Abstract:
A small sized injection molding machine by which a molded product can be produced with a desired level of precision with simple control. An injection molding machine with: a longitudinal injection cylinder to which stick-shaped molding materials are sequentially supplied in line from the upper side, the lower end of which is formed into a nozzle shape, and the lower side of which is constituted by a material having a good heat retaining property; a heater which heats the lower portion of the injection cylinder; and a pressing shaft which presses the stick-shaped molding materials downward. When the stick shaped-molding material located at the uppermost side is pressed by the pressing shaft, the molding material located at the lowermost side which has already been completely melted, is injected into a cavity, and the heat from the heater is transmitted to the die side through a nozzle touch portion.

Description:
TECHNICAL FIELD 
     The present invention relates to a downsized and simplified injection molding apparatus. 
     BACKGROUND ART 
     In a related-art injection molding apparatus, a synthetic resin molding material, which has been supplied from a hopper in a form of pellets and the like, is plasticized and molten in a heating cylinder, then, is carried by a screw and injected to a mold cavity to be molded. Then, after the molding is solidified, the mold is opened and the molding is pushed out by an ejector pin. 
     In the above injection molding apparatus, the heating cylinder and the mold are separated, and the structure and molding conditions are independently devised from an aspect of control so that the optimum performance is fulfilled in both components, therefore, the entire apparatus has become large in size as well as the control of molding conditions has become complicated. 
     CITATION LIST 
     Patent Literature 
     
         
         Japanese Laid Open Patent Literature 1: JP-A-2008-302634 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     Recently, labor and costs for transport of moldings are becoming problems, and it has been proposed that the transport itself is not performed by manufacturing the necessary number of moldings according to need by the place of each end user. However, it is difficult to respond to the above proposal because of reasons such that the related-art injection molding apparatus has been large in size. 
     The present invention has been made in view of the above problems, and an object thereof is to provide an injection molding apparatus capable of reducing the size as well as manufacturing moldings with a desired accuracy under simple control, which will be installed in the place of the end user in future. 
     Another object of the present invention is to provide a stick-shaped molding material suitable for the above injection molding apparatus. 
     Solution to Problem 
     The present invention has been made for solving the above problems, and there is provided a first aspect of an injection molding apparatus comprising: a mold including a lower-side mold and an upper-side mold forming a cavity with the lower-side mold; a vertical injection cylinder having a nozzle in a lower end, to which stick-shaped molding materials are sequentially supplied in line from the upper side; a heating means generating a temperature gradient in which the temperature increases from above to below inside the injection cylinder; and a push-in means including a push-in shaft pushing the stick-shaped molding materials downward in the injection cylinder, wherein, when the stick-shaped molding material in the highest level is pushed by the push-in shaft, the molding material in the lowest level, which has been completely molten, is injected to the cavity, and heat is transmitted from the injection cylinder to the mold through a nozzle touch from the nozzle. 
     There is provided a second aspect of the injection molding apparatus according to a first aspect, wherein the push-in shaft includes a centering mechanism. 
     There is provided a third aspect of the injection molding apparatus according to the second aspect, wherein the push-in shaft includes an upper-side shaft and a lower-side shaft, with the lower-side shaft entering into a lower, cylindrical portion of the lower-side shaft from the lower end, and being supported to the upper-side shaft such that the lower-side shaft moves freely in a horizontal direction and a vertical direction relatively to the upper-side shaft, and the lower-side shaft being elastically fit into a low end side of the upper-end shaft in a radial direction. 
     There is provided a fourth aspect of the injection molding apparatus according to any one of the first to third aspects, further comprising: an ejector mechanism, in which an ejector pin rises by the rising of the guide rod, the ejector mechanism having a guide rod having a pair of wheels provided on right and left both sides thereof, a rear stopper plate fixed to a lower-side mold attachment board and abutting on the rear side of the guide rod, and a guide path having a pair of inclined paths provided in parallel right and left and a concave portion provided therebetween, wherein, when the guide rod is pushed by the rear stopper plate from the rear side, the wheels climb up while rolling on the inclined paths so that the guide rod rises with respect to the rear stopper plate, whereas the rear stopper plate itself enters the concave portion. 
