Abstract:
Disclosed are a resin material supply apparatus and a method thereof ensuring a predetermined amount of resin material to be supplied and the molding quality to be improved without the need of storing many types of tablets or managing products by separation of damaged ones or by other methods. This resin material supply apparatus comprises; a weighing unit which allows a predetermined amount of resin material to be loaded into each of weighing pots, an agitating unit which allows resin material to be received from weighing pots into agitating cups and permits agitation to be performed by the rotation of each of plungers with an agitating rod protruded from the tip within cups, a traveling unit which allows the aforementioned agitating unit to travel in the forward and backward directions in the space between the aforementioned weighing unit and a molding die by a traveling motor capable of forward/reverse drive, and a supply unit which permits resin material having been agitated and molten in agitating cups to be extruded into a mold pot of the molding die by means of the aforementioned plungers via a vertical traveling motor capable of effecting forward/reverse drive.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    This invention relates to an apparatus for supplying a resin material to a molding die by weighing and agitating in the process of plastic encapsulation molding of electronic parts, etc, and to a method thereof.  
           [0003]    2. Description of the Related Art  
           [0004]    Conventionally, an apparatus illustrated in FIG. 5 is extensively used as the one of this type.  
           [0005]    A molding die  61  for forming a plastic encapsulation mechanism shown in FIG. 5 is configured in such a way that a top mold half  61 A and a bottom mold half  61 B are provided removably, and these top and bottom mold halves  61 A and  61 B are provided with multiple cavities  63  engraved therein. Multiple mold pots  62  are provided among the cavities of the bottom mold half  61 B, and these pots  62  are communicated to cavities  63  through runners  64  and gates  65 .  
           [0006]    Accordingly, when tablets  72  as resin material are put in the mold pots  62  of the molding die  61  heated and held at a high temperature, and plungers  67  fitted slidably in the mold pots  62  are operated to move up toward the top mold half  61 A as indicated by the arrow, then the tablets  72  are pressed and are molten as they are heated by the molding die  61 . They are then charged via the runners  64  and gates  65  into the cavities  63  provided with lead frames  63   a  connected with electronic parts or the like in advance, and plastic encapsulation is carried out in this mechanism.  
           [0007]    However, a resin material according to the aforementioned prior art plastic encapsulation is used in the form of tablets  72 . This makes it necessary to store many types of the tablets  72  each having a sizes conforming to the capacity of the cavities  63  of the molding die  61  when manufacturing various types of moldings.  
           [0008]    Furthermore, the corner portion in particular is damaged during transportation and storage of the tablets  72 , and the weight is reduced. This results in a short-shot accompanied by non-performing products. This requires tablets  72  to be managed by separation of damaged ones or a similar method.  
         SUMMARY OF THE INVENTION  
         [0009]    Thus, an object of the present invention is to provide a resin material supply apparatus and method which will ensure a predetermined amount of resin material to be supplied and the molding quality to be improved, without the need for storing many types of tablets or managing the products by separation of damaged ones or by other methods.  
           [0010]    To attain the above object, a first embodiment of the present invention provides a resin material supply apparatus comprises a weighing unit, an agitating unit, a traveling unit, and a supply unit.  
           [0011]    The weighing unit allows a predetermined amount of the aforementioned resin materials to be loaded into each of weighing pots arranged below via weighing means which has a screw inserted in the weighing tube on the bottom of a hopper storing resin materials.  
           [0012]    The agitating unit permits agitation to be performed by the rotation of each of plungers with an agitating rod protruded from the tip via agitating means having the aforementioned plungers inserted in multiple agitating cups where the aforementioned resin materials are exchanged between the aforementioned weighing pots and the aforementioned multiple agitating cups arranged in parallel with these pots.  
           [0013]    The traveling unit allows the aforementioned agitating unit to travel in the forward and backward direction in the space between the aforementioned weighing unit and the molding die via traveling means provided with a pulley and belt mounted on the shaft of a motor capable of forward/reverse drive.  
           [0014]    The supply unit permits the resin material in agitating cups to be extruded into the mold pot of the molding die by means of the aforementioned plungers via vertical traveling means provided with a pulley and belt mounted on the shaft of a motor capable of forward/reverse drive.  
           [0015]    Thus, the first embodiment of the present invention has the effect of eliminating the need for using resin materials having been weighed and formed into tablets in advance, because the resin material is weighed, agitated and molten, and is supplied to the molding die.  
