AU764022B2 - Powder discharge apparatus and method for using the same - Google Patents

Description

S&F Ref: 419586D1

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name and Address of Applicant: Actual Inventor(s): Address for Service: Invention Title: Nylok Fastener Corporation 15260 Hallmark Drive Macomb Michigan 48042 United States of America Richard J. Duffy, Eugene Sessa Spruson Ferguson St Martins Tower,Level 31 Market Street Sydney NSW 2000 Powder Discharge Apparatus and Method for Using the Same The following statement is a full description of this invention, including the best method of performing it known to me/us:- 5845c Powder Discharge Apparatus and Method for Using the Same Background of the Invention The present invention relates to a powder feeding apparatus. More specifically, the invention relates to an apparatus and method which convert a powder flow stream E originating from a single source into one or more continuous powdered resin streams.

When powdered resins are fused to articles such as fasteners to enhance their frictional engagement and to create self-locking fasteners, it is important to uniformly coat each individual fastener with an equivalent amount of powder. A uniform coating ensures that each individual fastener of a batch of processed fasteners will display the iJO, same performance characteristics which may include, among others, the same locking and torquing characteristics. Thus, improvements in the even distribution of powdered S resins directly enhance the performance and quality of the fasteners to which the powdered resins are applied.

Prior art approaches that attempt to improve the uniform distribution of powdered *1i resins to a system's spray nozzles are disclosed in U. S. Patent Nos. 4,815,414 and 5,571,323. U.S. Patent No. 4,815,414 discloses a system which uses a conical surface to direct the powder stream into a plurality of troughs for channeling the powder to the spray nozzels. U.S. Patent No. 5,571,323 teaches using an adjustable metering valve, among other structure, for controlling the amount of powdered resin supplied to the spray nozzles.

-1- Object of the Invention It is an object of the present invention to overcome or ameliorate some of the disadvantages of the prior art, or at least to provide a useful alternative.

Summary of the Invention There is firstly disclosed herein a self-locking double-ended stud, comprising: a first end and an opposing second end; l0 a first self-locking patch comprised of a coating of powdered resin material located on a select portion of said first end; a second self-locking patch comprised of a coating of powdered resin material located on a select portion of said second end; and said self-locking patches having different break-away torques as a result of 15 having different amounts of powdered resin material applied thereto.

o There is further disclosed herein a method for creating a double-ended stud having ends with different break-away torques as a result of having different amounts of S"powdered resin material applied to the ends, comprising the steps of: creating a first falling powdered resin stream by discharging powdered resin o 20 through a discharge port located on a powdered resin reservoir; positioning a first receptacle below said discharge port, said first receptacle adapted to receive said first falling powdered resin stream and further adapted to create a second falling powdered resin stream by discharging said powdered resin through a o discharge port; o o 25 positioning a second receptacle having a divider positioned between a plurality of hoppers below said discharge port of said first receptacle, said divider directing powdered resin that impinges upon said divider into the hoppers which are in communication with a corresponding plurality of passageways; dividing said second powdered resin stream into powdered resin streams containing disproportionate amounts of powdered resin by positioning said divider of said second receptacle relative to said discharge port of said first receptacle in a position that results in a greater amount of powdered resin being directed into one of the passageways; and directing said disproportionate powdered resin streams through said passageways and to spray nozzles for the application of said disproportionate amounts of said powdered resin to the ends of said double-ended stud.

