KR100462700B1 - Injection molding apparatus and injection molding method - Google Patents

Abstract

An object of the present invention is to accurately control the pressure and amount of a thermoplastic resin filled in a cavity to obtain a product with stable quality and high precision.

In the mold apparatus used in the present invention, the stationary mold includes a substrate, and a movable plate which is collided with a movable mold supported movably in a direction in which the stationary mold and the movable mold are movable in the opening and closing directions, . The substrate has a convex portion penetrating the moving plate. The concave portion to which the convex portion engages is movable, and a cavity is formed between the convex portion and the concave portion. Runners and gates to the cavity between the movable and movable molds are formed.

At the time of molding, the mold is closed by a mold clamping force, the movable plate and the movable mold are closed, and the resin is filled in the cavity while the movable plate and the substrate are slightly opened. At this time, the opening amount between the moving plate and the substrate is increased by the pressure of the resin, so that the pressure of the resin in the cavity is kept constant. Thereafter, the clamping force is increased to close the moving plate and the substrate. During this time, the resin in the cavity returns to the runner, and a certain amount of resin remains in the cavity at the time when the convex part is joined to the concave part and the gate is closed. Thereafter, the resin in the cavity is compressed.

Description

Injection molding apparatus and injection molding method

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding apparatus for a molding material such as a resin, and an injection molding method used in the injection molding apparatus. More particularly, the present invention relates to blocking of a gate and compression of a molding material in a cavity.

For example, in the injection molding of a thermoplastic resin, a molten resin is filled in a cavity of a product shape formed in a mold apparatus, and the product is solidified by cooling it.

In the conventional injection molding, a molding process (metering process), a filling process, and a pressure holding process are performed in the molding machine. Taking the in-line screw type molding machine as an example, in a heating cylinder device, a predetermined amount of molten resin is contained in the front end side of the cylinder body while the rotating screw is retracted (metering step). Next, the screw is advanced so that resin is injected into the mold apparatus from the nozzle at the tip end of the cylinder body, and the resin is filled in the cavity (filling step). Thereafter, a suitable pressure is applied to the resin in the cylinder body by the screw, and the amount of resin to be shrunk by cooling is supplemented in the cavity (pressure holding step).

On the other hand, the volume of the cavity in the mold apparatus is constant. As a result, the pressure or amount of the resin filled in the cavity is basically determined by the control of the molding machine. Therefore, if there is an error in the control on the molding machine side, an error occurs in the pressure or amount of the resin filled in the cavity. In order to eliminate this error, it is considered to control the screw or the like of the molding machine precisely. However, the cause of the error varies with the temperature and the property of the resin body. For example, although there is a long resin passage from the screw to the cavity, if there is an error occurring in the resin passage, even if the control of the screw is temporarily controlled, an error is caused in the pressure or amount of the resin filled in the cavity do. As a result, it is difficult to solve the error caused in the cavity only by controlling the molding machine.

In addition, in the conventional injection molding compression, for example, as disclosed in Japanese Patent Application Laid-Open No. 6-71698, after the resin is filled in the cavity, the constituent parts of a part of the mold apparatus are moved, The resin in the cavity is compressed by reducing the volume of the cavity itself by switching the mold clamping force or the like. However, compressing the resin by reducing the volume of the cavity does not have an effect of relieving the pressure or amount error of the resin filled in the cavity.

However, in the injection molding, in the case of compressing after closing the gate from the resin passage to the cavity, the conventional mold apparatus has a separate means for closing the gate and a means for compressing. On the other hand, in the mold apparatus described in Japanese Patent Laid-Open No. 6-71698, a means for closing the gate and a means for compressing are commonly used. To this end, the sleeve is mounted on the stationary side plate by moving it in the opening and closing direction, and the sleeve is pushed in the direction of the movable type by the spring so that the cavity is pressed against the concave portion of the stationary side plate and the convex . Then, the movable mold side plate and the sleeve are brought into contact with each other while the weak mold force is closed, but the fixed side plate and the movable mold side plate are slightly opened so that the resin is filled in the cavity in a state in which the concave and convex portions are not engaged. Next, when the fixed side plate and the movable side plate are closed by strengthening the fastening force, the concave portion and the convex portion close the gate and are compressed.

However, in the mold apparatus described in the above publication, since the resin passage to the cavity is formed by the gap between the fixed side plate and the movable side plate, by closing the fixed side plate and the movable side plate, The resin enters the cavity while being compressed, but must return to the molding machine side. Even if the resin in the resin passage returns to the molding machine side, since the resin in the resin passage around the cavity is subjected to the compression action by the fixed side plate and the movable side plate, the final resin amount and pressure in the cavity are unstable do.

Incidentally, in this publication, nothing is disclosed in the above publication on means for sealing the resin passage formed between the fixed side plate and the movable side plate from the outside. As can be seen from the description of the drawings, in the mold apparatus described in the above publication, the resin in the resin passage leaks to the outside.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and it is an object of the present invention to precisely control the pressure and amount of the molding material filled in the cavity.