           [0016]    It should be noted that the resin material can be exemplified by a molding material for encapsulation of electronic parts by plastic molding. Thermosetting epoxy resin is a common material.  
           [0017]    The molding material frequently used in the prevent invention is powdery or granular, and is characterized by the grade where the temperature of the agitating cups is kept at about 120 degrees Celsius to melt the material, and the molding die temperature is kept at about 180 degrees Celsius to set it.  
           [0018]    A second embodiment of the present invention provides a resin material supply apparatus according to the first embodiment further characterized in that;  
           [0019]    the aforementioned weighing means comprises a screw for forming a weighing unit, wherein the aforementioned screw is mounted vertically inside the hopper to lead to the bottom end of the weighing tube on the bottom of the hopper and is connected to a weighing motor, and  
           [0020]    a pot unit movable in the forward and reverse directions is provided on the bottom end of the aforementioned weighing tube, wherein a weighing pot equipped with a shutter plate opened and closed by sliding on the underside is arranged.  
           [0021]    Thus, the second embodiment of the present invention has the effect of eliminating a defect or variation in weight which may occur to the tablets (resin materials) formed in advance, and hence removing the need for tablet management by separation or the like, because a screw is inserted into the weighing cylinder for rotation, and a predetermined amount of the resin material can be weighed and loaded into the weighing pot.  
           [0022]    A third embodiment of the present invention provides a resin material supply apparatus according to the first embodiment further characterized by the aforementioned agitating means, wherein  
           [0023]    agitating cups are moved by the pulley and belt mounted on the shaft of the cup traveling motor to the bottom of the weighing pot moved by a weighing pot traveling cylinder so that the aforementioned resin material is received;  
           [0024]    the aforementioned multiple agitating cups are moved to the bottom of the aforementioned plunger mounted on the bottom linking plate installed on a guide post;  
           [0025]    an agitating rod is protruded from the tip of the plunger by the action of an agitating cylinder mounted on the bottom linking plate; and  
           [0026]    gears mounted on the aforementioned plungers are meshed with each other by the action of the agitating motor with gears mounted on the shaft thereof so that the aforementioned plungers are rotated,  
           [0027]    thereby allowing the aforementioned resin material inside the agitating cup to be agitated.  
           [0028]    Thus, the third embodiment of the present invention has the effect of ensuring homogenized agitation and melting at a high speed because the resin material received in the agitating cup can be agitated by the rotation of a protruded plunger.  
           [0029]    A fourth embodiment of the present invention provides a resin material supply apparatus according to the first embodiment further characterized by the aforementioned traveling means, wherein  
           [0030]    a traveling motor is installed on the stay extending downwardly of multiple rails along which a running cart with the agitating unit mounted therein travels, and  
           [0031]    the aforementioned running cart engaged with the belt can be moved in the forward and reverse directions in the space from the aforementioned weighing unit to the aforementioned molding die by the forward and reverse drive of the traveling motor via the pulley and belt mounted on the shaft of this motor.  
           [0032]    Thus, the fourth embodiment of the present invention has the effect of ensuring direct transmission of the forward and reverse drive of the motor and hence high-speed traveling and accurate positioning in traveling, because the agitating unit mounted on the running cart is engaged with the belt.  
           [0033]    A fifth embodiment of the present invention provides a resin material supply apparatus according to the first embodiment further characterized by the aforementioned vertical traveling means, wherein  
           [0034]    ball screws are arranged in parallel with one another among the aforementioned multiple guide posts installed on the aforementioned agitating unit;  
           [0035]    these ball screws are meshed with ball screw nuts;  
           [0036]    the aforementioned multiple plungers installed in a row on the bottom linking plate mounted on these screw nuts are moved downward via the pulley and belt mounted on the shaft of the vertical traveling motor; and  
           [0037]    a shutter plate provided on the bottom surface of the agitating cup so as to be opened or closed through sliding is made to slide and open, whereby the molten resin material from the agitating cup is supplied to the mold pot of the aforementioned molding die.  
           [0038]    Thus, the fifth embodiment of the present invention has the effect of ensuring powerful, accurate and simultaneous lowering of the bottom linking plate where multiple plungers are mounted in a row, because a ball screw mechanism linked to a vertical traveling motor is used.  