     There is provided a fifth aspect of the injection molding apparatus according to any one of the first to fourth aspects, wherein the push-in shaft comes down by manual operation of a push-in lever. 
     There is provided a sixth aspect of the injection molding apparatus according to the fifth aspect, wherein a reservoir is provided below a gate of the upper-side mold, and a piston biased upward is housed in the reservoir. 
     There is provided a seventh aspects of the injection molding apparatus according to any one of the first to sixth aspects, wherein the injection cylinder and the mold are made of plural materials having different heat conductivities, which are respectively heated by heat from a heater, and it is adjustable that a period of time taken until the stick-shaped molding material, after having come to the lowest level by the push of the push-in shaft, is changed to a completely molten state is approximately equal to a period of time taken until the molding material is solidified, after having been injected into the cavity. 
     There is provided an eighth aspect of a stick-shaped molding material to be supplied to an injection cylinder of an injection molding apparatus according to any one of the first to seventh aspects, having an approximately columnar shape, wherein many concave grooves extending in an axis line direction are formed on an outer peripheral surface thereof. 
     There is provided a ninth aspect of the stick-shaped molding material according to the eighth aspect, wherein a volume thereof is adjusted to correspond to a volume of a piece of final molding. 
     The injection molding apparatus according to the present invention enables apparatus size reduction and simple control manufacturing of moldings with a desired accuracy. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of an injection molding apparatus according to an embodiment of the present invention. 
         FIG. 2  is a partially-exploded perspective view of the injection molding apparatus of  FIG. 1 . 
         FIG. 3  is a cross-sectional view of an internal portion of side plates of the injection molding apparatus of  FIG. 1 . 
         FIG. 4  are explanatory views of a mold, particularly, a drive mechanism of an upper-side mold of the injection molding apparatus of  FIG. 1 . 
         FIG. 5  is an explanatory view of a mold, particularly, a drive mechanism of a lower-side mold of the injection molding apparatus of  FIG. 1 . 
         FIG. 6  is a perspective view of an ejector mechanism of the injection molding apparatus of  FIG. 1 . 
         FIG. 7  are explanatory views of the ejector mechanism of  FIG. 6 . 
         FIG. 8  is an explanatory view of operations of the mold opening and the drawing of the lower-side mold of the injection molding apparatus of  FIG. 1 . 
         FIG. 9  are explanatory views of a structure of a push-in shaft of  FIG. 1 . 
         FIG. 10  is a perspective view of a stick-shaped molding material. 
         FIG. 11  is a cross-sectional view in a state where the molding material of  FIG. 10  is inserted into a cylinder body. 
         FIG. 12  is an explanatory view of a forming process of a molding M by the injection molding apparatus  1  of  FIG. 1 . 
         FIG. 13  is an explanatory view continued from  FIG. 12 . 
         FIG. 14  is an explanatory view continued from  FIG. 13 . 
         FIG. 15  is a perspective view of a lower-side mold having a different structure from  FIG. 2 . 
         FIG. 16  is a partial cross-sectional view of a mold having a different structure from  FIG. 3 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     An injection molding apparatus  1  according to an embodiment of the present invention will be explained with reference to the drawings. 
     In  FIG. 1 , numerals  3 ,  3  denote a pair of leg portions and a mounting base  5  is fixed on the pair of leg portions  3 ,  3 . A pair of side plates  7 ,  7  is installed to stand on right and left both end sides of the mounting base  5  so as to be parallel to each other. In the side plates  7 ,  7 , plate surfaces face right and left directions, and front and back directions in which the side plate  7  does not exist are opened. A top plate  8  is disposed between upper end surfaces of the side plates  7 ,  7 . 
     In a space surrounded by the mounting base  5 , the right and left side plates  7 ,  7  and the top plate  8 , a mold  9  and an injection cylinder  61  are arranged, in which the injection cylinder  61  is positioned above the mold  9 . 