In order to achieve the above object, according to the present invention, there is provided a fixed type and a movable type which are provided with cavities between each other when the mold is opened and closed with each other, wherein the fixed type comprises a substrate, And a deflecting means for pushing the movable plate in the direction of the movable die with respect to the substrate, wherein the movable die and the movable plate are moved in the closed form And the gate is closed from the material passage to the cavity as the moving plate and the substrate are closed as the plate and the substrate are opened and closed to change the volume of the cavity.

A material supply device for supplying a preformed molding material to the material passage of the mold device and a mold clamping device for opening and closing the fixed mold and the movable mold of the mold device and capable of adjusting the mold clamping force are used.

The movable plate and the movable mold are closed while the fixed mold and the movable mold are closed with a weak mold clamping force, and the mold plate and the movable mold are closed from the material supply device to the material channel of the mold apparatus A molding material is supplied and charged into the cavity (filling step). At this time, the moving plate and the movable die with respect to the substrate are displaced by the balance of the pressure of the molding material in the mold apparatus and the mold clamping force, and the pressure of the molding material in the cavity is adjusted (regulating step).

After the supply of the molding material is stopped in the material supply device, the mold clamping force is increased to close the substrate and the moving plate. The molding material on the cavity side returns to the material supply device side, and a certain amount of molding material remains in the cavity at the time when the gate is closed (metering step), and thereafter, The plates are closed until they collide with each other, and the molding material in the cavity is compressed (compression process).

Even if there is an error in the amount of the molding material supplied by the material supply device by the compression process, the error is absorbed by displacement of the moving plate and the movable mold with respect to the substrate, and the pressure of the molding material in the cavity is constant do. On the other hand, at the end of the pressure regulating process, the amount of the molding material on the cavity side is not constant, but in the subsequent measuring process, as the substrate and the moving plate are closed, the molding material on the cavity side returns At the time when the gate is closed, a certain amount of molding material remains in the cavity side. In this manner, the pressure and amount of the molding material filled into the cavity side can be easily and accurately controlled by the pressure control step and the metering step. As a result, a high-quality product with stable quality can be obtained. Further, after the gate is closed, the molding material in the cavity is compressed, so that the shrinkage is compensated by the solidification of the molding material, and it is not necessary to perform the pressure holding control on the material supply device side because of this compensation.

As a more specific form of the mold apparatus, the following can be used. For example, the substrate integrally holds a recess, and the movable die has a recess in which the fixed concave portion is removably engaged so that the cavity is formed by the recess and the convex portion, Is closed by the convex portion coupled to the concave portion. Further, the material passage is formed between the moving plate and the movable die. Furthermore, the force by which the deflecting means, such as a spring, pushes the moving plate is set to a force that maintains the closed form of the moving plate and the movable mold against the pressure of the molding material in the material passage.

In this way, when the material passage is formed between the moving plate and the movable mold, in addition to the substrate, finally the pressure of the molding material with respect to the pressure regulation is added to the substrate only in the cavity, and the pressure is regulated on the basis of the cavity. On the other hand, the pressure of the molding material in the material passage acts to close the moving plate and the movable mold, but the pressure is resisted by the deflecting means, and the moving plate and the movable mold are kept closed. Further, in the metering step, the volume of the material passage does not change, so that the molding material in the cavity smoothly returns to the material passage, and the pressure of the molding material in the cavity is kept constant. As a result, the pressure and metering can be made more accurate.

Furthermore, the mold apparatus may have an overflow portion, which is cut off from the cavity when the convex portion is coupled to the concave portion, over substantially the whole circumference of the cavity. For this purpose, for example, the moving plate slidably penetrating the recess may surround the convex portion, and a peripheral portion forming the overflow portion together with the material passage and the gate may be formed.

With such an overflow portion, the gas and the molding material flow out from the peripheral portion of the cavity to the overflow portion during filling processing, the fluidity of the molding material in the peripheral portion of the cavity is improved, and the peripheral portion of the cavity And also the molding material is preferably filled. As a result, it is possible to improve the characteristics such as dimensions at the peripheral portion of the product to be molded. Thereafter, in the metering process, the molding material in the cavity returns to the material passage side through the gate, or further flows out to the overflow portion. Then, after the gate is closed and the overflow portion and the cavity are cut off from each other, the molding material in the cavity is compressed.

Further, the cooling of the molding material at the peripheral portion of the cavity is delayed by the overflow portion. Thus, at the time of the metering process, the molding material flows out more smoothly from the cavity to the material passage or the overflow portion, and at the same time, the mold closing operation for performing the compression process can be performed quickly.

