Abstract:
A foldable table includes a table top, two leg frames foldably coupling with a bottom side of the table top, and a torsion resistance frame including two longitudinal side frames parallelly provided along two longitudinal side portions of the table top respectively, and two lateral side reinforcing members laterally extended between the longitudinal side frames at two lateral side portions of the table top to form an anti-torsion frame for encircling with a peripheral portion of the table top. The torsion resistance frame is integrated with the bottom side of the table top, making it a one-piece table frame structure with increased rigidity at its maximum level, resistance to the external force of torsion and distortion. The table, having the maximum utility with minimum materials, has increased durability, comfort in usage and convenience for transportation and has lowered energy consumption in the manufacture of household furniture.

Description:
BACKGROUND OF THE PRESENT INVENTION  
       [0001]    1. Field of Invention 
         [0002]    The present invention relates to a table structure, and more particularly to a table structure which includes a table top and a foldable frame arrangement enhancing the rigidity of the table top and the torsion-resistance on the table top. 
         [0003]    2. Description of Related Arts 
         [0004]    Conventional household furniture, such as dinning table, conference table or other types of work station, etc., in which its table top is made of wood or synthetic wood plank, has the advantageous of being substantively rigid and durable. In particularly, the one important feature of this kind of table which is integrally constructed is that the table is highly resistant to torsion. However, the use of wood plank in this kind of table has the following disadvantages: the material wood plank is heavy, inconvenience for storage and transportation, and has high consumption of wood materials. 
         [0005]    Household furniture makes use of contemporary technologies to enable the use of light materials such as plastic for the table top. The use of plastic table top can lower the weight and hence convenience for transportation, however, the rigidity and stability of the table top will be significantly decreased because the strength of this type of plastic table top is very weak. In order to solve the problems and provide sufficient strength to the table top, an additional supporting structure made of metal has to be provided under the table top. Therefore, the cost of manufacture is highly increased and the convenience for transportation is lowered. In addition, since the contemporary technologies generally make use of movable connecting frame for support, such as U.S. Pat. No. 6,112,674 in which the table top is made of plastic, the leg poles of the supporting structure are mounted to the table frame at the bottom of the table top in a movable manner. Since the table frame is located at the bottom of the table top, the supporting structure and the table frame are mounted and positioned in an unsecured manner, thus the supporting structure and the supporting frame do not provide an integral structure to provide protection against the force of torsion while the mounting of supporting structure and supporting frame onto the bottom of the inherently weak table top cannot increase the resistance of the table against torsional force on the table top. This drawback in relation to the effect of torsion becomes prominent and uncovered when the table as a whole is being moved or when a relatively great external force is imposed onto the table top. 
       SUMMARY OF THE PRESENT INVENTION  
       [0006]    An object of the present invention is to solve the problems of conventional table as described above, to provide a support structure for in a one-piece integrated table frame securely mounted in the bottom of a table top, such that the one-piece table frame can increase the rigidity at its maximum level, so as to resisting to the external force of torsion and protecting the table top from distortion. Another object of the present invention is to provide a foldable table with the maximum utility by using the minimum quantity of materials which has increased durability, comfort in usage and convenience for transportation, that the foldable table has lowered energy consumption in the manufacture of household furniture. 
         [0007]    Accordingly, in order to accomplish the above objects, the present invention provides a foldable table comprising a table top and a leg frame for supporting the table top at the bottom side thereof. The foldable table further comprises a torsion resistance frame rigidly coupling between the table top and the leg frame for resisting an external force of torsion exerted at the table top. 
         [0008]    The foldable table further comprises a leg folding arrangement which is provided between the table top and the leg frame such that the leg frame can be folded to its unfolded position and folded position and is incorporated with the torsion resistance frame such that the table top is resistant to the external force of torsion. 
         [0009]    The torsion resistance frame comprises two longitudinal side frames provided two longitudinal side portions of the table top at the bottom side thereof respectively, and two lateral side reinforcing members laterally extended between the outer ends of the longitudinal side frames to form an anti-torsion frame for encircling with the peripheral portion of the table top. 