     A section of the mold  9  will be explained at the beginning. 
     First, the structure of the mold  9  will be explained. 
     As shown in  FIG. 2 , a fixed lower-side mold  11  and a movable upper-side mold  13  are provided as the mold  9 , which are respectively attached to a lower-side mold attachment board  15  and an upper-side mold attachment board  17  so as to be arranged between these boards. 
     When the molds are clamped, concave portions  19  of the lower-side mold  11  and the upper-side mold  13  are sealed to form a cavity  21  as shown  FIG. 3 . The cavity  21  is shaped in accordance with the shape of a molding. A gate  23  communicating with the cavity  21  is provided in the upper-side mold  13 . The gate  23  extends to pierce the upper-side mold  13  in the vertical direction. At four corners on an upper surface of the lower-side mold  11 , positioning pins are respectively provided though not shown. 
     A part around the concave portion  19  of the lower-side mold  11  and a part around the gate  23  of the upper-side mold  13  are made of iron (Fe) having a good heat retaining property, that is, having a relatively poor heat conductivity, and other parts are made of aluminum (Al) having a good heat radiation property, namely, having a relatively good heat conductivity. 
     The lower-side mold attachment board  15  is made of iron (Fe) and the upper-side mold attachment board  17  has a two-layer structure, in which a thick upper-layer portion occupying the most of the upper-side mold attachment board  17  is made of iron (Fe) and a thin lower-layer portion is made of epoxy glass (Ep) having a good heat insulation property. 
     As described later, heat is transmitted first to the gate  23 , then, the heat is transmitted to surrounding portions from there. The portions around the gate  23  and the concave portion  19  of the lower-side mold  11  are made of iron (Fe) having a good heat retaining property and other portions are made of aluminum (Al) having a good heat radiation property, therefore, a molten molding material flows into the cavity  21  from the gate  23  smoothly and sufficiently, and the material is rapidly cooled after the material sufficiently flows in. 
     Next, a drive mechanism of the mold  9  will be explained. 
     As shown in  FIG. 3 , support shafts  25 ,  25  respectively project from right and left both sides of the upper-side mold attachment board  17 , and respective support shafts  25  extend outward through long holes  27  extending in the vertical direction of respective side plates  7  as shown in  FIG. 1 . 
     A numeral  29  denotes a handle. The handle  29  has a C-shaped bar as a whole, and slightly bends in folding directions both end sides thereof. The handle  29  is arranged so as to surround the right and left side plates  7 ,  7  from the front side, and the support shafts  25  pierce the bending portions at both end sides and fixed. 
     Guide arms  31 ,  31  are respectively connected to both end sides of the handle  29  so as to turn freely by pin connection. Each guide arm  31  bends in an arc shape and swells backward, and a lower end thereof extends to a cutout portion of the leg portion  3  through a cutout portion of the mounting base  5 , being connected by the pin in the cutout portion so as to turn freely. In each guide arm  31 , a concave portion  32  is formed in the front side, and the support shaft  25 , which is projecting outward, enters the concave portion  32  from the front side to be engaged. 
     As a slide guide mechanism (not shown) is provided between the side plate  7  and the upper-side mold attachment board  17 , the upper-side mold attachment board  17  can relatively move with respect to the side plates  7  smoothly. 
     Accordingly, when the handle  29  is lifted up as shown in  FIG. 4 , respective guide arms  31  slightly turn backward and respective support shafts  25  are released from the engaged state and move upward in the long holes  27 . Due to the movement, the upper-side mold  13  moves upward with the upper-side mold attachment board  17  connected to the support shafts  25  to open the mold. 
     Next, the relation between the upper-side mold attachment board  17  and the lower-side mold attachment board  15  will be explained. 