1 to 7 show a first embodiment of the present invention. The present embodiment is applied to injection molding using a thermoplastic resin as a molding material, and uses an in-line screw type injection molding machine as shown in Fig. In Fig. 7, reference numeral 1 denotes a heating cylinder device in the material supply device. The heating cylinder device (1) has a substantially cylindrical cylinder body (2). The cylinder body 2 is provided with a heater 3 on the outer circumference and a nozzle 4 is provided on the tip end (left side in the drawing). A hopper 5 is provided on the rear side of the cylinder main body 2. A screw 6 is rotatably accommodated in the cylinder body 2 so as to be movable in the axial direction (indicated in the right direction of the drawing). On the rear side of the screw 6, the piston rod 12 of the hydraulic cylinder 11 is fixedly connected. That is, the hydraulic cylinder 11 drives the screw 6 in the axial direction. Further, the screw 6 is rotatably driven by the electric servomotor 13.

The rotation transmitting gear 15 is spline coupled to the spline cylinder 14 fixed to the outer periphery of the piston rod 12 to transmit the rotation from the servo motor 13 to the screw 6. [ That is, although the gear 15 is prevented from rotating with respect to the screw 6, the gear 15 freely moves in the axial direction.

Reference numeral 21 denotes a direct-pressing type mold clamping apparatus. The mold clamping apparatus 21 has a fixed side platen 22 and a movable side platen 23. [ The movable platen 23 is movable in the left and right direction as shown in the drawing due to the tie bar 24. The movable platen 23 is moved by the hydraulic cylinder 25 via the mold clamping ram 26 . The hydraulic cylinder 25 is driven by a drive control device 27 such as a servo valve so that the mold clamping force can be adjusted. The fixed mold 32 is attached to the fixed platen 22 and the movable mold 33 is attached to the movable platen 23. [ The mold clamping device 21 and the heating cylinder device 1 are integrally controlled by a control device such as a computer.

The construction of the mold apparatus 31 will be described in detail with reference to Figs. 1 to 6. Fig. In Fig. 1 to Fig. 6, what is denoted by a hatched line is a resin. The stationary mold 32 and the movable mold 33 which are movable are opened and closed by the movement of the movable platen 23 so as to form a cavity 34 of a product shape when the mold is closed. The product to be molded is cylindrical roller 101, and its axial direction coincides with the mold opening / closing directions of the fixed mold 32 and the movable mold 33. [

The fixed die 32 includes a fixed side attachment plate 36 attached to the fixed side platen 23 and a fixed side support plate 36 fixed to the movable die 33 side surface of the fixed side attachment plate 36. [ Side fixing plate 37 and the fixed-side mounting plate 36 and the fixed-side supporting plate 37 constitute the substrate 38. The fixed- A location ring 39 and a square portion 40 are fixed to the fixed side attachment plate 36. A nozzle 4 of the heating cylinder device 1 is connected to the square portion 40. A spool 41 which is a material passage is provided inside the square portion 40, 37 so as to protrude toward the movable die 33 side.

On the movable die 33 side of the fixed-side support plate 37, a movable plate 46 is supported so as to be movable in a predetermined range in the die opening / closing direction. A sleeve 50 fixed by the bolt 49 as well as the stopper 48 is fixed to the movable die 33 side of the fixed side support plate 37 so that the movable plate 46 can be slidably inserted . The stopper 48 contacts the moving plate 46 from the side of the movable die 33 to regulate the maximum clearance between the moving plate 46 and the substrate 38, that is, the maximum opening amount . The movable plate 46 is urged against the substrate 38 by the spring 51 which is a biasing means fitted in a compressed form between the fixed side attachment plate 36 and the movable plate 46, Direction. The tip end of the square portion 40 is slidably coupled to the through hole 52 formed in the moving plate 46.

The sleeve 38 is fixed to the stationary side support plate 36 and the fixed side support plate 37 so that the sleeve 56 is fixed to the fixed support plate 37 And the distal end side of the sleeve 56 is slidably coupled to the through hole 57 formed in the moving plate 46. [ The distal end portion of the sleeve 56 does not have the convex portion 58 protruding toward the movable die 33 more than the moving plate 46. [

The movable die 33 has a movable side attachment plate 61 attached to the movable platen 23 and a spacer block 62 on the side of the fixed side 32 of the movable side attachment plate 61 And a movable side plate 64 fixed to a surface of the movable side support plate 63 on the fixed side 32 side. The movable side plate 64 is in contact with and closes the movable plate 46 of the fixed die 32. In order to guide the movable side plate 64 and the movable plate 46 to each other, A guide pin 66 is fixed to the movable side plate 46 and a through hole 67 through which the guide pin 66 is slidably engaged is formed in the movable side plate 64. [

The movable side plate 64 is formed with a recess 71 in which the convex portion 58 of the fixed die 32 is inserted and removed. A pin portion 73 formed in the fixed core 72 is buried in the movable side plate 64 and coaxially protrudes into the convex portion 71. The fin portion 73 is inserted and released in the sleeve 56 forming the concave portion 58 of the stationary die 32. The engaging surface between the convex portion 58 and the convex portion 71 and the engaging surface between the fin portion 73 and the sleeve 56 form a columnar surface parallel to the mold opening and closing direction, 101, there is almost no gap between them so that burrs do not occur. The final product type cavity 34 is formed by the convex portion 58 and the concave portion 71. That is, the tip end face of the convex portion 58 forms one end face of the roller 101, the bottom face of the concave portion 71 forms the other end face of the roller 101, The outer circumferential surface of the roller 101 is formed, and the pin portion 73 forms the inner circumferential surface of the roller 101. [

