JP5854471B2 - Injection molding method using hot runner unit - Google Patents

Description

  The present invention relates to an injection molding method using a hot runner unit.

  For example, when relatively large resin parts such as bumpers and instrument panels are manufactured by injection molding, a plurality of injections of molten resin supplied to a plurality of injection points are stabilized to ensure molding accuracy. An injection molding machine equipped with an injection unit may be used (see, for example, Patent Document 1 below).

  Recently, a single injection molding machine may be used to mold multiple types of resin parts. In this case, the fixed mold is removed from the fixed platen of the injection molding machine, and the resin parts to be molded next are molded. The work of carrying in the corresponding fixed mold (mold replacement work) is performed. Here, as described in Patent Document 1 below, when connecting a plurality of injection units to a fixed mold, avoid the loading / unloading direction of the fixed mold and place the injection unit above or below the fixed mold. Although it is necessary to install this type of injection unit, this type of injection unit is very large, so that a plurality of injection units are arranged around the fixed mold, resulting in a significant increase in installation space. In addition, since the location of the injection unit is limited to the vertical direction of the mold, there is a need to temporarily lift the injection unit disposed on the upper surface of the fixed mold when replacing the mold. The number of changeover man-hours increases, leading to a decrease in productivity.

  In order to solve the above problem, the present applicant has proposed an injection molding machine shown in Patent Document 2 below. That is, in Patent Document 2 below, a plurality of injection units are arranged around the fixed platen, and the fixed platen is provided with a number of hot runners corresponding to the injection units, and these hot runners are all fixed molds. On the other hand, an injection molding machine is described in which the nozzle portion of the hot runner can be brought into contact with the nozzle receiving portion of the fixed mold when receiving a pressing force from the injection unit by being arranged so as to be able to advance and retreat. The patent document describes an injection molding machine in which a guide plate portion is fixed to a hot runner that is not collinear with the injection unit, and the guide plate portion is slidably supported with respect to a fixed platen. At the same time, the hot runner is advanced toward the fixed mold by pressing the injection nozzle of the injection unit against the mold clamping direction against the nozzle receiving part of the hot runner to which the guide plate portion is fixed. Thus, a method is described in which the tip of the hot runner is brought into contact with the fixed mold with a predetermined pressing force, and then the molten resin is injected.

JP 2009-61693 A JP 2011-73179 A

  As described in Patent Document 2, by fixing a guide plate portion slidable with respect to a fixed platen to a hot runner, for example, an injection unit arranged so as to be able to advance in a direction inclined with respect to a mold clamping direction. When a pressing force is applied to the hot runner, the component force in the direction of bending the hot runner (the component force in the direction perpendicular to the mold clamping direction) of the pressing force can be received by the guide plate portion. This prevents bending deformation of the hot runner when the nozzle is touched. However, when the injection molding machine described in Patent Document 2 is put into practical use, there are still concerns about the following problems. That is, when the injection unit and the hot runner are separated from each other, in order to ensure that the molten resin injection operation can be performed, not only between the hot runner and the fixed mold, Both are required to be in pressure contact with the hot runner to the extent that injection is possible. However, the injection molding machine described in Patent Document 2 allows the mold to be replaced by moving (retracting) the hot runner disposed in the fixed platen away from the fixed mold. At the start of the first injection molding after the mold replacement, the hot runner is at a position shifted backward from the position at the time of nozzle touch. For this reason, when the injection unit is disposed so as to be able to advance in a direction inclined with respect to the mold clamping direction, the center axis of the injection nozzle and the center axis of the nozzle receiving portion of the hot runner are shifted (see FIG. 5). In this case, it is difficult to accurately press the injection nozzle against the nozzle receiving portion of the hot runner.

  For example, a means for moving the hot runner and the injection unit forward toward the fixed mold integrally after bringing the injection nozzle of the injection unit into contact with the nozzle receiving portion in a state where the hot runner is retracted is also conceivable. However, in this case, it is not sufficient to move the injection unit forward in one oblique direction, and it is necessary to further move the injection unit in a direction (for example, a direction along the mold clamping direction) to approach the fixed mold. . Therefore, a mechanism for moving the injection unit in two directions is required, and the mechanism becomes complicated. Further, position control becomes difficult as the moving mechanism becomes complicated.