[R:\LIBLL]08612.doc:zg Brief Description of the Drawings These and other features, objects and advantages of the present invention will become apparent from the following description and drawings by way of example only wherein like reference numerals represent like elements in the several views, and in which: Figure 1 is a front view of one preferred embodiment of the present invention; e [R:\LIBLL]08612.doc:lzg Figure 2 is a side view of a resin reservoir with portions removed to show the modified helix feeder contained therein; and Figure 3 is side view, in partial cross-section, of the embodiment shown in Figure 1; S Figure 4 is a front view of the embodiment shown in Figure 1 showing how the distribution of powdered resin is controlled by the rotation of at least one passageway; and Figure 5 is a front view of a double-ended stud manufactured by one preferred, embodiment of the present invention.

iO i Detailed Description Of The Preferred Embodiments *With reference to the drawings, the apparatus of the present invention is illustrated in one preferred embodiment for the application of resin powder onto S: threaded fasteners. While the illustrated embodiment makes reference to a fastener, the present invention is useful in coating a wide variety of threaded or unthreaded articles such as screws, bolts, studs, nuts or collars. The present invention may also be employed to apply a variety of coatings in the form of a gas-borne powder stream.

Such powders may include thermoplastic and thermosetting resins such as nylons, polyolefins, epoxies and teflons. In addition, the present invention expands and improves upon the powder dispensing system disclosed in our copending and -4commonly assigned application, US. Serial No. 08/779,684, filed January 7, 1997, (now US 6,004,627), which is incorporated by reference herein.

In accordance with a preferred embodiment shown in FIGURE 1, -powder feeding apparatus 10 includes a powdered resin reservoir 12 having a discharge port 14. As shown in FIGURE 2, contained within reservoir 12 is a feeder 80 that conveys powdered resin through discharge port 14. As shown, feeder 80 may be a helix-type feeder 80 or some other type of known feeder. A preferred feeder is an AccuRate® volumetric powder metering unit, available from Schenck AccuRate of White Water, Wisconsin. The AccuRate® feeder uses a helix to convey the resin powder through discharge port 14.

*'.00i Powder flow streams may also be developed by a variety of other volumetric and/or gravimetric powder feeders. Examples are screw feeders, belt feeders, rotary valve feeders and louvered feeders, as well as loss-in-weight and gain-in-weight systems. Any of these systems, as well as other powder flow systems known to those of ordinary skill in the art, may be used with and are within the scope of the present invention.

i Referring now to FIGURES 1 and 3, a first receptacle 20 is positioned directly below discharge port 14. Receptacle 20 includes a hopper 22 positioned to receive the powder discharged through port 14. Hopper 22 is in communication with tube 24, which defines a passageway 25 that terminates in a second discharge port 26.

Powdered resin exits discharge port 26 as a second powdered resin stream 102.

A second receptacle 30 is positioned directly below second discharge port 26.

Receptacle 30 includes a divider 32 that separates a first hopper 34 and a second hopper 36. Hopper 34 is in communication with tube 38, which defines a passageway 42 that terminates in discharge port 46. Resin exits port 46 as powdered resin stream 104. Hopper 36 is in communication with tube 40, which defines a passageway 44 that terminates in discharge port 48. Resin exits port 48 as powdered resin stream 106.

To convert powdered resin streams 104 and 106 into four powdered resin O streams, a third receptacle 50 may be provided. As with receptacle 30, receptacle includes dividers 52 and 54 which separate hoppers 56-59. Hoppers 56-59 are in o* communication with tubes 60-63, respectively, which define passageways 64-67. If additional powdered resin streams are desired, additional tiers of similarly constructed receptacles may be provided.

Passageways 64-67 can be connected to suitable structure to con.ey the powdered resin streams to the spray nozzles where the powder is applied to the workpieces. While gravity acts to draw the powdered resin through receptacles 20 and 30, a preferred manner in -6which to draw the powdered resin through receptacle 50 and to prepare it for spraying by thoroughly entraining the powder in the air steam is disclosed in this copending application.

Alternatively, receptacles 50, 30 and 20 may be encased, leaving hopper 22 exposed to the atmosphere, to assist gravity in moving the powder through the system more rapidly. Configuring the apparatus in this matter is helpful when spraying a large volume of powder.

Of course, if fewer nozzles are to be employed, persons of ordinary skill in the art will recognize that the above-described apparatus may be configured so that receptacle 20 is in direct communication with a spray nozzle. Alternatively, passageways 42 and 44 of receptacle 30 may also be in direct communication with a set of spray nozzles.