         [0010]    The torsion resistance frame further comprises a mid-support arrangement. 
         [0011]    The mid-support arrangement comprises a longitudinal mid-support member extended between the corresponding lateral side reinforcing members. Each of the rotating members has a receiving groove provided at the mid-portion thereof such that when the rotating members are rotatably coupled with the lateral side reinforcing members respectively, the longitudinal mid-support member can connect to the corresponding lateral side reinforcing members at the receiving grooves of the rotating members. 
         [0012]    Another object of the present invention is that the table top comprises two top units foldably coupled with each other such that the table top can be pivotally folded in half. The two leg frames are supported at the two top units respectively. The foldable table further comprises a leg folding arrangement coupling between the table top and the leg frame for enhancing the folding structure of the leg frame to fold the leg frame between an unfolded position and a folded position. The torsion resistance frame is provided at the bottom side of the table top for resisting the external force of torsion exerted at the table top and protecting the table top from distortion. The torsion resistance frame comprises a tabletop folding arrangement incorporating with the longitudinal side frames to enable the table top being folded in half by pivotally overlapping the two top units with each other and being unfolded to align the two top units edge-to-edge. 
         [0013]    The tabletop folding arrangement comprises a first connector provided at the corresponding inner end of each of the first and second longitudinal side reinforcing members, and a second connector pivotally coupling two corresponding first connectors with each other so as to pivotally connect the first and second longitudinal side reinforcing members end-to-end. 
         [0014]    The torsion resistance frame further comprises a mid-support arrangement. 
         [0015]    The mid-support arrangement comprises two lateral mid-support members laterally extended between the inner ends of the first and second longitudinal side reinforcing members. Preferably, each of the lateral mid-support members is coupled with two corresponding first connectors at the inner ends of the first and second longitudinal side reinforcing members. The torsion resistance frame further comprises two lateral side reinforcing members which are laterally extended between the outer ends of the first and second longitudinal side reinforcing members and are extended parallelly to the first and second lateral mid-support members. Each of the leg frames comprises a rotating member rotatably coupling with the corresponding lateral side reinforcing member, wherein the rotating member is coaxially coupling with the corresponding lateral side reinforcing member to enable the rotating member being rotated with respect to the lateral side reinforcing member. The mid-support arrangement further comprises two longitudinal mid-support members extended between the corresponding lateral side reinforcing members and the lateral mid-support members. 
         [0016]    The two top units of the table top are supported by the torsion resistance frame, wherein the longitudinal side reinforcing members are parallelly extended with each other and are longitudinally extended along two longitudinal side portions of the two top units at the bottom side thereof to reinforce the table top at two longitudinal sides thereof. The lateral side reinforcing members are laterally extended between the outer ends of the longitudinal side reinforcing members, wherein the lateral side reinforcing members not only reinforce the two outer lateral sides of the table top but also enable the rotating members being rotatably coupled underneath the table top. Accordingly, when the rotating members are rotatably coupled with the lateral side reinforcing members respectively, the longitudinal mid-support members can connect to the lateral side reinforcing members at the receiving grooves of the rotating members. The two top units of the table top are foldably coupled with each other through the tabletop folding arrangement. Accordingly, the two longitudinal side reinforcing members are pivotally connected end-to-end through the tabletop folding arrangement, such that the table top can be pivotally folded in half by overlappedly folding the two top units with each other. In addition, the two lateral mid-support members are laterally extended between two inner ends of the longitudinal side reinforcing members at a position that the lateral mid-support members are laterally extended along the two inner lateral sides of the table top to reinforce the structure of the table top. 
         [0017]    The present invention has the following advantages over the contemporary technology: 
         [0018]    1. The foldable table of the present invention provides direction to the table frame design in the bottom portion of the table top for improvement, such that the foldable table has an increased level of sturdiness, the connection between elements of the folding arrangement and the leg folding arrangement are concrete and strong which is not easy to break, especially by the application of external force of torsion. 
         [0019]    2. The foldable table of the present invention can carry a greater weight or loading at the table top. 
