Patent Document

BACKGROUND OF THE INVENTION 
     The present invention relates generally to bedrail and hookplate assembly and, more particularly, to an apparatus that automatically mounts hookplates to bedrails in an efficient and accurate manner. 
     Typically, in wooden bed frames, a flat, metal plate having hooks for engaging a post associated with a headboard or footboard, is mounted in a slot or on the side of both ends of a wooden bedrail. The hookplate usually includes multiple apertures through which multiple pins or other fasteners extend in order to securely attach the hookplate to the bedrail. These types of hookplates are standard in the wooden bedrail manufacturing industry. 
     Conventional bedrail manufacturing plants use manual labor to mount the hookplates to the ends of the bedrails. One of the reasons that manual labor is used is that when mounting the hookplates to the bedrails with the pins, it is important that the apertures in the bedrail are aligned with the apertures in the hookplate. If the apertures are not appropriately aligned, the powerful forces used in inserting the pins cause significant damage to the bedrail and/or the hookplate. For example, the wood surfaces surrounding the apertures become damaged and the hookplate bends out of shape. A human being is able to accurately align the apertures in the bedrail and the hookplate to avoid such damage. 
     As with any type of manufacturing, economics is of primary importance. The use of manual labor to mount the hookplates to the bedrails is generally associated with costly labor expenses and less than desired manufacturing efficiency. 
     Thus, there remains a need for an efficient and accurate apparatus that automatically mounts hookplates to bedrails. 
     SUMMARY OF THE INVENTION 
     The present invention fulfills this need in the art by providing an apparatus that automatically mounts a hookplate to a bedrail including a bedrail transport mechanism that transports a bedrail to a hookplate receiving position, a hookplate feeder that places a hookplate in a hookplate mounting position, and a pin driving mechanism that drives at least one pin through the bedrail and the hookplate to mount the hookplate to the bedrail. The bedrail transport mechanism typically includes pusher dogs that transport the bedrail to the hook receiving position. 
     In a preferred embodiment the hookplate feeder includes a hookplate hopper that stores a plurality of hookplates. The hopper is preferably positioned above a planar surface such that a single hookplate at a time falls onto the planar surface and rests between a bottom of the hopper and a top of the planar surface. A first hookplate pusher slides between the bottom of the hookplate hopper and the top of the planar surface to push the hookplate that falls from the hookplate hopper to a first position. A second hookplate pusher pushes the hookplate from the first position to the hookplate mounting position. The second hookplate pusher includes a clamp having a first end and a second end, the first end being configured to clamp down onto the hookplate. The clamp includes a fulcrum such that when the second end of the clamp is directed towards the planar surface, the first end of the clamp is directed away from the planar surface. When the clamp is waiting for the hookplate from the first hookplate pusher, the second end of the clamp is held under a clamp base in a position directed toward the planar surface such that first end of the clamp is directed away from the planar surface and is open to receive the hookplate. When the first hookplate pusher pushes the hookplate into the first position, the clamp moves away from the clamp base and a spring supports the second end of the clamp in a position directed away from the planar surface so that the first end of the clamp clamps down on the hookplate. The clamp base includes a roller that holds the second end of the clamp in the position directed toward the planar surface and permits the second end of the clamp to slide away from the clamp base. 
     The pin driving mechanism preferably includes at least one pin driver that drives the pin through the bedrail and the hookplate. In a first step, the pin driver fully extends into an aperture in the bedrail and an aperture in the hookplate to align the apertures. The pin driver then retracts. A pin supply chamber is provided that stores a plurality of pins. At least one pin is transported from the pin supply chamber to the pin driving mechanism after the pin driver retracts. A pin holding plate is provided that has at least one generally cylindrical opening that temporarily holds the pin after it is transported from the pin supply chamber to the pin driving mechanism. The generally cylindrical opening in the pin holding plate includes a set of spring loaded detents that prevent the pin from passing through the holding plate when the pin first enters the holding plate. The pin driver then drives the pin past the detents and substantially completely through the aperture in the bedrail and the aperture in the hookplate to mount the hookplate to the bedrail. 
     A plurality of pneumatic cylinders may be used to drive the bedrail transport mechanism, the hookplate feeder, and the pin driving mechanism. The position of the pneumatic cylinders may be detected by electronic sensors. A programmable logic controller may be used to control the plurality of pneumatic cylinders. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will become apparent to those skilled in the art after reading the following description of the preferred embodiments when considered with the drawings. 
     FIG. 1A is a front schematic view of an apparatus for mounting bedrail hooks constructed according to a preferred embodiment of the present invention. 