A runner 76 as a material passage for communicating the spool 41 with the cavity 34 is provided between the movable plate 46 of the closed fixed mold 32 and the movable side plate 64 of the movable mold 33, And a gate 77 are formed. A circular annular peripheral portion surrounding the convex portion 58 is formed on the movable plate 33 side of the moving plate 46 so that the overflow portion 78 Is formed. The overflow portion 78 communicates with the runner 76 and forms a portion of the runner 76 and a gate 77 from the runner 76 to the cavity 34. The gate 77 is closed by the convex portion 58 of the stationary die 32 engaging with the convex portion 71 of the movable die 33. The force by which the spring 51 pushes the moving plate 46 is set to a force such that the moving plate 46 and the stationary mold 33 are kept closed with respect to the pressure of the resin in the runner 76. [

Further, an injector plate (not shown) is supported between the movable side attachment plate 61 and the movable side support plate 63 so as to be movable in the mold opening / closing direction. An injector pin 82 for projecting the formed roller 101 and a runner injector pin 83 for projecting the solidified resin in the runner 76 are fixed to the injector plate.

The heating cylinder device 1, the mold clamping device 21 and the mold device 31 having the above-described configuration are provided with a control device such as a computer, a charge control means for performing the filling process described below, A pressure control means to be performed, a metering control means to perform a metering process, and a compression control means to perform a compression process.

A method of injection molding will be described. In the heating cylinder device 1, the plasticizing step and the injection step are repeatedly performed. In the plasticizing step, the thermoplastic resin supplied into the cylinder body 1 from the hopper 5 is melted and plasticized by heating by the heater 3 and kneading by rotation of the screw 6. Simultaneously with this plasticization, the resin is forwardly fed by the rotation of the screw 6, and is contained in the tip end side of the cylinder body 1. Accordingly, the screw 6 is retracted by the pressure of the resin. Also, during the plasticizing process, a suitable back pressure is applied to the screw 6 by the compression cylinder 11 in the forward direction. When the screw 6 is detected to be retracted to a predetermined position, the screw 6 is advanced by driving of the compression cylinder 11 so that the resin at the tip end in the cylinder body 1 is ejected from the nozzle 4, 31 to the spool 41. When it is detected that the screw 6 is advanced to a predetermined position, or when the screw advances to the mechanical advance limit, the plasticizing process is repeated.

The mold clamping apparatus 21 first molds the stationary mold 32 and the movable mold 33 with a weak constant mold clamping force. At this time, as shown in Fig. 1, the movable plate 46 of the stationary die 32 and the movable die 33 are brought into contact with each other and closed. On the other hand, the base 38 and the moving plate 46 of the stationary die 32 are opened with the initial closing amount A1, but the stopper 48 is not brought into contact with the moving plate 46. That is, the clamping force and the force of the spring 51 are combined. The convex portion 58 of the fixed die 32 is not coupled to the concave portion 71 of the movable die 33 and the runner 76 and the cavity 34 are communicated with each other by the open gate 77 have. In this state, the resin is injected from the heating cylinder device 1 to the spool 41. This resin is charged from the spool 41 into the cavity 34 through the runner 76 and the gate 77 (filling step).

In the heating cylinder device 1, even after the cavity 34 is filled with the resin, the screw 6 is not ejected until it is detected that the screw 6 has advanced to the predetermined position, or until the screw 6 is advanced to the advancing limit The process continues, and the supply of the resin from the heating cylinder 1 to the mold apparatus 31 still continues. In the meantime, the shape is weak. Therefore, as shown in Fig. 2, by the pressure of the resin in the mold apparatus 31, the outflow of the oil from the hydraulic cylinder 25 is not stopped, and against the mold-clamping force applied by the mold clamping apparatus 21, The movable plate 46 and the movable die 33 relative to the substrate 38 of the fixed die 32 are displaced in the opening direction. The enlarged opening amount A2 between the substrate 38 and the moving plate 46 is determined by a balance between the pressure of the resin in the mold apparatus 31 and the clamping force. More specifically, by the combination of the mold clamping force, the force of the spring 51, and the force of the resin in the mold apparatus 31 to move the movable plate 46 and the movable mold 33, the opening amount A2 is determined do. This opening amount A2 is increased so that more resin can be supplied into the mold apparatus 31. [ In other words, even when there is an error in the amount of resin supplied from the heating cylinder device 1, the error is absorbed by the change in the amount of opening, and the pressure of the resin in the cavity 34 is adjusted and becomes constant ). In this way, the pressure of the resin in the cavity 34 can be accurately controlled.

As the opening amounts A1 to A2 are increased, the force of the spring 51 is slightly weakened. By returning the mold clamping ram 26 together with the movable mold 33, 25 are slightly changed. However, the force of these springs 51 and the change of the mold clamping force are negligible. That is, the unevenness of the pressure of the resin combined with the force or the mold-clamping force of the spring 51 changing in accordance with the displacements of the moving plate 46 and the movable die 33 is such that the resin of a constant volume is charged Is very small compared with the unbalance of the pressure generated when the pressure is applied.

