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Linear Compensation Variable Pitch Assembly Fixture

IP.com Disclosure Number: IPCOM000051436D
Original Publication Date: 1981-Jan-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 3 page(s) / 66K

Publishing Venue

IBM

Related People

Harris, RH: AUTHOR

Abstract

This article details a linear placement compensation mechanism for an assembly machine intended for inserting a number of key buttons or similar small objects into a regular rectangular matrix. The matrix may be a molded plastic framework having a number of equidistantly spaced openings into which key buttons are to be placed. A problem with molded plastic frameworks is that upon cooling, a linear shrinkage takes place so that the center-to-center spacing of apertures in the rectangular matrix array vary as their distance from the center of the framework increases.

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Linear Compensation Variable Pitch Assembly Fixture

This article details a linear placement compensation mechanism for an assembly machine intended for inserting a number of key buttons or similar small objects into a regular rectangular matrix. The matrix may be a molded plastic framework having a number of equidistantly spaced openings into which key buttons are to be placed. A problem with molded plastic frameworks is that upon cooling, a linear shrinkage takes place so that the center-to-center spacing of apertures in the rectangular matrix array vary as their distance from the center of the framework increases. This variance is linear, with those center-to-center distances farthest from the center being linearly displaced from their desired location by the maximum shrinkage amount, while those closer to the center are displaced only a small distance from their ideal desired position.

Fig. 1 illustrates an assembly mechanism intended for compensating for this linear variation in center-to-center placement of the desired key button matrix. In Fig. 1, the assembly mechanism has a frame 1 through which a number of apertures 2 extend. A number of proportional spacing bars 3 centered on pivot pins 4 and having apertures 5 for engaging the ends 6 of the key button pick up head mechanisms 7 are shown. A link 8 engages the tops 6 protruding from the surface of the proportioning bars 3. As shown by the arrow 12, the adjusting link 8 can be moved horizontally to rotate the proportioning bars 3 about the pivot pins 4 through a small arc.

In Fig. 2A, a horizontal cross section to a mechanism similar to that shown in Fig. 1 is illustrated. There is sufficient clearance in each aperture 2 through which the stem 6 of the pick-up head mechanism 7 passes so that some individual variation in the center-to-center spacing of the pins 6 and their...