         [0020]    3. The foldable table of the present invention not only can save the use of materials, such as wood or synthetic wood plank and energy during manufacture, but also increase the durability, comfort in usage and convenience for transportation of the foldable table. 
         [0021]    These and other objectives, features, and advantages of the present invention will become apparent from the following detailed description, the accompanying drawings, and the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]      FIG. 1  is an exploded perspective view of the foldable table with anti-torsion arrangement according to a first preferred embodiment of the present invention. 
           [0023]      FIG. 2  is a bottom perspective view of the foldable table with anti-torsion arrangement according to the first preferred embodiment of the present invention. 
           [0024]      FIG. 3  is an exploded perspective view of the foldable table with anti-torsion arrangement according to a second preferred embodiment of the present invention. 
           [0025]      FIG. 4  is a top perspective view of the foldable table with anti-torsion arrangement according to the second preferred embodiment of the present invention. 
           [0026]      FIG. 5  is a perspective view of the leg folding arrangement of the foldable table with anti-torsion arrangement according to the second preferred embodiment of the present invention. 
           [0027]      FIG. 6  is an exploded perspective view of the foldable table with anti-torsion arrangement according to a third preferred embodiment of the present invention. 
           [0028]      FIG. 7  is a bottom perspective view of the foldable table with anti-torsion arrangement according to the third preferred embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0029]    Referring to  FIGS. 1 and 2  of the drawings, a foldable table, which is resistance to the force of torsion, according to a first preferred embodiment of the present invention is illustrated. 
         [0030]    The foldable table according to the first preferred embodiment of the present invention comprises a plastic made table top  10  defining a first top unit  103  and a second top unit  104  preferably identical to the first top unit  103 , a leg frame  30  foldably supported underneath each of the first and second top units  103 ,  104  of the table top  10 , a leg folding arrangement  40  provided between the table top  10  and the leg frame  30  to guide the leg frame  30  being folded between a folded position and an unfolded position. 
         [0031]    The foldable table further comprises a torsion resistance frame  20  rigidly coupled at the table top  10  for resisting to the external force of torsion exerted at the table top  10 , wherein the torsion resistance frame  20  is embedded into the bottom side of the tablet top  10 . Accordingly, the table top  10  has a plurality of pre-arranged indentation grooves provided at the bottom side for the torsion resistance frame  20  being embedded thereat. 
         [0032]    The torsion resistance frame  20  comprises two longitudinal side frames provided at the first top unit  103  and the second top unit  104  respectively. Each of the longitudinal side frames comprises first and second longitudinal side reinforcing members  2011 ,  2012 ,  2021 ,  2022  longitudinally coupling at two longitudinal side portions of each of the first and second top units  103 ,  104  at the bottom side thereof. In other words, one pair of the first and second longitudinal side reinforcing members  2011 ,  2021  are coupled at the first top unit  103  while another pair of first and second longitudinal side reinforcing members  2012 ,  2022  are coupled at the second top unit  104 . Accordingly, the first longitudinal side reinforcing members  2011 ,  2012  are pivotally coupled with each other end-to-end by a tabletop folding structure  60 . In addition, the second longitudinal side reinforcing members  2021 ,  2022  are pivotally coupled with each other end-to-end by the tabletop folding structure  60 . Therefore, the first and second top units  103 ,  104  can be pivotally folded in an overlapped manner via the pivot structure  60  and can be unfolded to align the top side of the first top unit  103  with the top side of the second top unit  104  to form a flat top supporting surface of the table top  10 . 
         [0033]    The tabletop folding arrangement  60  comprises a first connector  601 ,  602  provided at the corresponding inner end of each of the first and second longitudinal side reinforcing members  2011 ,  2012 ,  2021 ,  2022 , and a second connector  603  pivotally coupling two corresponding first connectors  601 ,  602  with each other so as to pivotally connect the first and second longitudinal side reinforcing members  2011 ,  2012 ,  2021 ,  2022  end-to-end. Preferably, the first connector  601 ,  602  is a hinge plate having a through hole. The second connector  603  is a rivet pivotally coupling two hinge plates through the through holes. 
