JP5856532B2 - Injection molding equipment - Google Patents

Description

  The present invention relates to an injection molding apparatus that supplies molten resin injected from an injection machine to a cavity formed in a mold.

  Injection molding is a well-known technique for supplying a molten resin injected from an injection machine to a cavity formed in a mold and then cooling and curing the molten resin to obtain a molded product.

  In injection molding, a resin is melted by an injection machine, and after the molten resin obtained thereby is injected from the injection machine, it is distributed through a hot runner. The molten resin is further introduced into a product part that forms a part of the cavity via a sprue or a gate formed in the mold. Immediately before (on the upstream side of) the cavity, for example, a nozzle is disposed as described in Patent Document 1, and the molten resin may be led out from the nozzle and supplied to the cavity.

  The temperature of the hot runner is maintained at, for example, about 200 ° C. to 220 ° C., while the temperature of the mold is approximately room temperature. Therefore, the molten resin injected into the cavity is deformed (that is, molded) along the shape of the cavity, and further, is cured by lowering the temperature as heat is taken away to become a molded product.

In such injection molding, in order to reduce the amount of resin used to reduce the product cost and to obtain a lightweight molded product for reducing the amount of CO ₂ generated, It is attempted to produce a thin-walled material having a small thickness. However, in this case, if the injection conditions are the same as when molding a thick product having a large thickness, the flow distance of the molten resin may be shortened.

  When such a situation occurs, for example, the molten resin does not reach the end of the product portion. That is, filling failure occurs, and thus a defective molded product in which the portion is missing or so-called deformation occurs is produced.

  In order to avoid this problem, it is recalled that the injection pressure of the molten resin is increased. In this case, since the pressing force against the molten resin is increased, it is expected that the flow distance of the molten resin is increased. However, if the injection pressure of the molten resin is increased, burrs are likely to occur near the parting surface, particularly in the vicinity of the gate. Therefore, it is conceivable to increase the mold clamping pressure and reduce the gap where burrs are generated as much as possible. However, in order to obtain a large mold clamping pressure, the movable mold is displaced to clamp and open the mold. A large displacement mechanism or a high output displacement mechanism is required. For this reason, the injection molding apparatus is enlarged and the weight is also increased. Moreover, since such a displacement mechanism is generally expensive, capital investment increases.

  From the above viewpoint, in Patent Document 2, in order to mold a resin molded product having a thin portion at a low equipment cost, the first and second resin passages are formed in the mold, and the product portion is formed from the first resin passage. After the molten resin introduced into the portion passes through the portion where the thin portion is formed, the valve provided in the second resin passage is opened, and the molten resin is supplied from the second resin passage to the unfilled portion in the product portion. It has been proposed to supply.

Japanese Patent Laid-Open No. 11-105079 JP 2003-154562 A

  In the prior art described in Patent Document 1, the elapsed time from the start of injection of the molten resin so that the control device stores the timing of opening the valve, in other words, the timing of supplying the molten resin from the second resin passage. And it is necessary to obtain | require previously the relationship between the arrival position of the molten resin in a product part by repeating a test. Therefore, it is complicated, and it takes a long time to perform the test.

  As described in paragraph [0027] of Patent Document 2, it is conceivable that a detection means is provided in the product portion and the detection means detects that the molten resin has passed a predetermined position. The injection pressure of the molten resin must be changed according to the position of the means.

  Therefore, by setting the melting temperature of the resin in the injection machine to a high temperature, the temperature of the molten resin is raised and the viscosity is lowered. After maintaining the high temperature and low viscosity state with a hot runner, the molten resin is introduced into the cavity. It is also possible to do. However, according to the earnest study by the present inventors, in this case, a molded product with insufficient strength is often obtained due to the change in physical properties of the molten resin.

  Moreover, the injection molding apparatus disclosed in Patent Document 2 is a so-called multi-point gate in which there are a plurality of gates for introducing a molten resin into the product portion, but because a weld line is formed for this purpose, The appearance quality of the molded product is degraded. In addition, since a plurality of valve gates must be installed, the mold cost increases.

  The present invention has been made to solve the above-described problems, and it is possible to fill a molten resin over the entire product portion forming the cavity, and to obtain a molded product exhibiting sufficient strength. It is an object of the present invention to provide an injection molding apparatus that can shorten the cycle time for obtaining a product, or can prevent the molded product from falling off when performing mold opening.

In order to achieve the above object, the present invention provides an injection molding apparatus for supplying a molten resin injected from an injection machine to a cavity formed in a mold.
A hot runner that is a flow passage for the molten resin is formed, and is provided in a part of the hot runner to raise the molten resin to a temperature higher than the melting temperature in the injection machine With
A passage opening / closing means for opening or closing the upstream flow passage or the downstream flow passage of the temperature raising section is provided.

  As described above, in the present invention, the upstream flow passage or the downstream flow passage of the temperature raising section is opened and closed by the passage opening / closing means. For example, when the downstream flow passage of the temperature raising portion is closed, the molten resin remaining in the temperature raising portion and the molten resin filled in the cavity are blocked by this closing during injection molding. Therefore, heat transfer from the molten resin remaining in the temperature raising portion to the molten resin filled in the cavity is hindered. For this reason, since the molten resin filled in the cavity is efficiently cooled, the cycle time until a molded product is obtained is shortened.