     As shown in  FIG. 5 , lifting and lowering shafts  33  are respectively attached to right and left both sides of the upper-side mold attachment board  17 . Cam plates  35  are respectively attached to right and left both sides of the lower-side mold attachment board  15 . A cam groove  37  of the cam plate  35  in the vertical direction at the front side and is inclined from the extended upper portion toward the back side in an oblique upward direction. A cam follower  38 , which is freely fit to the cam groove  37 , is connected to the lower end side of the lifting and lowering shaft  33 . 
     Accordingly, when the upper-side mold attachment board  17  moves upward, the lower-side mold attachment board  15  on which the lower-side mold  11  is mounted is drawn forward due to the cam mechanism. 
     A pair of slide rails  39 ,  39  is attached to the undersurface of the lower-side mold attachment board  15 . The pair of slide rails  39 ,  39  is respectively engaged with a pair of guide rails  41 ,  41  installed on the mounting base  5  so as to be smoothly guided in the front and back directions in a sliding manner. 
     An ejector mechanism for ejecting a molding M is provided in the lower-side mold  11 . In the ejector mechanism, there are provided an ejector plate  43  placed in parallel to a lower surface of the lower-side mold  11  which is opposite to the side where the cavity  21  is formed, two guide rods  45  installed to stand below the undersurface of the ejector plate  43  at an interval to each other and ejector pins  47  installed to stand on an upper surface of the ejector plate  43 . The ejector pins  47  pierce the lower-side mold  11  so as to slide freely, and tips thereof form the same planes as the surface of the concave portion  19  for forming the cavity  21  in a standby state, which configure a surface of the molding. 
     A pair of wheels  49 ,  49  are attached on right and left both sides of a lower end portion of the guide rod  45 . Board thickness surfaces on the side portion side of rear stopper plates  51  abut on the rear side of the guide rods  45 . The rear stopper plates  51  has an approximately triangle shape and are tapered toward lower portions, board thickness surfaces on the upper side thereof are fixed to the undersurface of the lower-side mold attachment board  15 . The tapered lower ends of the rear stopper plates  51  enter between the pair of wheels  49 ,  49 . 
     Numerals  53  denote guide paths, and the guide paths  53  are attached on the mounting base  5 . The two guide paths  53  are positioned between the pair of guide rails  41 ,  41 . 
     The guide paths  53  have a trapezoidal shape when seen from the right and left directions, in which upper surfaces  57  on the backside are inclined, and upper surfaces  55  on the front side are horizontal. The upper surfaces are rolling contact surfaces of the pair of wheels  49 ,  49 . 
     In each guide path  53 , a concave portion  59  piercing from the upper surface to a lower surface is formed. The concave portion  59  extends from the middle of the horizontal upper surface to the end of the back side. The concave portion  59  is a space where the above rear stopper plate  51  enters when drawn forward. 
     Accordingly, when the lower-side mold attachment board  15  is drawn forward, the guide rods  45  are pushed form the back side by the rear stopper plates  51  fixed to the lower-side mold attachment board  15 . The wheels  49  climb up while rolling on the inclined upper surfaces  57  (inclined paths) of the guide paths  53 , roll on the horizontal upper surfaces  55  as the wheels have climbed up there, and further travel forward. At that time, the rear stopper plates  51  themselves enter the concave portions  59 , and when the front surfaces thereof abut on front surfaces of the concave portions  59 , any further travelling is blocked. 
     As the rear stopper plates  51  push the rear side of the guide rods  45  over the entire length thereof, a drawing force to the front directly becomes a rolling contact force of the wheels  49 , therefore, the wheels  49  climb up on the inclined upper surface  57  smoothly even when the drawing is performed with a light force. Additionally, the lower-side mold attachment board  15  is provided with the rear stopper plates  51  instead of a cylindrical flange, therefore, the guide rods  45  can be further elevated as the flange does not exist. Accordingly, the height of the entire injection molding apparatus  1  can be suppressed. Furthermore, as the rear stopper plates  51  enter the concave portions  59  and are guided when the wheels  49  roll forward, the guide rods  45  do not deviate right or left. 