         [0034]    The torsion resistance frame  20  further comprises a mid-support arrangement  50 . 
         [0035]    The mid-support arrangement  50  comprises a first lateral mid-support member  503  laterally extended between two inner ends of the first and second longitudinal side reinforcing members  2011 ,  2021  along an inner lateral side portion of the second top unit  104 , and a second lateral mid-support member  502  laterally extended between two inner ends of another first and second longitudinal side reinforcing members  2012 ,  2022  along an inner lateral side portion of the first top unit  103 . Preferably, the first lateral mid-support member  503  is coupled with two corresponding first connectors  602  at the inner ends of the first and second longitudinal side reinforcing members  2011 ,  2021  while the second lateral mid-support member  502  is coupled with two corresponding first connectors  601  at the inner ends of the first and second longitudinal side reinforcing members  2012 ,  2022 . The torsion resistance frame  20  further comprises two lateral side reinforcing members  203 ,  204  which are laterally extended between the outer ends of the first and second longitudinal side reinforcing members  2011 ,  2012 ,  2021 ,  2022  and are extended parallelly to the first and second lateral mid-support members  503 ,  502 . Each of the leg frames  30  comprises a rotating member  301  rotatably coupling with the corresponding lateral side reinforcing member  203 ,  204 , wherein the rotating member  301  is coaxially coupling with the corresponding lateral side reinforcing member  203 ,  204  to enable the rotating member  301  being rotated with respect to the lateral side reinforcing member  203 ,  204 . The mid-support arrangement  50  further comprises a first longitudinal mid-support member  5011  extended between the corresponding lateral side reinforcing member  203 ,  204  and the first lateral mid-support member  503  at the first top unit  103 , and a second longitudinal mid-support member  5012  extended between the corresponding lateral side reinforcing member  203  and the second lateral mid-support member  502  at the second top unit  104 . Preferably, the first and second longitudinal mid-support members  5011 ,  5012  are positioned at the middle of the first and second longitudinal side reinforcing members  2011 ,  2012 ,  2021 ,  2022 . In addition, each of the rotating members  301  has a receiving groove  3011  provided at the mid-portion thereof such that when the rotating members  301  are rotatably coupled with the lateral side reinforcing members  203 ,  204  respectively, the first and second longitudinal mid-support members  5011 ,  5012  can connect to the corresponding lateral side reinforcing members  203 ,  204  at the receiving grooves  3011  of the rotating members  301 . Accordingly, the leg folding arrangement  40  is operatively coupled between each of the leg frames  30  with the corresponding first and second longitudinal mid-support member  5011 ,  5012 . 
         [0036]    Each of the leg frames  30  further comprises two supporting legs  302  downwardly and spacedly extended from table top  10 . The leg folding arrangement  40  comprises a table connector  401  and a leg connector  402  pivotally coupling with the table connector  401 . The table connector  401  has one end pivotally coupled with one of the first and second longitudinal mid-support members  5011 ,  5012  and an opposed end pivotally coupled with the leg connector  402 . The leg connector  402 , having a Y-shaped configuration, has one end pivotally coupled with the table connector  401  and two corresponding ends pivotally coupled with the supporting legs  302  respectively. Therefore, when the table connector  401  is pivotally folded to overlap with the leg connector  402 , the supporting legs  302  of the leg frame  30  can be pivotally folded on the bottom side of the table top  10  and when the table connector  401  is pivotally folded to extend the leg connector  402  end-to-end, the supporting legs  302  can be pivotally fold to transversely extend from the table top  10 . The leg folding arrangement  40  further comprises a lock unit  403  for releasably locking the table connector  401  with the leg connector  402  to lock up the pivotal movement between the table connector  401  and the leg connector  402 . 