  In view of the above circumstances, in this specification, regardless of the arrangement mode of the injection unit, it is possible to reliably form a press-contact state that can be injected between the hot runner and the fixed mold, thereby stabilizing injection. Guaranteeing the operation is a technical problem to be solved by the present invention.

The solution of the technical problem is achieved by an injection molding method using the hot runner unit according to the present invention. That is, in this injection molding method, the injection nozzle of the injection unit is pressed from a direction inclined with respect to the mold clamping direction onto a hot runner unit that is integrally provided with a hot runner and can be advanced and retracted toward the fixed mold. Therefore, in the injection molding method for pressing the hot runner against the fixed mold, the hot runner unit is advanced along the mold clamping direction by the advance / retreat drive means provided separately from the drive unit of the injection unit, and the hot runner is fixed to the fixed mold. Then, the injection unit is advanced by the drive device in a direction inclined with respect to the mold clamping direction, and the injection nozzle is pressed against the hot runner unit that is in contact with the fixed mold. It is characterized by a point that presses against a fixed mold with a nozzle touch force.

  As described above, according to the present invention, a force (load) required for performing an operation (also referred to as a nozzle touch) for forming a pressure contact state that can be injected between the hot runner and the fixed mold is several tons. However, the force (load) required to move the hot runner unit having the hot runner toward the fixed mold is smaller than the force required for the nozzle touch (hereinafter simply referred to as nozzle touch force). The driving means (driving device) used for applying the nozzle touch force and the driving means (advancing / retreating driving means) used for advancing the hot runner unit are separately provided, and the advancing / retreating driving means After the hot runner unit is moved forward with the hot runner abutting against the fixed mold, the injection nozzle is moved forward by the drive device and pressed against the hot runner unit. Characterized in that the urge with nozzle touch force Na in the fixed mold. In this way, the nozzle touch force can be maintained in a state where the hot runner unit is positioned with respect to the fixed mold by performing the forward drive of the hot runner unit and the pressing operation of the hot runner against the fixed mold with separate driving means. Can be granted. As a result, even when the injection unit is disposed so as to be able to advance in an inclined direction with respect to the mold clamping direction, the center axis of the injection nozzle and the center axis of the nozzle receiving portion of the hot runner unit are in a state of being aligned. The injection nozzle can be accurately pressed against the nozzle receiving portion. Therefore, it is possible to reliably form a pressure contact state that can be injected between the injection nozzle and the nozzle receiving portion and between the hot runner and the fixed mold.

  Further, the forward drive operation of the hot runner unit and the operation of applying the nozzle touch force are performed by separate drive means (advance / retreat drive means, drive device), so that the forward drive force in the same direction as the forward direction of the hot runner unit is advanced / retreated. It can be applied by driving means. Therefore, the forward movement of the hot runner unit can be accurately performed also by this. Also, since the injection unit needs only to move forward in a single direction, it is possible to accurately press the injection nozzle against the hot runner unit while avoiding the complexity of the moving mechanism including the drive unit.

  Further, the injection molding method according to the present invention provides a mold clamping direction gap between the fixed platen to which the fixed mold is attached and the hot runner unit in a state where the hot runner is in contact with the fixed mold. The size of the gap may be detected, and the quality of the contact state between the hot runner and the fixed mold may be determined based on the detected size of the clamping direction gap.

  As described above, in principle, the hot runner unit is accurately positioned if the injection nozzle is pressed against the hot runner unit while the hot runner unit is advanced to the position where the hot runner contacts the fixed mold. The nozzle touch force can be applied in the state. However, in an environment where the molten resin is repeatedly injected and supplied, the remainder of the molten resin and other foreign substances may accumulate between the hot runner and the stationary mold, so that the hot runner can move forward. In spite of this, a good contact state is not formed between the hot runner and the fixed mold, in other words, the hot runner unit contacts in a state of being shifted rearward from a predetermined position. Things can happen. Therefore, in the present invention, with the hot runner in contact with the fixed mold, a clamping direction gap is provided between the fixed platen and the hot runner unit, and the size of this gap is detected, and the detection result is obtained. Based on this, the quality of the contact state between the hot runner and the fixed mold is judged. Thereby, for example, when the detected size of the clamping direction gap is equal to or less than a preset value (reference value), a good contact state is formed between the hot runner and the fixed mold. Therefore, the hot runner pressing operation by the forward operation of the injection unit can be performed. Also, if the detected gap size exceeds the reference value, there is a good contact between the hot runner and the fixed mold because some foreign matter is interposed between the hot runner and the fixed mold. The injection operation can be interrupted assuming that the contact state is not formed. Therefore, it is possible to determine whether or not the hot runner unit is accurately positioned before actually pressing the injection nozzle against the hot runner unit. Therefore, the injection unit is driven forward only when it is accurately positioned. This makes it possible to reliably perform nozzle touch.