     According to the above structure, when the handle  29  is lifted upward as shown in  FIG. 8 , the upper-side mold  13  moves upward and opens, and the lower-side mold  11  is drawn forward, then, the molding M, which has been cooled and solidified, is ejected by the ejector pins  47  and taken out from the concave portion  19 . 
     Next, a section of the injection cylinder  61  will be explained. 
     As shown in  FIG. 3 , a cylinder body  63  is installed to stand on the upper-side mold attachment board  17 . The cylinder body  63  has a two-stage structure, in which an upper side is made of copper (Cu) having a better heat radiation property than iron (Fe), and a lower side is made of iron (Fe). Then, a cylindrical heater  65  is fitted to the lower half on the lower side from the outside. Accordingly, as the temperature is the lowest in the copper (Cu) portion on the upper side in the cylindrical body  63 , the molding material is not molten when the material is inserted there. As the portion surrounded by the heater  65  in the lower side is heated most strongly, the molding material coming down there is completely molten. 
     A nozzle  67  is connected to the lower end side of the cylinder body  63 , which is made of iron (Fe). A peripheral edge defining a nozzle hole  69  of the nozzle  67  has a flat end surface  71 . As shown in  FIG. 2 , the nozzle  67  enters a through hole  73  which pierces vertically and formed in the upper-side mold attachment board  17 , and the flat surface  71  around the nozzle hole  69  is faced to and pressure-welded on the upper surface of the upper-side mold  13 , which configures a so-called nozzle touch mechanism. 
     A material agitation body (not shown) is put in the cylinder body  63 . 
     The nozzle hole  69  is communicated to the gate  23 , and the completely molten molding material is injected from the nozzle hole  69  toward the cavity  21  through the gate  23 . 
     As the lower layer side of the upper-side mold attachment board  17  is made of epoxy glass (Ep) having a good heat insulation property, heat can be transmitted between the injection cylinder  61  and the mold  9  only through the nozzle touch portion. Heat quantity transmitted from the injection cylinder  61  to the mold  9  is increased when the area of the flat surface  71  is increased and reduced when the area of the flat surface  71  is reduced, therefore, the heat quantity to be transmitted can be increased/reduced by increasing and reducing the area. 
     Next, a push-in means will be explained. 
     In the  FIG. 1 , a numeral  75  denotes a push-in shaft, and the push-in shaft  75  pierces through a through hole of the top plate  8  disposed between the upper end surfaces of the pair of side plates  7 ,  7 . A rack (not shown) is attached to the back surface side of the push-in shaft  75 . 
     A numeral  77  denotes a push-in lever, and the push-in lever  77  is connected to a support shaft (not shown). The support shaft is horizontally arranged between the pair of side plates  7 ,  7 , and the right-side end portion thereof pierces the side plate  7  and projects outward. The push-in lever  77  is connected to the support shaft at the projecting right-end portion. The support shaft is provided with a pinion  79 . The pinion  79  is engaged with the rack near the push-in shaft  75 , strictly, the rack near an upper-side shaft  80 . 
     According to the above structure, when a head portion of the push-in lever  77  is grasped and leaned in a counterclockwise direction as shown by an arrow in  FIG. 1 , the push-in shaft  75  comes down due to a rack-pinion mechanism. The push-in lever  77  is biased in a direction turning in a clockwise direction, therefore, when a hand is released from the push-in lever  77 , the push-in lever  77  rises and the push-in shaft  75  rises at the same time. 
     Next, a structure of the push-in shaft  75  will be explained with reference to  FIG. 9  ( 1 ). 
     The push-in shaft  75  includes a large-diameter upper-side shaft  80  and a small-diameter lower-side shaft  83 . 
     A lower half portion of the upper-side shaft  80  has a cylindrical shape, and a support pin  81  is fixed so as to be horizontally laid inside the cylinder. Moreover, an annular elastic member  82  is fixed on the lower-end side. 
     A through hole  84  piercing in the horizontal direction is formed in the lower-side shaft  83 , and the through hole  84  extends long in the vertical direction. 