  In addition, the molten resin flowing through the hot runner is passed through the temperature raising section to increase the temperature so that the temperature is higher than the melting temperature in the injection machine and the viscosity is decreased. Can be increased.

  That is, for example, even when there is a portion that forms a thin portion in the product part, the temperature of the molten resin is high even if heat is taken away by the mold because the temperature of the molten resin is high. . Therefore, the molten resin easily passes through the portion with a relatively low viscosity and reaches the end of the product portion. For this reason, it is possible to obtain a molded product in which the occurrence of defects is avoided.

  Moreover, since the time during which the molten resin is kept at a high temperature is short compared to the case where the melting temperature of the resin in the molding machine is set high, the molded product becomes brittle due to a change in physical properties of the molten resin. In addition, it is possible to avoid the occurrence of defects in the appearance of the molded product due to the generation of gas. That is, the obtained molded product shows sufficient strength.

  In addition, in the present invention, it is sufficient to control the temperature of the temperature-raising part and the time during which it is held at a high temperature in order to ensure the strength of the molded product. There is no need to make it. In addition, since it is not particularly necessary to use a multipoint gate, the concern that a weld line is generated is eliminated. Moreover, the mold cost does not increase.

  In this case, it is not necessary to increase the injection pressure of the molten resin in order to increase the flow distance of the molten resin. For this reason, it is expected that it is not necessary to increase the clamping pressure in order to avoid the occurrence of burrs as the injection pressure is increased.

  For the reasons as described above, it is possible to avoid an increase in the size and weight of the injection molding apparatus. Moreover, since a small displacement mechanism is generally cheaper than a large displacement mechanism, it is possible to avoid an increase in capital investment.

Channel opening and closing means, for example, that make up the so-called valve gate. That is, in this case, the passage opening / closing means includes a valve member that opens or closes the upstream flow passage or the downstream flow passage, and a displacement mechanism that displaces the valve member.

Note that Ru is provided stirring means for stirring the molten resin flowing through the heating unit. Due to this stirring, it is possible to avoid temperature unevenness in the molten resin. Accordingly, the temperature of the molten resin, and hence the viscosity, becomes substantially uniform. This avoids the formation of a highly viscous portion in the molten resin, so that it is easy to increase the flow distance of the molten resin.

  In this case, in order to provide the valve member so as not to interfere with the stirring means, the valve member extends in a direction parallel to the longitudinal direction of the stirring means, and the inlet or outlet of the stirring means and the upstream flow passage or What is necessary is just to provide the communicating path which connected the said downstream flow path and inclined with respect to the longitudinal direction of the said stirring means.

  Or you may make it extend a valve member in the direction which inclines with respect to the longitudinal direction of a stirring means.

  Further, the valve member may be passed through the stirring means. That is, an insertion hole may be formed in the stirring blade constituting the stirring means, and the valve member may be passed through the insertion hole.

  In general, a plurality of stirring blades are joined to each other. However, if the insertion hole is formed in the joint, the joint strength decreases. In this case, if the injection pressure is excessively large, the stirring blade may be deformed. Therefore, it is preferable to form the insertion hole in a portion other than the joint portion between the stirring blades. In this case, the stirring means may be provided at a position where the central axis is offset with respect to the central axis of the upstream flow passage or the downstream flow passage.

  Alternatively, a pipe member may be inserted into the insertion hole, and the valve member may be passed through the insertion hole via the through hole of the pipe member. Even in this case, deformation of the stirring blade can be avoided.

  If the displacement mechanism is installed in a fixed mold and the downstream flow passage is opened or closed by the valve member, the molten resin in the temperature raising section and the molten resin in the cavity are blocked, so that the cavity It becomes easy to shorten the cycle time for efficiently cooling the molten resin to obtain a molded product.

  Further, when the displacement mechanism is installed in the movable mold and the downstream flow passage is opened or closed by the valve member, the molded product is supported by the valve member when the mold is opened. Therefore, it is avoided that the molded product falls off.

  A plurality of the temperature raising section and the passage opening / closing means may be provided. Thereby, even when the hot runner is branched, the above-described effects can be obtained.

  In the case where a plurality of the temperature raising parts and the passage opening / closing means are provided, the plurality of passage opening / closing means are individually operated so that the molten resin is individually supplied to the cavity from each of the plurality of temperature raising parts. It may be. In this case, for example, when there is a wide part in the cavity, the plurality of passage opening / closing means are installed so as to supplement each filling amount, whereby the part can be tightly filled with the molten resin.

  According to the present invention, the upstream flow passage or the downstream flow passage of the temperature raising section is opened and closed by the passage opening / closing means. For example, the molten resin remaining in the temperature raising section or its upstream side, and the cavity Thus, the heat transfer from the molten resin remaining in the temperature rising portion or the upstream side to the molten resin filled in the cavity can be prevented. For this reason, the molten resin with which the cavity was filled is cooled efficiently. As a result, the cycle time until a molded product is obtained can be shortened.

  In addition, when the displacement mechanism is installed on the movable mold and the downstream flow passage of the temperature raising section is opened or closed by the valve member, the molded product may be supported by the valve member when the mold is opened. it can. For this reason, it is possible to avoid the molded product from falling off.

It is a principal part schematic longitudinal cross-sectional view of the injection molding apparatus which concerns on embodiment of this invention. It is a principal part schematic longitudinal cross-sectional view which shows the state which the channel | path opening-and-closing means shown in FIG. 1 opened the opening by the side of the entrance of a sprue. It is a principal part schematic longitudinal cross-sectional view of the injection molding apparatus which provided the valve member which comprises a channel | path opening / closing means, without inserting in the stirring means. It is a principal part schematic longitudinal cross-sectional view of the injection molding apparatus which provided the valve member which comprises a channel | path opening / closing means so that it might incline with respect to the longitudinal direction of a stirring means. It is a principal part enlarged view which shows the front-end | tip vicinity of a valve member when the injection molding apparatus shown in FIG. 4 exists in an open state. It is a principal part enlarged view which shows the front-end | tip vicinity of the valve member when the injection molding apparatus shown in FIG. 4 exists in a closed state. It is a principal part enlarged view which shows an open state when the front-end | tip of a valve member is a shape different from FIG.5 and FIG.6. It is a principal part enlarged view which shows a closed state when the front-end | tip of a valve member is a shape different from FIG.5 and FIG.6. It is a principal part schematic longitudinal cross-sectional view of the injection molding apparatus which let the valve member pass so that the junction part of the stirring blade of a stirring means might be avoided. FIG. 10 is a schematic vertical cross-sectional view of a main part of an injection molding apparatus having a configuration different from that of FIG. It is a principal part schematic longitudinal cross-sectional view of the injection molding apparatus which provided the passage opening / closing means in the movable mold | type. It is a principal part schematic longitudinal cross-sectional view which shows the state which the channel | path opening-and-closing means shown in FIG. 11 opened the opening by the side of the entrance of a sprue. FIG. 12 is a schematic vertical sectional view of an essential part of an injection molding apparatus in which a passage opening / closing means having a configuration different from that of FIG. It is a principal part schematic longitudinal cross-sectional view which shows the state which the channel | path opening-and-closing means shown in FIG. 13 opened the opening by the side of the entrance of a sprue. It is a principal part schematic longitudinal cross-sectional view of the injection molding apparatus which can open and close the downstream flow path of a temperature rising part. It is a principal part schematic longitudinal cross-sectional view of the injection molding apparatus provided with two or more temperature rising parts and channel | path opening / closing means. It is a principal part schematic longitudinal cross-sectional view of the injection molding apparatus which inserted the valve rod (valve member) in the pipe member, and let it pass through the insertion hole of the stirring means.

  Preferred embodiments of an injection molding apparatus according to the present invention will now be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic vertical sectional view of an essential part of an injection molding apparatus 10 according to the present embodiment. The injection molding apparatus 10 includes a fixed mold 12 and a movable mold 14 that approaches or separates from the fixed mold 12 under the action of a displacement mechanism (not shown). A cavity including the runner 16 is formed by the fixed mold 12 and the movable mold 14.

  A hot runner block 20 in which a first hot runner 18 is formed is attached to the fixed mold 12. A hot runner manifold 24 in which a second hot runner 22 is formed is provided on the downstream side of the hot runner block 20.

  The hot runner block 20 is provided with a touch piece 26. An introduction hole 28 is formed through the touch piece 26, and an injection nozzle 32 of an injection machine 30 is seated in the opening of the introduction hole 28.

  The first hot runner 18 communicates with the introduction hole 28. The second hot runner 22 includes a guide path 34 that communicates with the first hot runner 18, and a plurality of branch paths 36 that branch radially from the guide path 34. In FIG. 1, two of the plurality of branch paths 36 separated from each other by approximately 180 ° are shown.

  The second hot runner 22 further includes a communication path 40 provided in the hot nozzle 38 and a temperature raising part 42 as a terminal part. That is, the branch path 36 communicates with the temperature raising unit 42 via the communication path 40. In other words, the communication path 40 is an upstream flow path of the temperature raising unit 42.

  In the vicinity of the first hot runner 18, the branch path 36 and the communication path 40, heating means such as a heater (not shown) is provided. For this reason, the molten resin flowing through the first hot runner 18, the branch path 36, and the communication path 40 is maintained at a predetermined temperature between 200 ° C. and 220 ° C., for example.

  In the present embodiment, the temperature raising unit 42 is configured by winding a band heater 46 around the outer peripheral wall of the static mixer 44. The inner wall of the end of the static mixer 44 facing the hot nozzle 38 is a threaded portion, and this threaded portion is screwed into the threaded portion provided on the outer wall of the end facing the static mixer 44 of the hot nozzle 38. ing.

  As is well known, the static mixer 44 is a tube member in which a mixing blade 48 is provided. The molten resin flowing in the static mixer 44 moves along the shape of the mixing blade 48 when passing through the mixing blade 48. This movement stirs the molten resin. As understood from this, the static mixer 44 is a stirring means that does not require power.

  The band heater 46 wound around the outer peripheral wall of the static mixer 44 transfers heat to the mixing blade 48 through the outer peripheral wall. Accordingly, heat is also transmitted to the molten resin passing through the mixing blade 48. Further, depending on the shape of the mixing blade 48, shearing heat is generated. Accordingly, the temperature of the molten resin increases. That is, the temperature raising part 42 is for raising the temperature of the molten resin flowing through the temperature raising part 42. Note that the temperature of the band heater 46, and hence the temperature of the temperature raising unit 42, is controlled according to a value measured via a thermocouple (not shown).

  A nozzle tip 52 in which a sprue 50 is formed is disposed downstream of the static mixer 44. The molten resin that has passed through the temperature raising portion 42 is introduced into the runner 16 that is a part of the cavity via the sprue 50. That is, the sprue 50 is a downstream flow passage of the temperature raising unit 42. In addition, the sprue 50 is diameter-expanded in a taper shape from the end part on the side close to the temperature raising part 42 (upstream side) toward the end part on the side close to the movable mold 14 (downstream side).

  In the above configuration, the hot runner block 20 or the hot runner manifold 24 is provided with a hydraulic cylinder 54 (displacement mechanism) that constitutes a passage opening / closing means. That is, the hydraulic cylinder 54 is supported by the fixed mold 12 via the hot runner block 20 or the hot runner manifold 24. Alternatively, the hydraulic cylinder 54 may be provided directly on the fixed mold 12.

  A valve rod 60 (valve member) constituting a passage opening / closing means together with the hydraulic cylinder 54 is connected to the tip of the piston rod 56 of the hydraulic cylinder 54 via a coupling 58. The valve stem 60 is supported by a bearing 62 provided in the hot runner manifold 24 and is inserted into the branch path 36. The valve stem 60 further extends so as to exceed the communication passage 40 and the temperature raising portion 42 of the hot nozzle 38.

  On the other hand, the mixing blade 48 is formed with a plurality of insertion holes along the central axis of the static mixer 44, and the valve stem 60 passes through all the insertion holes and enters the nozzle tip 52. doing.

  In the sprue 50, the size of the opening facing the temperature raising portion 42 is substantially equal to the size of the tip of the valve stem 60. For this reason, the tip of the valve stem 60 can close the opening. Of course, when the valve stem 60 is retracted to the right in FIG. 1, the opening is opened (see FIG. 2). That is, the inner wall near the opening functions as a valve seat.

  The movable mold 14 is formed with a runner 16 that forms part of the cavity and a gate (not shown). A product part for obtaining a product is provided downstream of the gate. That is, the sprue 50 communicates with the product part via the runner 16 and the gate.

  Here, the axial direction of the runner 16 is substantially orthogonal to the axial direction of the sprue 50. For this reason, the flow direction of the molten resin derived from the sprue 50 is converted by the runner 16.

  In FIG. 1 and FIG. 2, the temperature raising portion 42, the sprue 50, the runner 16 and the like are shown enlarged for easy understanding, but the scales in FIG. 1 and FIG. 2 correspond to actual dimensions. is not. For example, the dimension (length) in the axial direction of the static mixer 44 is actually set to be significantly smaller than the first hot runner 18 and the branch path 36. Of course, the lengthwise dimension of the valve stem 60 is the same. That is, the flow distance of the molten resin in the static mixer 44 is smaller than the flow distance of the molten resin in the first hot runner 18 and the branch path 36. Therefore, the amount of molten resin staying inside the temperature raising unit 42 is small.

  The injection molding apparatus 10 according to the present embodiment is basically configured as described above. Next, the operation and effect of the injection molding apparatus 10 and the injection molding method performed by the injection molding apparatus 10 will be described. Explain in relation.

  When performing injection molding, first, the movable mold 14 is displaced toward the fixed mold 12 under the action of the displacement mechanism (not shown), and the mold is clamped. Before or after that, the resin is melted at a predetermined temperature in the injection machine 30 to obtain a molten resin.

  Next, by energizing the hydraulic cylinder 54 and retracting the piston rod 56, as shown in FIG. 2, the valve member is retracted to the right and the valve rod 60 is moved from the inner wall (valve seat) near the opening. Separate. As a result, the sprue 50 is opened, and the introduction hole 28 enters the cavity through the first hot runner 18, the second hot runner 22 (the guide path 34, the branch path 36, and the temperature raising portion 42), the sprue 50, and the runner 16. Communicate.

  In this way, the introduction hole 28 communicates with the cavity, and the molten resin is injected from the injection nozzle 32 of the injection machine 30. The injected molten resin reaches the first hot runner 18 through the introduction hole 28 formed in the touch piece 26, and then reaches the branch path 36 through the guide path 34 of the second hot runner 22. The molten resin further flows along each of the plurality of branch paths 36.

  As described above, the first hot runner 18 and the second hot runner 22 are heated by a heating means (heater or the like) (not shown). Therefore, the molten resin is substantially held at the temperature at the time of melting. The first hot runner 18 and the second hot runner 22 flow. Of course, this temperature is a temperature at which sufficient strength can be secured when the molten resin is cooled and cured to form a molded product.

  The melting temperature or holding temperature is set according to the type of the molten resin, but is generally between 200 ° C. and 220 ° C., more preferably between 205 ° C. and 215 ° C.

  The molten resin that has flowed through the branch path 36 of the second hot runner 22 is led out from the communication path 40 of the hot nozzle 38 into the static mixer 44 that constitutes the temperature raising unit 42. Here, heat from the band heater 46 is transmitted to the static mixer 44 so that the inside of the static mixer 44 becomes higher than the temperature at the time of melting in the injector 30. Further, when the molten resin passes through the mixing blade 48, shearing heat is generated. Such heat is transferred to the molten resin passing through the mixing blade 48. As a result, the molten resin has a higher temperature than the temperature when it is melted in the injection machine 30 or when it flows through the branch path 36, and the viscosity decreases accordingly.

  The set temperature of the static mixer 44 is preferably a high temperature of about 10 ° C. to 150 ° C., more preferably a high temperature of about 20 ° C. to 100 ° C., compared to the melting temperature in the injector 30. If it is this temperature, it will be avoided that a molded article with insufficient strength is produced.

  As the molten resin passes through the mixing blade 48, it is heated as it receives a shearing force. That is, the temperature of the molten resin rises only by passing through the mixing blade 48. If the temperature increase is sufficient, the set temperature of the static mixer 44 may be the same as the melting temperature in the injection machine 30.

  The melting temperature in the injection machine 30 is set to the minimum necessary for melting the resin, and the temperature of the temperature raising portion 42 is set to the minimum necessary to make the viscosity necessary for filling the entire product portion with the molten resin. By setting to, the power consumption of the injection molding apparatus 10 can be suppressed.

  In the present embodiment in which the static mixer 44 is provided, as the molten resin passes through the mixing blade 48, the molten resin close to the inner peripheral wall moves toward the center of the diameter, and the molten resin close to the diameter center moves. Move toward the inner wall. For this reason, the molten resin having a relatively high temperature in the vicinity of the band heater 46 that is a heat source and the molten resin having a relatively low temperature that is separated from the band heater 46 flow continuously through the static mixer 44. Will do. Therefore, the occurrence of temperature unevenness in the molten resin is avoided, and as a result, a molten resin having a substantially uniform temperature regardless of the portion, in other words, a substantially uniform viscosity can be obtained.

  Moreover, even if the material for obtaining the molten resin is, for example, a masterbatch material or a metallic original material, it is sufficiently dispersed by stirring of the static mixer 44, so that a molded product having excellent appearance quality can be obtained. it can. In addition, after performing the first injection molding, when the second injection molding is performed by changing the color and material type, the molten resin injected during the first injection molding remains and is newly injected. Even if mixed into the resin, both the molten resins are sufficiently stirred by the static mixer 44, so that, for example, streaky appearance defects due to the remaining molten resin hardly occur in the molded product. For this reason, the number of occurrences of defective products can be reduced.

  In addition, when the static mixer 44 is employed, it is not necessary to provide power for stirring. For this reason, it is avoided that the structure of the injection molding apparatus 10 is complicated, and the mold investment is prevented from rising. Further, power consumption does not increase.

  After passing through the sprue 50, the molten resin that has passed through the temperature raising section 42 is introduced into the product section through the runner 16 and a gate (not shown). The molten resin introduced into the runner 16 is sufficiently lowered in viscosity by being heated by the heating portion 42 as described above. In addition, since the temperature of the molten resin is relatively high due to the temperature rise, even if the heat of the molten resin is taken away by the movable mold 14, the temperature is hardly lowered. Accordingly, the flow distance of the molten resin is increased, and therefore, even when there is a portion where a thin portion is formed in the product portion, the molten resin easily passes through the portion to the end of the product portion. To reach. That is, the molten resin is tightly filled in the entire cavity.

  When a predetermined time elapses after the molten resin is injected, the hydraulic cylinder 54 is energized and the piston rod 56 moves forward to the right. Following this, the valve stem 60 also moves forward to the right, and its tip is seated on the inner wall (valve seat) near the opening. That is, the sprue 50 is closed.

  The temperature of the product part is usually adjusted so as to be approximately room temperature. Therefore, the heat of the molten resin introduced into the product part is taken away. Further, since the sprue 50 is closed, the molten resin filled in the cavity and the molten resin present in the temperature raising portion 42 are blocked from each other. For this reason, the heat of the molten resin existing in the temperature raising unit 42 is prevented from being transmitted to the molten resin filled in the cavity.

  For the reasons described above, the molten resin filled in the cavity is efficiently cooled and cured to form a molded product. That is, according to the present embodiment, it is possible to shorten the cycle time from the start of the injection of the molten resin until the molded product is obtained.

  Before the molten resin is introduced into the temperature raising section 42, the molten resin is held at a temperature at which sufficient strength can be ensured when cooled and hardened into a molded product, and the first hot runner 18, the guide path 34 and the branch path 36. Flow. Thereafter, it passes through the temperature raising unit 42, but the circulation time at this time is short. In other words, the time during which the molten resin is at a higher temperature than during melting in the injection machine 30 is short. For this reason, since it is avoided that a molten resin causes a physical-property change, the molded article which shows sufficient intensity | strength can be obtained. In addition, since the molten resin reaches the end of the product portion and is cooled and hardened, it is possible to avoid the occurrence of defects in the molded product.

  Further, since it is not necessary to increase the injection pressure of the molten resin, it is not necessary to increase the mold clamping pressure in order to avoid the occurrence of burrs. Therefore, a small displacement mechanism (such as a hydraulic cylinder) for clamping and opening the mold is sufficient. For this reason, it is avoided that the injection molding apparatus 10 is increased in size and weight. Further, since an expensive displacement mechanism is unnecessary, it is possible to avoid an increase in capital investment.

  In addition, since the multipoint gate is not employed in the present embodiment, the concern that a weld line is formed is eliminated. In addition, since the temperature of the temperature raising unit 42 may be controlled, there is an advantage that it is not necessary to repeatedly perform a test for setting the injection conditions.

  If the movable mold 14 is moved away from the fixed mold 12 and the mold is opened under the action of the displacement mechanism, the molded product can be exposed. The molded product is pushed out by, for example, a knockout pin (not shown) and is separated from the injection molding apparatus 10.

  The molded product is obtained as a product in which the resin that has remained on the sprue 50, the runner 16, and the gate and is cooled and hardened is integrally connected to the product portion. Such a part is cut | disconnected from the product part of a molded article, for example, it grind | pulverizes to make it the starting material of the next injection molding.

  The molten resin remaining in the temperature raising unit 42 is kept warm by the band heater 46. In addition, since the molten resin filled in the cavity is cut off, heat is prevented from being taken away by the molten resin. Accordingly, the molten resin remaining in the temperature raising portion 42 maintains a molten state, and is filled into the cavity in the same manner as described above when the next injection molding is performed.

  Therefore, in the next injection molding, it is avoided that the cured piece of the molten resin remaining in the temperature raising portion 42 becomes a foreign substance and enters the molded product. For this reason, the molded article which is excellent in the aesthetics from which the generation | occurrence | production of a defect was suppressed is obtained. Of course, the occurrence of burrs is also avoided as described above. That is, as the sprue 50 is opened and closed by the valve rod 60, the quality of the molded product is not affected.

  Incidentally, as is well known, the mixing blade 48 has a plurality of stirring blades 70 joined together by brazing. The mutual joining site is the diametrical center. That is, in the above-described embodiment, an insertion hole for allowing the valve rod 60 to pass is formed in the joint portion. In such a case, the mixing blade 48 may be deformed when the injection pressure of the molten resin is extremely large.

  When there is such a concern, for example, as shown in FIG. 3, a bypass block 72 may be provided between the temperature raising unit 42 and the nozzle chip 52. The bypass block 72 may be supported by the fixed mold 12 via the positioning pin 74. Note that reference numerals 76, 78, and 80 in FIG. 3 denote a positioning ring, a positioning pin, and a support block, respectively. In this case, the bearing 62 is provided in the bypass block 72.

  In the bypass block 72, a communication passage 82 as a communication passage is formed. The longitudinal direction of the communication passage 82 intersects with the longitudinal direction of the static mixer 44 so as to be inclined at a predetermined angle. On the other hand, the valve stem 60 extends parallel to the longitudinal direction of the static mixer 44. In other words, the valve stem 60 and the static mixer 44 are parallel to each other.

  In this case, although the temperature raising portion 42 and the sprue 50 are separated from each other, the communication passage 82 exists between them, so that the temperature raising portion 42 and the sprue 50 are communicated with each other via the communication passage 82. Thereby, it is possible to fill the cavity with the molten resin in the same manner as described above.

  Alternatively, as shown in FIG. 4, the valve stem 60 may extend in a direction inclined with respect to the longitudinal direction of the static mixer 44. In this case, the bearing 62 can be provided on the outer wall of the static mixer 44, for example. In this case, as shown in FIG. 5 and FIG. 6, the inner wall of the opening on the inlet side of the sprue 50 may have a shape in which the tip of the valve rod 60 extending in an inclined manner can be seated and separated.

  Here, FIG. 5 and FIG. 6 show the case where the tip of the valve stem 60 is substantially hemispherical. However, similarly, when the tip of the sprue 50 is shaped like a truncated cone as shown in FIG. 7 and FIG. The shape of the inner wall of the opening on the inlet side may be matched with the shape of the tip of the valve stem 60.

  Furthermore, as shown in FIG. 9, the insertion hole may be formed so as to avoid a joint portion (diameter center) between the stirring blades 70. In this case, the communication passage 40 of the hot nozzle 38 is inclined as a crank shape or a reducer shape, and the axial center (diameter center) of the outlet of the communication passage 40 matches the axial center (diameter center) of the static mixer 44. In addition, the axial center of the sprue 50 may be provided at a position offset from the axial center of the static mixer 44. Alternatively, as shown in FIG. 10, the communication path 40 of the hot nozzle 38 may be provided at a position offset from the axial center of the hot nozzle 38.

  In this way, the molten resin stays between the communication path 40 and the temperature rising part 42 by matching the axial center of the outlet of the communication path 40 with the axis center of the temperature raising part 42. Can be avoided.

  In the above embodiment, the case in which the passage opening / closing means is provided in the fixed mold 12 has been described as an example, but the passage opening / closing means may be provided in the movable mold 14.

  For example, in the embodiment shown in FIG. 11, a displacement mechanism having a motor 90, a rotating shaft 92, a pinion gear 94, and a rack 96 is provided in the movable mold 14. A bearing 98 is interposed between the rotary shaft 92 and the movable mold 14.

  A valve stem 60 is connected to the tip of the rack 96 via a coupling 58. The tip of the valve stem 60 is seated or separated from the inner wall near the opening on the inlet side of the sprue 50. That is, when injection molding is performed, the motor 90 is energized, whereby the rotating shaft 92 starts rotating. Following this, when the pinion gear 94 provided on the rotary shaft 92 rotates, the rack 96 meshed with the pinion gear 94 moves backward. As a result, as shown in FIG. 12, the valve stem 60 is displaced to the left and the tip thereof is separated from the inner wall of the opening on the inlet side of the sprue 50. Therefore, similarly to the above, communication from the introduction hole 28 to the cavity communicates.

  In this state, molten resin is supplied. The molten resin passes through the temperature raising part 42 and is filled into the product part via the runner 16. When this filling is completed, the motor 90 is re-energized and the rack 96 moves forward. Following this, the valve stem 60 is displaced to the right, and its tip closes the opening on the inlet side of the sprue 50 as in FIG. Thereafter, the molten resin is cooled and hardened, and a molded product in which the valve rod 60 enters is obtained.

  After the molded product is obtained in this way, the mold is opened. At this time, the molded product is supported by the retracted valve stem 60. Therefore, the concern that the molded product falls off the mold is eliminated. At this point, the molded product is fixed to the movable mold 14.

  After the mold opening, an ejector pin (not shown) operates to push the molded product away from the movable mold 14. Further, the motor 90 is re-biased as necessary, and the valve stem 60 is displaced to the right. That is, the state in which the molded product is supported by the valve rod 60 is maintained, and the molded product is prevented from falling off.

  After the molded product is removed from the valve stem 60, the ejector pin and the valve stem 60 are displaced to the left and return to their original positions. In the molded product, the portion through which the valve stem 60 passes is a through-hole, but this portion may be cut off including the vicinity and reused.

  If there is no concern that the molded product will fall off, the molded product may be separated from the movable die 14 by operating only the ejector pin without displacing the valve stem 60 to the right. The valve stem 60 may be displaced leftward at this time and returned to the original position.

  As shown in FIG. 13, the displacement mechanism may be configured to include a first cam member 104 and a second cam member 106 provided on the piston rod 102 of the hydraulic cylinder 100. That is, the first cam member 104 is provided with a convex cam portion 108 extending in a direction inclined with respect to the longitudinal direction of the piston rod 102, while the second cam member 106 is provided with the convex cam portion. A concave cam portion 110 with which 108 engages is provided. Of course, the convex cam portion 108 is slidably engaged with the concave cam portion 110.

  In this case, the valve stem 60 is connected to the second cam member 106 via a coupling 58 provided at the tip of the second cam member 106. The tip of the valve stem 60 is seated or separated from the inner wall near the opening on the inlet side of the sprue 50 in the same manner as described above. That is, when injection molding is performed, the hydraulic cylinder 100 is urged, and thereby the piston rod 102 is lowered. At this time, since the convex cam portion 108 is slidably engaged with the concave cam portion 110, the second cam member 106 is displaced to the left. As a result, as shown in FIG. 14, the valve stem 60 is displaced to the left, and its tip is separated from the inner wall near the opening on the inlet side of the sprue 50. Therefore, similarly to the above, communication from the introduction hole 28 to the cavity communicates.

  In this state, molten resin is supplied. The molten resin passes through the temperature raising part 42 and is filled into the product part via the runner 16. When this filling is completed, the hydraulic cylinder 100 is re-energized. As a result, when the piston rod 102 is raised, the second cam member 106 is displaced rightward under the interaction between the convex cam portion 108 and the concave cam portion 110. Following this, the valve stem 60 is displaced to the right, and its tip closes the opening on the inlet side of the sprue 50 as in FIG. Thereafter, the molten resin is cooled and hardened, and a molded product in which the valve rod 60 enters is obtained.

  Thereafter, operations similar to those in the embodiment shown in FIGS. 11 and 12 are performed. That is, after the mold opening is performed, the molded product is pushed out under the action of the ejector pin to be separated from the movable mold 14. At this time, the hydraulic cylinder 100 is re-biased as necessary, and the valve stem 60 is displaced to the right. Of course, if there is no concern that the molded product will drop off, the molded product may be separated from the movable die 14 by operating only the ejector pin without displacing the valve stem 60 to the right. The valve stem 60 may be displaced leftward at this time and returned to the original position.

  After the molded product is removed from the valve stem 60, the ejector pin and the valve stem 60 are displaced to the left and return to their original positions. Although the portion through which the valve stem 60 has passed is a bottomed hole or a through hole, this portion may be cut including the vicinity.

  Apart from the above, as shown in FIG. 15, the communication passage 40 that is the downstream flow passage of the temperature raising section 42 may be opened and closed. In this case, in the communication path 40 of the hot nozzle 38, the opening at the inlet (upstream side) facing the branch path 36 is narrowed in a reducer shape. The valve stem 60 is seated and separated from the inner wall near the throttled opening.

  Further, as shown in FIG. 16, a plurality of temperature raising sections 42 and a plurality of passage opening / closing means may be provided. In this case, for example, when the runner 16 and the product part are expanded toward the lower product part, the hydraulic cylinders 54 are sequentially changed in the order from the upper part to the lower part. What is necessary is just to perform sequence control so that it may energize.

  That is, in this case, the uppermost hydraulic cylinder 54 is energized and the valve rod 60 opens the opening on the inlet side of the sprue 50, whereby the molten resin is introduced into the runner 16 only from the uppermost sprue 50. Next, the central hydraulic cylinder 54 is energized, and the valve stem 60 opens the opening on the inlet side of the sprue 50, whereby molten resin is introduced into the runner 16 from both the uppermost and central sprues 50. .

  Finally, the lowermost hydraulic cylinder 54 is energized, and the valve stem 60 opens the opening on the inlet side of the sprue 50. Thereby, the molten resin is introduced into the runner 16 from all of the uppermost, central and lowermost sprues 50.

  In this way, by installing a plurality of temperature raising portions 42 and passage opening / closing means so as to supplement each filling amount, even if the runner 16 and the product portion are wide, the injection pressure and the clamping force There is an advantage that the molten resin can be supplied to the cavity without excessively increasing the thickness, and there is an advantage that a molded product excellent in appearance quality without weld can be obtained.

  It should be noted that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention.

  For example, in this embodiment, the temperature raising unit 42 is configured by winding the band heater 46 around the static mixer 44. However, the coil mixer or cartridge heater is embedded in the static mixer 44 to raise the temperature. The unit 42 may be configured.

  Further, the stirring means is not particularly limited to the static mixer 44, and may be a screw that rotates by power, for example.

  The stirring means is not essential. For example, in the case where a straight pipe having a small temperature unevenness width is used for the temperature raising unit 42 due to the small diameter, the stirring means may be omitted.

  Furthermore, it goes without saying that air cylinders can be employed instead of the hydraulic cylinders 54 and 100.

  Furthermore, as shown in FIG. 17, a pipe 120 (tube member) may be passed through an insertion hole formed in the mixing blade 48. In this case, the valve rod 60 may be passed through the through hole of the pipe 120. That is, the valve stem 60 is passed through the insertion hole through the through hole of the pipe 120.

  Even in this case, deformation of the mixing blade 48 can be avoided.

DESCRIPTION OF SYMBOLS 10 ... Injection molding apparatus 12 ... Fixed mold 14 ... Movable type 16 ... Runner 18 ... 1st hot runner 22 ... 2nd hot runner 30 ... Injection machine 32 ... Injection nozzle 34 ... Guide path 36 ... Branch path 38 ... Hot nozzle 40 ... Communication path 42 ... Temperature riser 44 ... Static mixer 46 ... Band heater 48 ... Mixing blade 50 ... Sprue 52 ... Nozzle tip 54, 100 ... Hydraulic cylinder 56,102 ... Piston rod 60 ... Valve rod 70 ... Agitating blade 72 ... Bypass block 82 ... Communication passage 90 ... Motor 92 ... Rotating shaft 94 ... Pinion gear 96 ... Rack 104 ... First cam member 106 ... Second cam member 108 ... Convex cam part 110 ... Concave cam part 120 ... Pipe

Claims (10)

In an injection molding apparatus that supplies molten resin injected from an injection machine to a cavity formed in a mold,
A hot runner that is a flow path of the molten resin is formed ,
A temperature raising portion provided in a part of the hot runner, and for setting the molten resin to a temperature higher than the temperature at the time of melting in the injection machine ;
Passage opening and closing means for opening or closing the upstream flow passage or the downstream flow passage of the temperature raising section ;
Stirring means for stirring the molten resin flowing in the temperature raising part;
A communication path communicating with the inlet or outlet of the stirring means and the upstream flow path or the downstream flow path and inclined with respect to the longitudinal direction of the stirring means;
With
The passage opening / closing means includes a valve member that opens or closes the upstream flow passage or the downstream flow passage, and a displacement mechanism that displaces the valve member,
The injection molding apparatus , wherein the valve member extends in a direction parallel to a longitudinal direction of the stirring means . In an injection molding apparatus that supplies molten resin injected from an injection machine to a cavity formed in a mold,
A hot runner that is a flow path of the molten resin is formed ,
A temperature raising portion provided in a part of the hot runner, and for setting the molten resin to a temperature higher than the temperature at the time of melting in the injection machine ;
Passage opening and closing means for opening or closing the upstream flow passage or the downstream flow passage of the temperature raising section ;
Stirring means for stirring the molten resin flowing in the temperature raising part;
With
The passage opening / closing means includes a valve member that opens or closes the upstream flow passage or the downstream flow passage, and a displacement mechanism that displaces the valve member,
The said injection member extends in the direction which inclines with respect to the longitudinal direction of the said stirring means, The injection molding apparatus characterized by the above-mentioned . In an injection molding apparatus that supplies molten resin injected from an injection machine to a cavity formed in a mold,
A hot runner that is a flow path of the molten resin is formed ,
A temperature raising portion provided in a part of the hot runner, and for setting the molten resin to a temperature higher than the temperature at the time of melting in the injection machine ;
Passage opening and closing means for opening or closing the upstream flow passage or the downstream flow passage of the temperature raising section ;
Stirring means comprising a stirring blade for stirring the molten resin flowing in the temperature raising part;
With
The passage opening / closing means includes a valve member that opens or closes the upstream flow passage or the downstream flow passage, and a displacement mechanism that displaces the valve member,
The stirring blade, along with the insertion hole is formed, an injection molding apparatus wherein the valve member is characterized that you have passed through the insertion hole. 4. The molding apparatus according to claim 3 , wherein the insertion hole is formed in a portion other than a joint portion between the stirring blades. 5. The injection molding apparatus according to claim 4 , wherein the stirring means is provided at a position where the central axis is offset with respect to the central axis of the upstream flow passage or the downstream flow passage. 4. The injection molding apparatus according to claim 3 , wherein a pipe member is inserted into the insertion hole, and the valve member is passed through the insertion hole through a through hole of the pipe member. . The molding apparatus according to any one of claims 1 to 6 , wherein the displacement mechanism is installed in a fixed mold, and the valve member opens or closes the downstream flow passage. apparatus. The molding apparatus according to any one of claims 1 to 6 , wherein the displacement mechanism is installed in a movable mold, and the valve member opens or closes the downstream flow passage. apparatus. The injection molding apparatus according to any one of claims 1 to 8 , comprising a plurality of the temperature raising section and the passage opening / closing means. The molding apparatus according to claim 9 , wherein the plurality of passage opening / closing means are individually operated, and the molten resin is individually supplied to the cavity from each of the plurality of temperature raising portions. Molding equipment.

Images