Abstract:
A chair comprising a combination of injection molded components. The combination includes a gas assist molded rear frame and a gas assist molded front frame. A seat is injection molded using regular injection molding. The seat joins the uppermost part of the front from to a mid-portion of the rear frame. In addition, four connecting rods are insert molded such that plastic jackets surround metal cores. The metal cores have fastening means integrated into their ends. Each of the connecting rods joins and abuts protrusions formed in and extending from the front and rear frames. All of the resin used to mold the frames, seat and connecting rods is a polycarbonate which provides a chair made of the combination with a crystal-like appearance.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
       [0001]    The inventions described herein relate to a chair of the type known as a Chiavari-style chair. In particular, the inventions described herein relate to an injection molded chair in which the main structural components are generally hollow and made using a process known as gas assist injection molding (GAIM). 
         [0002]    Chiavari-style chairs are well known in the art. For example, U.S. Pat. No. 6,666,518 shows a stackable Chiavari-style chair. In addition, a company called Commercial Seating Products in Ridgefield Park, N.J. sells a Chiavari chair having an outer layer of plastic and a steel inner frame that extends throughout the chair. See the website of Commercial Seating Products at http://www.cspevents.com/products/rb700.html where the chair described at that site is said to be the subject of a pending patent application Ser. No. 11/291,792, filed Dec. 1, 2005. The plastic-coated steel frame chair of Commercial Seating Products is said to be made of K-resin which is a styrene butadiene block copolymer material. 
         [0003]    The inventions described herein make use of an injection molding technology known as gas assisted injection molding or GAIM. GAIM is known to improve cycle times, lower product weight and reduce the amount of plastic used to make products. GAIM also affords design flexibility and allows the manufacture of structurally stronger parts. GAIM involves the use of a gas, preferably nitrogen, to displace resin in flow channels of a mold. Nitrogen gas is preferred because it is relatively inert, dry, non-toxic, and odorless. Nitrogen has the ability to contact melted resin at high temperatures without introducing oxidation of the resin. 
         [0004]    Chiavari chairs are very popular for use at events such as weddings. Rental companies typically maintain a large inventory of Chiavari chairs. However, because the design of Chiavari chairs is more elegant than structurally robust, Chiavari chairs have typically had a relatively short life cycle, requiring rental companies to purchase replacement Chiavari chairs on a regular basis. 
         [0005]    Typically, Chiavari-style chairs are made of wood and are quite fragile, particularly when used as rental chairs where the chair is not generally treated in careful manner appropriate to their structural strength. The chair offered by Commercial Seating Products may be more structurally robust, but is both expensive and heavy because of its structural steel frame. 
         [0006]    The Chair described herein is both durable and structurally robust without being excessively expensive. The chair is comprised of a front and rear frame each of which contains two at least partially hollow posts at opposite sides. Connecting in the posts are rods that are preferably at least partially hollow. Preferably four front-to-rear connecting rods join the front and rear frames. The connecting rods are comprised of insert molded jackets surrounding a simple metal core adapted to be fastened at each end to one of the frames. A seat comprising a circumferential lip as sockets near the frontend of the seat adapted to receive the upper ends of the posts of the front frame. Preferably a total of 10 fasteners are used to assemble the chair. Two fasteners connect the rear of the seat to the middle portion of the rear frame. Eight fasteners, one for each end of the four front-to-rear connecting rods are used to fasten the connecting rods to the front and rear frames. The front and rear frames are preferably made using GAIM technology, which allows the formation of large portions of the volume of the front and rear frames to be hollow, thereby saving in resin and weight. The plastic used to injection mold the front and rear frames, the seat, and the jackets surrounding the front-to-rear connecting rods is preferably a polycarbonate, because of its strength, toughness and transparency. 