         [0037]    The lock unit  403  comprises a positioning member and a lock member cooperatively engaging with the table connector  401  and the leg connector  402  in the open position. The table connector  401  is pivotally connected to the leg connector  402  to define an overlapping connecting portion between the table connector  401  and the leg connector  402  at the unfolded position. The positioning member of the lock unit  403  having a positioning hole is positioned on the overlapping connecting portion of the table connector  401  and the leg connector  402 . In particular, the positioning member of the lock unit  403  slidably encloses the overlapping connecting portion of the table connector  401  and the leg connector  402 . The table connector  401  has an elongated groove corresponding to the position of the positioning hole. The leg connector  402  has a U-shaped groove corresponding to the position of the elongated groove of the table connector  401  and the positioning hole of the positioning member of the lock unit  403 , such that when the positioning hole of the lock unit  403 , the elongated groove of the table connector  401  and the U-shaped groove of the leg connector  402  are aligned and overlapped to form a lockable through hole, the lock member penetrating the lockable through hole locks the position of the table connector  401 , the leg connector  402  and the lock unit  403  such that the relative movement of the table connector  401  and the leg connector  402  is restricted. That is to say, the table connector  401  and the leg connector  402  are locked securely by the lock unit  403  in the unfolded position. 
         [0038]    According to the first preferred embodiment of the present invention, the structure of the torsion resistance frame  20  is described. The first and second top units  103 ,  104  of the table top  10  are supported by the torsion resistance frame  20 , wherein the first and second longitudinal side reinforcing members  2011 ,  2012 ,  2021 ,  2022  are parallelly extended with each other and are longitudinally extended along two longitudinal side portions of the first and second top units  103 ,  104  at the bottom side thereof to reinforce the table top  10  at two longitudinal sides thereof. The lateral side reinforcing members  203 ,  204  are laterally extended between the outer ends of the first and second longitudinal side reinforcing members  2011 ,  2012 ,  2021 ,  2022 , wherein the lateral side reinforcing members  203 ,  204  not only reinforce the two outer lateral sides of the table top  10  but also enable the rotating members  301  being rotatably coupled underneath the table top  10 . Accordingly, when the rotating members  301  are rotatably coupled with the lateral side reinforcing members  203 ,  204  respectively, the first and second longitudinal mid-support members  5011 ,  5012  can connect to the lateral side reinforcing members  203 ,  204  at the receiving grooves  3011  of the rotating members  301 . The first and second top units  103 ,  104  of the table top  10  are foldably coupled with each other through the tabletop folding arrangement  60 . Accordingly, the first and second longitudinal side reinforcing members  2011 ,  2012 ,  2021 ,  2022  are pivotally connected end-to-end through the tabletop folding arrangement  60 , such that the table top  10  can be pivotally folded in half by overlappedly folding the first and second top units  103 ,  104  with each other. In addition, the first and second lateral mid-support members  503 ,  504  are laterally extended between two inner ends of the first and second longitudinal side reinforcing members  2011 ,  2021 ,  2012 ,  2022  at a position that the first and second lateral mid-support members  503 ,  504  are laterally extended along the two inner lateral sides of the table top  10  to reinforce the structure of the table top  10 . 
         [0039]    As shown in  FIGS. 3 ,  4 , and  5 , a foldable table according to a second embodiment illustrates an alternative mode of the first embodiment. 
         [0040]    The foldable table according to the second embodiment comprises a table top  10 , a leg frame  30  supported underneath the table top  10 , a leg folding arrangement  40  provided between the table top  10  and the leg frame  30  to guide the leg frame  30  being folded between a folded position and an unfolded position, and a torsion resistance frame  20  rigidly coupled at the table top  10  for resisting to the external force of torsion exerted at the table top  10 . 
         [0041]    Each of the leg frames  30  further comprises two supporting legs  302  downwardly and spacedly extended from table top  10 . The mid-support arrangement  50  comprises a longitudinal mid-support member  501  longitudinally extended along a mid-portion of the table top  10  at the bottom side thereof The leg folding arrangement  40  comprises a table connector  401  and a leg connector  402  pivotally coupling with the table connector  401 . The table connector  401  has one end pivotally coupled with the longitudinal mid-support member  501  and an opposed end pivotally coupled with the leg connector  402 . The leg connector  402 , having a Y-shaped configuration, has one end pivotally coupled with the table connector  401  and two corresponding ends pivotally coupled with the supporting legs  302  respectively. Therefore, when the table connector  401  is pivotally folded to overlap with the leg connector  402 , the supporting legs  302  of the leg frame  30  can be pivotally folded on the bottom side of the table top  10  and when the table connector  401  is pivotally folded to extend the leg connector  402  end-to-end, the supporting legs  302  can be pivotally fold to transversely extend from the table top  10 . The leg folding arrangement  40  further comprises a lock unit  403  for releasably locking the table connector  401  with the leg connector  402  to lock up the pivotal movement between the table connector  401  and the leg connector  402 . 
