

light sources

81 and 82 for illuminating the slotted region of the mask from opposite sides of a vertical centerline 83. The latter is positioned to be in registration with the slot 42 in the mask when the latter is fully displaced from the surface 61 as shown. In this position, a reflected image (not shown) from the slotted region of the mask is directed toward a lens and mirror arrangement 84 (FIG. 7) disposed in a generally L-shaped portion 86 of the housing 55 (FIG. 5). The arrangement S4 (FIG. 7) is designed to project an enlarged image of the slotted region in the mask on a vertically mounted projection screen 87. For this purpose, the arrangement 84 may include a double-convex lens 88 having unequal focal lengths and carried in a tube 89 coaxial With the centerline 83. The tube is mounted, by means not illustrated, partially within the portion 86. A planar reflecting mirror 91 is suitably mounted at a distance X above the lens 88 at an angle of 45 to the horizontal for routing upwardly directed light rays from the lens 88 to the screen 87. The latter is assumed to be located at a distance Y from the mirror.

The longer focal length of the lens 88 is the distance X -i-Y, while the shorter focal length is equal to the distance Z from the lens to a plane 92 of the slot in the mask. A light shield 93 is placed over the screen 87 to facilitate viewing in a lighted room.

The embodiment of FIGS. 5-7 functions in a manner identical in all respects to that described in connection with FIGS. 1-4.

It is to be understood that the above-described arrangements are merely illustrative ofthe principles of the invention. Numerous other modifications will suggest themselves to those skilled in the art. For example, if the gold contact on the spring is displaced from the center .of the protuberance, the `sides of the slot in the mask may be suitably shaped to allow eficientcentering of the gold contact region in the slot and illumination thereof by the optical projection system. Such modifications may be devised without departing from the spirit and scope of the invention.

What is claimed is:

1. In an apparatus for gaging the location of a protuberance on an article that is moved into an inspection station:

a planar mask disposed at the inspection station and having a slot generallycoextensive with the protu* berance; j

means for movably supporting the mask in the path of movement of the article with the slot normally out of alignment `with the protuberance; and

camming means carried by the mask for engagement with a first side of the protuberance on the moving article for moving the mask in a direction tending to align the slot with the protuberance, the amount of movement of the mask being indicative of the location of the protuberance on the article.

2. Apparatus as defined in claim 1, in which the carnming means comprises:

a planar member projecting obliquely from the mask to define acute angles with the slot and with the plane of the mask, respectively.

3. Apparatus as defined in claim 1, in which the protuberance includes an overlying layer of contrasting color having a nominal first width, the width of the slot on the mask being less than the first width.

4. Apparatus as defined in claim 1, in which the spacing bet-Ween the camming means and the slot on the mask is chosen so that the movement of the mask within predetermined limits efiects the registration of the s-lot with the overlying layer on the protuberance.

5. In an apparatus for gaging the size of a predetermined portion of a component:

a mask having a slot slightly smaller than the width of the portion;

means for supporting the component with the portion exposed;

means for moving the supporting means to advance the component into engagement with the mask; and

means mounted on the mask in engageable relation With the advancing component for moving the mask relative to the component to position the slot in registration with the portion.

6. In an apparatus for gaging an area on an article:

a mask havin-g a gaging opening therein;

means for movably mounting the mask;

means for supporting the article with the area exposed;

means for imparting relative motion between the supporting means and the mask to advance the article and mask in overlapping relationship; and

means on the mask for engaging the article during the relative motion to position the opening in the mask over the area to be gaged.

7. Apparatus for inspecting a protuberant portion of an article, which comprises:

a mask having a slot generally' co-extensive With the protuberant portion;

means for urging the mask into a reference position;

means slidably mounting the mask for lateral movement in one direction away from the predetermined position;

means for moving the article into engagement with the mask; and

camming means carried by the mask in the path of the protuberance for effecting the displacement of the mask in the one direction upon engagement of the mask and the article.

8. Apparatus as defined in claim 7, in which the urging means comprises, in combination:

a lever; and means for ypivoting the lever to define arms of unequal length with the shorter arm of the lever in engagement With the mask.

References Cited UNITED STATES PATENTS 2,424,373 7/1947 Spiller et al. 356-172 2,929,148 3/ 1960 Werth. 3,402,813 9/1968 Molbach 209-80 RONALD L. WIBERT, Primary Examiner I ROTHENBERG, Assistant Examiner U.S. C. X.R.