     FIG. 1B is a top schematic view of the apparatus of FIG.  1 A. 
     FIG. 1C is an end view of flexed pusher dogs that index the bedrails down an assembly line according to the present invention. 
     FIG. 1D is an end view of the pusher dogs of FIG. 1C in a relaxed position. 
     FIG. 2A is a perspective view of a hookplate hopper according to an embodiment of the present invention. 
     FIG. 2B is an end view of the hookplate hopper of FIG.  2 B. 
     FIG. 3A is a top view of a hookplate pusher constructed according to the present invention. 
     FIGS. 3B and 3C are end views of the hookplate pusher of FIG.  3 A. 
     FIG. 4 is a top view of the various positions into which a hookplate is moved to reach a bedrail mounting position according to the present invention. 
     FIG. 5A is an end view of a bedrail and hookplate assembly according to the present invention. 
     FIG. 5B is a top view of the bedrail and hookplate assembly of FIG.  5 A. 
     FIG. 6 is a front view of a pin driving section constructed according to an embodiment of the present invention. 
     FIG. 7 is an end view of the hookplate mounting section of the embodiment of FIGS. 1A and 1B. 
     FIG. 8A is a top view of the holding plate of FIG.  7 . 
     FIG. 8B is a side sectional view taken along line  8 B of the holding plate of FIG.  8 A. 
     FIG. 9 is a flow chart of an exemplary mode of operation. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following description, like reference characters designate like or corresponding parts throughout the several views. Also in the following description, it is to be understood that such terms as “forward,” “rearward,” “left,” “right,” “up,” “down,” and the like are words of convenience and are not to be construed as limiting terms. Referring now to the drawings, it will be understood that the illustrations are for the purpose of describing a preferred embodiment of the invention and are not intended to limit the invention thereto. 
     As best seen in FIGS. 1A and 1B, an apparatus for mounting a hookplate to a bedrail, generally designated  10 , is shown constructed according to the present invention. The apparatus includes an assembly line  12  that moves a plurality of bedrails  14  into a position to receive a hookplate  16  on either one or both ends of each of the bedrails  14 . In a preferred embodiment, pusher dogs  18  pivot on a bar  70  that reciprocates back and forth to move the bedrails  14  down the assembly line  12 . As shown in FIG. 1C, the pusher dogs  18  rotate upwardly when the bar  70  moves in the direction of the assembly line  12  to index the bedrails  14 . As shown in FIG. 1D, the pusher dogs  18  rotate downwardly when the bar  70  moves backwards to slide under the previously indexed bedrail  14  and prepare to index the next bedrail  14  on the assembly line  12 . 
     Conventional bedrails  14  include a hookplate  16  mounted on both ends of the bedrail  14  so that the bedrail  14  can engage a post in both a headboard and a footboard. Thus, in the embodiment illustrated in FIGS. 1A and 1B, a hookplate mounting section  21  is located on either side of the apparatus  10  to mount a hookplate  16  on both ends of the bedrail  14 . While the following description of the mounting machinery refers to only one side of the apparatus  10 , it will be understood that the same description applies to the machinery on the opposite side of the apparatus  10 , laid out generally as a mirror image. 
     Once the bedrail  14  is located in a position to receive a hookplate  16 , a pressure foot  66  (shown in detail in FIG. 6) extends down to hold the bedrail  14  in position. 
     Turning now to FIGS. 2A and 2B, there is shown a hookplate hopper  20  that stores a plurality of hookplates  16  waiting to be mounted onto the bedrails  14  on the assembly line  12 . The hopper  20  is preferably located slightly above a hookplate mounting surface  22  such that that the height between then the bottom of the hopper  20  and the mounting surface  22  is substantially equal to the thickness of one hookplate  16 . This configuration permits only one hookplate  16  at a time to rest between the hookplate mounting surface and the hopper  20 . A thin plate  24 , having a height that is also about the same height as the hookplate  16 , slides under the hopper  20  and pushes the bottom hookplate  16 , resting on the surface  22 , to a first position (B of FIG.  4 ). When the thin plate  24  retracts, the next bottom-most hookplate in the hopper  20  falls out of the hopper  20  by gravity and onto the hookplate mounting surface  22  so that it can mounted into the next bedrail  14  on the assembly line  12 . 
     As shown in FIG. 3A, a second hookplate pusher  26  is configured to clamp onto the hookplate  16  after it is moved to the first position, and push the hookplate  16  to a hookplate mounting position. Preferably, the second hookplate pusher  26  includes two finger-like clamps  28  that are configured to clamp down on the two hooks ( 51 ,  54  of FIG. 5B) of a conventional hookplate, such as hookplate  16 . It should be understood that the second hookplate pusher  26  may be adapted to clamp down on non-conventional hookplates  16 . For example, the second hookplate pusher  26  may include a single finger-like clamp  28  to clamp down on a hookplate  16  having only one hook. 