     A base end portion of the lower-side shaft  83  enters the inside of the cylinder of the upper-side shaft  80  from the lower side, and the support pin  81  is fitted freely in the through hole  84  so that the lower-side shaft  83  can relatively move in the vertical direction and the horizontal direction freely. The lower-side shaft  83  is fitted to the elastic member  82  so as to elastically contact the elastic member  82  in a radial direction. 
     According to the above structure, the relative position of the lower-side shaft  83  with respect to the upper-side shaft  80  can be changed while elastically deforming the elastic member  82  as shown in  FIG. 9  ( 2 ). 
     Accordingly, the lower-side shaft  83  of the push-in shaft  75  is centered with respect to the cylinder body  63  by escaping when abutting on an inner wall of the cylinder body  63 , therefore, it is possible to prevent the lower-side shaft  83  of the push-in shaft  75  from scraping the inner wall of the cylinder body  63  even when there is a little design error or a certain degree of deformation occurs due to many used hours in the push-in shaft  75  or the cylinder body  63 . 
     Next, a stick-shaped molding material S will be explained. 
     As shown in  FIG. 10 , the stick-shaped molding material S has an approximately columnar shape, and many concave grooves “t” extending in the axis line direction are formed on an outer peripheral surface thereof. A diameter and a length of the stick-shaped molding material S are set in consideration of an injection pressure and workability. The stick-shaped molding material S is not a final molding, the shape of which is a simple and does not require such high accuracy in size, therefore, mass production with a reasonable price is possible. 
     As shown in  FIG. 11 , a diameter of the stick-shaped molding material S is set so as to be inserted with a slight gap remaining inside the cylinder body  63 . 
     When the above-described device in the structure and the structural material are suitably combined, adequate heat can be given to necessary portions respectively in the section of the injection cylinder  61  and the section of the mold  9  by the output of one heater  65 , and further, a period of time taken until the molding material coming to the lowest level of the injection cylinder  61  is completely molten into a hot-water state can be approximately equal to a period of time taken until the molding material injected into the mold  9  is cooled and solidified. 
     Next, a manual operation of the injection molding apparatus  1  and a forming process of the molding M will be explained with reference to  FIG. 12  to  FIG. 14 . 
     As shown in  FIG. 12 , when an operator supplies a stick-shaped molding material S 1  to the cylinder body  63  of the injection cylinder  61  from the upper side by inserting the material by a hand, part of the material protrudes upward from the cylinder body  63 . At that time, a molding material S 2  in a middle level, which has been already supplied, is in a half-molten state in which the lower side is molten, and a molding material S 3  in the lowest level is completely molten in the hot-water state. 
     As shown in  FIG. 13 , when the operator push the molding material S 1  by operating the push-in lever  77  to allow the push-in shaft  75  to come down, the molding material S 2  in the middle level pushes, as a piston, the molding material S 3  which is completely molten in hot-water state to be injected into the mold  9 . As the lower end side of the molding material S 2  is molten and buries the space in the cylinder body  63  and the nozzle  67 , the effect of an airtight stopper is high. Air (K) is being generated during being molten of the materials S 1 , S 2 . The air (K), upon generation, is immediately escaped upward through the concave grooves “t” of the molding materials S 2 , S 3 , therefore, the occurrence of voids in the molding M is significantly reduced. 
     As shown in  FIG. 14 , at the time when the injection of the molding material S 3  is completed, the molding material S 2  has moved to the place where the molding material S 3  was positioned, then, the molding material is heated and molten completely into the hot-water state. 
     When the injection for one molding material to the mold  9  is completed, a buzzer (not shown) sounds and a timer (not shown) starts to measure time. Meanwhile, the operator inserts a molding material anew into the cylinder body  63 . As the buzzer sounds again after a certain period of time passes, the operator waits for the buzzer, lifting the handle  29  upward to open the mold and take out the protruding molding M by picking it by fingers. Then, after returning the handle  29  to the original position, the operator operates the push-in shaft  75  again and repeats the above operation. Accordingly, the molding M will be sequentially manufactured. 