         [0042]    The lock unit  403  comprises a positioning member and a lock member cooperatively engaging with the table connector  401  and the leg connector  402  in the open position. The table connector  401  is pivotally connected to the leg connector  402  to define an overlapping connecting portion between the table connector  401  and the leg connector  402  at the unfolded position. The positioning member of the lock unit  403  having a positioning hole is positioned on the overlapping connecting portion of the table connector  401  and the leg connector  402 . In particular, the positioning member of the lock unit  403  slidably encloses the overlapping connecting portion of the table connector  401  and the leg connector  402 . The table connector  401  has an elongated groove corresponding to the position of the positioning hole. The leg connector  402  has a U-shaped groove corresponding to the position of the elongated groove of the table connector  401  and the positioning hole of the positioning member of the lock unit  403 , such that when the positioning hole of the lock unit  403 , the elongated groove of the table connector  401  and the U-shaped groove of the leg connector  402  are aligned and overlapped to form a lockable through hole, the lock member penetrating the lockable through hole locks the position of the table connector  401 , the leg connector  402  and the lock unit  403  such that the relative movement of the table connector  401  and the leg connector  402  is restricted. That is to say, the table connector  401  and the leg connector  402  are locked securely by the lock unit  403  in the unfolded position. 
         [0043]    The torsion resistance frame  20  comprises two longitudinal side frames provided two longitudinal side portions of the table top  10  at the bottom side thereof respectively, wherein each of the longitudinal side frames comprises a longitudinal side reinforcing member  201 ,  202  extended along the respective longitudinal side portion of the table top  10 . The torsion resistance frame  20  further comprises two lateral side reinforcing members  203 ,  204  which are laterally extended between the outer ends of the longitudinal side reinforcing members  201 ,  204  at the lateral side portions of the table top  10 . Preferably, the lateral side reinforcing members  203 ,  204  are perpendicularly extended between the outer ends of the longitudinal side reinforcing members  201 ,  204  to form a rectangular anti-torsion frame for encircling with the peripheral portion of the table top  10 . Each of the leg frames  30  comprises a rotating member  301  rotatably coupling with the corresponding lateral side reinforcing member  203 ,  204 , wherein the rotating member  301  is coaxially coupling with the corresponding lateral side reinforcing member  203 ,  204  to enable the leg frame  30  being rotated with respect to the lateral side reinforcing member  203 ,  204 . 
         [0044]    The torsion resistance frame  20  further comprises a mid-support arrangement  50 . 
         [0045]    The mid-support arrangement  50 , which is longitudinally extended at a mid-portion of the table top  10 , comprises a longitudinal mid-support member  501  extended between the corresponding lateral side reinforcing members  203 ,  204  to reinforce the table top  10  at the mid-portion thereof. Each of the rotating members  301  has a receiving groove  3011  provided at the mid-portion thereof such that when the rotating members  301  are rotatably coupled with the lateral side reinforcing members  203 ,  204  respectively, the longitudinal mid-support member  501  can connect to the corresponding lateral side reinforcing members  203 ,  204  at the receiving grooves  3011  of the rotating members  301 . 
         [0046]    As shown in  FIGS. 6 and 7 , a foldable table according to a third embodiment illustrates an alternative mode of the first embodiment. 
         [0047]    The foldable table according to the second embodiment comprises a table top  10 , a leg frame  30  supported underneath the table top  10 , a leg folding arrangement  40  provided between the table top  10  and the leg frame  30  to enable the leg frame  30  being folded between a folded position and an unfolded position, and a torsion resistance frame  20  rigidly coupled at the table top  10  for resisting to the external force of torsion exerted at the table top  10 . 