     Referring now to FIGS. 3B and 3C, the finger-like clamps  28  are balanced on a fulcrum  30  so that they can rock up and down like a seesaw. When one end of the clamp  28  is pointed toward the hookplate mounting surface  22 , the other end is pointed away from the hookplate mounting surface  22 . When the second hookplate pusher  26  is idle, (i.e. retracted to the right from the position shown in FIG. 3B) one end ( 28   a ) of each of the finger-like clamps  28  is located under a roller  32  on a base  34 , as shown in FIG.  3 C. The rollers  32  hold these ends ( 28   a ) of the fingers  28  down so that the opposite ends ( 28   b ) of the fingers  28  are open to receive the hookplate  16  from the thin plate pusher  24 . Once the hookplate  16  is located in the first position and is ready to be clamped, the second hookplate pusher  26  moves away from the base  34  and towards the bedrail  14 . As soon as the ends ( 28   a ) of the fingers  28  slide from under the rollers  32 , springs  36  that are located under the ends ( 28   a ) of the fingers  28  extend to hold those ends ( 28   a ) of the fingers  28  in an upward position. This forces the opposite ends ( 28   b ) of the fingers  28  to clamp down on the hooks  51 ,  54  of the hookplate  16 , as shown in FIG.  3 B. The second hookplate pusher  26  then continues to push the hookplate  16  towards the hookplate mounting position. 
     The various steps just described in which the apparatus  10  moves the hookplate  16  into hookplate mounting position, are illustrated in FIG.  4 . In step A, the hookplate  16  drops from the hopper  20  and is moved by the thin plate  24  to the first position. In step B, the fingers  28  slide away from the rollers  32  and clamp onto the hookplate  16 . In step C, the second hookplate pusher  26  moves the hookplate  16  from the first position to the hookplate mounting position to form a bedrail and hookplate assembly. 
     FIGS. 5A and 5B illustrate the bedrail  14  and hookplate  16  assembly prior to being fastened by the pins  38 . Although the hookplate  16  may be mounted on the side of the bedrail  14 , it is preferably mounted in a slot  60  extending into the end of the bedrail  14 . As discussed above, conventional hookplates, such as hookplate  16 , include a first downwardly extending hook  51  forming a first indentation and a second downwardly extending hook  54  forming a second indentation. A conventional hookplate  16  also includes first and second apertures  56 ,  58  through which pins extend to fasten the hookplate  16  to the bedrail  14 . The apertures  56 ,  58  are large enough to provide passage of the pin  38  and may be oversized and elongated to provide for a certain amount of play for the hookplate  16 . Providing play in the hookplate  16  allows for slight adjustments in hookplate  16  orientation as the bedrail  14  is mounted to the headboard or footboard. The hookplate  16  position will normally adjust and conform to a secure location and orientation. Providing oversized or elongated apertures  56 ,  58  also allows for greater tolerances associated with the placement of the pins  38 , which ultimately engage and hold the hookplate  16 . 
     Prior to the bedrail  14  being placed on the assembly line  12 , two apertures or bores  62 ,  64  are made near the end of the bedrail. Preferably, the apertures  62 ,  64  do not extend completely through the bedrail  14 , but rather extend from the one side past the slot  60  and into the other side of the bedrail  14 . A remaining portion  62  remains in order to provide an uninterrupted and unobstructed outer side of the bedrail  14  for aesthetics. Thus, in the preferred embodiment, the pins  38  extend through the apertures  62 ,  64  of the bedrail  14  and the apertures  56 , 58  of the hookplate  16  and stop just prior to reaching the remaining portion  62 . 
     Turning now to FIG. 7, two pipes  50  extend upwardly from either side of a pin driving section  44  and are aligned with cylindrical openings  46  in a holding plate  42 . A cylindrical pin driver  52  having a chamfered bottom, is located inside each of the pipes  50  and is used to drive the pins  38  to mount the hookplate  16  to the bedrail  14 . 
     The process of driving the pins  38  into the bedrail  14  and hookplate  16  involves several steps. First, the pressure foot  66  is released and the pin drivers  52  fully extend into the apertures  56 , 58  in the hookplate  16  and the apertures  62 , 64  in the bedrail  14  to slightly move any misaligned pieces into alignment. Releasing the pressure foot  66  allows the bedrail  14  to move as needed to ensure alignment of the apertures  56 , 58 , 62 , 64 . Such alignment avoids damage to the bedrail  14  and hookplate  16  during the pin insertion process. While the pin drivers are still inside the apertures  56 , 58 , 62 , 64 , the pressure foot  66  re-extends to hold the bedrail  14  in place during the pin insertion process. 