As is shown in Figure 2, a helix feeder 80 is contained within reservoir 12.

This feeder has a continuous helix conveyor that creates a pulse in the powder flow which results in the discharge of an irregular amount of powdered resin, on a perrevolution basis, through port 14. This results in an uneven application of powdered °resin onto an article to be sprayed.

To solve this problem, it has been discovered that placing a weir 90 in the path S'of powdered resin stream 100 at the throat of feeder 80 (see Figure 1) eliminates this 20 irregular flow of powder. The weir partially restricts the powder flow thereby producing a small amount of back pressure that is sufficient to provide a continuous and uniform stream of powder -7to the spray nozzles. This, in turn, results in a uniform application of material onto the article.

Weir 90 preferably only causes a slight amount of back pressure in order to avoid powder packing inside the auger. The resulting blockage of powder may not only Sinterrupt the powder flow, it may also damage the feeder itself.

As illustrated in FIGURE 1, weir 90 can take the form of an ordinary spring that does not need to be stretched across discharge port 14. We have found that for use with a discharge port having a one inch diameter, a spring having an outside diameter of five sixteenths of an inch, made of thirty-thousandths wire, and having eight turns per o i* °T inch is suitable for achieving the objects of our invention. All dimensions given herein will be inches.

.el.ei The spring is affixed to the device by uncurling each end of the spring and clamping the ends to the device. The spring is mounted so that the centerline of the eo spring is positioned slightly below the centerline of the discharge port in an unstretched S 5 configuration.

operation, as shown in FIGURES 1 and 2, feeder 80 conveys a stream of powder 100 through discharge port 14 and past weir 90. Weir 90, while permitting powder flow, also produces back pressure that compresses the powdered resin stream to convert the irregular flow created by the helix into a continuous, uniform flow of powder. This in turn creates, a first falling powder stream 100 that is continuously -8received by hopper 22 of receptacle 20. Gravity then causes the powdered resin to fall through passageway 25 where it is discharged by port 26 to create a second falling powdered resin stream 102 which falls upon divider 32 of receptacle Divider 32 uniformly splits powder stream 102 in half by diverting one-half of the stream to hopper 34 and the other half of the stream into hopper 36. The newly created powdered resin streams are then transported through passageways 42 and 44 where they are discharged through ports 46 and 48, respectively, to create falling powdered resin streams 104 and 106.

Powdered resin streams 104 and 106 then fall onto dividers 52 and 54, where "b the streams are further equally divided and directed into separate hoppers 56-59. The four resulting uniform powdered resin streams may then be conveyed by passageways 64-67 to additional receptacles for further distribution in the manner set forth above.

Alternatively, passageways 64-67 may be configured to convey the powdered resin

I

streams to four corresponding spray nozzles for application of powdered resin onto the articles. Persons of ordinary skill in the art will recognize that the present invention will also find useful application when an odd number of powdered resin streams are desired.

To help back pressure reduce pulsing of the powder at discharge, it is preferable to use a vibrator 110, as shown in FIGURE 1. In addition, to accurately divide a stream of powder it should be of constant cross section and direction, and be correctly aimed -9at the divider. As shown in Figure 3, these conditions are established by positioning tubes 24, 38 and 40 at an angle of about 300-450 to the horizontal. Angling the tubes allows gravity to consolidate the powder stream by concentrating the stream at the bottom of the tube.

For high volume, four powder stream applications, tubes 24, 28 and 40 were sized at 5/8 OD x 18 gage x 2 long. For a smaller volume spray application, such as processing nuts, a 3/16 OD x .016 wall x 1/ long tube worked satisfactorily.

In another application of the present invention, the amount of powdered resin t.at is distributed to the spray nozzles may be controlled and proportionally divided through the selective positioning of the passageways with respect to the devices they are located above. It has been found that at least one passageway may be rotated or pivoted to direct a greater proportion of the powdered resin stream to flow onto one side of the divider located below the discharge port of the passageway and into the corresponding hopper. This, in turn, provides an increased amount of powdered resin 1 to the spray nozzle that is in communication with the hopper.