The pressure of the resin acting to open the substrate 38 of the stationary die 32 and the movable plate 46 and the movable die 33 in the pressure regulating step is set so as to be parallel to the die opening / Is the pressure acting on the gas 38 in one direction. This is the pressure on the pressure. On the other hand, in the mold apparatus 31 of the embodiment, the runner 76 is formed between the movable plate 46 and the movable mold 33 of the stationary mold 32, The pressure of the resin acting to open the movable die 33 and the movable die 33 acts on the base 38 only in the cavity 34 only (including the square section 40 precisely). As a result, the pressure is regulated on the basis of the cavity 34. On the other hand, the pressure of the resin of the runner 76 acts to open the moving plate 46 and the movable die 33, but the pressure of the resin in the runner 76 opposes the force of the spring 51, (46) and the movable die (33) are kept closed. This is the same in the following metering process.

After completing the pressure regulating process, the mold clamping device 21 strengthens the mold clamping force. As a result, the substrate 38 and the moving plate 46 of the stationary mold 32 are closed. The remaining resin in the cavity 34 returns to the runner 76 from the gate 77 which is still open or flows out to the overflow portion 78. The resin in the mold apparatus 31 And returns to the cylinder body 2 of the heating cylinder 1. [ The screw 6 is retracted by the amount of the resin to be returned. 3, when the convex portion 58 of the stationary die 32 is engaged with the concave portion 71 of the movable die 33, the gate 77 is opened and the overflow portion 78, the cavity 34 is shut off, and at this point, a certain amount of resin remains in the cavity 34 (metering step).

After the weighing process, as shown in Fig. 4, the substrate 38 of the stationary die 32 and the moving plate 46 are closed until they come into contact with each other, whereby the resin in the cavity 34 is pressed (Compression process). This compression amount B is equal to the opening amount A3 between the substrate 38 and the moving plate 46 at the end of the weighing process.

The volume of the cavity 34, that is, the amount of resin in the cavity 34, is not constant at the time when the pressure regulation process is completed. However, in the subsequent weighing step, as described above, the resin in the cavity 34 returns to the runner 76, and a certain amount of resin remains in the cavity 34 at the instant when the gate 77 is closed. As described above, the pressure and amount of the resin filled in the cavity 34 are accurately controlled by the pressure regulating step and the metering step.

As a result, by forming the runner 76 between the moving plate 46 of the stationary mold 32 and the movable mold 33 in the mold apparatus 31, The volume does not change. Therefore, the resin smoothly returns from the cavity 34 having a small volume to the runner 76, and the pressure of the resin in the cavity 34 is maintained to be exactly constant. In addition, the mold closing operation can be performed quickly.

The moving plate 46 is provided with an overflow portion 78 which surrounds the convex portion 58 and forms a part of the runner 76 and a gate 77, The cooling of the periphery of the cavity 34 is delayed and the resin returns more smoothly from the cavity 34 to the runner 76 during the metering process. On the other hand, if the overflow portion 78 is not present and the gate is a simple side gate, cooling and fixing of the resin in the cavity generally advances more quickly near the periphery of the cavity, The resin may not smoothly return to the runner. In order to sufficiently exhibit the effect of the overflow portion 78, it is necessary to make the overflow portion 78 have a size corresponding to the thickness of the roller 101. [

The resin in the cavity 34 is compressed. However, in the metering process, a constant amount of pressure is left in the cavity 34, so that the compression is smoothly performed . The shrinkage due to the solidification due to the cooling of the resin is compensated by the compression. As a result, it is not necessary to perform the pressure holding step to the heating cylinder device 1 side for this compensation. Of course, compression also has the effect of allowing the resin in the cavity 34 to be solidified quickly.

After the resin in the cavity 34 is sufficiently cooled and solidified, the stationary mold 32 and the movable mold 33 are closed by the mold clamping device 21. Accordingly, the resin in the cavity 34, that is, the resin solidified in the roller 101 and the runner 76 and the spool 41 is first separated from the fixed mold 32. [ The runner injector pin 83 projects the solidified resin in the runner 76 and the spool 41 to form a movable mold (not shown in the figure provided on the mold clamping device 21 side) 33 and the product injector pin 82 is released from the movable die 33 by protruding from the roller 101. In addition, Further, after the resin solidified in the runner 76 and the spool 41 and the roller 101 are taken out, the mold is closed again, and the above process is repeated.

In the above embodiment, the product to be molded is the roller 101, but the present invention can be applied to the molding of various products. The second embodiment shown in Fig. 8 is the application of the present invention to the molding of the optical lens 102 of the maniscus type, and the third embodiment shown in Fig. The present invention is applied to the molding of Parts corresponding to the mold apparatuses of the first embodiment shown in Figs. 1 to 7 described above are denoted by the same reference numerals, and a description thereof will be omitted. 8 and Fig. 9, only the vicinity of the cavity 34 is described, but the overall configuration of the mold apparatus is the same as that of the mold apparatus of the first embodiment. Fig. 10 shows the substrate 103 of the IC card to be molded. The board 103 of the IC card has a thin flat plate shape, and on one side thereof, a concave IC chip mounting portion 104 is formed.