     The pin drivers  52  then retract back into pipes  50 , to make room for the pins  38  that are used to fasten the hookplates  16  to the bedrail  14 . As shown in FIG. 7, a pin supply chamber  36  that stores a plurality of pins  38  is preferably located above the hookplate mounting surface  22 . The pin supply chamber is configured to release two pins  38  at a time, one pin  38  for each aperture in the hookplate  16 . It should be understood that when mounting a hookplate  16  having only one aperture, the chamber  36  may be configured to drop only one pin  38 . 
     When pins  38  are dropped from either side of the chamber  36 , the pins  38  fall by gravity through a pair of tubes  40  to the pin driving section  44 . The pin driving section  44  includes a holding plate  42  that temporarily holds the pins  38  below the pin drivers  52  before they are inserted into the hookplate  16  and the bedrail  14 . The holding plate  42 , as shown in FIG. 8A, is formed of two metal plates  42   a ,  42   b  that fit together to form a plate  42  having two cylindrical openings  46 . Each of the cylindrical openings  46  in the holding plate  42  includes a set of spring-loaded detents  48 . The detents extend into the openings  46  to frictionally engage the pins  38 , as shown in FIG. 8B, thereby preventing the pins  38  from going through the holding plate  42  until they are ready to be driven into the bedrail and hookplate assembly. 
     Next, the pin drivers  52  drive the pins  38  past the detents  48  and almost completely through the bedrail  14 , stopping the pins  38  just prior to reaching the remaining portion  62  of the bedrail  14 . At this point, the hookplate  16  is securely fastened to the bedrail  14  and the mounting process is complete. The pressure foot  66  is released, the fingers  28  release the clamp on the hookplate  16 , and the pusher dogs  18  move the completed bedrail  14  and hookplate  16  assembly down the assembly line  12 . 
     In each of the embodiments discussed above, the various components of the apparatus  10  are driven by pneumatic cylinders, which are known in the art. Photoelectric and proximity sensors are used to detect the positions of the various cylinders and a programmable logic controller (PLC) is used to control the cylinders based on their detected positions. For example, a photoelectric sensor may be used to determine when a bedrail and hookplate assembly is ready to be fastened so that a PLC may direct the driving cylinders  78  to operate the pin drivers  52  to drive the pins  38 . 
     A flow chart explaining a simplified operation of the cylinders is shown in FIG.  9 . In step  90 , the pusher dogs  18  place a new bedrail  14  in the hookplate receiving position. In step  92 , a holding cylinder  76  (shown in FIG. 6) moves the pressure foot  66  to hold the bedrail  14  while the hookplate  16  is inserted. In step  94 , a first positioning cylinder  72  (shown in FIGS. 2A and 2B) moves the thin plate  24  to push the hookplate  16  to the first position. In step  96 , a second positioning cylinder  74  (shown in FIGS. 3A and 3B) moves the second hookplate pusher  26  away from the base  34  so that the fingers  28  clamp down on the hookplate  16 . In step  98 , the holding cylinder  76  retracts in preparation for the step that aligns the apertures in the hookplate and the bedrail. In step  100 , driving cylinders  78  (shown in FIG. 7) fully extend to drive the pin drivers  52  into the bedrail and hookplate assembly to ensure alignment of the apertures. In step  102 , the holding cylinder  76  re-extends to hold the bedrail  14  during the pin insertion process. In step  104 , the driving cylinders  78  retract the pin drivers  52  to prepare to insert the pins  38 . In step  106 , the driving cylinders  78  partially drive the pin drivers  52  to insert the pins  38  into the bedrail and hookplate assembly, thereby completing the pin insertion process. Finally, in step  108 , the driving cylinders  78 , the holding cylinder  76 , the second positioning cylinder  74 , and the first positioning cylinder  72  retract to prepare to fasten the next bedrail and hookplate assembly. 
     Certain modifications and improvements will occur to those skilled in the art upon a reading of the foregoing description. By way of example, the apparatus  10  may be adapted to mount a hookplate  16  to only one end of a bedrail  14 . Further, the apparatus  10  may be adapted to mount a hookplate  16  having only one hook or one aperture. In addition, the present invention may be driven by sources of power other than pneumatic cylinders. It should be understood that all such modifications and improvements have been deleted herein for the sake of conciseness and readability but are properly within the scope of the following claims.

Technology Category: 4