Inventor: Ioannis Evreniadis

FIELD OF THE INVENTION

This invention generally relates to fastener deforming apparatus and more particularly to apparatus for transferring fasteners into a deforming die.

BACKGROUND OF THE INVENTION

The manufacture of specialty nails such as ring nails or spiral shank nails generally involves the deformation of smooth shank nails between stationary and rotating parts of a deforming die. Figure 1 is a top plan view diagramatically illustrating a typical prior art deforming die arrangement.

The deforming die arrangement of figure 1 includes a deforming die assembly 10 having a fixed die part 12 and a rotating die part 14. Nails 34 are fed into a space 16 between the fixed die part 12 and rotating die part 14 by a transfer device generally identified by reference 18.

The transfer device 18 includes a cam 20 which is rotated by the rotating die part 14, a cam follower 22 mounted to one end of a rocker arm 24 pivotably mounted on a spindle 26. A pusher 28 mounted to the opposite end of the rocker arm 24 and a leaf spring 30 complete the transfer device. Reciprocal motion in the direction of arrows 32 is imparted to the cam follower 22 by the cam 20 as the cam 20 rotates. The reciprocal motion is transferred by the rocker arm 24 to the pusher 28.

Nails, identified by reference 34 are fed along a supply track 36 to the deforming die 10 at the crook of a V defined between a corner 38 of the stationary die 12 and the leaf spring 30. Each of the nails 34 are in turn initially pushed by the action of the pusher 28 into the crook of the V for alignment generally parallel to a rotational axis of the die which is generally perpendicular to the plane of Figure 1. Further pushing by the pusher 28

causes resilient deformation of the leaf spring 30 enabling each nails 34 in turn to be forced past the corner 38 into the gap 16.

A problem with the prior art transfer device 18 is rapid wear of the corner 38 by the pressing of the nails 34 between the leaf spring 30 and corner 28. Once the corner 38 wears down, the nails 34 can pass freely into the deforming die through the resulting gap between the corner 38 and leaf spring 30 without proper alignment or indexing. Misalignment may cause expensive damage to the deforming die assembly 10. Improper indexing (i.e. failure to maintain consistent inter-nail spacing) results in inconsistent pressure between the die parts 12 and 14.

Proper alignment of the nails parallel to the axis of rotation of the rotating die part 14 is crucial to produce high quality finished nails. For example when making ring nails having many closely spaced rings, a relatively small amount of misalignment may result in many of the rings not forming.

High quality fasteners are extremely important for use in collated nails for air tools and the like. Such equipment will not tolerate off specification nails that may nevertheless be packaged as boxed nails.

Control of alignment in the prior art device is not very good because of the very short feed time and the failure to match the speed of the nails 34 to the speed of the rotating die part 14.

Feed rate in the prior art system is limited by the time required for the pusher 28 to be clear of the nail path in order to enable the next nail 34 to advance in place and the time required for the pusher 28 to press the nail 34 into alignment between the leaf spring 30 and the corner 38 of the fixed die part 12. Accordingly the prior art system will typically have a maximum feed rate of 600 to 1200 nails per minute. In practice it has been found that operating the pusher at 1200 strokes per minute will not result in 1200 nails entering the deforming die 10 which is indicative of the poor control inherent in the prior art device.

It is an object of the present invention to provide a transfer device for transferring nails between a supply track and a deforming die which ensures consistent indexing and alignment of the nails and minimizes wear at the entrance of the fixed die part. It is a further object of the present invention to provide a transfer device capable of high speed and consistent transfer to ensure high quality fasteners at high production rates.