           [0039]    A sixth embodiment of the present invention provides a resin material supply apparatus according to the first to fifth embodiments further characterized in that the aforementioned resin material is powdery or granular.  
           [0040]    Thus, the sixth embodiment of the present invention has the effect of reducing the material cost because the resin material is powdery or granular.  
           [0041]    A seventh embodiment of the present invention provides a resin material supply method comprising;  
           [0042]    a weighing step of weighing resin materials stored in a hopper and loading it into a weighing pot,  
           [0043]    an agitating step of feeding the aforementioned weighed resin materials into multiple agitating cups, and agitating and melting them via an agitating unit,  
           [0044]    a traveling step of moving the agitating unit in the forward and reverse directions in the space from the weighing pot area to the molding die, and  
           [0045]    a supply step of extruding and supplying the aforementioned resin materials molten in the agitating cup into the pot of the aforementioned molding die;  
           [0046]    wherein the aforementioned resin material supply method is capable of weighing, agitating and molding a predetermined amount of resin materials even when these materials are powdery or granular.  
           [0047]    Thus, the seventh embodiment of the present invention has the effect of eliminating the need of storing and managing many types of tablets and checking possible damages or managing weight, thereby cutting down management expenses. This is because the resin material can be powdery or granular; it is not required to have been formed in a tablet. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0048]    [0048]FIG. 1 is a drawing representing the side of a resin material supply apparatus as an embodiment of the present invention;  
         [0049]    [0049]FIG. 2 is a drawing representing a resin material supply apparatus viewed in the direction of arrow A of FIG. 1;  
         [0050]    [0050]FIG. 3 is a drawing representing a resin material supply apparatus viewed in the direction of arrow B of FIG. 1;  
         [0051]    [0051]FIG. 4 is a drawing representing a resin material supply apparatus viewed in the direction of arrow C of FIG. 1; and  
         [0052]    [0052]FIG. 5 is a cross sectional view of molding of a resin material according to a conventional technique. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0053]    A resin material supply apparatus according to the preferred embodiments of the present invention will be described with reference to FIG. 1.  
         [0054]    The resin material supply apparatus  20  shown in FIG. 1 comprises a weighing unit  21 , an agitating unit  31 , a traveling unit  51  and a supply unit  41 .  
         [0055]    The weighing unit  21  loads into a weighing pot  25  a resin material  71  stored in a hopper  22  by leading it into a weighing tube  24   a  through the rotation of a screw  24 , and weighing it with this tube  24   a  in terms of the speed of this screw.  
         [0056]    The agitating unit  31  for allows the weighed resin material  71  to be exchanged between a weighing pot  25  and an agitating cup  32  and permits a plunger  33  protruding from the tip of an agitating rod  33   a  to be inserted into this cup  32  so that this resin material is agitated and molten by the rotation of the plunger.  
         [0057]    The traveling unit  51  moves the agitating unit  31  to a molding die  61  while operating it.  
         [0058]    The supply unit  41  operates the plunger  33  mounted on the agitating unit  31  and supplies the molten resin material  71  in the agitating cup  32  to the mold pot  62  upon traveling of the agitating unit  31  in such a way that the agitating cup  32  is positioned at the mold pot  62  mounted on the molding die  61 .  
         [0059]    The aforementioned resin material supply apparatus  20  is further characterized in that, similarly to the case of a conventional molding die illustrated in FIG. 5, the molten resin material  71  supplied to the mold pot  62  is extruded into the cavity  63  and molded via the molding plunger  67  inserted into the molding die  61 .  
         [0060]    The following describes the details of the constituent units.  
         [0061]    (Weighing Unit)  
         [0062]    The weighing unit will be described mainly with reference to FIGS. 1 and 2 showing the side and front (view A in FIG. 1) of the weighing unit.  
         [0063]    Multiple frame bodies  29  are mounted on this weighing unit  21 , which is installed in position by being lifted from above.  
         [0064]    A supply port  22   a  of the resin material  71  penetrating the top of the hopper  22  so that resin material  71  can be supplied from the outside.  
         [0065]    Furthermore, the vertically penetrating screw  24  is installed at the center of the hopper  22 , and the top of this screw  24  is connected with a joint which penetrates a rotary disk  22   b,  and is connected with the shaft of the weighing motor  23 . Furthermore, multiple collapse pins  22   c  are suspended from this disk  22   b  in such a way that collapse pins  22   c  can enter the resin material  71  of the hopper  22 .  