Since the lens 102 and the substrate 103 of the IC card do not have through holes, the mold apparatus of the second and third embodiments is provided with the sleeve 56 of the mold apparatus of the first embodiment, Shaped or block-shaped particles 86. The particles 86 and the core 72 of the movable die 33 are not bonded to each other. The molding method is also the same as that of the first embodiment. 8 and 9 show a state in which the gate 77 is closed by the convex portion 58 at the tip end of the particles 86 bonded to the concave portion 71 of the movable die 33 after the compression process is completed 8 and 9 are the positions of the particles 86 when the gate 77 is opened in the charging step, the pressure regulating step or the metering step.

The present invention is suitable for molding a product such as the lens 102 that requires high precision, and also improves the optical characteristics of the lens 102. An overflow portion 78 is particularly effective for a product having a relatively small thickness such as the lens 102 and the substrate 103 of the IC card. In the conventional injection molding, when the resin is filled in the cavity from the gate, the execution is stopped at the periphery of the cavity, so that the filling property of the resin deteriorates. In addition, the leading end of the flow of the resin deteriorates the product characteristics due to the distortion of residual stress and the like, even if solidification due to cooling proceeds rapidly and insufficient filling does not occur. For example, defects such as that the thickness of the peripheral portion of the product becomes slightly larger than the thickness of the other portions may occur. Further, in the injection molding, since the gas (air and resin gas) in the cavity must be drawn out by filling resin in the cavity with the resin, for example, However, when the gap dimension is set too large, a burr is generated. On the other hand, when the gap dimension is set too small, there arises a problem that charging failure occurs. On the contrary, in the present invention, gas and resin flow out from the cavity 34 to the overflow portion 78 at the time of the filling step, whereby gas vents are surely generated, and at the same time, The fluidity of the resin in the peripheral portion of the cavity 34 is improved, so that the resin is well filled up to the peripheral portion of the cavity 34. [ This makes it possible to reduce the distortion of the residual stress in the peripheral portion of the product and improve the characteristics such as the dimensions of the peripheral portion of the product. The overflow portion 78 is finally disconnected from the cavity 34 by engaging the convex portion 58 of the stationary mold 32 with the concave portion 71 of the movable mold 33, Nor does it cause burdens on the product.

Furthermore, the fourth embodiment shown in Figs. 11 to 15 applies the present invention to the roller holder 106, which is used as a tip of a roller pen of a stationery. As shown in Figs. 14 and 15, the roller holder 106 has a cylindrical body portion 107 at its lower portion, and a stepped portion (not shown) bent inward in the radial direction from the upper end portion of the main body portion 107 108 and a thin cylindrical tubular tapered portion 109 protruding upward from the inner peripheral portion of the stepped portion 108. [ Inside the tapered portion 109, there is provided a bending portion 110 for cutting it in the radial direction.

When the roller holder 106 having such a shape is molded by ordinary injection molding, defective charging tends to occur especially in the case of the thin tapered portion 109 or the like. The shrinkage due to cooling also causes a sync mark to be generated on the outer surface of the tapered portion 109, particularly at a portion where the bridge portion 110 is screwed. Such problems can be solved by applying the present invention.

The mold apparatus of the fourth embodiment for forming the roller holder 106 basically has the same configuration as that of the mold apparatus of the first embodiment, and the same reference numerals are given to corresponding parts, and the description thereof is omitted do. The product forming surface 91 for forming the outer surface of the tapered portion 109 of the roller holder 106 is formed inside the tip end portion of the sleeve 56 in the mold apparatus of the fourth embodiment. On the inner surface of the sleeve 56, a hole portion 92 continuous to the product forming surface 91 is formed. Furthermore, the pin 38 is fixed to the substrate 38 by being fitted by the fixed-side attachment plate 36 and the sleeve 56. [ The protruding piece portion 94 is inserted into the hole 92 of the sleeve 56. The protruded piece portion 94 is formed at the distal end of the pin 93. The protruded piece 94 is inserted into the hole 92 of the sleeve 56. [

On the other hand, in the core 72 of the movable die 33, a protruding portion 96 protruding in the direction of the fixed die 32 by coaxially penetrating the recessed portion 71 is formed. The projecting portion 96 forms the inner surface of the roller holder 106 including the tapered portion 109 by its outer surface. The distal end of the protruding portion 96 becomes the engaging portion 97 to be engaged with the hole 92 of the sleeve 56 of the fixed die 32 when the mold is closed. A slit portion 98 is formed at the distal end side of the protruding portion 96 including the engaging portion 97. The slit portion 98 is drawn out to a pair of side surfaces and a front end surface of the protruding portion 96 and is engaged with the protruding piece portion 94 of the pin 93 of the fixed mold 32 when the mold is closed. The protruding portion 96 penetrates through the tapered portion 109 of the roller holder 106 to be molded and protrudes from the front end opening of the tapered portion 109. [ The coupling surface between the convex portion 58 and the concave portion 71 and the coupling surface between the hole portion 92 and the coupling portion 97 and the coupling surface between the protrusion portion 94 and the slit portion 98, And there is almost no clearance therebetween so as not to cause burrs in the roller holder 106 to be molded.