For example, as shown in FIGURE 4, receptacle 20 may be rotated or pivoted about fastener 21 and towards hopper 34. This rotation directs a greater amount of the powder contained in powdered resin stream 102 down onto the side of divider 32 that feeds hopper 34. This, in turn, will result in powdered resin stream 104 having a greater proportion of powdered resin than powdered resin stream 106.

Of course, the device may be configured to create a greater proportion of powder in powdered resin stream 106 by reversing the procedure described above and having hopper 36 receive a proportionally greater share of powder from powdered resin stream 102. This same procedure may also be performed further along in the system at receptacle 30 or at any other point where a powdered resin stream is directed down onto a divider. Alternatively, the divider may be adjustably positioned with respect to the passageway and corresponding discharge port. By configuring our device in a manner described above, an operator may adjust the amounts of powdered resin flowing to each individual spray nozzle used by the system.

The ability to deliver different amounts of powdered resin to each spray nozzle may be used to create a double-ended stud that has two torque zones, with each zone having adifferent installation or break-away torque. As shown in FIGURE 5 and using the methods described above, a double-ended stud 110 may be created wherein selflocking patch 112 of end 114 has a greater amount of powdered resin than patch 116 Sof end 118. As will be appreciated by those of skill in the art, the greater amount of material applied to patch 112 will cause the break-away torque value for end 114 to be greater than the break-away value for end 118.

The ability to deliver different amounts of powdered resin to each spray nozzle may also be used in applications where it is desirable to apply successively larger or smaller amounts of powdered resin to a work piece. Thus, given the invention's ability -11 to deliver successively larger or smaller amounts of identical powdered resin to the spray nozzles, additional layers of larger or smaller amounts of material may be applied to a work piece, as compared with systems that deliver a constant amount of powdered resin to the spray nozzles.

SWhile the preferred embodiments of the present invention have been illustrated and described, it will be understood by those of ordinary skill in the art that changes and other modifications can be made without departing from the invention in its broader ~aspects, as described in the following claims.

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Claims (4)

1. A self-locking double-ended stud, comprising: a first end and an opposing second end; a first self-locking patch comprised of a coating of powdered resin material located on a select portion of said first end; a second self-locking patch comprised of a coating of powdered resin material located on a select portion of said second end; and said self-locking patches having different break-away torques as a result of having different amounts of powdered resin material applied thereto.

2. A method for creating a double-ended stud having ends with different break-away torques as a result of having different amounts of powdered resin material 15 applied to the ends, comprising the steps of: •creating a first falling powdered resin stream by discharging powdered resin through a discharge port located on a powdered resin reservoir; positioning a first receptacle below said discharge port, said first receptacle adapted to receive said first falling powdered resin stream and further adapted to create a S second falling powdered resin stream by discharging said powdered resin through a discharge port; positioning a second receptacle having a divider positioned between a plurality of hoppers below said discharge port of said first receptacle, said divider directing powdered resin that impinges upon said divider into the hoppers which are in communication with a corresponding plurality of passageways; S dividing said second powdered resin stream into powdered resin streams containing disproportionate amounts of powdered resin by positioning said divider of said second receptacle relative to said discharge port of said first receptacle in a position that results in a greater amount of powdered resin being directed into one of the passageways; and directing said disproportionate powdered resin streams through said passageways and to spray nozzles for the application of said disproportionate amounts of said powdered resin to the ends of said double-ended stud. -13- [R:\LIBLL]10395.doc:SSL

3. A self-locking double-ended stud, substantially as hereinbefore described with reference to Figure s

4. A method for creating a double-ended stud having ends with different break-away torques as a result of having different amounts of powdered resin material applied to the ends, substantially as hereinbefore described with reference to the accompanying drawings. Dated 21 February, 2001 Nylok Fastener Corporation Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON 0* 0 S O 0 -14- [R:\LIBLL 10395.doc:SSL