     In the injection molding apparatus  1 , since the stick-shaped molding material S, which is an injected molding, with a prescribed volume is supplied in the injection cylinder  61 , therefore, plasticization, mixing and even measurement are not necessary. Moreover, the push-in shaft  75  in the push-in means does not require such high heat resistance and high accuracy in size. Furthermore, the temperature of the entire apparatus can be controlled only by controlling the temperature of the heater  65 . Additionally, the height is suppressed by devising an ejector mechanism in the section of the mold  9 . 
     Accordingly, the apparatus can be drastically reduced in size and simplified in control successfully. 
     The embodiment of the present invention has been explained as the above, and specific structures are not limited to the embodiment and design alternations within a scope not departing from the gist of the invention are also included in the invention. 
     Though the above embodiment is the manual apparatus using the push-in lever  77 , the apparatus can be an automatic system using an air cylinder. 
     The mold  9  is not limited to the above arrangement and types of materials, and for example, in the lower-side mold  11  of the mold  9 , a part around the concave portion  19  is made of iron, an outer peripheral part thereof is made of aluminum, holes  91  are provided at an outer periphery thereof, and the holes  91  are filled with copper or are remained open, thereby changing thermal characteristics in respective parts in accordance with the shape of the molding, as a result, the entire molding which is sufficiently solidified can be obtained after a certain solidification time passes. 
     In the case where the push-in shaft  75  is lowered by the manual operation of the push-in lever  77 , the mold  9  is floated and burrs are generated in the molding when the push-in pressure is increased too high by the operation of an unskilled operator. When a reservoir  97  is formed below a gate  95 , as shown in  FIG. 16 , and a piston  101  to which a spring  99  is connected as a biasing means is housed there so as to slide freely in the vertical direction, excessive pressure is absorbed there and does not affect the cavity  103 . 
     It is also conceivable that a push-in force by the push-in shaft is measured by a micro switch and so on and that lamps of red, yellow and so on are lighted when the force is too high based on a signal to thereby alert the operator. 
     Moreover, the volume of the stick-shaped molding material S is set to the approximately the same volume of the molding M, however, it is also possible to set the volume to a larger volume in consideration of work efficiency and so on. 
     INDUSTRIAL APPLICABILITY 
     The present invention can be used for a manufacturing industry which manufactures moldings by injection molding using a molding material. 
     REFERENCE SIGNS LIST 
     
         
           1  injection molding apparatus 
           3  (a pair of) leg portions 
           5  mounting base 
           7  (a pair of) side plates 
           8  top plate 
           9  mold 
           11  lower-side mold 
           13  upper-side mold 
           15  lower-side mold attachment board 
           17  upper-side mold attachment board 
           19  concave portion (of a cavity) 
           21  cavity 
           23  gate 
           25  support shaft 
           27  long hole 
           29  handle 
           31  guide arm 
           32  concave portion (of the guide arm) 
           33  lifting and lowering shaft 
           35  cam plate 
           37  cam groove 
           38  cam follower 
           39  (a pair of) slide rails 
           41  (a pair of) guide rails 
           43  ejector plate 
           45  guide rod 
           47  ejector pin 
           49  wheel 
           51  rear stopper plate 
           53  guide path 
           55  front-side horizontal upper surface 
           57  back-side inclined upper surface 
           59  concave portion 
           61  injection cylinder 
           63  cylinder body 
           65  heater 
           67  nozzle 
           69  nozzle hole 
           71  flat surface (of the nozzle) 
           73  through hole 
           75  push-in shaft 
           77  push-in lever 
           79  pinion 
           80  (push-in shaft) upper-side shaft 
           81  support pin 
           82  annular elastic member 
           83  (push-in shaft) lower-side shaft 
           84  through hole (of the lower-side shaft) 
           91  hole 
           93  mold 
           95  gate 
           97  reservoir 
           99  spring 
           101  piston 
           103  cavity 
         S stick-shaped molding material 
         t concave groove (of the molding material) 
         M molding 
         K air