Automated powder-coating method

An automated powder-coating system and method is provided. A series of conveyor belts are arranged end to end to transition one or more work pieces between the conveyor belts. Sensors are used to determine the current location of a work piece with respect to the series of conveyor belts. An induction heating coil for preheating work pieces and a powder-coating apparatus for powder coating work pieces are located adjacent to the conveyor belts. A control unit independently starts and stops the individual conveyor belts based on the current location of the work piece. A cooling area may also be included in the powder-coating system. The powder-coating system and method may be used to powder coat varying lengths of work pieces.

CROSS-REFERENCE TO RELATED APPLICATIONS

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TECHNICAL FIELD

The present invention generally relates to an automated powder-coating method. More particularly, the invention relates to an automated powder-coating method and system for powder coating various lengths of work pieces, such as steel under-frame support parts for furniture pieces.

BACKGROUND OF THE INVENTION

In the manufacture of steel-framed finished products, individual steel pieces are typically coated with a powder-coating material. As an example, the rails that form the floor rails for differing furniture pieces are powder coated. This involves delivering individual pieces of the steel frame along a conveyor belt and into a powder-coating apparatus. Induction heating is commonly used to preheat the steel pieces prior to powder coating. The overall process may also involve the use of a series of conveyor belts that deliver the steel pieces through induction, powder coating, and on to cooling.

One automated method of powder coating involves delivery of steel pieces along a continuous conveyor belt, or series of conveyor belts and/or roller conveyors. The steel pieces are preheated using induction heating coils and delivered at a consistent pace through a powder-coating apparatus. Having passed through the powder-coating apparatus, the steel pieces are transferred along the continuous conveyor belt for cooling and further processing. In some instances, the powder-coated pieces are manually hung in order to allow additional drying time for the powder-coating material. Using this method, the conveyor belt moves at a continuous pace, constantly moving pieces along the conveyor belt and through the powder-coating apparatus. Because the powder-coating method is continuous, and the pieces being delivered along the conveyor belt are the same or similar in length, the consistent speed of the conveyor belt is determined by the time needed to preheat and powder coat the similar-length pieces. The pieces of similar length are typically longer pieces of steel, which allows for a longer time to dry as the longer pieces exit the powder-coating apparatus.

One problem with current automated powder-coating methods is the application of powder coating to shorter-length steel pieces. Using a traditional, continuous conveyor belt method, longer and/or continuous-length steel pieces can wait a longer distance before needing to be contacted upon exiting the powder-coating apparatus, and therefore are able to dry before subsequent contact with the next portion of the conveyor belt. In other words, longer pieces travel a longer distance before contact is required. Conversely, shorter pieces are quicker to require contact upon exiting the powder-coating apparatus, and may not have enough time to sufficiently dry, or “cure,” before subsequent contact with the next portion of the conveyor belt. As such, freshly coated surfaces of shorter pieces may have more markings on the pieces from earlier contact with the conveyor belt.

Another problem with current powder-coating methods is the inability to handle inconsistent or varying lengths of steel pieces. For example, traditional powder-coating methods use continuous conveyor belts to transfer steel pieces, which does not take into account the length of the piece and the amount of time it takes the individual piece to complete each step of the process. Timing of the traditional powder-coating process is based on the continuous pace to powder coat longer-length pieces, regardless of the amount of time required for preheating with induction coils, the amount of time required to pass the steel piece through the powder-coating apparatus, and the amount of time required to dry the steel piece at the end of the process.

Accordingly, a need exists for an automated powder-coating method for coating variable lengths of steel pieces.

BRIEF SUMMARY OF THE INVENTION

The present invention generally relates to an automated powder-coating method and system for coating variable sizes of steel pieces. Throughout the remainder of this application, reference will be made to powder coating “work pieces.” It should be understood that the invention contemplates powder coating various types of work pieces, both steel under-frame support parts for furniture pieces and otherwise, and that the invention is not limited to the specific component being powder coated. The length and/or size of a work piece may vary. For example, in some embodiments, a work piece may be as short as 17 inches in length. The powder-coating method includes a series of sections of independently moving conveyor belts. As used herein, the term “conveyor belt(s)” refers to any means for conveying one or more work pieces, including using conveyor belts, conveyor rollers, and the like. The current location of a work piece with respect to each conveyor belt section is identified using a sensor. The method also includes an induction heating coil and a powder-coating apparatus located adjacent to the series of conveyor belts. The powder-coating method carries out a novel, automated method for powder coating varying lengths of work pieces.