  For example, a method of arranging the block between the fixed platen and the hot runner unit and positioning the hot runner unit (position detection) using the block as a stopper is also conceivable, but in that case, the pressing force from the injection unit A part of (nozzle touch force) is dispersed in the block, and there is a possibility that a sufficient nozzle touch force cannot be applied between the hot runner and the fixed mold. In contrast, in the present invention, since the gap in the mold clamping direction is positively provided in a state where the hot runner is in contact with the fixed mold, the above problem can be avoided and the push from the injection unit can be avoided. It is possible to transmit the pressure between the hot runner and the fixed mold and reliably form a pressure contact state between the two.

  As described above, according to the present invention, it is possible to reliably form a press-contact state that can be injected between the hot runner and the fixed mold irrespective of the arrangement mode of the injection unit, and thereby stable injection. Operation can be guaranteed.

It is a flowchart which shows the flow of the injection molding method using the hot runner unit which concerns on one Embodiment of this invention. It is sectional drawing of the hot runner unit for injection molding machines which concerns on one Embodiment of this invention, Comprising: It is AA sectional drawing of the hot runner unit shown in FIG. FIG. 3 is a side view of the hot runner unit shown in FIG. It is a principal part expanded sectional view of the hot runner unit shown in FIG. FIG. 3 is a plan view of the hot runner unit shown in FIG. 2 as viewed from the direction of arrow C, and is a plan view for explaining a series of operations related to nozzle touch. FIG. 3 is a plan view of the hot runner unit shown in FIG. 2 as viewed from the direction of arrow C, and is a plan view for explaining a series of operations related to nozzle touch. FIG. 3 is a plan view of the hot runner unit shown in FIG. 2 as viewed from the direction of arrow C, and is a plan view for explaining a series of operations related to nozzle touch.

  Hereinafter, an example of an injection molding method using a hot runner unit according to an embodiment of the present invention will be described with reference to FIGS. In the following description, the “width direction” refers to a direction orthogonal to both the vertical direction and the clamping direction.

  FIG. 1 is a flowchart showing an injection molding method using a hot runner unit according to an embodiment of the present invention, and particularly showing an injection molding flow centering on the operation of the hot runner unit. As shown in the figure, this injection molding method includes step S1 in which the hot runner unit is advanced by advancing and retracting drive means provided separately from the injection unit drive device, and the hot runner is brought into contact with the fixed mold, Step S2 for detecting the size of the mold clamping direction gap formed between the fixed platen and the hot runner unit with the runner in contact with the fixed mold, and the detected size of the mold clamping direction gap. Based on step S3 for determining whether or not the contact state between the hot runner and the fixed mold is good, and when it is determined that a good contact state is formed, the injection unit is advanced by the drive device. And step S4 for pressing the hot runner against the fixed mold with a nozzle touch force by pressing the injection nozzle against the hot runner unit in contact with the fixed mold. To.

  First, the hot runner unit used for the injection molding method will be described. FIG. 2 is a sectional view of the hot runner unit 10 for an injection molding machine according to the present invention. This sectional view corresponds to an AA sectional view of the hot runner unit 10 shown in FIG. 3 (a view in which the hot runner unit is viewed in the center in the width direction). As shown in FIG. 2, the hot runner unit 10 according to the present invention is disposed in a fixed platen 11, and its tip is brought into contact with a fixed mold 12 attached to the fixed platen 11, thereby injecting the injection unit 13 ( A hot runner 14 capable of supplying the molten resin injected from (see FIG. 5) to a cavity (not shown) in the fixed mold 12 is provided. In this embodiment, the hot runner unit 10 includes a hot runner 14 and a guide plate portion 16 in which the hot runner 14 is integrated and which can slide with respect to a plurality of guide pins 15 erected on the fixed platen 11. As the guide plate portion 16 slides, the hot runner 14 integrated with the guide plate portion 16 is configured to be movable back and forth with respect to the fixed mold 12. Further, as shown in FIG. 2, the hot runner unit 10 may further include a runner holding portion 17 that holds the base end of the hot runner 14, and in this case, the runner holding portion 17 is provided with a plurality of fastening members 18a. , 18b is fixed to the guide plate portion 16 so that the hot runner 14 and the guide plate portion 16 are integrated in a non-contact manner while being slidable integrally with the guide plate portion 16.