The injection molding method using the mold apparatus is also basically the same as the first embodiment. 11, the convex portion 58 of the stationary mold 32 does not engage with the movable concave portion 71, but the concave portion 71 of the stationary mold 32 does not engage with the concave portion 71 of the movable mold 32. In this case, The resin is filled into the cavity 34 from the gate 77. [ The substrate 38 and the moving plate 46 of the stationary mold 32 are closed so that the remaining resin in the cavity 34 is in contact with the runner 76 The resin of the cavity 34 is compressed after the convex portion 58 is closed by the concave portion 71 as shown in Fig.

In this molding, the product forming surface 91 of the sleeve 56 of the stationary mold 32 forms the upper surface of the stepped portion 108 of the roller holder 106 and the outer surface of the tapered portion 109, The concave portion 71 of the movable mold 33 forms the outer surface of the body portion 107 and the movable portion 33 of the movable mold 33 forms the outer surface of the body portion 107, The projecting portion 96 of the flange portion 33 forms a pair of the side surface and the bottom edge of the inner surface of the roller holder 106 and the bridge portion 110.

The tapered portion 109 of the roller holder 106 is inclined with respect to the mold opening and closing direction so that even if the tapered portion 109 finally molded is thin, The surfaces of the movable die 33 on which the tapered portions 109 are formed are largely separated from each other. As a result, the resin flows smoothly into the portions of the cavity 34 constituted by the tapered portions 109 So that charging failure does not occur. In addition, in the compression process, the sleeve 56 compresses the tapered portion 109, so that the thin tapered portion 109 can be securely formed without fail, and the bridge portion 110 is screwed There is no possibility that a sync mark is generated on the outer surface of the tapered portion 109 at the portion where the tapered portion 109 is formed. As a result, the tapered portion 109, which is inclined with respect to the mold opening / closing direction, is more strongly compressed than the main body portion 107. The movable die 33 is provided with a protruding portion 96 penetrating through the tapered portion 109 and a slit portion 98 surrounding the bridge portion 110. The fixed die 32 is provided with the substrate 38, A hole portion 92 to which the projecting portion 96 is integrally coupled and a stone piece portion 94 to be engaged with the slit portion 98 are provided. To be compressed.

In other cases, the present invention can be suitably used for molding various products such as pre-casting of a pencil. Furthermore, the present invention is not limited to the above-described embodiment, and various modifications can be made. For example, in the above embodiment, an injection molding machine of an inline screw type is used as an example, but a molding machine such as a plunger type molding machine may be used for the molding machine. In addition to the above-described embodiments, various types of mold clamping devices such as a toggle type mold clamping device can be used as the mold clamping device. The driving source of the mold clamping device is not limited to the hydraulic cylinder, but may be an electric motor or the like. Furthermore, the mold apparatus is not limited to the above embodiment. For example, as a deflecting means for pushing the moving plate, an injector or the like other than the spring may be used. Although the injection molding of a thermoplastic resin is used as an example in the above embodiment, the present invention can be applied to various molding materials such as injection molding of ceramic used as a binder of a thermoplastic resin, injection molding powder molding, injection molding of a thermosetting resin, Injection molding.

According to the present invention, it is possible to accurately control the pressure and amount of the molding material filled in the cavity.

Fig. 1 is a cross-sectional view of a part of a mold apparatus used in the first embodiment applied to the formation of a roller, showing a filling process.

Fig. 2 is a cross-sectional view of a part of a mold similar to that of Fig. 1, showing a pressure regulation step.

Fig. 3 is a cross-sectional view of a part of the same mold as Fig. 1, showing a weighing step.

Fig. 4 is a cross-sectional view of a part of the same mold as Fig. 1, showing a compression process.

Fig. 5 is an enlarged view of the vicinity of the cavity of the mold apparatus of Fig. 4;

Fig. 6 is a bottom view of the vicinity of the projection of the mold apparatus of Fig. 4;

Fig. 7 is a side view showing, in cross section, a part schematically showing the entire device used in the first embodiment of the present invention. Fig.

8 is a cross-sectional view of a part of a mold apparatus used in a second embodiment in which the present invention is applied to molding a lens.

9 is a cross-sectional view of a part of a mold apparatus used in a third embodiment in which the present invention is applied to the molding of a substrate of an IC card.

10 is a perspective view showing an IC card formed by the mold apparatus shown in Fig.

Fig. 11 is a cross-sectional view of a part of a mold apparatus used in the fourth embodiment in which the present invention is applied to the formation of a roller holder, showing the time of filling processing.