SUMMARY OF THE INVENTION

A transfer device for transferring fasteners from a supply track to a deforming die at evenly spaced intervals, said transfer device comprising: an index wheel mounted for rotation about a wheel axis in a direction opposite to a direction of rotation of a rotating part of said deforming die; said index wheel having a plurality of outwardly facing slots generally evenly spaced about its periphery and substantially parallel to said wheel axis; said index wheel having a circumferential groove extending radially inwardly thereabout to define upper and lower parts thereof; a pusher bar extending across said groove, said pusher bar having a guide surface at one end thereof facing said rotary die part, said pusher bar being resiliently biased toward said rotating die part to press a fastener out of said slots as said slots rotate past said guide surface of said pusher bar, press said fasteners against said rotating die part and guide said fasteners into a space defined between said rotating die part and a corresponding fixed die part; a guide extending about said index wheel between said supply track and said guide surface of said pusher bar, said guide interacting with said fasteners to prevent ejection of said fasteners from said slots as said index wheel rotates; and drive means for rotating said index wheel.

DESCRIPTION OF DRAWINGS

The present invention is described in more detail below with reference to the accompanying drawings in which:

Figure 1 is a top plan view diagramatically illustrating a prior art arrangement;

Figure 2 is a top plan view diagramatically illustrating the operation of a transfer device according to the present invention; Figure 2A is a plan view of a nail deforming apparatus including a transfer device according to the present invention;

Figure 2B is a front elevation corresponding to Figure 2A;

Figure 3 is a perspective view illustrating an index wheel and part of a drive means according to the present invention; Figure 4 is a front elevation corresponding to Figure 3;

Figure 5 is a top plan view of an upper part of an index wheel according to the present invention;

Figure 6 is a perspective view of a rotating part of a deforming die;

Figure 7 is a front elevation of a pusher bar assembly according to the present invention;

Figure 8 is a to plan view of a pusher bar assembly according to the present invention with a top cover removed to show the inside of the assembly; and

Figure 9 is a perspective view illustrating a guide according to the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

A fastener deforming apparatus is generally indicated by reference 50 in Figure 2. The fastener deforming apparatus includes a supply track 52, a transfer device 54 and a deforming die 56. The deforming die 56 includes a fixed part 57 and a rotating part 59.

The transfer device 54 includes an index wheel 58 which is also illustrated in Figures 3 and 4. The index wheel has a top part 60 and a bottom part 62 separated by a radially inwardly extending circumferential groove 64. The index wheel 58 is mounted on an axle 66 for rotation about a wheel axis 70. A bearing 72 may be used to mount the index wheel 58 to the axle 66.

The index wheel 58 has a plurality of outwardly extending slots 74 generally evenly spaced about its periphery 76 and substantially parallel to the wheel axis 70. The slots 74 receive fasteners 92 from the supply track 52. A pusher bar 80 extending from a pusher assembly generally indicated by reference 82 in Figures 2, 7 and 8 extends across the groove 64. The pusher bar 80 has a guide surface 84 at one end thereof facing the rotating die part 59. The pusher bar 80 is resiliently biased toward the rotating die part 59 by any suitable means such as a spring 86 acting between the pusher bar 80 and a pusher bar housing 88. Figure 8 illustrates the pusher assembly 82 with its cover 90 in Figure 7 removed for illustrative purposes.

The pusher bar 80 is provided to press the fasteners 92 out of the slots 74 and against the rotating die part 59. The pusher bar 80 thereby guides the fasteners 92 into a space 94 between the fixed die part 59 and the stationary die part 57. A semi-circular guide generally indicated by reference 100 in Figures 2 and 9 extends partially about the circumference of the index wheel 58 between the supply track 52 and the guide surface 84 of the pusher bar 80 to prevent ejection of the fasteners 92 by centrifugal forces arising from rotation of the index wheel 58. Drive means such as a pulley 102 in Figures 3 and 4 are provided to case the index wheel 58 to rotate in the direction of arrow 104, opposite to the direction of rotation of the rotating die part 59 indicated by arrow 106. Preferably the rotational speed of the periphery 76 of the index wheel 58 should correspond to that of the periphery 108 of the rotating die part 59 to ensure a smooth transition of the fasteners 92 into the gap 94.