  The hot runner 14 has a substantially cylindrical runner body portion 19 (also referred to as a gate bush) and a nozzle provided at the tip of the runner body portion 19 for discharging molten resin that has passed through the runner body portion 19. Part 20. The hot runner 14 having the above-described configuration is disposed in the through hole 21 in a state in which a gap having a size capable of heat insulation is provided between the inner surface of the through hole 21 provided in the fixed platen 11. In addition, a band heater 22 for keeping the molten resin passing through the inside of the runner body 19 at a high temperature is disposed on the outer periphery of the runner body 19.

  Further, a guide portion 23 is provided on the front end side of the hot runner 14 so as to be in sliding contact with the fixed platen 11 and capable of moving forward and backward integrally with the hot runner 14. The guide portion 23 has, for example, a ring shape and is formed of a material (for example, stainless steel) having a lower thermal conductivity than the hot runner 14 or the fixed platen 11. In this illustrated example, a sleeve portion 24 such as an oilless bush is fitted and fixed to the through-hole 21 of the fixed platen 11, and a guide portion 23 is fitted to the sleeve portion 24, and the inner peripheral surface of the sleeve portion 24. Since the outer peripheral surface of the guide portion 23 is in sliding contact with the nozzle portion 20, the nozzle portion 20 of the hot runner 14 can be brought into contact with the nozzle receiving portion 25 of the fixed mold 12. The runner body 19 and the nozzle 20 of the hot runner 14 can be formed separately. By making them separate, for example, the nozzle part 20 that requires wear resistance and the runner body part 19 that requires bending toughness can be formed of different materials or different processing processes (such as quenching). it can. Also, it is possible to easily replace only the nozzle portion 20 that is heavily worn. In this case, as shown in FIG. 2, a guide portion 23 is disposed on the outer periphery of the runner main body portion 19, and the guide outer periphery is screwed with the distal end outer periphery of the runner main body portion 19 and the proximal end inner periphery of the nozzle portion 20. The portion 23 is clamped and fixed in the axial direction by the runner body 19 and the nozzle 20.

  The guide plate portion 16 has, for example, a substantially rectangular shape, and has an insertion hole 26 through which the hot runner 14 can be inserted in the center in the width direction, and a sliding contact hole 27 capable of sliding contact with the guide pin 15. In this embodiment, as shown in FIGS. 2 and 3, a plurality (four in this illustrated example) of guide pins 15 are erected in a direction parallel to the mold clamping direction of the injection molding machine. A number of sliding contact holes 27 corresponding to the guide pins 15 are formed at point-symmetrical positions (positions in the vicinity of the four corners in the illustrated example) centered on the insertion hole 26 position of the hot runner 14 in the guide plate portion 16.

  Further, in this embodiment, a recess 29 for disposing the advancing / retreating drive means 28 to be described later is provided in the vicinity of the sliding contact portion between the guide plate portion 16 and the guide pin 15 (in this illustrated example, the upper and lower portions 2 The advancing / retreating drive means 28 such as a hydraulic cylinder is disposed in the recess 29. The advancing / retreating drive means 28 fixes, for example, a fixing plate 30 attached to the main body portion 28a (cylinder portion in the case of a hydraulic cylinder) to both sides of the concave portion 29 of the guide plate portion 16 with bolts and the like, and an extendable portion 28b (hydraulic cylinder In this case, by fixing the tip of the rod part) to the fixed platen 11, the expansion / contraction force (reaction force) is applied to the guide plate part 16 to which the main body part 28a is fixed in accordance with the expansion / contraction movement of the expansion / contraction part 28b relative to the main body part 28a. It is to be transmitted. Further, in this embodiment, two advance / retreat drive means 28 are provided, and the center of gravity of these two advance / retreat drive means 28 is guided by considering the weight balance when fixed to the guide plate portion 16, for example. A recess 29 is formed at a position that coincides with the center of gravity of the plate portion 16, in other words, at a position that is point-symmetric about the insertion hole 26 of the hot runner 14.