         [0066]    Accordingly, if the screw  24  is rotated by the operation of the weighing motor  23 , the collapsing rods  22   c  also rotate around the screw  22  at the same time, thereby collapsing the resin material  71  in the hopper  22  and facilitating meshing with the screw  24 .  
         [0067]    Furthermore, a weighing unit  21 A is configured in such a way that this screw  24  is inserted into the weighing tube  24   a  provided on the bottom, and a predetermined amount of resin material  71  can be weighed in terms of the speed of the screw  24  in this weighing tube  24   a.    
         [0068]    A ball screw nut  27   b  is installed on the right side of the weighing unit  21 A to ensure that the weighing unit  21 A configured and assembled in one integral body can be moved on the bottom frame of the frame body  29 , and a ball screw  27   a  is installed so that it is meshed with a nut  27   b.  Further, a sliding section is provided on the left side of the weighing unit  21 A to permit sliding with the rail  29   a  mounted on the bottom frame of the frame body  29 .  
         [0069]    Thus, a feed motor  27  mounted on the frame body  29  is operated to rotate the ball screw  27   a,  whereby the weighing unit  21 A is moved by sliding on the rail  29   a  on the left, and the weighing unit  21 A moves on each of weighing pots  25  arranged on the bottom. This allows the weighed resin material  71  to be loaded into each of weighing pots  25  from the weighing tube  24   a.    
         [0070]    The bottom end surface of this pot  25  is provided with a shutter plate  26   a  whose bottom end port is opened or closed by being slid by an open/close cylinder  26 , whereby a pot unit  25 A is formed.  
         [0071]    This pot unit  25 A is configured as shown in FIG. 2. Namely, a pot traveling cylinder  28  is operated, and each of weighing pots  25  filled with resin material  71  and arranged in position is moved in the right-hand direction. The open/close cylinder  26  is operated, and the shutter plate  26   a  is opened, and the resin material  71  in the weighing pot  25  is loaded into the agitating cup  32  on the agitating cup  32  (see FIG. 3) fed in the left-hand direction from the bottom end surface of the weighing pot  25 .  
         [0072]    (Agitating Unit)  
         [0073]    This agitating unit will be described mainly with reference to FIGS. 1 and 3 showing the side and front (view B in FIG. 1) of this unit.  
         [0074]    The agitating cups  32  are arranged to receive the resin material  71  from a weighing pot  25 . The plunger or a cup traveling motor  33  or moves this cup  32  in the lateral direction. Numeral  34  denotes four upright rectangular guide posts installed so as to surround the agitating cups  32 , and  35  represents a top linking plate for connecting these four posts  34  on the top end to fix them in position.  
         [0075]    Numeral  36  denotes a bottom linking plate which is assembled slidably with four guide posts  34 . An agitating cylinder  36   a,  a plunger  37  arranged at the center and an agitating motor  38  are mounted at four positions inside these four guide posts  34 .  
         [0076]    A large-diameter gear  38   a  mounted on the shaft of this motor  38 , and a small-diameter gear  38   b  is also mounted on the shaft on the top end portion of each plunger  37  in such a way that adjacent gears  38   a  and  38   b  are meshed with each other, where gears  38   a  and  38   b  are interlocked with each other.  
         [0077]    Accordingly, a movable plate  44  is lowered by the operation of an agitating cylinder  36   a,  and an agitating rod  37   a  is protruded. At the same time, each of plungers  37  is rotated by the operation of the agitating motor  38 , and resin material  71  in the agitating cup  32  is agitated and molten by external heating (not shown) at the same time.  
         [0078]    Numeral  39  denotes a plunger section traveling cylinder which is provided on each of the front and back of the agitating unit  31 . The agitating unit  31  with the plunger  37  mounted thereon is fed back and forth in the lateral direction by this traveling cylinder  39 .  
         [0079]    Accordingly, the cylinder  39  is extended to the left in the process of agitation as shown in FIG. 3, and is positioned to permit insertion into the agitating cup  32 . In the same manner, the traveling cylinder  39  is extended on the molding die  61  and the position is aligned with the mold pot  62 , as shown in FIG. 4.  
         [0080]    When the resin material  71  (not shown) is weighed, the traveling cylinder  39  is retracted to pull back the agitating unit  31 , and operation is performed in such a way that there is no interference between the agitating unit  31  and weighing unit  21 .  