The guide 100 has an entrance end 110 adjacent the supply track 52 and an exit end 112 adjacent the fixed die part 57. The contour of the guide 100 provides a gap between the guide 100 and the periphery 76 of the index

wheel 58 which is broader at the entrance end 110 and narrows toward the exit end 112. The broader portion of the gap enables acceptance of both straight fasteners 92 and bent fasteners 92 between the guide 100 and the index wheel 58. Straight fasteners 92 will pass unhindered between the guide 100 and the index wheel 58.

Bent fasteners will be initially accepted into the broader gap between the guide 100 and the index wheel 58 but will jam between the guide 100 and the index wheel 58 as the gap therebetween narrows. Accordingly the drive means for rotating the index wheel 58 should preferably be provided with a torque limited coupling to enable rotation of the index wheel 58 to cease in the event that a bent fastener 92 causes jamming between the guide 100 and the index wheel 58. In this manner a bent fastener 92 may be prevented from entering into the gap 94 between the fixed die part 57 and the rotating die part 59. Accordingly an opportunity is provided to remove the bent fastener 92 prior entry into and consequent damage to the deforming die 54.

A simple torque limited coupling may comprise a belt ( not shown) extending between a drive motor (not shown) and the pulley 102. More sophisticated commonly known torque limited couplings may also be utilized such as a friction clutch or a resiliently biased cam and cam follower driven arrangement such as commonly used for electrically actuated automobile aerials.

To assist in transfer of the fasteners 92 from the supply track 52 into the slots 74 in the index wheel 58, the periphery of the index wheel 58 is tapered inwardly along a tapered portion 75 into a leading face 120 of the slots 74. Opposite the leading face of the slots 174 is a trailing face 122 which is generally perpendicular to the direction of travel 104 of the index wheel 58 and extends radially outwardly beyond the leading face 120. Accordingly the

fasteners may move radially inwardly along tapered portion 75 to be snatched up by the trailing face 122.

The transfer device of the present invention feeds fasteners 92 in pre¬ determined spaced apart intervals into the deforming die 54. The pusher bar 80 avoids wear of the fixed die upon entry into the gap 94 which is inherent in the prior art arrangement. Furthermore the transfer device 56 of the present invention prevents entry of bent fasteners into the deforming die 54 thereby eliminating sorting of bent fasteners 92 previously required prior to loading of the fasteners 92 into the supply track 52. The action of the index wheel 58 and the guide 100 ensure that all fasteners 92 are perfectly aligned with the axis of the rotating part 59 of the deforming apparatus 60. Furthermore the fasteners 92 are accelerated up to the surface speed of the rotating part 59 to minimize any chance of cocking on transfer. Alignment time at any given feed rate is much greater in the transfer device of the present invention than in the prior art device. For example assume that the index wheel has ten slots 74 and five of those slots are at any given time opposite the guide 100. Each fastener 92 therefore has available for alignment the time that it takes to feed five fasteners in to the deforming die 56. In contrast the prior art device only allowed part of the time to feed one fastener into the deforming die for alignment.

The transfer device 54 of the present invention provides much better alignment of nails and can operate at considerably higher speeds than the prior art device while still maintaining high product quality. Prototype devices have been tested at 1300 fasteners per minute and it is expected that considerably higher speeds are possible.

For long life of the index wheel 5, it may be manufactured from ASP 21 steel hardened to 60R.

The transfer device 56 of the present invention was originally designed for nails however it is conceivable that other metal wire based fasteners may be transferred using such a device and accordingly the expression "fasteners" has been used to include nails and any other suitable fasteners.

The above description is intended in an illustrative rather than a restrictive sense. Variations to the specific description may be apparent to persons skilled in the relevant art without departing from the spirit and scope of the invention as defined by the claims set out below, it is intended that any such variations which fall within the scope of the claims be considered as part of the present invention and within the scope of the claims.