  In this embodiment, as shown in FIGS. 2 to 4, the runner holding portion 17 includes a ring portion 32 interposed between a flange portion 31 provided at the base end of the hot runner 14 and the guide plate portion 16. By fixing to the guide plate portion 16 via the plurality of fastening members 18a and 18b, the flange portion 31 can be sandwiched between the ring portion 32 and the hot runner 14 and the guide plate portion 16 can be integrated in a non-contact manner. The runner block 33 that is provided, and a nozzle receiving portion that is provided on the runner block 33 and that can form a pressure contact state with the injection nozzle 34 by pressing the injection nozzle 34 (see FIG. 5) of the injection unit 13. 35.

  More specifically, the ring portion 32 has a first annular portion 36 that allows the flange portion 31 of the hot runner 14 to be disposed on the inner periphery, and a smaller inner diameter than the first annular portion 36, and the runner body portion of the hot runner 14. And a second annular portion 37 through which 19 can be inserted. Accordingly, the flange portion 31 of the hot runner 14 is fitted and disposed in the first annular portion 36 of the ring portion 32, and a plurality of fastenings are performed with the runner block 33 in contact with the proximal end surface of the flange portion 31. By fastening and fixing the runner block 33 to the guide plate portion 16 via the members 18a and 18b, the flange portion 31 is sandwiched between the runner block 33 and the ring portion 32, and the ring portion 32 is sandwiched between the flange portion 31 and the guide plate portion. 16. Thereby, the hot runner 14 and the guide plate portion 16 are integrated with each other with a predetermined gap in a state where the base end side end surface of the flange portion 31 is in close contact with the runner block 33. In this case, in order to secure the contact state between the hot runner 14 (the flange portion 31) and the runner block 33, the thickness dimension of the first annular portion 36 of the ring portion 32 is set to that of the flange portion 31, as shown in FIG. It may be made slightly smaller. Further, in consideration of thermal expansion caused by the molten resin passing through the hot runner 14, between the first annular portion 36 and the flange portion 31, and between the second annular portion 37 and the runner main body portion 19. Each may be provided with a predetermined gap. In consideration of the fact that the ring portion 32 is in close contact with the guide plate portion 16 as described above, the ring portion 32 is formed of a material having a lower thermal conductivity than a guide plate portion such as stainless steel. Good.

  In this embodiment, a cooling water passage 38 is formed in the guide plate portion 16 so that heat transfer from the hot runner 14 to the sliding contact portion between the guide plate portion 16 and the guide pin 15 can be interrupted. In other words, a cooling water passage 38 that passes between the sliding contact portion of each guide pin 15 in the guide plate portion 16 and the insertion hole 26 of the hot runner 14 is formed. For example, as shown in FIG. 3, the cooling water passage 38 has one end 38 a opened in the inner surface of the lower concave portion 29 provided in the guide plate portion 16, and extends in the direction of the long side (along) of the guide plate portion 16. It extends so as to pass directly below (on an extension line of the fastening member 18a) and in the vicinity of a plurality of (five right side in FIG. 3) fastening members 18a arranged side by side. The cooling water passage 38 is bent and extends in the short side direction (width direction) of the guide plate portion 16 after passing through the vicinity immediately below the plurality of fastening members 18a, and further bent in the long side direction. Then, after passing through the vicinity immediately below the plurality of fastening members 18b arranged in parallel, it bends again in the short side direction, and finally bends in the long side direction. The other end 38b is opened to finish.

  As described above, the cooling water passage 38 is continuous, and the cooling water flowing in from the one end 38a is discharged from the other end 38b through the above-described path. Then, by forming the cooling water passage 38 in this way, the guide plate portion 16 is seen in plan view so as to surround the contact portion between the ring portion 32 and the guide plate portion 16 as shown in FIG. In addition, a cooling water flow path is formed. Thereby, the heat transfer from the hot runner 14 to the sliding contact portion via the ring portion 32 can be cut off.

  Further, as described above, when the runner holding portion 17 (runner block 33) is fixed to the guide plate portion 16 via the plurality of fastening members 18a and 18b, the runner holding portion 17 (runner block 33) passes near the plurality of fastening members 18a and 18b. Thus, the flow path of the cooling water is formed. Accordingly, heat transfer from the runner block 33 to the sliding contact portion via the fastening members 18a and 18b can be blocked.

  Next, a configuration for controlling the hot runner unit having the above configuration will be described. Between the fixed platen 11 and the hot runner unit 10, the hot runner unit 10 is advanced toward the fixed mold 12 and the hot runner 14 is in contact with the fixed mold 12. A gap detecting unit 39 for detecting a mold clamping direction gap d (see FIG. 6) formed between the fixed platen 11 and the fixed platen 11 is provided. In this embodiment, as shown in FIG. 5, a counter recess 40 is provided on the surface of the fixed platen 11 that faces the guide plate portion 16 of the hot runner unit 10, and the gap detector 39 is not projected from the counter recess 40. Is installed. As the gap detection unit 39, an arbitrary one can be used as long as it can detect the mold clamping direction gap d in a state where the hot runner 14 is in contact with the fixed mold 12 as described above. In addition to a type of sensor (distance sensor) that can measure the distance to the guide plate portion 16), a type of sensor (for example, a limit switch) that detects only whether or not the detection target is within a predetermined distance range is used. it can.

  The gap detection unit 39 is electrically connected to the control unit 41, and the drive unit (not shown) of the injection unit 13 and the advance / retreat drive means 28 described above are also electrically connected to the control unit 41. Therefore, it is controlled so as to operate (drive and detection operations) in accordance with a control program described later incorporated in the control unit 41.

  As described above, the control unit 41 uses the advance / retreat drive means 28 to advance the hot runner unit 10 toward the fixed mold 12 to bring the hot runner 14 into contact with the fixed mold 12, and the hot runner Step S2 for detecting the size of the mold clamping direction gap d formed between the fixed platen 11 and the hot runner unit 10 with the 14 in contact with the fixed mold 12, and the detected mold clamping direction gap Step S3 for determining whether or not the contact state between the hot runner 14 and the stationary mold 12 is good based on the size of d, and when it is determined that a good contact state is formed, the driving device Then, the injection unit 13 is advanced and the injection nozzle 34 is pressed against the hot runner unit 10 in contact with the fixed mold 12, so that the hot runner 14 is moved to the fixed mold 12. Comprising incorporating a control program and a step S4 for pressing with at Ji force.

  Hereinafter, the flow of injection molding using the hot runner unit 10 having the above configuration will be described focusing on the control mode of the hot runner unit 10.

  First, a movable platen and a movable mold (not shown) are moved, and the movable mold and the fixed mold 12 are clamped. Further, along with this mold clamping operation, the advance / retreat driving means 28 is driven to contract in response to a command from the control unit 41, whereby the hot runner unit 10 is advanced toward the fixed mold 12 from the state shown in FIG. 14 is brought into contact with the fixed mold 12 (step S1). Here, the hot runner unit 10 is advanced to a position where the hot runner unit 10 can be advanced by the advance / retreat driving means 28, whereby the tip (nozzle portion 20) of the hot runner 14 is moved to the nozzle receiving portion 25 of the fixed mold 12. Make contact.

  Next, in this state (the state shown in FIG. 6), the size of the mold clamping direction gap d between the hot runner unit 10 and the fixed platen 11 is detected (step S2). In this embodiment, in accordance with a command from the control unit 41, the gap detection unit 39 installed in the opposed recess 40 of the fixed platen 11 is configured so that the gap size between the gap detection unit 39 and the opposing surface of the guide plate unit 16 (gap in the mold clamping direction) d) is detected.

  After detecting the mold clamping direction gap d as described above, the quality of the contact state between the hot runner 14 and the fixed mold 12 is determined based on the detected size of the mold clamping direction gap d (step S3). Specifically, according to a control program incorporated in the control unit 41, for example, the magnitude relationship between the detected size (detected value) of the clamping direction gap d and a preset value (reference value) is compared. Thus, the quality of the contact state is determined. Here, when the detected value is equal to or less than the reference value, it is considered that a good contact state is formed between the tip of the hot runner 14 (nozzle part 20) and the fixed mold 12, in other words, It is determined that the injectable pressurized contact state can be formed by the pressing operation of the injection unit to be performed, and the injection unit 13 is advanced by the driving device. Then, as shown in FIG. 7, the hot runner unit 10 in a state in which the hot runner 14 is in contact with the fixed mold 12 is provided with a pressing force (nozzle touch force) that can form an injectable pressurized contact state. The injection nozzle 34 is pressed against the nozzle receiving portion 35. Thereby, the pressing force from the injection unit 13 is transmitted to the hot runner 14 through the nozzle receiving portion 35 and the runner block 33. At this time, the moving direction d1 of the injection unit 13 and the advancing / retreating direction d2 of the corresponding hot runner 14 do not coincide with each other, and the component (component force) of the pressing force from the injection unit 13 is parallel to the mold clamping direction. ) Is transmitted to the corresponding hot runner 14. In this embodiment, the receiving member 43 is disposed in the gap 42 between the runner block 33 and the guide plate portion 16 and on the side (the left side in FIG. 3) whose width dimension is narrowed by the pressing of the injection unit 13. ing. Therefore, a component (component force) of the pressing force in a direction orthogonal to the mold clamping direction can be received by the receiving member 43 and the guide plate portion 16, and transmission of the orthogonal component to the hot runner 14 is possible. Can be avoided.

  When the pressing force is transmitted to the hot runner 14 in this manner, the nozzle portion 20 of the hot runner 14 is pressed against the nozzle receiving portion 25 of the fixed mold 12 with an appropriate force. No. 35 is in a pressure-contacted state to a level at which injection is possible, and the nozzle touch is completed (step S4). Therefore, by injecting the molten resin from the injection unit 13 from this state, the injected molten resin becomes the flow path in the nozzle receiving portion 35 and the runner block 33, the flow path in the hot runner 14, and the fixed mold. 12 is supplied to a cavity (not shown) after passing through a flow path in the inside. The same operation is performed on, for example, one or a plurality of (for example, two) hot runner units and injection units arranged side by side with the illustrated hot runner unit 10 (not shown), thereby melting a predetermined amount. Resin is fed into the cavity.

  By performing the injection operation as described above, the molten resin is filled into the cavity, and a workpiece (injection molded product) having a shape corresponding to the cavity is formed. At this time, by using the hot runner unit 10 provided with the above-described guide plate portion 16, as shown in FIG. 5, the injection unit 13 can be disposed in an inclined state with respect to the mold clamping direction. Therefore, even in an environment where the installation space is limited, a plurality of (for example, three) injection units 13 can be arranged adjacent to the fixed platen 11. Since injection molding can be performed using a plurality of injection units 13 in this way, the injection flow rate of the molten resin that should be borne by each injection unit can be reduced and the cavity can be filled at high speed. As a result, even a large injection molded product such as a bumper or an instrument panel can be molded in a short time.

  When the size of the mold clamping direction gap d detected in step S3 exceeds the reference value, some foreign matter is interposed between the nozzle portion 20 of the hot runner 14 and the nozzle receiving portion 25 of the fixed mold 12. For the reason described above, the hot runner unit 10 is regarded as being displaced rearward from the predetermined position, and the subsequent injection operation is interrupted. In other words, even in the state where it abuts on the fixed mold 12, the center axis of the nozzle receiving portion 35 of the hot runner unit 10 and the center axis of the injection nozzle 34 are regarded as being shifted, and the advance of the injection unit 13 is advanced. Driving is stopped (step S5). Thereby, it is not necessary to perform a wasteful injection operation, and the yield can be improved.