Fig. 12 is a cross-sectional view of a part of the mold apparatus similar to Fig. 11, showing a weighing step.

Fig. 13 is a cross-sectional view of a part of the mold apparatus similar to that of Fig. 11, showing the compression process, and differs from Fig. 11 and Fig.

FIG. 14 is a front view showing a roller holder formed by the mold apparatus shown in FIG. 11 to FIG. 13, in which two cross sections are shown.

Fig. 15 is a side view of the roller holder shown in Fig. 14, in which two cross sections are shown.

Claims (5)

And a stationary die (32) and a movable die (33) for forming a cavity (34) between each other when the die is closed and closed. The stationary die (32) comprises a substrate (38) A moving plate 46 which is movably supported in the opening and closing directions of the movable mold 32 and the movable mold 33 and is brought into contact with and closes the movable mold 33, And the substrate 38 has a concave portion 71 to which the block portion 58 of the stationary mold 32 is inserted so as to be capable of being inserted and released, The cavity 34 is formed by the convex portion 71 and the convex portion 58 and a material passage is formed between the moving plate 46 and the movable die 33. In addition, And the gate 77 is formed such that when the substrate 38 and the moving plate 46 are closed, And said convex portion to a mold configuration (31) which is made of a closed, by 58 is coupled to 71, A material supply device for supplying a molding material of a prism shape to the material passage of the mold apparatus (31) A mold clamping device (21) capable of opening and closing the fixed mold (32) and the movable mold (33) of the mold apparatus (31) The moving plate 46 and the movable plate 33 are closed while the fixed plate 32 and the movable plate 33 are closed with a weak clamping force while the moving plate 46 and the substrate 38 are opened, , A charging control means for supplying a molding material from the material supply device to the material passage of the mold apparatus (31) and charging the molding material into the cavity (34) By the combination of the mold clamping force and the force of the deflecting means and the force of the resin in the mold apparatus 31 to retract the movable plate 46 and the movable mold 33 during charging by the charge control means, Pressure control means for adjusting the pressure of the molding material in the cavity (34) by displacing the moving plate (46) and the movable die (33) with respect to the cavity (34) The substrate 38 and the moving plate 46 are closed and the molding material on the cavity 34 side is returned to the material supply device side after the pressure is regulated by the pressure control means, 77) is closed, a predetermined amount of molding material is left in the cavity (34) After the metering control by the metering control means is completed, the substrate 38 and the moving plate 46 are closed until they are brought into contact with each other, and the convex portion 71 and the concave portion 58 in the engaged state close the cavity 38, And compression control means for compressing the molding material in the injection molding apparatus (34). The method as claimed in claim 1, wherein when the convex portion (58) is engaged with the concave portion (71), an overflow portion (78) blocked from the cavity (34) Of the injection molding apparatus. 3. The apparatus of claim 2, wherein the convex portion (58) slidably penetrates the moving plate (46) and surrounds the convex portion (58) on the moving plate (46) 77) and a peripheral portion forming the overflow portion (78). The injection molding apparatus according to claim 1, wherein said deflection means is a spring (51). And a fixed mold 32 and a movable mold 32 which form a cavity 34 between molds when the mold is opened and closed with respect to the mold 38. The fixed mold 32 includes a substrate 38, A moving plate 46 which is movably supported in the opening and closing directions of the movable mold 32 and the movable mold 33 and is brought into contact with and closes the movable mold 33, And a convex portion 58 integrally provided on the substrate 38. The movable mold 33 has convex portions 58 of the stationary mold 32, The cavity (34) is formed by the concave portion (71) and the convex portion (58), and the moving plate (46) and the movable portion A gate 77 is formed from the material passageway to the cavity 34 and the gate 77 is connected to the gate electrode A mold apparatus 31 configured to be closed by the convex portion 58 coupled to the concave portion 71, A material supply device for supplying a molding material in a preliminary state to the material passage of the mold apparatus (31) A mold clamping device 21 capable of opening and closing the fixed mold 32 and the movable mold 33 of the mold apparatus 31 and adjusting the mold clamping force is used, The fixed mold 32 and the movable mold 33 are closed with a weak mold force so that the movable plate 46 and the movable mold 33 are closed while the movable plate 46 and the substrate 38 are opened , A molding material is supplied from the material supply device to the material passage of the mold apparatus (31) and charged into the cavity (34) At this time, by the combination of the mold clamping force and the force of the biasing means and the force of the resin in the mold apparatus 31 to retract the movable plate 46 and the movable mold 33, Displacing the plate (46) and the movable die (33) to adjust the pressure of the molding material in the cavity (34) After the supply of the molding material from the material supply device is stopped, the mold clamping force is increased to close the substrate and the moving plate (46) The molding material on the side of the cavity 34 is first returned to the material supply device side to leave a certain amount of molding material in the cavity 34 at the time the gate 77 is closed, The molding material in the cavity 34 is compressed by the block portion 58 and the concave portion 71 in the engaged state by closing the movable plate 38 and the moving plate 46 until they are in contact with each other, .