DETAILED DESCRIPTION OF THE INVENTION

A first embodiment of an automated powder-coating system10is seen inFIGS. 1-6. As shown inFIG. 1, the powder-coating system10includes a plurality of conveyor belts arranged end to end to transition one or more work pieces between the plurality of conveyor belts. The powder-coating system10includes a first conveyor belt12arranged end to end with a second conveyor belt14. The first conveyor belt12includes a plurality of conveyor belt rollers13. In embodiments, the conveyor belt rollers13may be stopped and started, depending on the location of a work piece with respect to the first conveyor belt12.

The second conveyor belt14includes a plurality of conveyor belt rollers16for transferring a work piece along the second conveyor belt14, as best seen inFIG. 2. A first sensor18and a second sensor20are located adjacent to the second conveyor belt14. The first sensor18and second sensor20detect the location of a work piece with respect to the second conveyor belt14. As will be understood, sensors located adjacent to the plurality of conveyor belts in the powder-coating system10may be any type of sensor used to detect the presence or absence of a tangible object. For example, a sensor may be a visual sensor, a weight sensor, a heat sensor, a motion-detection sensor, and the like.

The first conveyor belt12starts and stops based on detection of a work piece by the first sensor18. If the first sensor18detects that no work piece is currently passing along the first conveyor belt12and onto the second conveyor belt14, and that no work piece is currently passing by the first sensor18, then the first conveyor belt12is turned on and a work piece is passed along the conveyor belt rollers13of the first conveyor belt12. Once the first sensor18detects that the entire work piece has passed, the first conveyor belt12is turned off and the conveyor belt rollers13of the first conveyor belt12stop.

A third conveyor belt22is arranged end to end with the second conveyor belt14. As shown inFIG. 2, the third conveyor belt22includes a plurality of conveyor belt rollers24, and an induction heating coil26located adjacent to the third conveyor belt22. The induction heating coil26is used to preheat a work piece prior to being powder coated by the powder-coating system10. The conveyor belt rollers24of the third conveyor belt22may facilitate preheating a work piece using the induction heating coil26. For example, the conveyor belt rollers24may transfer a work piece through the center of the induction heating coil26. The second sensor20, upon detection of a work piece along the second conveyor belt14, turns on the induction heating coil26and slows down the third conveyor belt22in order to allow enough time for the induction heating coil26to pre-heat the work piece.

Arranged end to end with the third conveyor belt22is a fourth conveyor belt28, which is partially depicted inFIG. 2. The fourth conveyor belt28includes a plurality of conveyor belt rollers30and a third sensor32. The second sensor20and the third sensor32may be used to detect the current location of a work piece with respect to the induction heating coil26and/or the third conveyor belt22.

In embodiments, one or both of the second conveyor belt14and the fourth conveyor belt28are slowed down when the third conveyor belt22is slowed down during heating with the induction heating coil26. The third sensor32senses when a work piece is no longer in contact with the third conveyor belt22, and shuts off the induction heating coil26. In embodiments, the third sensor32also speeds up the pace of one or both of the second conveyor belt14and the fourth conveyor belt28after the work piece is heated by the induction heating coil26. In other words, based on detection by the third sensor32, conveyor belts14,22, and28are returned to their original speed prior to heating, and the induction heating coil26is turned off.

As best seen inFIG. 3, a fourth sensor34is positioned adjacent to the fourth conveyor belt28. The third sensor32and fourth sensor34detect the location of a work piece with respect to the fourth conveyor belt28. Located adjacent to the fourth conveyor belt28is a powder-coating apparatus36. The powder-coating apparatus36powder coats work pieces transferred along the plurality of conveyor belts in the powder-coating system10using a quick-drying powder-coating media. A work piece enters the powder-coating apparatus36through a first opening60. The powder-coating process taking place inside the powder-coating apparatus36may be visually monitored using a second opening62. As will be understood, a plurality of conveyor belt rollers may be used to transfer the work piece through the powder-coating apparatus36.

Located adjacent to the powder coating apparatus36is a fifth conveyor belt38, with a plurality of conveyor belt rollers40, as best seen inFIG. 4. A fifth sensor42and a control unit44are located adjacent to the fifth conveyor belt38. A work piece is transferred onto the fifth conveyor belt38after exiting the powder-coating apparatus36through a third opening64of the powder-coating apparatus36. The fourth sensor34and the fifth sensor42are used to control when to turn the powder-coating apparatus36on and off.