         [0081]    (Traveling Unit)  
         [0082]    This traveling unit will be described mainly with reference to FIGS. 1 and 3 showing the side and front (view B in FIG. 1) of this unit.  
         [0083]    Numeral  51  denotes a traveling unit. A traveling motor  52  is mounted on the stay  58  suspended downward from the rails  56  and  57  along which traveling cart  31 A runs. A timing belt  54  is applied between a pulley  53   a  mounted on the shaft of this motor  52  and two pulleys  53   b  and  53   c  mounted on both ends of the rail  56 . A belt clamp  55  extending from the traveling cart  31 A and the timing belt  54  are connected between two pulleys  53   b  and  53   c  of this belt  54 .  
         [0084]    Thus, a brake can be applied to the movement of the agitating unit  31  mounted on the traveling cart  31 A by means of limit switches  56   a  provided on the front and back positions through the forward and reverse of the traveling motor  52 . Stoppers  56   b  provided on the front and back ends ensure safety during traveling in the forward and reverse on the rails  56  and  57  from the weighing unit  21  to the molding die  61 .  
         [0085]    (Supply Unit)  
         [0086]    The supply unit will be described mainly with reference to FIGS. 1 and 4 showing the side and front (view C in FIG. 1) of this unit.  
         [0087]    The supply unit  41  is build in the agitating unit  31 , and moves integrally with the agitating unit  31  to the molding die  61  indicated by a dot chain line in FIG. 1.  
         [0088]    Numeral  42  denotes a ball screw, and  43  a ball screw nut which is connected to a vertical traveling motor  45  through a pulley  45   a  and belt  45   b.  The bottom linking plate  36  is fixed to the ball screw nut  43 , and multiple plungers  37  are mounted on this linking plate  36  in array.  
         [0089]    Accordingly, when the vertical traveling motor  45  operates, the bottom linking plate  36  is locked by the rotation of ball screw  42 , and the ball screw nut  43  provided with multiple plunger  37  in a row operates downwardly to open a shutter plate  32   b  (FIG. 3) at the bottom end of the agitating cup  32 , whereby the resin material  71  is extruded into the agitating cup  32 .  
         [0090]    (Molding Die)  
         [0091]    The following description will be given mainly with reference to FIGS. 1 and 4 representing the side and front (viewed in the direction of arrow C of FIG. 1) of a molding die:  
         [0092]    The resin material  71  is supplied into the mold pot  62 . The molding plunger  67  is inserted in this pot  62 . The cavity  63  is engraved on the molded product profile and is assembled with a chase block  66 . It can be taken out from the mold proper  61 A together with this block  66  for mold replacement.  
         [0093]    Accordingly, resin material  71  supplied into the mold pot  62  is pushed into the cavity  63  which is heated by molding plunger  67  and is held at a high temperature, and is heated and set. Then the molding operation completes.  
         [0094]    The following describes the operation.  
         [0095]    As described above, a predetermined amount of the powdery or granular resin material  71  supplied to the weighing unit  21 A of the weighing unit  21  is fed to the molding die  61  at an appropriate melting temperature by the agitating unit  31 , traveling unit  51  and supply unit  41  each performing a series of operation. Thus, excellent molded products are manufactured by their interaction.  
         [0096]    A series of these operations is shown in FIG. 1. In the weighing unit  21 , the resin material  71  is supplied to the hopper  22 . The collapse pin  22   c  is also rotated around the screw  24  rotated by the operation of the weighing motor  23  in the hopper  22 , and the resin material  71  is collapsed without bridging this collapse pin. The resin is supplied in such a way that it can easily be engaged into the thread of the screw  24 . This screw  24  weighs a predetermined amount at a predetermined drive speed in the weighing tube  24   a,  and resin is loaded into the weighing pot  25  of the pot unit  25 A from the weighing unit  21 A.  
         [0097]    Traveling on the upper end face  25   a  of each weighing pot by the operation of the feed motor  27 , the weighing unit  21 A allows all the weighing pots  25  to be filled with resin material  71 .  
         [0098]    When all weighing pots  25  have been filled with resin, the pot traveling cylinder  28  is operated to move the pot unit  25 A in the lateral direction. The cup traveling motor  33  (FIG. 3) is also operated so that the agitating cup  32  moves to the left so as to accept it. The open/close cylinder  26  is operated on the bottom of the weighing pot  25  to open the shutter plate  26   a,  thereby receiving the resin material  71  having been weighed. This step is followed by the return movement to the right until it is positioned below the plunger  37 .  