         [0007]    These and other advantageous features of the chair described herein will be better understood and appreciated by those skilled in the art by referenced to the following specification, read in conjunction with the accompanying drawings. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is an exploded perspective view of a chair including a seat, front and rear frames and four front-to-rear connecting rods (fasteners are not shown); 
           [0009]      FIG. 2  is a rear elevational view of the rear frame of the chair shown in  FIG. 1 ; 
           [0010]      FIG. 3  is a rear elevational view of the front frame of the chair shown in  FIG. 1 ; 
           [0011]      FIG. 4  is an elevational view of a front-to-rear connecting rod of the chairs shown in  FIG. 1 ; 
           [0012]      FIG. 5  is a bottom exploded plan view of the seat of the chair shown in  FIG. 1 ; 
           [0013]      FIG. 6  is a an enlarged perspective view of the upper part of the front frame shown in  FIG. 1 ; and 
           [0014]      FIG. 7  is an upwardly directed exploded view in partial section of a chair embodying the inventions described herein. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]      FIG. 1  is an exploded view of a chair embodying the inventions described herein. A front frame  12  and a rear frame  10  are facing each other such that four front-to-rear connecting rods  16  may connect the front frame  12  to the rear frame  10  with the front portion of the seat  14  adapted to engage the top of the front frame  12  and the rear potion of the seat adapted to be connected to a middle portion of the rear frame  10 . 
         [0016]      FIG. 2  shows the rear frame  10  in more detail. Two substantially hollow posts  19  and  20  are the main structural members of the rear frame  10 . In this particular exemplary embodiment, five crossbars extend from one post to the other. While this particular arrangement is designed to result in a Chiavari-style chair, it will be recognized by persons of skill in the art of injection molding and chair design that the inventions described herein have ready application to chairs other than Chiavari-style chairs. An upper crossbar  24  and a second crossbar  26  have a series of vertical rods  27  extending between them. The upper crossbar  24  has a partially hollow core formed by hollow cores  34  and  36  separated by a solid center core  38 . Crossbar  26  is configured in a partially hollow manner, similar to cross bar  24 , as are the crossbars  28 . The hollow core  19  within the post  18  is in fluid communicates with (i.e., is open to) the hollow core  21  of post  20  through the hollow core  23  in the lower crossbar  22 . 
         [0017]    The hollow cores  34  of the crossbars  24 ,  26  and  28  do not extend entirely through those crossbars, but could be, if desired, depending on their size and other variable used in the GAIM process, such as the viscosity of the resin, diameter of the sections and the pressure of the gas. The viscosity and size of the flow channels in the cavity used to make the rear frame  10  result in the hollow sections produced by the pressurized gas during the GAIM process, and a substantial majority of the axial length of the elongate portions that comprise the rear frame and the front frame are hollow and made entirely of gas assist molded plastic. The fact that a majority of the interior of the segments of the rear and front frames is hollow substantially saves on the resin used to make the rear frame  10 , making the chair both light and very strong, particularly when the resin used is polycarbonate. 
         [0018]    The rear frame  10  contains features that facilitate assembly of the chair described herein. At the level where the seat  14  attaches to the rear frame  10 , two ears  30  and  32  extend laterally inwardly from the posts  20  and  18 , respectively. At that same elevation, recesses  34  and  42  are formed in the rear face of the posts  20  and  18 , respectively, for accommodating the heads of fasteners (not shown) that connect the rear of the seat  14  to the rear frame  10 . Similarly, at the elevation of the front-to-rear connecting rods a series of recesses  40  are formed in the rear face of the posts  20  and  18 . The recesses  34 ,  40  and  42  are adapted to receive the head of a bolt or screw (not shown) that engages the ends of the front-to-rear connecting rods  16 . 
         [0019]      FIG. 3  is a rear elevational view of the front frame  12 . As with the rear frame  10 , the front frame  12  is comprised of two main structural members in the form of post  48  and post  50 , each of which has a substantially hollow core,  49  and  51 , respectively. Each of the posts  48  and  50  has a tapered upper end forming a D-shaped plug  62  and  64 , respectively. The D-shaped plugs  62  and  64  fit tightly into corresponding recesses  78  formed in the underside of the seat  14  (see  FIG. 5 ). Each of the posts  48  and  50  have a pair of protrusions  66  that contain an annular flat against which a shoulder on the connecting rods  16  bears. 
         [0020]    The front frame  12  shown in  FIG. 3  has a substantially hollow interior portion comprised of hollow cores  49  and  51  inside the posts  48  and  50 , respectively. The hollow core  49  communicates with the hollow core  51  through a hollow core  53  in the upper rung  52 . Hollow sections  56  and  58  are formed in the lower rung  54 , and are separated by a solid portion  60  inside the lower rung  54 . It should be noted that, depending upon the material used and the pressures used during the GAIM process, the lower rung  54  could be hollow throughout its length as is the upper rung  52 . Alternatively, the upper rung  52  could be partially hollow as is the lower rung  54 , as depicted in  FIG. 3 . 
         [0021]    In each of the rear frame  10  and front frame  12 , the hollow areas within those frames are formed by the insertion of gas during the molding process at ports which are formed at the upper ends of each frame, and the frames  10  and  12  have not metal reinforcing, i.e., they are unreinforced. In the particular embodiment shown, the rear frame has first and second ports  91  and  93  at the upper ends of the posts  18  and  20  respectively at the elevation of the upper crossbar  24 . The ports  94  and  96  in the front frame  12  are similarly located, i.e., just below the upper ends of the posts  48  and  50 , respectively. It should be noted that locating the ports at alternative locations could result in a formation of a hollow interior which is configured to somewhat differently than is depicted in  FIG. 3  with respect to the front frame and a different configuration of hollow areas could be formed in the rear frame member than is depicted in  FIG. 2 . 
         [0022]      FIG. 4  shows a connecting rod  16 , which is preferably made without the use of GAIM technology, but instead uses insert molding technology whereby a steel rod  72  is placed in a mold and a jacket  74  is molded around the steel rod  72 . The connecting rod  16  has annular flats  70  at each end of the jacket  74 . The annular flat  70  engages similarly shaped annular flats  66  on the front frame  12  and similarly shaped annular flats  68  on the rear frame  10 . Internally threaded bores  76  receive a bolt or screw (not shown) that extends through either the front frame  12  or the rear frame  10 , depending on which end of the rod is being connected. While the particular embodiment shown herein uses an internally threaded bores, connection could alternatively be made by other types of connections, such as a slightly longer steel rod with externally threaded ends, which could then allow the rods  16  to be connected by nuts bearing against the front and rear frames. Persons of skill in the art may use any of several other alternative connecting systems well-known in the art. 
         [0023]    The seat  14  shown in  FIG. 5  has D-shaped sockets  78  in the corners of the front side of the seat  14 . The D-shaped sockets  78  are adapted to receive and tightly engage the tapered D-shaped plugs  62  and  64  on the upper ends of the posts of the front frame  12 . The seat  14  has a downwardly depending substantially circumferential flange  84  extending around three sides, i.e., the front and the two sides of the seat. The flange  84  has two inwardly pointing extensions  86  and  88  that, in combination with a rear flange  90 , form slots  80  into which the ears  30  and  32  are intended to fit to provide vertical support for the seat  14 , when the chair is in the upright position. Concave portions  98  and  98  on the flange  84  are positioned to abut the posts  18  and  20  and are configured to match the curvature of the posts  18  and  20 , respectively, at the point of connection between the seat  14  and the rear frame  10 . Fasteners  82  extend through the rear frame posts  18  and  20  to secure the rear of the seat  14  to the rear frame  10 . 
         [0024]      FIG. 6  is an enlarged perspective view of the front frame  12 . Protrusions  66  extends rearwardly and are adapted to engage the shoulders or annular flats  70  at the ends of the jackets  74  which form the outside portions of the connecting rods  16 . Recesses  67  in the front face of the front frame  12  are adapted to receive the heads of fasteners used to connect the front frame  12  to the front-to-rear connecting rods  16 . As discussed above, the D-shaped tapered plugs  62  and  64  are adapted to snugly fit into the D-shaped tapered recesses or sockets  78  that are formed in the front corners of the seat  14 . 
         [0025]      FIG. 7  is an exploded upwardly directed view in partial section of the chair that embodies the inventions described herein. At the seat level, the front frame  12  is wider than the rear frame  10 . Therefore, the connecting rods  16 A and  16 B are not parallel to each other. In order to assemble the chair depicted in  FIG. 7 , holes are drilled at the locations of the protrusions  66  in the front frame  12  and at the locations of the protrusions  66  in the rear frame  10 . The protrusion  66   a  on the rear frame  10  faces the protrusions  66   c  on the front frame  12 , and the corresponding annular flats  68   a  and  68   c  are generally parallel to each other. Similarly, protrusion  66   b  on the rear frame  10  faces the protrusions  66   d  on the front frame  12 , and the corresponding annular flats  68   b  and  68   d  are generally parallel to each other. The protrusion  66   a  has annular flat  68 A that abuts the annular flat  70   a  on one end of connecting rod  16   a , and protrusion  66   c  on the rear frame  10  has annular flat  68   c  which abuts the corresponding annular flat  70   c  on the opposite end of the connecting rod  16   a  when fasteners are used to assemble the connecting rod  16   a  between the front frame  12  and the rear frame  10 . Similarly, protrusion  68   b  on the front frame  12  has an annular flat  66   b  that engages and abuts the annular flat or shoulder  70   b  at one end of the connecting rod  16   b . The rear frame  10  has a protrusion  66   d  with an annular flat  68   d  that abuts and engages an annular flat  70   d  on the shoulder of one end of the connecting rod  16   b  when fasteners are used to connect each end of the connecting rod  16   b  between the front frame  12  and the rear frame  10 . 
         [0026]    As can be seen in  FIG. 7 , the front frame  12  is generally wider than the rear frame  10 , at least at the elevation where the seat  14  and the front-to-rear connecting rods  16  connect to the front and rear frames. The protrusions  66   a , b, c and d, therefore, must be formed at angles to each other such that the rods  16   a  and  16   b , when connected between the front and rear frames, are not parallel, but instead form an angle B of about 96 degrees with respect to the cross bar  22  of the rear frame  10  and an angle A of about 84 degrees with respect to the upper rung  52  of the front frame  12 . It is important that the annular flats  68  be formed in accordance with these angles so that when the fasteners used to connect the frames to the connecting rods, the annular flats on the frames will tightly and securely bear against the annular flats  70  at the ends of the connecting rods  16 . It is also important that the holes drilled in the frame through which the fasteners used to connect the rods  16  to the frames be drilled perpendicular to the respective annular flats  68 . Angle C (about 72 degrees) as shown  FIGS. 7 and 5  shows the direction of the holes used to connect the rear of the seat  14  to the rear frame  10 . Angle C can also be seen in  FIG. 5 . 
         [0027]    Polycarbonate is particularly well-suited for use in making chairs of the kind shown and described herein. First, the viscosity of polycarbonate is well-suited to GAIM technology. Second, the strength and toughness of polycarbonate allows the relatively elegant and thin and hollow sections of a Chiavari chair to be highly durable and suitable for use as rental equipment. However, other resins, such as Acrylic or Nylon, could be used, depending upon the priorities given to things such as transparency, strength, cost and other factors. 
