MXPA00004829A - Method and apparatus for application of 360 degree coatings to articles - Google Patents

Abstract

A method and apparatus for applying coatings to a portion of the internal bore or threads of a fastener or similar article having an opening on at least one end is provided. A 360 degrees coating with material is provided using centrifugal force to assist in direction the material to a desired surface, which does not require use of a pressurized air stream in orderto propell the coating material toward the walls of the article desired to be coated.

Description

METHOD AND APPARATUS FOR APPLYING 360 ° COATINGS TO ARTICLES BACKGROUND OF THE INVENTION This invention relates generally to a method and an apparatus for applying coatings to fasteners having internal holes. More particularly, the present invention relates to a method and an apparatus for applying powder coating materials to portions of the internal diameter of a fastener or similar article that is open at at least one end, using mainly centrifugal force, instead of a air stream to propel the coating material towards the surface of the fastener, in order to form a 360 ° coating on it. Various methods and apparatuses have been described in the prior art for applying powder coatings to articles such as fasteners. Most of these efforts have been directed towards the application of coatings to fasteners having an external threaded surface. Since the threads of the bra that is REF .: 33159 > To be coated, they are in such cases fully exposed, they do not possess the increased difficulty that is present when it is desired to provide coatings on fasteners or threaded articles having internal diameters or threads. Existing solutions to provide a 360 ° coating on internal threads or an internal diameter of a fastener have been problematic and inefficient to date, giving result inconsistencies and increased production costs. In most of these prior devices, the internally threaded fasteners to be coated are first heated and then a nozzle is inserted into the opening threaded, which distributes dust particles entrained in a stream of air which merge and coalesce when they come into contact with the hot threads of the fastener. Typical of such systems is the apparatus described in the Patent of the United States No. 4,835,819. In this device, a significant air pressure is required to be induced through a network of spider-shaped tubes exiting at the end through the small nozzles at the end of the tubes directing the coating material towards the threads of the - • "* ~» a * - - "'-' - - * - fastener. The generation of a current of air under significant pressure required by such systems is expensive and difficult to regulate. Having to divide the generated air stream equally into multiple tubes also adds problems. This is particularly true given the small size diameters of the tube and the nozzle openings when small, internally threaded articles are being processed. The device also requires the powder to change direction multiple times during its trip in the air stream through the nozzle tube. Again, given the dimensions, these systems have been susceptible to regular plugging of the tubes or nozzles, as well as inconsistent powder flow. The force generated by the air stream against the internal walls of the fastener is significant and requires that the entire outer surface of the fastener be surrounded by an accessory in order to prevent horizontal movement in the fastener during processing due to this force. Various other types of methods and apparatus for the formation of 360 ° coating on internal diameters or fastener threads have also traditionally been used. For example, U.S. Patent No. 4,865,881 discloses an apparatus and a process for making securing slide nuts. In this device, an opening of the fastener is filled with securing material in a quantity significantly greater than the amount required to form the coating of the threads. A non-rotating free-space spike is inserted into the opening to attempt to direct material into the area of the fastener adopted for internal threading before heating, and remain in that position while the fastener is heated and the coating material adheres as expected to the internal walls of the fastener. The slack pin may then have to be used selectively to clear a passageway through the securing material, either before or after the heating step. In this device, although the slack pin serves to divert some of the dust towards the walls of the internal opening of the fastener, it does so with insufficient force to maintain a significant amount of that dust against the walls. In addition, any vertical movement of the slack pin after the coating has been formed can easily detach the entire coating from the desired area of the internal opening of the fastener. 5 U.S. Patent No. 4,891,244 discloses a method and apparatus for making self-securing fasteners using a mechanical propelling device which comprises a rotary deflector or sling. The sling or deflector drives the particles by centrifugal force against the hot threaded surfaces of the fasteners. This device, however, only contemplates the coating of threaded fasteners on a circumference of 180 ° or less.

The system also requires that the powder be fed and confined in four tubes of small diameter at different vertical heights that are circumferentially spaced every 90 ° along the disc, in order to be discharged towards the surfaces of the fastener. The faceless surface requires the disk to be of a large diameter, in order to accelerate the dust particles at a rate that will spray horizontally over the significant distance from the baffle towards the surface of the bolt. Speed The increased dust imparted to the dust particles causes the vast majority of dust to deviate from the fastener, contributing to inconsistent powder flow and inconsistent coating results. disadvantages described above with respect to the prior art devices, none of these devices had the ability to apply two different powder coating materials to a single fastener during the coating process.The previous known systems also fed significantly more coating material in powder to the threads that eventually ended up coalescing and forming the coating.This increased the frequency of dust flow problems when this excess powder was collected and eventually recirculated.It is apparent, therefore, that there is a need to be able to form 360 ° coatings on items such as fasteners that has n Open internal diameters in at least one end or threads, without the need to drag the powder coating material in a pressurized air stream. i = JÜ? - ~ * ^ »» - * - • - «-..- ^ .. i, *, t-áL -_- S.