         [0099]    As shown in FIG. 3, four agitating rod cylinders  36   a  operate to allow the agitating rod  37   a  to be protruded from the tip of the plunger  37 . Then the agitating motor  38  with the gear  38   a  mounted on its shaft is operated, and plunger  37  is rotated through gears  38   b  each mounted of the shaft of each of the plungers  37 , thereby agitating and melting the resin material  71  in the agitating cup  3 .  
         [0100]    In this case, the agitating cup  32  is heated to about 120 degrees Celsius—temperature for melting resin material  71 .  
         [0101]    Thus, while performing agitating operation, the agitating unit  31  quickly actuates the traveling motor  52  of traveling unit  51  and moves the timing belt  54  forward until limit switch  56   a  is actuated to apply a brake.  
         [0102]    Upon termination of agitation and melting, agitating cylinder  36 a is actuated to move the movable plate  44  upward so that the agitating rod  37   a  is pulled inside the cylinder  37  to get out of view.  
         [0103]    The supply unit  41  built in agitating unit  31  is operated where agitating unit  31  is stopped on the molding die  61 . Namely, the vertical traveling motor  45  is started, and ball screw  42  is rotated through the pulley  45   a  and belt  45   b  mounted on the shaft. Each plunger  37  mounted on the lowering ball screw nut  43  via the bottom linking plate  36  is lowered at a stretch, and the resin material  71  molten in the agitating cup  32  is supplied into the mold pot  62  on the bottom mold half  61 B of molding die  61 .  
         [0104]    The agitating unit  31  having supplied the resin allows the timing belt  54  to be fed backward by reverse drive of the traveling motor  52  to the pot unit  25 A of the weighing unit  21  where the operation is stopped by the limit switch  56   a.    
         [0105]    The bottom mold half  61 B of the molding die  61  is moved up toward the top mold half  61 A (not illustrated) to clamp the mold. Then the molding plunger  67  inserted in the mold pot  62  of bottom mold half  61 B operates to extrude the supplied and molten resin material  71  into the cavity  63 , whereby molding and setting are performed.  
         [0106]    The temperature of the cavity  63  is set at about 180 degrees Celsius for heating and setting.  
         [0107]    Then the aforementioned operation flow is repeated to perform resin molding.  
         [0108]    As described above, in the invention according to embodiment 1, the resin material is weighed, agitated and molten and is supplied to the molding die. This eliminates the need of using the tablet weighed and molded advance as a resin material, and therefore allows a resin material of any form to be used, and ensures stable quality free from variation in weight.  
         [0109]    In the invention according to embodiment 2, a screw is inserted into the weighing cylinder, and a predetermined amount of resin material is weighed by rotation and loaded into a weighing pot. This eliminates the step of sorting or separation to avoid defects or variations in weight, unlike the case of a pre-molded tablet (resin material). Thus, separation step is removed and cost reduction is ensured.  
         [0110]    In the invention according to embodiment 3, the resin material received in an agitating cup is agitated by the rotation of a protruded plunger, and this provides quick and uniform agitation and melting, as well as stable quality.  
         [0111]    In the invention according to embodiment 4, the agitation unit mounted on the running cart is engaged with the belt to permit quick traveling and positioning, with the result that productivity is improved.  
         [0112]    In the invention according to embodiment 5, a ball screw mechanism linked to the vertical traveling motor is employed to ensure powerful and accurate lowering of the bottom linking plate with multiple plungers mounted thereon at one time. This ensures uniform operations of multiple plungers, hence stable quality.  
         [0113]    In the invention according to embodiment 6, powdery or granular resin materials are used so that there is no need of molding a table. This ensures material cost reduction.  
         [0114]    The invention according to embodiment 7 removes the necessity of using various types of tablets as resin materials. It allows use of either powdery or granular materials, thereby eliminating the work of storing and controlling various types of tablets. It also removes a step of damage or weight management, thereby reducing management costs. Thus, this molding method allows a resin material of any form to be purchased at reduced material costs.  
         [0115]    Further, the mold pot of the conventional molding die can be used to hold resin materials instead of tablets directly without any modification. A special molding die need not be used. It can be used for various type of molding dies, with the result that the range of molding is expanded and production costs are reduced.