         [0028]    To mold and assemble a chair using with the features and attributes discussed above, the rear frame  10  and the front frame  12  are molded using GAIM technology. Polycarbonate is injected into a rear frame mold and pressurized gas (preferably nitrogen gas) is inserted into interior spaces of the posts  18  and  20  of the rear frame  10 , and gas is forced at least partially into the cross bars  24 ,  26  and  28  that bridge from post  18  to post  20 . Gas is inserted into the rear frame  10  through ports  91  and  93  at upper rear portions of the posts  18  and  20 , respectively. Once the posts  18  and  20  are substantially hollowed, and the cross bars  22 ,  24 ,  26  and  28  are at least partially hollowed by the displacement of polycarbonate by gas, and the polycarbonate has sufficiently cooled, the rear frame is ejected from the rear frame mold. The front frame is formed in a similar manner, i.e., polycarbonate is injected into a front frame mold and pressurized gas (preferably nitrogen gas) is inserted into interior spaces of the posts  48  and  50  of the front frame  12 , and gas is forced at least partially into the cross bars that bridge from post  48  to post  50 . Gas is inserted into the front frame  12  through ports  94  and  96  at the upper rear portion of the posts  48  and  50 , respectively. Once the posts  48  and  50  are substantially hollowed, and the rungs  52  and  54  are at least partially hollowed by the displacement of polycarbonate by gas, and the polycarbonate has sufficiently cooled, the front frame is ejected from the front frame mold. 
         [0029]    The front and rear frames  10  and  12  are drilled to form holes (at angles as depicted in  FIG. 7 ) to make way for the ten fasteners used to hold the chair together, as discussed below. 
         [0030]    The seat is formed using a regular (i.e., non-GAIM) injection mold. Polycarbonate is the preferred material, because of its clarity, strength and toughness, particularly for chairs that will be used as rental equipment. 
         [0031]    The front-to-rear connecting rods  16  are formed using insert molding. A polycarbonate jacket  74  is molded around a steel rod  72 . The rod  72  is place into a cavity in a connecting rod mold, the mold is closed and polycarbonate is injected into spaces around the central portion of the rod  72 , leaving the ends of the rod exposed. When the polycarbonate is sufficiently cooled, the rod  16  is ejected from the connecting rod mold. All four of the rods used to assembly a chair are preferably identical to each other making assembly simple, and making it less likely for assembly errors to occur. 
         [0032]    The clear and transparent nature of polycarbonate resin gives a chair made in accordance with the methods described herein a crystal-like appearance, and such appearance is popular and desirable, particularly for wedding and similar events, such as anniversaries. However, it is quite feasible to include colorant into the polycarbonate resin to render the resulting chair any number of tinted shades, while maintaining both translucence and transparency, while providing a different color accent to an event. Other colorants and/or additives may also be used to achieve various visual effects that may not be transparent or even translucent, such as to make the chair opaque white or to make a chair have a wood-look. 
         [0033]    Once all seven components of a chair are molded, the chair is ready for final assembly. Two bolts and two nuts are used to hold the rear of the seat  14  in place with the ears  30  and  32  of the rear frame  10  fitting into the slots  80  in the underside of the seat  14 . The D-shaped plugs  62  and  64  are pushed into the D-shaped sockets  78 . In addition to the seat being used to join the front and rear frames  10  and  12 , Eight bolts are used to connect the four front-to-rear connecting rods  16  to the front and rear frames  10  and  12 . The bolts extend through one of the frames and thread into the threaded bores  76  at each end of a rod  16 . The annular flats  70  on the shoulders of the jacket  74  of each rod  16  make abutting contact with a correspond flat  68  on the inwardly facing protrusions  66  on the front and rear frames to provide the chair with stability when the bolts are tightened. 
         [0034]    Although the inventions described and claimed herein (which collectively may sometimes be referred to herein as the “invention”—singular) have been described in considerable detail with reference to a particular embodiments, persons skilled in the art will appreciate that the inventions may be practiced in ways that differ from the particular embodiment that has been detailed above. The example that has been described was presented for purposes of illustration and not for purposes of limitation. Therefore, the spirit and scope of the appended claims should not be limited to the description of the particular embodiment shown and described herein. Indeed numerous variations, alternatives and modifications will be apparent to persons of skill in the art of injection molding and chair design, and it is intended that combinations that embody all such variations, alternatives and modifications be included within the scope of the appended claims.