BRIEF DESCRIPTION OF THE INVENTION The present invention overcomes the deficiencies of the prior art by providing a method and apparatus for applying 360 ° coatings to the internal diameter or threads of a fastener or similar article, in a consistent manner without requiring the use of an air stream to direct the dust into the hole or threads. An object of the present invention is to provide a method and an apparatus for applying 360 ° coatings to the inner diameter or threads of a fastener or similar article, which does not require the coating material to come out of a tube when it is directed to the area desired that is going to be coated. A further objective of the present invention is therefore to provide a method and apparatus that achieves the above result in a consistent, effective and low cost manner. Yet another object of the present invention is to provide a method and apparatus for applying 360 ° coating to the internal diameter or threads of a fastener or similar article, which allows a faster production speed of - "S-J" -. ----- such fasteners or articles as the known prior devices.Another objective of the present invention is to provide a method and an apparatus for applying coatings of 360 ° to the internal diameter or threads of a fastener or similar article, which provides an inspection and / or removal station on the device itself, to remove any coated articles that may be rejected Another yet further object of the present invention is to provide a method and apparatus capable of applying coatings 360 ° of the powder materials to the inner diameter or the threads of a fastener or similar article, using a lower particle speed and lower heating temperatures.Another objective of the present invention is to provide a method and an apparatus for apply 360 ° coating to the internal diameter or the threads of a fastener or similar article, which is capable of providing coatings of two or more different types of materials on the same fastener during a cycle of the device. A further object of the present invention is to provide a method and apparatus for applying 360 ° coatings to the internal diameter or threads of a fastener or similar article, which provides a continuous simultaneous stream of coating material directed towards the complete surface of 360. ° of the article in a prolonged period of time. Yet another object of the present invention is to provide a method and apparatus for applying 360 ° coatings to the inner diameter or threads of a fastener or similar article, with stations for cleaning and / or oiling the device during each rotation of the device. Yet another object of the present invention is to provide a method and apparatus for making coatings on fasteners having an internal diameter open at least at one end, wherein virtually all of the coating material fed to the fastener terminates on the fastener and does not need to be recirculated. These and other objects are met by a method and apparatus for making coatings on fasteners having an open internal diameter at at least one end, wherein the coating material is distributed without requiring the use of an air stream and forms a coating of 360 ° on it in a desired, predetermined locationBRIEF DESCRIPTION OF THE DRAWINGS The novel features that are characteristic of the present invention are described in the appended claims. The invention itself, however, together with its intended objectives and advantages will be better understood by reference to the following detailed description, taken in connection with the accompanying drawings, in which: FIGURE 1 is a perspective view of one embodiment of the apparatus of the present invention. FIGURE 2 is a top, diagrammatic view of the apparatus shown in Figure 1. FIGURE 3 is a perspective view of a typical internally threaded fastener containing a coating of self-insuring material applied using the present invention. FIGURE 4 is an enlarged view of the material distribution portion of the apparatus. FIGURE 5 is a top and partial plan view of the loading station and the nesting plate of the apparatus of the present invention. FIGURE 6 is a diagrammatic cross-sectional view of the material application station of the present invention, in its retracted position. FIGURE 7 is an enlarged view of the loading portion of the cam system of the apparatus of the present invention. FIGURE 8 is a side perspective view of the band drive system of the apparatus of the present invention. FIGURE 9 is a partial cross-sectional view of the powder application station of the apparatus of the present invention. FIGURE 1AA is a perspective view of an embodiment of a spike used by the present invention. FIGURE 10B is a perspective view of another alternative embodiment of a spike used by the present invention. FIGURE 10C is a perspective view of an alternative embodiment of a spike used by the present invention.

, ...............- "» .- FIGURE 10D is a perspective view of an alternative embodiment of a spike used by the present invention. FIGURE 1AA is a partial cross-sectional view of the spike illustrated in Figure 10A, applying coating material to the threads of an internally threaded fastener, in accordance with the apparatus of the present invention. FIGURE 11B is a partial cross-sectional view of the spike illustrated in Figure 10A, applying coating material to the threads of an internally threaded fastener at an increased rotational speed. FIGURE 12 is an enlarged side view of the rear or drive portion of the cam assembly of the apparatus of the present invention. FIGURE 13 is an enlarged side view of a parts ejector associated with the apparatus of the present invention. FIGURE 14 is an enlarged side view of the station for removing parts of the apparatus of the present invention. FIGURE 15 is a top plan view of the drain of the present invention illustrated in Figure 14.

FIGURE 16 is a partial cross-sectional view of the vacuum station of the apparatus of the present invention FIGURE 17 is an enlarged side view of a portion of the vacuum station illustrated in FIG. 18 is a partial side cross-sectional view of the lubrication station of the apparatus of the present invention, FIGURE 19 is a diagrammatic top plan view of yet another embodiment of the apparatus of the present invention FIGURE 20 is a graphic illustration of the exemplary results achieved using the present invention.

DETAILED DESCRIPTION OF THE INVENTION Referring now to the drawings and in particular to Figure 3, a typical, internally threaded fastener is illustrated, which has had a 360 ° coating of molten powder material, a nylon patch, deposited thereon in accordance with with the present invention. A nylon patch is illustrated as an example - »- J of only one of the many different types of coatings that can be achieved in connection with the use of the method and apparatus of the present invention. It should be noted that the present invention can be beneficially used to deposit all kinds of fine powder materials on a variety of different articles. The coating materials deposited by the present invention can serve various purposes including, but not limited to, the masking, isolation, lubrication, adhesion and / or increase of the torsional resistance of the articles, when they are coupled. A particularly preferred use of the present invention is to deposit powder materials of the thermoplastic type such as nylon 11 or fluoropolymers on a succession of discrete articles such as internally threaded fasteners, in order to give them self-insuring and / or isolation characteristics. It should be understood that the present invention can also be used beneficially in connection with a wide variety of other fasteners or articles having an internal diameter that is open on at least one end. It should be understood, therefore, that although the invention will be described in detail below with respect to the application of the powder material on the threads of an internally threaded fastener, it is intended that this terminology is not limiting and is used as a generality for any metal article having an internal opening open on at least one end, and for applications and any type of powder coating material according to the present invention. Referring now to Figures 1 and 2, the apparatus of the present invention is generally described. In its most preferred embodiments, the apparatus 10 includes a charging station 14, a material application station 16, a parts purge station 18, a parts removal station 20, a cleaning station 22 and a cleaning station 24. lubrication, circumferentially spaced around a marker disc 11. In such embodiments, the fasteners 12 are preferably preheated and loaded onto the device in station 14. After this, the disc 11 continues to rotate. The coating material is applied to the station 16, the coated fasteners 12 immediately pass to a ? _______________ l ____-- ^ _ ^ _ ^ _-- U _-- purge station 18 where these can be inspected on disk 11 and the rejected fasteners can be simultaneously removed. The fasteners 12 continue to rotate on the disk 11 until they are removed in the station 20. The disk 11 continues its rotation past the cleaning station 22, where any dispersed coating material is removed before the time in which the apparatus 10 complete a complete revolution again up to the charging station 14. A lubrication station 24 can be provided to lubricate the applicators 50 of the apparatus 10 without removing them or stopping the rotation of the disc 11, as will be described later. With reference now to Figures 1, 2, 4, and 6, the present invention will be described in more detail. In the preferred embodiments, the fasteners 12 are first accommodated before they are introduced onto the upper part of the disc 11, so that their openings are similarly oriented and the edges of the successive fasteners 12 are in contact with each other using a vibrating bowl 26 or similar device known. The fasteners 12 exit the bowl 26 on a downward sliding guide 30 which 'feeds the fastener 12 towards the disc 11. Along the length of the downward sliding guide 30, the fasteners 12 can be heated in any way well. known by 5 those of ordinary experience in the art. Although the fasteners could be heated while they are on the disk 11, heating them on the downward sliding guide 30 is beneficial, since this provides more space as disc length for other operations and further reduces exposure and heat buildup in the pins 72 and other parts of the apparatus 10. An induction heating coil 28 is preferably used to preheat the fasteners as they move along the downward sliding guide 30. The energy for the induction coil 30 is regulated to adjust the temperature of the fastener. This allows the preheating of the fasteners to different temperatures, depending on the requirements of a particular situation, to fuse the powder coating materials to the fasteners. The sliding down guide 30 has upper and lower sections 32 and 34 that are - * "-» - * - *** --- • < made of steel These sections are connected to an intermediate section 36 made of non-ferritic material, preferably a phenolic material. area of the sliding guide 30, around which the heating coil 28 is wound. This is due to the fact that the phenolic materials are not heated due to the electromagnetic field of the induction coil 28. The fasteners 12 are automatically supplied to the nesting or nesting plate 38 for the exhaust or drain 40. The exhaust or drain 40 can use either a cam and a spring or an optical sensor and a spring, in order to distribute a simple fastener to each of the bags 60 of the nesting plate 38, as they rotate past the drain 40. Alternatively, as illustrated in Figure 5, the drain or exhaust 40 can utilize back pressure generated from the feed of the fasteners. the bowl 26 on the slide guide 30, the force of gravity acting on the clips on the angled portion of the slide guide and the configuration of the bags 60 alone, to distribute a single clip 12 within each of bags 60 of the plate 38. In this embodiment, the front sliding guide 41 of the sliding guide 30 terminates at a short distance from the outer circumferential edge of the plate 38, while the rear sliding guide 42 terminates at a short distance. distance from point 31. Apparatus 10 characterizes a disk 11 that includes plates 46, 38 and 44, respectively. The disc 11 preferably includes a base plate 46, which is secured to a variable speed motor 47 in a manner to allow rotational movement of the plate. The outer periphery of the plate 46 is provided with a series of equally spaced apertures 52. As can be particularly observed in Figures 1, 6 and 9, for example, each of the openings 52 includes a bushing 56. Each bushing 56 in turn accommodates and allows an applicator 50 of material to rotate both 360 ° and move vertically to a limited degree. The base plate 46 further provides the walls 54 on both sides of the upper portion of each opening 52. In certain preferred embodiments the area between the walls 54 around each opening 52 is also closed from the interior of the plate 46. The walls 54 can optionally also defining a series of slots 49 equally spaced, facing the center of the disk. The nesting plate 38 is connected to the base plate 46 and its outer edge rests on a portion of the walls 54 of the plate 46. The nesting plate 38 has holes 58 equally spaced around its periphery. Each orifice 58 is aligned with an opening 52 of the base plate 46. Each of the holes 58 is of suitable dimensions to make it possible for the upper portion of a material applicator 50 to pass therethrough without contacting the sides of the device. orifice 58. A bag 60 is located around the inner portion of each of the holes 58 of the nesting plate 38. Although the bags 60 can take a variety of configurations or geometries, a preferred design for nesting and accommodating the fasteners internally threaded, such as nuts with flat outer sides, is illustrated in Figure 5. These bags 60 in the form of a semicircular shell, allow a nut to be slid therein without requiring any additional guidance. The radius of the semicircular bags 60 keeps the center of the fasteners in line with the axis of the _____________ holes 58 and applicators 50. Each bag 60 further preferably contains an angled edge 62 which further aids in removing fasteners 12 from plate 38 once they have been coated, as will be described in more detail below. The funnel plate 44 is located above the nesting plate 38 and is connected to the base plate 46 so that it rotates at the same speed as the plates 46 and 38. The plate 44 includes a plurality of cavities 64 in shape funnel spaced evenly around its outer periphery. As can be seen with reference to Figures 1 and 4, the cavities 64 are uniformly spaced one against the other with a substantial amount of overlap. This allows a continuous flow of powder coating material to be deposited in the successive cavities 64 as the plate 44 rotates past the application station 16 without creating dead spots or deposit of coating material at any other site than the internal part. of the cavities 64. As an additional aid to this desired result, as illustrated in Figure 4, the center of the wall 66 between the successive cavities is preferably shorter than the rest of the upper wall of each cavity 64. The cavities 64 accept coating material that is directed downwardly from the application station 16. The material leaves the cavities 64 through a discharge hole 68 in the bottom of the cavity under the force of gravity. The exact geometry of the shape of the cavity is influenced by several factors. It is generally desirable to have the fasteners 12 as close as possible to the plate 38 to allow smooth flow of the fasteners 12 from the downward slide guide 30 and also to maximize the number of fasteners that can be processed at a given disk speed. . It is widely understood in the industry that wall angles that are at least about 60 ° from the horizontal are beneficial for the efficient flow by gravity of the powders from the funnels or the cones. A value above 60 ° is in many cases even more preferred. The more tightly fastened or nested fasteners are on plate 38, however, the angles of cavity 64 are potentially higher. Higher cavity angles result in a smaller objective for the coating material to fall within a shorter exposure period at a given disk rotation speed. If the angles of the wall of the cavity greater than 60 ° are used, then the performance of the powder can be continuously spread over a longer length of the cavities in the path as it rotates, as will be described in detail below. The size of the discharge orifice 68 of each cavity 64 is also important. To a greater degree, the smaller the discharge orifice, the more precisely is the powder current passing through the cavity 64, which can be directed to the absolute center of the rotating pin 70 below, resulting in the more consistent centrifugal throwing of the powder. The goal is to utilize a discharge port 68, of efficient size to ensure that the powder is allowed to fall into the cavity 64 and does not bounce above the discharge orifice 68, but rather to fill instantly instantaneously through the orifice. In this way, it is not intended that the cavity 64 be the storage device that is filled and then emptied over time. If this were the case, then common flow problems displayed in the prior known devices could be introduced due to dust moisture and powder packing, for example, resulting in inconsistent powder flow and inconsistent coating results. The preferred method of operation, therefore, is to gradually dose the powder into the cavity 64 with a discharge orifice 68 that is large enough to allow the powder to come out quickly, which is still small enough to confine the current to the center of the pin 70 as it falls into the hole. It has been found, for example, that when the present invention is used to introduce 360 ° nylon self-bead patches onto the M-10 nuts, the outlet orifice is preferably approximately 1.93 mm (0.076 inches). When the same coatings were placed on M-20 nuts, the diameter of the discharge orifice is preferably about 2.54 mm (0.100 inches). As previously described, there is an applicator 50 associated with each of the cavities 64. Each of the cavities 64 is designed to direct the powder coating material to an individual applicator 50. As indicated, for example, in the figures 5 and 6, the applicator 50 has an axis 72 with a knob 74 at the lower end of the shaft, and a peg 70 at the upper end of the e e. The shaft 72 is articulated in a bearing or sleeve 56 that allows linear and rotational movement of the shaft, as illustrated. A flange 76 is provided on the shaft 72 to limit downward travel of the spigot 70 and assist in keeping any loose powder material to prevent it from entering the bearing 56. Any of a number of widely known bearings could be used, such as a standard bronze bearing A particularly useful bearing or bushing has been found to be a brass bearing made of a sintered material such as bronze impregnated with oil. Since this bearing is self-lubricating, it prevents seizure if the bearing is even covered by dust. A bearing of this type that shows these characteristics is commercially available under the trade name Oilite®, from Beemer Precision, Inc., of Ft. Washington, Pennsylvania. The knob 74 is intended to be coupled to the drive belt 88, rotating, adjacent via friction and pressure that positively drives it towards the desired rotational speed. The outer surface of the knob 74 is preferably knurled to increase the friction between the drive belt and the knob 74. The knob 74 could have a diameter that is as small as that of the shaft 72 of the spike if the bags are tightly spaced apart. along the plate 38. In the most preferred embodiments, however, the knobs 74 have a diameter greater than that of the shaft 72 of the pin, in order to allow the creation of more drive torque. Each knob 74 also has a raised end 80 designed to be coupled with a cam plate 82, for raising and lowering the applicator 50 on the bearing 56. The spindle shaft 72 characterizes a pin 70 at the opposite end of the knob 74 It is the pin 70 that rotates and retains the powder coating material under the centrifugal force towards the surfaces of the fastener 12 to be coated. The pins 70 are preferably made of solid steel rods, with the retaining end being ground, constructed or cut with facets, grooves or ridges. As will be described in more detail below, the revolution speed of the spout 70 and the articulation of the spigot surfaces influence the direction and pattern of the material retained towards the threads of the fastener, causing the patch applied thereto to be thinner or thicker. The diameter of the pin 70 is preferably about 65 to 85% of the internal diameter of the fastener that is coated. Free space must be left to compensate for any vibration in the ratio of the bearing 56 and spindle axis 72 and the tolerance of the bags 60 to the fasteners 12. Also, any powder material that does not adhere by itself to the walls of the fastener 12 after it has been centrifugally directed by the applicator 50, it must have a space that makes it possible for it to fall vertically downwards under the force of gravity, and in the end, it has recovered. If desired, the recovered powder can be automatically recirculated to the hopper 83 using recognized vacuum collection systems. It should be understood that the pins 70 can be rotated either clockwise or counterclockwise with similar results. The length of the applicator 50 is important within certain broad parameters for the proper operation of the apparatus 10. At a minimum when the applicator 50 is in its lowered, or retracted position, as illustrated in Figure 6, the upper part of the spike 70 must be below the floor 78 of the bag 60 to allow the fastener 12 to be fed unhindered into or out of the bag 60 by a simple horizontal sliding movement. In the most preferred embodiments, the applicator 50 is lowered so that the upper part of the peg 70 rests very well below the bottom of the nesting plate 38. When the latter is not rotating and applying coating material, it provides a improved opportunity to cool the spike of any heat that has radiated accumulated while the shank 70 was in its elevated position within a hot fastener 12. This further facilitates the cleaning of the shank 70 of any loose powder between the applications of the material of coating using an air jet or a vacuum without having to remove the applicator '50 from the disc 11 as will be described later in detail. The applicator 50 also needs to be long enough to be raised by the cam plate 82 to the highest coating position required for the particular fasteners, to be processed by the apparatus 10. A barrel nut, for example, may need a patch or layer in a much higher position of the 78th floor of the bag 60 than a standard nut. The unique features and details of the apparatus 10 will now be described by tracking the trajectory of a fastener 12 processed with a 360 ° coating by the present invention. Referring now to Figures 1, 2, 5 and 6, since the fasteners 12 pass through the induction coil 28 previously described, and reach the exhaust 40, they have usually been heated to a temperature above the point of softening of the coating material that will subsequently be applied to them. In the case of nylon coating powder 11, for example, fasteners 12 are usually heated to a temperature of about 177 ° to 204 ° C (350 ° to 400 ° F). As described in detail below, the efficiency of the simultaneous application at 360 °, of lower speed of the powder, has allowed the use of temperatures somewhat lower than the previous known systems. The exhaust or drain 40 distributes a fastener 12 to each of the bags 60 of the nesting plate 38, as they rotate past the exhaust. The exhaust 40 places a fastener 12 in the bag 60 so that the internal opening of the fastener 12 is centered over the hole 58 of the nesting plate 38. In addition, the flat sides 13 of the fastener 12 engage a portion of the wall 84 of the bag in order to ensure proper centering. As a result, the fasteners can be fed onto the plate by simply sliding them into the bag 60 without further guidance, since the radius of the bag 60 keeps the fastener centered in line with the axis of the pin 70 below. It is further important to note that the present invention does not require the nesting or snapping of the fasteners with a static outer grille on all sides of the fastener, or requires that the walls 84 of the bag fit precisely to the configuration of the sides of the fastener 12. In many previous systems, it was necessary to surround and make contact with the fastener very precisely on all sides, in order to rotate either the fastener as the coating material was applied., or resist the force of the powder applied from a nozzle having a directional velocity that could otherwise cause the fastener to move. Since the applicators 50 of the present invention utilize centrifugal force, rather than a pressurized air stream, to distribute the powder particles towards the internal walls of the fastener, this is not necessary in the present invention. In addition, the centrifugal application method of the present invention causes the particles themselves to be diffused simultaneously in all directions creating a canceling force around the entire 360 ° internal surface of the fastener. Furthermore, in the present invention, the fasteners are held stationary during the entire material application process, and do not require any type of rotation. Once the fastener 12 is placed in the bag 60 with the disc 11 rotating, an optional centering device, such as a static bar 86 or a spring guide, can also be used to push the fastener 12 into its bag 60 to further ensuring that it is centered above the hole 58 in the nesting plate 38, as illustrated in Figure 6, with the fasteners 12 nested in the bag 60. At this point in time, the applicator is in its full position retracted, not rotating. As the disc 11 continues its rotation, the raised end 80 of each applicator 50 is brought into contact with the cam plate 82. As particularly illustrated in Figures 7 and 9, the cam plate 82 is angled to lift each applicator 50 vertically from its fully retracted position to its fully extended position as the disc rotates. In its fully extended position, the upper part of the peg 70 is completely within the opening of the holder and is vertically above the floor 78 of the bag 60. The cam plate 82, therefore, serves to raise the peg 70. at the desired height within the holder 12 before the powder begins to fall into its corresponding cavity 64. A variety of different designs can be used for the cam plate 82 depending on the desired result. In a preferred design, the cam plate 82 is a single piece of curved steel on which the ends 80 of the applicators 50 travel, with the plate 82 having two variable height settings, one at each end. Depending on the desired result, the plate 82 can be adjusted to bring the pin 70 upwards, then hold it level, then lower it to the fully retracted position. Alternatively, the cam plate 82 could be tilted so that the pin 70 is continuously rising or falling as the end of the pin is in the opening of the fastener. In addition to the shape of the upper end of the shank 70 having influence on the width of the applied 360 ° patch or layer, any shank 70 that moves up or down while receiving the powder also tend to widen the layer or patch . Once the applicators 50 are in their fully extended position, they should be rotated before receiving any powder coating material from the cavity 64. The rotation of the disc 11 then causes the knobs 74 of the applicators 50 to engage with each other. a band 88 along a defined length of its arched path. The band 88 contacts and rotates with several knobs 74 at a time. The band is driven by a variable speed d / c motor at a revolution speed set by a remote digital meter. The web tension is controlled by the adjustment of the position of a idler 92. The web 88 can be made of any material, such as a rubber compound, which exhibits sufficient frictional qualities against the knobs 74. It is preferred to use a synchronization style or toothed band in order to provide a positive drive of the band 88 by the motor, without any skidding. The number of applicators 50 that have to be coupled by the band 88 is directly related to how long it is desired to have the dosage of the powder or to continue the application. For example, some parts requiring large, heavy layers or patches may require a longer powder feed time and, therefore, require a longer turning distance. The construction of the present invention can provide a much longer rotation or application distance than those required to obtain industry standard torsion values on an M-10 nut unit. It may be understood by those of ordinary skill in the art that reciprocating spinning designs, such as a chain that engages two sprocket wheels at the end of knobs 74, could also be used. As the disc 11 continues to rotate the fasteners 12, they go to meet the material application station 15. It is here that the coating material such as, for example, nylon powder is continuously fed to the successive cavities 64 in a pulse-free direct current. Although a variety of different known powder feed mechanisms could be used, a particularly preferred powder feed mechanism is a rotary bowl feeder 94, as more fully described in U.S. Patent No. 5,656,325, the description of which is incorporated by reference herein. It is known that the use of such feeding mechanism produces a consistent, pulsed, continuous flow of powder. The powder material can be directed downwardly from the outlet of the feeder 94 under the force of gravity by a tube 96 whereby a concentrated stream of powder is delivered to the cavities 64. Alternatively, the discharge of the feeder 94 can be supplied over a wider area through the use of hinged sheet metal. The use of extended length nozzles (greater than 3.81 cm (1/2 inch)) in the art for applying nylon powders to externally threaded fasteners, has proven superior to the use of either a single short nozzle or multiple nozzles of the same small size. Such single or multiple short nozzles have had difficulty in supplying dust and in making a suitable nylon patch or layer when the fasteners are passed at a high speed. In the present invention, the limitation of the cavity of a small diameter can be overcome by the continuous supply of powder to the cavity over a greater length of the path or path of each cavity. In this way, the powder could be dosed to the rotating pin 70 for a longer period of time. In the present invention, multiple discrete streams from a bowl feeder or multiple streams from a multiple bowl feeder could be directed within a step cavity 64, either without any delay between the currents or with a delay between the currents Subsequent, to allow the substantially complete melting of the first amount of powder applied between the application of the two streams. This also allows the possibility in the present invention of applying a binary coating composed of a patch or base layer of material such as nylon, followed by a thin top coating of a lubricant such as molybdenum or Teflon. The present invention allows only the application of multiple dissimilar materials to form a single coating in a passage of the disc 11. The dispersion of the powder flow of each cavity 64 over a longer distance from its arcuate path also provides another potential benefit. As previously described, it is often desired to nest or fit the fasteners 12 on the nesting plate 38 as tightly as possible. Such nesting or fitting requires higher cavity wall angles, resulting in a smaller objective for the powder to fall from within the cavities 64 for a shorter exposure period at a given rotation speed. The application of the powder to the cavities 64 over a larger portion of the arcuate path of each cavity, allows all the benefits of tighter nesting of the fasteners, higher cavity wall angles, and a longer period of time for the powder is fed into the cavities 64. This, in turn, requires less disk speed to achieve a given production speed. As the powder is applied to each cavity 64, it is directed through the discharge orifice 68 in a continuous stream with no reinforcement above the orifice. The powder is emptied after the hole 68 and is directed to the center of the rotating pin 70 which centrifugally holds the powder towards the internal threads of the hot fastener 12, to form a coating on it. A wide variety of different spike shapes can be used. A particularly preferred form in the formation of 360 ° nylon coatings on a preselected number of threads of the internally threaded fastener has been found to be a spike with a four-sided faceted top at 45 °, with a point central as illustrated in Figure 10A. Other exemplary, preferred spike designs are illustrated in Figures 10B to D, respectively. The designs may include grooves, facets of acute angles, points, rounded depressions or combinations thereof. Previous centrifugal devices for the application of powder material to fastener threads used large-diameter, faceless rotating discs, which needed to accelerate the powder particles at a high speed in order to allow the particles to travel horizontally over a significant distance to the surface of a bolt. The rotating pins of the present invention are compact in design and frequently use facets or similar forms, in order to accelerate the particles towards the fastener. The distance from the spikes and facets to the inner surface of the fastener is very small. As a result, a lower speed is needed to propel the particles, and fewer particles bounce off the surface of the fastener once they are in contact with it. As a result of the use of the powder feed system of the present invention, less dust deflects the fasteners during the application process and a smaller capacity vacuum is required to contain, collect or clean the machine from dust particles that are not adhere during the application process than previous systems. In addition, the simultaneous 360 ° retention of the powder creates a layer or patch on the fastener faster than a spray nozzle, which is directional. This also allows for faster processing speeds and more efficiency, by applying powder around the full 360 ° circumference at a given time after the fastener leaves the heater. The revolution speed of the pins 70 also seems to have an effect on the application of the powder. Preferred speeds for the pins, such as those illustrated in Figures 10A to 10D, are usually in the range of 1,000 to 2,000 rpm. Figures HA and 11B illustrate what is believed to be the influence of a spike shape and two different revolution speeds thereof on the last formed patch or layer. In general, the higher the rotation speed of the spike 70, the wider the patch or layer formed. Referring now to Figures 2, 12 and 13, as the disc 11 rotates to a position where the powder is no longer applied to a cavity 64, the knob 74 moves out of contact with the web 88 and ceases rotation. At the same time, the rear end of the cam plate 82 is angled downwardly causing the applicator 50 to defend its fully retracted position where it is no longer in contact with the cam plate 82. As the disk continues to rotate, the fasteners 12 with the coating material now applied to their internal threads, are immediately found with the part purge station 18. There are scenarios in which poorly or incompletely processed parties can exit processing and be intermixed with acceptable parts in a collection tray at the part removal station. For example, to achieve uniform heating of the fasteners, they must all spend the same amount of time coming through the induction coil 28 on the downward sliding guide 40. In addition, each of the fasteners 12 must rotate between the charging station 14 and station 16 for applying material in the same amount of time to further ensure that they are all at the same temperature when the powder or other coating material is applied to them. Interruptions in the feed fasteners due to a failure or clogging in the down slide guide 40 or the disk 11 or an induction heater of malfunction, can also introduce potentially heating inconsistencies. Further, if the disc 11 is even stopped, and then actuated again, it is likely that the fasteners 12 already on the machine from the start of the induction coil 28 to the station 16 for applying the material, should be rejected. In order to achieve this purpose, a logic controller 98 triggered by a signal from the charging station 14 and / or from another source such as one or more optical sensors, are used in combination. Each time the device 10 is started, the sensor 100 counts a preselected number of fasteners and sends a signal to the pneumatic actuators 102 to lower the purge gate 104, to remove these fasteners from the plate 38 for subsequent inspection. further, in order to determine whether sufficient coating material or a layer or patch is present on the predetermined internal surface of the coated fasteners 12, an optical sensor such as the sensor 101 can be used to inspect the presence of a sufficient layer of material of coating. If a sufficient layer is detected, then the gate 104 remains open, allowing the coated fasteners to continue on the disk 11 towards the removal station 20. However, if the sensor 101 detects an insufficient layer present on the fasteners, a signal to the pneumatic actuators 102 to lower the purge gate 104 to remove the fastener on which the insufficient layer was detected, as well as the additional surrounding fasteners, if desired. Although a variety of different commercially available devices can be used to achieve the purposes of the purge station 18, it has been found that a SunX FX-7 optical fiber sensor, manufactured by SunX Trading Company Ltd., of Tokyo, Japan, a Keyence PZ101 photoelectric sensor manufactured by Keyence Corporation of Tokyo, Japan, and the solid state synchronizers, digital counters and photoelectric switches sold by Omron Corporation, of Kyoto, Japan, under Models Nos. H7CR, H3CA and E3A2 have worked effectively . When a start or reject restart condition is detected by the part purge station 18, the gate 104 will be lowered to engage the required number of fasteners 12 by forcing them out of the plate 38. As the plate 11 rotates past the station of purge 18 only the appropriately coated fasteners 12 remain in the bags 60 of the plate 38. The rotation of the disc 11 then leads the coated fasteners 12 to the removal or removal station 20. As illustrated in Figures 14 and 15 in the removal station, the upper portion of the fasteners 12 encounters an angled remover 106 which directs each fastener 12 out of its bag 60 along its angled edge 62 and at the end, out of the plate 38 and over the ramp 108 for the collection. As the disk continues to rotate, an optional cleaning station 22 may be provided immediately. This station 22 may be provided in any position on the disk 11 after the fasteners 12 have been coated and ejected. With reference to Figures 16 and 17, as the applicators 50 rotate within the cleaning station 22, their raised ends meet a cam plate 110 similar in construction to the cam plate 82 as previously described. As the ends 80 engage the cam plate 110 of the applicators 50, they are raised vertically to their fully extended position where they are exposed in the vacuum 114 at a static location attached to the base 17 of the machine. In this way, the loose powder is removed from around the base of the pin 70 and its flange 76. Similarly, the particles that can be electrostatically adhered to the cavities 64 are also removed in this manner. Optionally, an air jet 112 could be used in combination with the vacuum 114 to emit a pressurized jet of air through the optional slots 49 in the base plate, which correspond to the applicators 50. The cleaning station 22 allows the removal of the excess coating material from the applicators 50 and the neighboring area without retaining or delaying the rotation of the disc from the production speeds. Another optional station, a lubrication station 24 can also be provided along the disc 11. The lubrication station 24 is designed to minimize the wear rate of the bearings 56 by providing an oiling device that places a small amount of lubricant precisely on the axis 72 of the spike when the applicator 50 is in the extended position. As illustrated in Figure 18, the preferred way to achieve this is through the use of an optical sensor 116 or synchronizer which could determine when a pin shaft 72 is present and point out a liquid application gun 118 for supplying the lubricant. In this way, the shafts 72 can be lubricated at any desired interval without removing the applicators 50 or decelerating or stopping the disk 11. After a complete revolution of the disk 11, the apparatus 10 is now ready to accept and process additional fasteners. In an alternative embodiment, more than one fastener 12 could be applied to each bag 60 processed and removed prior to the completion of a rotation of the disc 11. Referring now to Figure 19, an alternative embodiment of the present invention is illustrated. The apparatus of this invention can be used to apply two or more coatings of powder material on each of a plurality of fasteners in a single rotation of the disc. One way to achieve this is to place two vibratory feeder systems 94 and 95 respectively, in close proximity around the disc. Such a configuration allows the application of a second coating of powder material either immediately after the application of the first coating of material, or at some pre-selected time after that. Although many systems could be used to achieve this final result, a particularly preferred embodiment is to use two vibratory powder feeders 94 and 95, spaced one apart from the other around the disc 11 as illustrated. This allows a second coating of powder material to be applied on top of a first coating. The second coating could be of a powder material, either the same or different from the first applied coating. This also allows the application of a second powder coating having not only the same melting point as the first, but also either a lower or higher melting point. Although the second powder vibratory feeder 95 is illustrated positioned adjacent the first feeder 94, it should be understood that it could easily be placed on the opposite side of the disc 11 from the first feeder 94, which could allow the potential for ejection of bad parts. , or the online cleaning stations that are placed between the time of application of the two coatings of the powder material. The application of the powder material supplied by a second vibratory feeder 95 in this embodiment could be achieved in the same manner as previously described with respect to the feeder 94. The following example is given to assist in the understanding of the invention. It should be understood that the invention is not limited to the particular procedures or parameters described in this example.

EXAMPLE 1 Internally threaded flange nuts (10 mm x 1.5) were processed with 360 ° nylon layer or patch coatings using the present invention. A 30 kilowatt Ameritherm induction heater was used with the following settings: Power setting - 26.5 Amps - 33 Volts - 81 Frequency - 213 The M-10 nuts were fed at the speed of 9, 000 per hour on the nesting plate . The following spike speed settings were used: Spike RPM - 1775 RPM motor - 900 Band speed - 143.5 meters per minute (471 ft) The fasteners were preheated and the nylon coating material was applied to the hot threads of the same to form the 360 ° self-healing layer or patch coating. The powder consumption was as follows: Powder assortment / hour - 336 grams Powder assorted per cone - 0.037 grams (based on the average of 12 samples) Powder adhered to the nut - 0.033 grams (based on the average of 12 samples) processed fasteners showed a torsional tension value as set forth in figure 20. Fasteners with 360 ° nylon coatings applied to them showed very consistent torsional stress behavior and exceeded the requirements of military specification MIL-F-18240F through twenty on and off cycles. In addition, the centrifugal application process of the present invention virtually resulted in all of the powdered material stocked to the internally threaded surface of the nut adhering thereto, which was a much higher level than in prior known devices.

It is noted that in relation to this date the best method known by the applicant to carry out the aforementioned invention is that it is clear from the present description of the invention.

Claims (40)

CLAIMS Having described the invention as above, the content of the following claims is claimed as property:

1. An apparatus for applying a coating to articles having an internal hole, characterized in that it comprises: a mobile support for transporting the articles; a heating station positioned adjacent to the movable support for heating said articles within a predetermined temperature range as the articles move with the support; and an applicator positioned adjacent said movable support which simultaneously applies a predetermined amount of powder coating material to the entire circumference of 360 ° of a selected portion of the internal bore.

2. The apparatus according to claim 1, characterized in that it further comprises a plurality of fasteners of parts that support and retain substantially stationary articles as said articles are transported by the mobile support.

3. The apparatus according to claim 1, characterized in that each of the fasteners of parts is substantially open on at least one of its sides.

4. The apparatus according to claim 1, characterized in that the applicator is a centrifugal applicator.

5. The apparatus according to claim 1, characterized in that the applicator has a faceted upper surface which helps to direct the powder coating material towards the predetermined portion of the internal orifice.

6. The apparatus according to claim 1, characterized in that the applicator is vertically movable.

7. The apparatus according to claim 1, characterized in that the upper end of the applicator is placed completely inside the internal hole when it is being applied 5 coating material.

8. The apparatus according to claim 1, characterized in that it further comprises: means adjacent to said movable support for detecting articles that have not had sufficient powder coating material applied thereto; and means adjacent to the mobile support for removing articles that have not had sufficient powder coating material applied thereto.

9. The apparatus according to claim 1, characterized in that it comprises 20 further means for removing the excess powder coating materials from said mobile support in the area of the applicator, adjacent to the mobile support. - -_- * - ,, - * - & _ »- &.

10. The apparatus according to claim 1, characterized in that it also comprises means for lubricating the applicator adjacent to the mobile support.

11. The apparatus according to claim 2, characterized in that each of the fasteners or part retainers has an opening on which a diameter or internal hole of a particle is centered.

12. The apparatus according to claim 11, characterized in that it further comprises means for directing a stream of powder material into the internal orifice of the articles through the upper part of the hole.

13. The apparatus according to claim 12, characterized in that the applicator is rotatable and vertically movable.

14. The apparatus according to claim 13, characterized in that the applicator is placed inside the internal hole of an article with its upper surface above the bottom of the article, when it applies the powder coating material.

15. The apparatus according to claim 1, characterized in that the heating station heats the articles to a temperature above the smoothing point of the powder material.

16. The apparatus according to claim 1, characterized in that the applicator applies two different coatings of powder coating material to the articles.

17. The apparatus according to claim 1, characterized in that it further comprises means for selectively rotating the applicator only during a portion of the time in which the articles are transported by the mobile support.

18. The apparatus according to claim 1, characterized in that it further comprises means for raising the applicators such that the upper parts of the applicators are located within the internal orifice substantially immediately before the time in which it applies the powder material to the orifice.

19. The apparatus according to claim 1, characterized in that it further comprises: means for detecting and sending a signal after the start of the mobile support; and means for removing a predetermined number of articles from the support in response to the signal from the detection means.

20. A method for applying 360 ° coatings using powder coating materials to a predetermined portion of an internal opening of a fastener, characterized in that it comprises the steps of: supporting and transporting the fasteners along the predetermined path; heating the fasteners above the softening point of the coating material; the application of the coating material to the predetermined portion of the internal aperture of the fastener in an amount greater than that required to form the coating; and the propulsion of the coating material applied in the application step towards the walls of the internal opening of the fastener to be coated, in a manner such that at least about 90% of the applied coating material remains adhered to the predetermined portion. of the internal opening of the fastener.

21. An apparatus for the application of 360 ° coatings of powder coating material, to a predetermined portion of an internal opening of a fastener, characterized in that it comprises: a support for transporting the fasteners along a predetermined trajectory; a heating station for heating the fasteners above the softening point of the coating material; and means for applying the coating material to the predetermined portion of the internal surface of the fastener, in an amount greater than that required to form a coating, such that at least about 90% of the applied coating material remains adhered to the predetermined portion of the coating. the internal opening of the fastener.

22. An internally threaded fastener having a self-fastening layer or patch, characterized in that it comprises: a threaded portion adapted for coupling with a threaded coupling fastener; and a layer of molten resin powder, resistant to high temperature, which adheres to at least a portion of the complete circumference of 360 ° of the threaded portion, the layer provides sufficient frictional engagement between the threaded fastener and the threaded fastener of coupling, to meet the minimum torsion removal requirements described in Mil-F-18240E for at least twenty consecutive withdrawals.

23. A method for applying a coating to articles having an internal hole, the coating being applied is characterized in that it comprises the steps of: movably supporting the articles for transportation: heating the articles within a predetermined temperature range as Items are transported; and the application of the coating material over the complete 360 ° circumference of a predetermined portion of the inner hole at the same time.

24. The method according to claim 23, further characterized by comprising the support of the articles in a generally fixed position during the transportation step, with the articles being free to move in at least one direction horizontally.

25. The method according to claim 23, characterized in that the support passage further comprises the positioning of the articles so that the upper part and the bottom of the internal opening is open.

26. The method according to claim 23, characterized in that the application step includes the centrifugal application of the material.

27. The method according to claim 23, characterized in that the application step further comprises the movement of an applicator vertically, so that its upper end is within the internal orifice of the article, immediately before and during the application step.

28. The method according to claim 23, characterized in that it further comprises: the supply of a powder stream through the upper opening of the internal orifice; and redirecting the material towards the inner walls of the hole, before the time when the material falls below the lower surface of said article.

29. The method according to claim 23, characterized in that it further comprises: the detection of articles that have not had sufficient powder coating material applied to them, while said articles are being movably supported; and the removal of any items that are detected in the detection step, which have not had sufficient powder coating material applied thereto.

30. The method according to claim 23, characterized in that it further comprises removal of the excess powder coating materials while said articles are being movably supported.

31. The method according to claim 23, characterized in that it further comprises: the provision of a plurality of applicators in the application step; and the lubrication of the applicators while the articles are being movably supported for transportation.

32. The method according to claim 23, characterized in that the application step includes: the provision of a plurality of applicators: the movement of the upper part of the applicators to a position above the bottom of the internal orifice; and the rotation of the applicators during the application step.

33. The method according to claim 23, characterized in that the heating step heats the articles to a temperature above the softening point of a powder material.

34. The method according to claim 23, characterized in that it further comprises the application of a second coating of coating material on top of a portion of the coating material applied in the first application step.

35. The method according to claim 34, characterized in that the second application step applies a different powder coating material than the first application step.

36. The method according to claim 32, characterized in that it further comprises selectively rotating the applicators only during a portion of the time that the articles are movably supported for transportation.

37. The method according to claim 32, characterized in that it further comprises the elevation of the applicators such that the upper parts of the applicators are placed inside the internal orifice substantially and immediately before the application step.

38. The method according to claim 23, characterized in that it further comprises the detection of the start of the moveable support step and the removal of a predetermined number of items when the start or start is detected.

39. An apparatus for the application of a powder coating material on its inner surfaces of an article with an internal hole, characterized in that it comprises: a rotating applicator having a smaller diameter than that of the internal orifice; and at least one depression located on the upper surface of the applicator.

40. The apparatus according to claim 38, further characterized in that it comprises means for selectively raising and lowering the applicator from a first position, wherein the upper part of the applicator is below the lower surface of the applicator, to a second position where the upper part of the applicator is above the bottom of the applicator, and below the upper surface of said article. METHOD AND APPARATUS FOR APPLYING 360o COATINGS TO ARTICLES SUMMARY OF THE INVENTION A method and apparatus for applying coatings to a portion of the internal bore or threads of a fastener or similar article having an opening on at least one end is disclosed. A 360 ° coating with material is provided using centrifugal force to assist in the direction of the material to a desired surface, which does not require the use of a pressurized air stream in order to propel the coating material towards the walls of the article. that you want to cover.