The control unit44variably controls the speed of the individual conveyor belts arranged end to end as part of the powder-coating system10. The control unit44is adapted to selectively start and stop the plurality of conveyor belts based on the current location of a work piece along the powder-coating system10. In embodiments, the control unit controls conveyor belts14,22,28, and38at the same pace, or at varying paces. For example, the conveyor belt22may be slowed down by the control unit44based on detection of a work piece by the second sensor20. As previously discussed, in addition to slowing down the conveyor belt22, the control unit44may also slow down conveyor belts14,28, and38. Further, based on detection of the end of a work piece by the third sensor32, the control unit44may speed up conveyor belts14,22,28, and/or38.

The current location of a work piece along the powder-coating system10is determined using one or more of the sensors located adjacent to the powder-coating system10, such as the first, second, third, fourth, and fifth sensors18,20,32,34and42. For example, the control unit44may individually start and stop the first conveyor belt12based on detecting the current location of a work piece using the first sensor18. As such, after the work piece is no longer in contact with the conveyor belt rollers13of the first conveyor belt12, based on detection of the end of the work piece by the first sensor18, the conveyor belt rollers13of the first conveyor belt12may be stopped by the control unit44. Similarly, based on the second sensor20detecting the location of a work piece along the second conveyor belt14, the control unit44may cause the conveyor belt rollers24of the third conveyor belt22to slow down, and the induction heating coil26to begin preheating the work piece. Additionally, the conveyor belt rollers16and30of the second and fourth conveyor belts14and28may also be slowed during induction heating.

The control unit44may also monitor or control different functions associated with the powder-coating system10, based on detection of the current location of a work piece by one or more sensors. For example, the fifth sensor42may be utilized by the control unit44to determine the current location of a work piece, in order to turn off the powder-coating apparatus36after a work piece exits the third opening64. Further, the control unit44may monitor the temperature of the induction heating coil26for preheating a work piece to a desired temperature prior to powder coating.

A cooling area46is located adjacent to the plurality of conveyor belts in the powder-coating system10, as best seen inFIGS. 5-6. The cooling area46utilizes air, water, and/or other cooling media to cool work pieces after powder coating by the powder-coating apparatus36. The cooling area46may include a staging area48located adjacent to the fifth conveyor belt38. The staging area48transfers work pieces after powder coating using a plurality of conveyor belt rollers50and transfer rollers and/or chains52. As will be understood, the staging area48may utilize any number of different means for conveying a work piece in addition or alternative to transfer rollers52. A sixth sensor54is located adjacent to the staging area48. The location of a work piece with respect to the cooling area46may be determined using the sixth sensor54.

As part of the cooling area46, the transfer rollers52transfer work pieces to the cool-down section56of the cooling area46. As shown inFIG. 5, the transfer rollers52are coupled to pairs of transfer wheels66, which rotate around a first center spindle68and a second center spindle70. The movement of the transfer wheels66around the first and second center spindles68and70causes the corresponding transfer rollers52to rotate around the pair of transfer wheels66. In order to transfer a work piece from the staging area48onto the cool-down section56, the first center spindle68raises upward so that a portion of the transfer rollers moves above the conveyor belt rollers50and into contact with a work piece on the staging area48. As such, the transfer rollers52are able to transfer a work piece (that was previously in contact with the conveyor belt rollers50) from the staging area48to the cool-down section56.

As part of the cooling area46, the cool-down section56may utilize air, water, and/or other cooling media to cool the work pieces powder coated by the powder-coating system10. As shown inFIG. 6, a seventh sensor58is located adjacent to the cool-down section56, and is used to detect the current location of a work piece with respect to the cool-down section56. The seventh sensor58may also be utilized to count work pieces that are being powder-coated by the powder-coating system10.

In use, the powder-coating system10can powder coat varying lengths of work pieces, such as the steel rails that are used for the floor rails for differing furniture pieces. The current location of a work piece along the series of conveyor belts is determined using the sensors located adjacent to the conveyor belts. The control unit44independently controls the conveyor belts while transferring the work piece along the conveyor belts. The control unit44may adjust the speed at which an individual conveyor belt moves, such as, for example, slowing down the third conveyor belt22during induction heating of the work piece, slowing down the speed at which the powder coating apparatus36powder coats a work piece, or speeding up any number of conveyor belts after previous slow-down during induction heating and/or powder coating. Monitoring the current location of the work piece and independently controlling the conveyor belts enables a greater variety of lengths of work pieces to be powder coated by the powder-coating system10.