         [0048]    Each of the leg frames  30  further comprises two supporting legs  302  downwardly and spacedly extended from table top  10 . The leg folding arrangement  40  comprises a table connector  401  and a leg connector  402  pivotally coupling with the table connector  401 . The table connector  401  has one end pivotally coupled with the bottom side of the table top  10  via a base connector  404  and an opposed end pivotally coupled with the leg connector  402 . Accordingly, the base connector  404  is affixed to the bottom side of the table top  10 . The leg connector  402 , having a Y-shaped configuration, has one end pivotally coupled with the table connector  401  and two corresponding ends pivotally coupled with the supporting legs  302  respectively. Therefore, when the table connector  401  is pivotally folded to overlap with the leg connector  402 , the supporting legs  302  of the leg frame  30  can be pivotally folded on the bottom side of the table top  10  and when the table connector  401  is pivotally folded to extend the leg connector  402  end-to-end, the supporting legs  302  can be pivotally fold to transversely extend from the table top  10 . The leg folding arrangement  40  further comprises a lock unit  403  for releasably locking the table connector  401  with the leg connector  402  to lock up the pivotal movement between the table connector  401  and the leg connector  402 . 
         [0049]    The lock unit  403  comprises a positioning member and a lock member cooperatively engaging with the table connector  401  and the leg connector  402  in the open position. The table connector  401  is pivotally connected to the leg connector  402  to define an overlapping connecting portion between the table connector  401  and the leg connector  402  at the unfolded position. The positioning member of the lock unit  403  having a positioning hole is positioned on the overlapping connecting portion of the table connector  401  and the leg connector  402 . In particular, the positioning member of the lock unit  403  slidably encloses the overlapping connecting portion of the table connector  401  and the leg connector  402 . The table connector  401  has an elongated groove corresponding to the position of the positioning hole. The leg connector  402  has a U-shaped groove corresponding to the position of the elongated groove of the table connector  401  and the positioning hole of the positioning member of the lock unit  403 , such that when the positioning hole of the lock unit  403 , the elongated groove of the table connector  401  and the U-shaped groove of the leg connector  402  are aligned and overlapped to form a lockable through hole, the lock member penetrating the lockable through hole locks the position of the table connector  401 , the leg connector  402  and the lock unit  403  such that the relative movement of the table connector  401  and the leg connector  402  is restricted. That is to say, the table connector  401  and the leg connector  402  are locked securely by the lock unit  403  in the unfolded position. 
         [0050]    The torsion resistance frame  20  comprises two longitudinal side frames provided two longitudinal side portions of the table top  10  at the bottom side thereof respectively, wherein each of the longitudinal side frames comprises a longitudinal side reinforcing member  201 ,  202  extended along the respective longitudinal side portion of the table top  10 . The torsion resistance frame  20  further comprises two lateral side reinforcing members  203 ,  204  which are laterally extended between the outer ends of the longitudinal side reinforcing members  201 ,  204 . Preferably, the lateral side reinforcing members  203 ,  204  are perpendicularly extended between the outer ends of the longitudinal side reinforcing members  201 ,  204  to form a rectangular anti-torsion frame to encircle with the peripheral portion of the table top  10 . Each of the leg frames  30  comprises a rotating member  301  rotatably coupling with the corresponding lateral side reinforcing member  203 ,  204 , wherein the rotating member  301  is coaxially coupling with the corresponding lateral side reinforcing member  203 ,  204  to enable the rotating member  301  being rotated with respect to the lateral side reinforcing member  203 ,  204 . 
         [0051]    One skilled in the art will understand that the embodiment of the present invention as shown in the drawings and described above is exemplary only and not intended to be limiting. 
         [0052]    It will thus be seen that the objects of the present invention have been fully and effectively accomplished. The embodiments have been shown and described for the purposes of illustrating the functional and structural principles of the present invention and is subject to change without departure from such principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims.