JP2013141777A - Injection molding apparatus and injection molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection molding apparatus and an injection molding method, in which a molten material can be surely supplied to a first cavity and a second cavity, a connection part for connecting a first molded product to a second molded product can be surely cut, and the first molded product and the second molded product can be easily taken out as a result.SOLUTION: The injection molding apparatus 10 fills molten resin into the first cavity 202a formed between a fixed mold 16 and an intermediate mold 20 in a mold closed state and the second cavity 202b formed between the intermediate mold 20 and a movable mold 24. A sprue 204 allowing the first cavity 202a and the second cavity 202b to communicate with each other and a cutting mechanism 22 for cutting the connection part 304 formed by solidifying the molten resin in the sprue 204 are provided in the intermediate mold 20.

Description

  The present invention relates to an injection molding apparatus and an injection molding method in which an intermediate mold is disposed between a first mold and a second mold.

  Conventionally, in order to form two or more resin products (molded products) at the same time, an injection molding apparatus including a mold called a stack mold (tandem mold) has been widely used.

  This type of injection molding apparatus generally includes an intermediate mold disposed between a fixed mold and a movable mold, and the mold is in a closed state between the fixed mold and the intermediate mold. In addition, a first cavity is formed, and a second cavity is formed between the movable mold and the intermediate mold.

  As such an injection molding apparatus, the molten resin (molten material) injected into the first cavity is supplied into the second cavity through a sprue (cold sprue) formed in the intermediate mold. There are some which mold a molded product.

  However, in this case, the first molded product molded in the first cavity and the second molded product molded in the second cavity are connected by the relay portion formed by solidification of the molten resin in the sprue. Therefore, it is not easy to take out the first molded product and the second molded product from the intermediate mold.

  As a method of taking out the first molded product and the second molded product from the intermediate mold, the sprue is formed so as to have a tapered diameter toward the first cavity, and the relay part is formed using a mold opening force. A technical idea of cutting a connection portion with a first molded product (a portion having a smallest cross-sectional area among relay portions) is known (see, for example, Patent Document 1).

JP 2004-66728 A

  However, in the above-described prior art, it is necessary to make the cutting force of the relay portion smaller than the tension force caused by the contraction of the first molded product to the fixed mold when the mold is opened. Therefore, depending on the cross-sectional area of the relay part or the material of the molten material, the first molded product may be released from the fixed mold without cutting the relay part. Then, it becomes difficult to take out the first molded product and the second molded product from the intermediate mold.

  Moreover, since it is necessary to supply a molten material reliably to a 2nd cavity, there exists a limit in diameter reduction of a sprue.

  The present invention has been made in view of such problems, and can reliably supply the molten material to the first cavity and the second cavity, and connect the first molded product and the second molded product. An object of the present invention is to provide an injection molding apparatus and an injection molding method capable of reliably cutting a relay portion to be removed and easily taking out the first molded product and the second molded product from an intermediate mold.

[1] An injection molding apparatus according to the present invention is arranged between a first mold and a second mold, which are opposed to each other so as to be close to and away from each other, and between the first mold and the second mold. A first cavity formed between the first mold and the intermediate mold in a closed state, and between the second mold and the intermediate mold. An injection molding apparatus capable of filling a molten material into a second cavity formed in the intermediate mold, wherein a sprue that communicates the first cavity and the second cavity is provided in the intermediate mold, and the mold is opened. It is characterized by having a cutting mechanism for cutting the relay part formed by the solidification of the molten material in the sprue sometimes.

  According to the injection molding apparatus according to the present invention, since the cutting mechanism for cutting the relay portion when the mold is opened is provided, the relay portion can be connected without excessively reducing the flow path diameter of the sprue (cross-sectional area of the relay portion). It can be cut reliably. Thereby, the molten material can be reliably supplied to the first cavity and the second cavity, and the first molded product molded in the first cavity and the second molded product molded in the second cavity It can be easily removed from the intermediate mold.

[2] In the above injection molding apparatus, the intermediate mold is formed with a through-hole that opens in each of a surface facing the first mold and a surface facing the second mold, The cutting mechanism is arranged in the through-hole so as to be capable of contacting the first mold or the second mold and constituting at least a part of the sprue and being displaceable along the mold opening direction. You may have the provided cylinder and the elastic body which urges | biases the said cylinder along a mold opening direction.

  According to such a configuration, since the cylindrical body can contact the first mold or the second mold, when the mold is closed, the first mold or the second mold causes the above-mentioned inside of the through hole to The elastic body can be compressed by displacing the cylinder. If it does so, the urging | biasing force along a mold opening direction can be made to act with respect to the said cylinder by the said elastic body at the time of mold opening. Thereby, since the tensile load along the mold opening direction acts on the relay part, the relay part can be automatically and suitably cut (broken).

[3] In the above injection molding apparatus, a reduced diameter portion may be formed in the sprue. According to such a configuration, since the reduced diameter portion is formed in the sprue, the reduced diameter portion is also formed in the relay portion. As a result, the relay portion can be easily cut at the reduced diameter portion.

[4] In the above injection molding apparatus, a plurality of the cylinders are provided, and the elastic body urges the cylinders in a direction in which the plurality of cylinders are separated from each other, The plurality of cylinders may be located at a contact portion.

  According to such a configuration, since the reduced diameter portion of the sprue is located at a portion where the plurality of cylindrical bodies contact each other, the intermediate portion of the relay portion (a portion separated from the first molded product and the second molded product) is contracted. A diameter part can be formed. Moreover, since each cylinder is urged | biased in the direction in which a some cylinder separates with an elastic body, the urging | biasing force of this elastic body can be made to act efficiently on the diameter reduction part of the said relay part. As a result, the reduced diameter portion of the relay portion can be more easily cut, and the first molded product and the second molded product are preferably prevented from being damaged when the reduced diameter portion of the relay portion is cut. Can do.

[5] In the above injection molding apparatus, the cutting mechanism may further include a stopper that prevents the cylindrical body from being detached from the intermediate mold. According to such a configuration, it is possible to prevent the cylinder from being detached from the through hole by the stopper, so that the relay portion can be easily taken out from the cylinder (sprue). In addition, since it is not necessary to set the cylinder in the through hole every time injection molding is performed, the cycle time of injection molding can be shortened.

[6] The injection molding method according to the present invention includes a first cavity formed between the first mold and the intermediate mold in the mold closed state, and between the second mold and the intermediate mold. An injection molding method for solidifying by filling a molten material into a second cavity to be formed and a sprue provided in the intermediate mold and communicating with the first cavity and the second cavity, the mold opening In some cases, a cutting process is performed in which the relay portion formed by solidifying the molten material in the sprue is cut by a cutting mechanism.

  According to the injection molding method of the present invention, the relay portion is cut by the cutting mechanism when the mold is opened, so that the relay portion can be reliably cut without excessively reducing the flow path diameter of the sprue. Thereby, the molten material can be reliably supplied to the first cavity and the second cavity, and the first molded product molded in the first cavity and the second molded product molded in the second cavity It can be easily removed from the intermediate mold.

[7] In the above injection molding method, the cutting mechanism includes a cylindrical body and an elastic member that constitute at least a part of the sprue, and in the cutting step, the inside of the through hole formed in the intermediate mold Further, the relay portion may be cut by urging the cylindrical body disposed so as to be displaceable along the extending direction of the through hole along the mold opening direction by the elastic member.

  According to such a method, the urging force along the mold opening direction can be applied to the cylindrical body by the elastic body at the time of mold opening. Thereby, since the tensile load along the mold opening direction acts on the relay part, the relay part can be automatically and suitably cut (broken).

[8] In the above injection molding method, a plurality of the cylinders are provided, and the sprue is formed with a reduced diameter portion at a portion where the plurality of cylinders are in contact with each other. You may cut | disconnect the said relay part by urging | biasing the said several cylinder arrange | positioned in the hole with the said elastic body in the direction which mutually spaces apart.

  According to such a method, since the reduced diameter portion of the sprue is formed at a portion where a plurality of cylindrical bodies contact each other, an intermediate portion of the relay portion (a portion separated from the first molded product and the second molded product) A reduced diameter portion can be formed. Moreover, since each cylinder is urged | biased in the direction in which a some cylinder separates with an elastic body, the urging | biasing force of this elastic body can be made to act efficiently on the diameter reduction part of the said relay part. As a result, the reduced diameter portion of the relay portion can be more easily cut, and the first molded product and the second molded product are preferably prevented from being damaged when the reduced diameter portion of the relay portion is cut. Can do.

  As described above, according to the present invention, since the relay part can be cut by the cutting mechanism when the mold is opened, the relay part can be obtained without excessively reducing the flow path diameter of the sprue (the cross-sectional area of the relay part). Can be cut reliably. Thereby, the molten material can be reliably supplied to the first cavity and the second cavity, and the first molded product molded in the first cavity and the second molded product molded in the second cavity It can be easily removed from the intermediate mold.

It is a partial cross section explanatory view of the mold closed state of the injection molding device concerning one embodiment of the present invention. It is a partial cross-section explanatory drawing which shows the mold open state of the said injection molding apparatus. It is a partially expanded cross-section explanatory drawing which shows the cutting | disconnection mechanism of FIG. 1, and its circumference | surroundings. It is a flowchart for demonstrating the injection molding method using the said injection molding apparatus. It is a partial cross section explanatory view which shows the state which filled the molten resin in the 1st cavity and 2nd cavity formed in the injection molding apparatus of FIG. It is a partial cross section enlarged explanatory view for demonstrating the state which the relay part cut | disconnected by mold opening of the said injection molding apparatus. It is a partial cross-section explanatory drawing which shows the state which the mold opening of the said injection molding apparatus was completed. It is a partial cross section explanatory view which shows the state which has taken out the 1st molded product and the 2nd molded product from the injection molding apparatus. It is a partially expanded sectional view for demonstrating the cutting mechanism which concerns on a modification. FIG. 10 is a partially enlarged cross-sectional explanatory view showing a state in which the relay portion is cut by the cutting mechanism of FIG.

  DESCRIPTION OF EMBODIMENTS Hereinafter, an injection molding method according to the present invention will be described in detail with reference to the accompanying drawings by exemplifying preferred embodiments in relation to an injection molding apparatus that performs the injection molding method.

  First, an injection molding apparatus 10 according to an embodiment of the present invention will be described. The injection molding apparatus 10 according to the present embodiment is an apparatus including a so-called stack mold. That is, the injection molding apparatus 10 includes an intermediate mold 20 disposed between a fixed mold 16 and a movable mold 24 as shown in FIG. The first cavity 202a formed between the movable mold 24 and the movable mold 24 and the second cavity 202b formed between the movable mold 24 and the intermediate mold 20 are filled with molten resin (molten material). Thus, two or more resin products (molded products) are molded simultaneously.

  Specifically, as shown in FIGS. 1 and 2, the injection molding device 10 is fixed to the fixed platen 12 and each corner of the fixed platen 12 and extends in the thickness direction of the fixed platen 12. A plurality of (for example, four) divers 14, a fixed mold (first mold) 16 fixed to the fixed platen 12, an injection mechanism 18 provided in the fixed mold 16, and the fixed mold An intermediate mold 20 supported so as to be movable with respect to the plurality of divers 14 so as to face 16, a cutting mechanism 22 provided in the intermediate mold 20, and the fixed mold of the intermediate mold 20 A movable mold (second mold) 24 disposed on the opposite side of 16, a movable plate 26 fixed to the movable mold 24 and supported so as to be movable with respect to the plurality of divers 14; And a control unit 28.

  One surface of the fixed mold 16 is fixed to the other surface of the fixed platen 12. The first runner 200a as a molten resin flow path (branch path) between the other surface of the fixed mold 16 and one surface of the intermediate mold 20 in the mold closed state, and a molding space for the resin product The first cavity 202a is formed. The first runner 200a is a flow path for guiding the molten resin guided from the injection mechanism 18 to the first cavity 202a.

  The injection mechanism 18 is provided inside an injection part 30 (see FIG. 1) for injecting molten resin at a predetermined pressure, an introduction part 32 disposed so as to penetrate the fixed platen 12, and the fixed mold 16. And a nozzle portion 34 connected to the introduction portion 32.

  The tip surface of the nozzle portion 34 is exposed on the other surface of the fixed mold 16. The resin flow path formed inside the nozzle portion 34 communicates with the first runner 200a. That is, the molten resin injected from the injection unit 30 is guided to the first runner 200a through the introduction unit 32 and the nozzle unit 34.

  The intermediate mold 20 is connected to the movable mold 24 by a tensile link (not shown). Thus, when the mold is opened, the intermediate mold 20 is moved from both the fixed mold 16 and the movable mold 24 only by moving the movable mold 24 to the side opposite to the side where the fixed mold 16 is located. Can be separated.

  A through hole 36 extending in the thickness direction is formed in the intermediate mold 20. That is, the through hole 36 opens on each of one surface of the intermediate mold 20 (surface facing the fixed mold 16) and the other surface of the intermediate mold 20 (surface facing the movable mold 24). ing.

  The second runner 200b as a molten resin flow path (branch path) between the other surface of the intermediate mold 20 and one surface of the movable mold 24 in the mold closed state, and a molding space for the resin product The second cavity 202b is formed. The second runner 200b is a flow path for guiding the molten resin guided from the sprue 204 described later to the second cavity 202b.

  As shown in FIG. 3, the cutting mechanism 22 includes a pair of cylinders (nestings) 38 and 40 disposed in the through hole 36, and an elastic body (attachment) disposed between the cylinders 38 and 40. Force means) 42 and a pair of stoppers 44 and 46 for preventing the pair of cylinders 38 and 40 from being detached from the through hole 36.

  The cylindrical body 38 includes a cylindrical main body 48 formed in a cylindrical shape, and a flange portion 50 formed on the outer peripheral surface of the cylindrical main body 48 in the approximate center in the axial direction. The length dimension of the cylinder body 48 (dimension along the axial direction of the cylinder body 48) is set to substantially half the length dimension of the through hole 36 (dimension along the extending direction of the through hole 36). Yes. The inner hole 52 of the cylindrical body 48 is formed as a tapered hole that gradually decreases in diameter toward the other end of the cylindrical body 48. The outer peripheral surface of the flange portion 50 is in sliding contact with the inner wall surface constituting the through hole 36.

  The cylindrical body 40 has the same configuration as the cylindrical body 38 described above, and is formed on the outer peripheral surface of the cylindrical main body 54 formed in a cylindrical shape and at the approximate center in the axial direction of the cylindrical main body 54. And a flange portion 56. The length dimension of the cylindrical body 54 is set to approximately half the length dimension of the through hole 36. The inner hole 58 of the cylindrical body 54 is formed as a tapered hole that gradually decreases in diameter toward one end of the cylindrical body 54. The outer peripheral surface of the flange portion 56 is in sliding contact with the inner wall surface constituting the through hole 36.

  The elastic body 42 is interposed between the flange portion 50 of the cylindrical body 38 and the flange portion 56 of the cylindrical body 40. That is, the elastic body 42 can urge the pair of cylinders 38 and 40 along the mold opening direction. In other words, the elastic body 42 can urge the cylindrical body 38 toward the side where the fixed mold 16 is located and urge the cylindrical body 40 toward the side where the movable mold 24 is located. As the elastic body 42, for example, a compression coil spring is used.

  Each stopper 44, 46 is formed in a ring shape. The stopper 44 is fixed to an inner wall surface constituting an opening on one end side of the through hole 36, and one end side of the cylindrical body 48 can be inserted into the inner hole of the stopper 44. The stopper 46 is fixed to an inner wall surface constituting an opening on the other end side of the through hole 36, and the other end side of the cylindrical body 54 can be inserted into the inner hole of the stopper 46.

  The stopper 44 or the stopper 46 may be formed integrally with the intermediate mold 20. In this case, the number of parts of the cutting mechanism 22 can be reduced.

  In the cutting mechanism 22 configured as described above, as understood from FIG. 2, the pair of cylinders 38 and 40 are separated from each other by the urging force of the elastic body 42 in the mold open state. That is, one end of the cylindrical body 48 projects from the through hole 36 toward the fixed mold 16 in a state where the flange portion 50 of the cylindrical body 38 is in contact with the stopper 44, and the flange portion 56 of the cylindrical body 40 is connected to the stopper 46. The other end of the cylindrical body 54 protrudes from the through hole 36 toward the movable mold 24 while being in contact with the movable die 24.

  On the other hand, in the mold closed state, as can be understood from FIG. 3, the other end surface of the cylinder body 48 and one end surface of the cylinder body 54 are in contact with each other in a state where the elastic body 42 is compressed. The inner hole 52 of the body body 48 and the inner hole 58 of the cylinder body 54 communicate with each other. That is, in the mold closed state, a sprue (cold sprue) 204 as a molten resin flow path is formed by the inner hole 52 of the cylindrical body 48 and the inner hole 58 of the cylindrical body 54.

  In addition, the inner hole 52 of the cylinder body 48 is a tapered hole whose diameter is gradually reduced toward the other end side, and the inner hole 58 of the cylinder body 54 is gradually reduced in diameter toward its one end side. Therefore, the sprue 204 is formed with a reduced diameter portion 206 at a portion where the pair of cylinders 38 and 40 are in contact with each other.

  The control unit 28 includes an injection control unit 62 that drives and controls the injection unit 30 and a movable platen drive control unit 64 that drives and controls the movable platen 26.

  The injection molding apparatus according to the present embodiment is basically configured as described above. Next, an injection molding method using the injection molding apparatus 10 will be described. In the following description, the mold open state is the initial state.

  First, the mold closing operation is started (step S1 in FIG. 4). That is, the movable platen drive control unit 64 drives the movable platen 26 and moves it to the intermediate mold 20 side. Then, after one surface of the movable mold 24 comes into contact with the other end surface of the cylinder body 54, the movable mold 24 and the intermediate mold 20 are integrally moved to the side where the fixed mold 16 is located. One end surface of the cylindrical body 48 contacts the other surface of the fixed mold 16.

  Subsequently, when the movable plate 26 is further moved, the elastic body 42 is displaced while being compressed along the direction in which the pair of cylinders 38 and 40 are close to each other (mold closing direction) (step S2), and the cylinder body 48 is moved. The other end surface of the tube and one end surface of the cylindrical body 54 come into contact with each other. Thereby, the inner hole 52 of the cylinder main body 48 and the inner hole 58 of the cylinder main body 54 communicate with each other to form the sprue 204 (see FIG. 3).

  When the mold closing operation is completed (step S3), the first runner 200a and the first cavity 202a are formed between the fixed mold 16 and the intermediate mold 20, and the intermediate mold 20 and the movable mold are formed. 24, a second runner 200b and a second cavity 202b are formed (see FIG. 1). Further, the resin flow path in the nozzle portion 34 communicates with the first runner 200a, and the sprue 204 communicates with the first runner 200a and the second runner 200b.

  Thereafter, the injection control unit 62 drives the injection unit 30 to inject a predetermined amount of molten resin from the injection unit 30 by a predetermined amount (step S4). If it does so, the molten resin inject | emitted from the injection part 30 will be guide | induced to the nozzle part 34 via the introduction part 32, and will be inject | poured into the 1st runner 200a.

  The molten resin injected into the first runner 200 a is guided to the first cavity 202 a and the sprue 204. The molten resin guided to the sprue 204 is guided to the second cavity 202b through the second runner 200b. As a result, the first runner 200a, the first cavity 202a, the sprue 204, the second runner 200b, and the second cavity 202b are filled with the molten resin (step S5).

  Subsequently, the filled molten resin is solidified (step S6). Accordingly, the first branch portion 300a is formed in the first runner 200a, the first molded product 302a is formed in the first cavity 202a, the second branched portion 300b is formed in the second runner 200b, and the second molded product 302b is formed in the second cavity 202b. The relay portions 304 are respectively formed on the sprues 204 (see FIG. 5). At this time, the first molded product 302 a sticks to the fixed mold 16 and the second molded product 302 b sticks to the movable mold 24 due to shrinkage accompanying the solidification of the molten resin.

  Thereafter, the mold opening operation is started (step S7). That is, the movable platen drive control unit 64 drives the movable platen 26 to move the movable die 24 to the side opposite to the side where the fixed die 16 is located. Then, since the urging force (elastic force) of the elastic body 42 along the mold opening direction acts on each of the cylinders 38 and 40, a tensile load along the mold opening direction acts on the relay portion 304. Thereby, the reduced diameter portion (the portion corresponding to the reduced diameter portion 206 of the sprue 204) 306 of the relay portion 304 is cut (ruptured) (see step S8, FIG. 6).

  The cylinders 38 and 40 are displaced along the mold opening direction by the urging force of the elastic body 42, and the flange portions 50 and 56 abut against the stoppers 44 and 46. Subsequently, by further moving the movable platen 26, the relay part 304 connected to the second branch part 300b is separated from the inner peripheral surface of the cylindrical body 54, and then is moved to the movable mold 24 by a tension link (not shown). When the connected intermediate mold 20 is pulled toward the movable mold 24, the relay part 304 connected to the first branch part 300 a is separated from the inner peripheral surface of the cylindrical body 48. Thereafter, the mold opening operation is completed (step S9, see FIG. 7).

  Thereafter, the first molded product 302a and the second molded product 302b are taken out (step S10). That is, as shown in FIG. 8, the first molded product 302 a (first branch portion 300 a) is intermediated by the push pin 102 provided in the fixed mold 16 while the first molded product 302 a is gripped by the gripping member 100. While pressing the mold 20, the second molded product 302 b (second branch portion 300 b) is intermediated by the push pin 106 provided on the movable mold 24 while the second molded product 302 b is gripped by the gripping member 104. Press toward the mold 20 side. At this stage, the procedure of the injection molding method according to this embodiment is completed.

  According to this embodiment, since the relay part 304 is cut by the cutting mechanism 22 when the mold is opened, the reduced diameter part 206 of the sprue 204 (the cross-sectional area of the reduced diameter part 306 of the relay part 304) is not excessively reduced. The relay unit 304 can be cut reliably. Accordingly, the molten resin can be reliably supplied to the first cavity 202a and the second cavity 202b, and the first molded product 302a and the second molded product 302b can be easily taken out from the intermediate mold 20. .

  In the present embodiment, in the mold closing process, the pair of cylinders 38 and 40 are brought close to each other while compressing the elastic body 42 so that the other end face of the cylinder body 48 and one end face of the cylinder body 54 abut. Therefore, when the mold is opened, the urging force of the elastic body 42 along the mold opening direction can be applied to the cylinders 38 and 40. Thereby, since the tensile load along the mold opening direction acts on the relay part 304, the relay part 304 can be cut automatically and suitably.

  In the present embodiment, the reduced diameter portion 206 of the sprue 204 is formed at the contact portion between the pair of cylinders 38 and 40 by forming the inner holes 52 and 58 of the cylinder bodies 48 and 54 as tapered holes. . As a result, the urging force of the elastic body 42 can be efficiently applied to the reduced diameter portion 306 of the relay portion 304 to cut the relay portion 304 more easily.

  Further, since the reduced diameter portion 306 is formed at an intermediate portion of the relay portion 304 (a portion separated from the first branch portion 300a and the second branch portion 300b), the reduced diameter portion 306 of the relay portion 304 is formed. It is possible to suitably prevent the first molded product 302a and the second molded product 302b from being damaged during cutting.

  According to the present embodiment, the stoppers 44 and 46 are provided to prevent the pair of cylinders 38 and 40 from being detached from the through hole 36. Therefore, in the mold opening process, the relay portion 304 is connected to the cylinder 38, 40 can be easily taken out. Further, since it is not necessary to set the pair of cylinders 38 and 40 in the through hole 36 every time injection molding is performed, the cycle time of injection molding can be shortened.

  The injection molding apparatus 10 according to the present embodiment is not limited to the configuration described above. The inner hole 52 of the cylindrical body 48 is not limited to the example formed as a tapered hole. For example, a small diameter hole having a constant inner diameter located at the other end of the cylindrical body 48 and a constant inner diameter communicating with the small diameter hole. You may have a large diameter hole. Similarly, the inner hole 58 of the cylindrical body 54 is not limited to the example formed as a tapered hole. For example, a small diameter hole having a constant inner diameter that is aligned with one end of the cylindrical body 54, and the small diameter hole. And a large-diameter hole having a constant inner diameter communicating with the.

  In this case, the reduced diameter portion 206 of the sprue 204 is formed by the small diameter hole of the cylindrical body 48 and the small diameter hole of the cylindrical body 54. In other words, the inner holes 52 and 58 of the cylinder bodies 48 and 54 may have any hole shape so that the reduced diameter portion 206 is formed in the sprue 204.

  Next, a cutting mechanism 22a according to a modification of the present embodiment will be described with reference to FIGS. As shown in FIG. 9, the cutting mechanism 22 a according to the modification includes a cylindrical body 70 disposed in the through hole 36, an elastic body 72 for biasing the cylindrical body 70, and the cylindrical body 70 is a through hole. And a stopper 74 for preventing separation from the inside.

  The cylindrical body 70 includes a cylindrical main body 76 formed in a cylindrical shape, and a flange portion 78 formed on the outer peripheral surface of the cylindrical main body 76 at the other end side in the axial direction. The length dimension of the cylindrical body 76 is set to be substantially the same as the length dimension of the through hole 36.

  The inner hole 80 of the cylindrical body 76 is formed as a tapered hole that gradually decreases in diameter toward one end of the cylindrical body 76. The inner hole 80 of the cylinder body 76 functions as the sprue 204. The outer peripheral surface of the flange portion 78 is in sliding contact with the inner wall surface constituting the through hole 36.

  The elastic body 72 is interposed between the protrusion 82 protruding from the inner wall surface constituting the opening at one end of the through hole 36 and the flange portion 78 of the cylindrical body 70. The stopper 74 has the same configuration as the stopper 44 described above, and is fixed to an inner wall surface constituting the opening at the other end of the through hole 36.

  In the cutting mechanism 22a according to the present embodiment, the flange portion 78 of the cylindrical body 70 urged by the elastic body 72 abuts against the stopper 74 and the other end portion of the cylindrical main body 76 in the mold open state, which is an initial state. Protrudes from the through hole 36 through the inner hole of the stopper 74 to the side where the movable mold 24 is located.

  On the other hand, in the mold closing process, the cylinder body 70 pressed by the movable mold 24 is displaced toward the fixed mold 16 side while compressing the elastic body 72. In this case, since the inner hole 80 of the cylindrical body 76 is a tapered hole that is gradually reduced in diameter toward one end thereof, a reduced diameter portion 206 is formed at one end of the cylindrical body 70 in the sprue 204. It will be.

  Therefore, when the molten resin is filled in the first cavity 202a and the second cavity 202b in the mold closed state and solidified, the diameter-reduced portion of the relay portion 304 (mostly) at the connection portion between the relay portion 304 and the first branch portion 300a. A portion 306 having a small cross-sectional area is formed (see FIG. 9).

  In this case, when the movable mold 24 is moved to the side opposite to the side where the fixed mold 16 is located in the mold opening process, the urging force of the elastic body 72 in the direction toward the movable mold 24 is applied to the cylinder 70. Therefore, a tensile load in the direction toward the movable mold 24 acts on the relay section 304 in a state where the first branch part 300a is in contact with the intermediate mold 20 and the fixed mold 16 (fixed state). . Thereby, the relay part 304 can be easily cut | disconnected by the reduced diameter part 306 (refer FIG. 10).

  According to this modification, the number of parts of the injection molding apparatus 10 (cutting mechanism 22a) can be reduced because only one cylindrical body 70 of the cutting mechanism 22a is required.

  The present invention is not limited to the above-described embodiment, and it is naturally possible to adopt various configurations without departing from the gist of the present invention. For example, the inner hole of the cylinder may not be a tapered hole.

DESCRIPTION OF SYMBOLS 10 ... Injection molding apparatus 16 ... Fixed mold (1st mold)
18 ... Injection mechanism 20 ... Intermediate mold 22, 22a ... Cutting mechanism 24 ... Movable mold (second mold)
36 ... Through-hole 38, 40, 70 ... Cylindrical body 42, 72 ... Elastic body 44, 46, 74 ... Stopper 48, 54, 76 ... Cylindrical body 50, 56, 78 ... Flange 52, 58, 80 ... Inner hole 82 ... Projection 200a ... 1st runner 200b ... 2nd runner 202a ... 1st cavity 202b ... 2nd cavity 204 ... Sprue 206, 306 ... Diameter reduction part 300a ... 1st branch part 300b ... 2nd branch part 302a ... 1st shaping | molding Product 302b ... Second molded product 304 ... Relay part

Claims (8)

A first mold and a second mold, which are opposed to each other in a state where they can be closely spaced from each other;
An intermediate mold disposed between the first mold and the second mold,
In a mold closed state, it melts into a first cavity formed between the first mold and the intermediate mold and a second cavity formed between the second mold and the intermediate mold. An injection molding apparatus capable of filling a material,
In the intermediate mold, a sprue that communicates the first cavity and the second cavity is provided,
An injection molding apparatus comprising a cutting mechanism for cutting a relay portion formed by solidification of the molten material in the sprue when the mold is opened. The injection molding apparatus according to claim 1, wherein
In the intermediate mold, a through-hole is formed in each of a surface facing the first mold and a surface facing the second mold,
The cutting mechanism is arranged in the through-hole so as to be capable of contacting the first mold or the second mold and constituting at least a part of the sprue and being displaceable along the mold opening direction. The installed cylinder,
An elastic body that urges the cylindrical body along a mold opening direction;
An injection molding apparatus comprising: The injection molding apparatus according to claim 2,
An injection molding device, wherein the sprue is formed with a reduced diameter portion. The injection molding device according to claim 3,
A plurality of the cylinders are provided,
The elastic body urges each cylinder in a direction in which the plurality of cylinders are separated from each other,
The reduced diameter portion is located at a portion where the plurality of cylindrical bodies are in contact with each other. The injection molding apparatus according to claim 2,
2. The injection molding apparatus according to claim 1, wherein the cutting mechanism further includes a stopper that prevents the cylindrical body from being detached from the intermediate mold. A first cavity formed between the first mold and the intermediate mold in a mold closed state, a second cavity formed between the second mold and the intermediate mold, and the intermediate mold An injection molding method in which a molten material is filled into a sprue provided in the first cavity and communicated with the second cavity, and solidified.
An injection molding method comprising: performing a cutting step of cutting a relay portion formed by solidifying the molten material in the sprue by a cutting mechanism when the mold is opened. The injection molding method according to claim 6, wherein
The cutting mechanism has a cylindrical body and an elastic member constituting at least a part of the sprue,
In the cutting step, the cylindrical body disposed so as to be displaceable along the extending direction of the through hole in the through hole formed in the intermediate mold is urged along the mold opening direction by the elastic member. An injection molding method characterized in that the relay part is cut. The injection molding method according to claim 7,
A plurality of the cylinders are provided,
The sprue is formed with a reduced diameter portion at a portion where the plurality of cylindrical bodies are in contact with each other,
In the cutting step, the relay part is cut by urging the plurality of cylinders disposed in the through hole by the elastic body in a direction away from each other.

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