  After the injection molding of a workpiece having a predetermined shape is performed one or more times as described above, the mold is exchanged in order to mold a workpiece having another shape with the same injection molding machine. In this case, the operation for removing the fixed mold 12 attached to the fixed platen 11 and attaching another fixed mold (not shown) corresponding to a workpiece having another shape is performed according to the following procedure. First, from the state shown in FIG. 7, the drive unit moves the injection unit 13 rearward (in a direction away from the fixed platen 11), so that the injection nozzle 34 of the injection unit 13 and the nozzle receiving portion 25 of the hot runner unit 10 come into contact with each other. The state is released (the state shown in FIG. 6 is set (step S6)). Then, the advancing / retreating drive means 28 connected to the guide plate portion 16 and the fixed platen 11 is driven to extend, and the hot runner unit 10 having the guide plate portion 16 integrally is moved in a direction to retreat with respect to the fixed mold 12. Thus, the contact state between the nozzle portion 20 of the hot runner 14 and the nozzle receiving portion 25 of the fixed mold 12 is released, and the hot runner 14 is retracted from the fixed mold 12 as shown in FIG. 5 (step S7). ). When there are other injection units, the hot runner units corresponding to these other injection units perform the same operation as described above, and the hot runner 14 is retracted from the carry-in / out area of the fixed mold 12. Thereafter, the fixed mold 12 is detached from the fixed platen 11 and is carried out in the horizontal direction (downward in FIG. 5), and a new mold (fixed mold) for a workpiece to be injection-molded next is obtained. Carry in and fix to the stationary platen 11. Thereby, the replacement of the mold is completed. In this manner, the hot runner 14 is disposed in the fixed platen 11 and the guide plate portion 16 in which the hot runner 14 is integrated is disposed so as to be slidable from the fixed platen 11 to the guide pins 15. Thus, the fixed mold 12 can be detached from the fixed platen 11 while avoiding interference with the hot runner 14 by only a slight backward movement of the hot runner unit 10. Further, a new fixed mold 12 can be easily attached to the fixed platen 11.

  When the replacement of the mold is completed as described above, the mold is clamped as described above, and the hot runner 14 is moved integrally with the guide plate portion 16 by driving the advance / retreat driving means 28, so that the nozzle of the hot runner 14 is moved. The part 20 is brought into contact with the nozzle receiving part 25 of the fixed mold 12 (see FIG. 6). Thereafter, the corresponding injection unit 13 is advanced, and the injection nozzle 34 is pressed against the nozzle receiving portion 35 provided in the runner holding portion 17, so that the nozzle portion 20 of the hot runner 14 is fixed with a required force. The molten resin is injected in a state where the nozzle 20 and the nozzle receiver 35 are pressed and brought into close contact with each other to a level at which injection is possible. Thus, the replacement of the mold and the injection molding for each mold are repeatedly performed, and the injection molding operation is completed when the total number of injection moldings reaches a predetermined number set in advance (step S8).

  Further, as described above, when the replacement of the mold and the injection molding for each mold are repeatedly performed, the molten resin passes through the flow path in the hot runner 14 and the runner holding portion 17 and the molten resin is in the cavity in the fixed mold 12. Therefore, the guide plate portion 16 expands due to heat transfer from the hot runner 14, and the gap (sliding gap) at the sliding contact portion with the fixed platen 11 (the guide pin 15) is clogged. There is a concern that smooth sliding is hindered. In this respect, in this embodiment, the cooling water passage 38 that can block heat transfer from the hot runner 14 to the sliding contact portion between the guide plate portion 16 and the guide pin 15 is formed in the guide plate portion 16. The cooling water circulated through the water passage 38 absorbs the heat of the guide plate portion 16 in the heat transfer path from the hot runner 14 serving as a heat source to the sliding contact portion. Thereby, the temperature rise on the side closer to the sliding contact portion than the coolant passage 38 in the guide plate portion 16 is prevented, and the thermal expansion of the guide plate portion 16 in the vicinity of the sliding contact portion is suppressed. Therefore, it is possible to avoid a situation in which the sliding gap formed between the guide plate portion 16 and the guide pin 15 is clogged in the sliding contact portion, and the guide plate portion 16 is smoothly slid, and thus integrated with the guide plate portion 16. The smooth forward / backward movement of the hot runner 14 can be ensured.

  Thus, in the present invention, the forward drive of the hot runner unit 10 and the pressing operation (pressing operation by the nozzle touch force) of the hot runner 14 to the fixed mold 12 are performed by separate driving means. A nozzle touch force can be applied to the hot runner unit 10 in a state where the hot runner unit 10 is positioned with reference to the fixed mold 12. Thereby, even when the injection unit 13 is disposed so as to be able to advance in a direction inclined with respect to the mold clamping direction, the central axis of the injection nozzle 34 coincides with the central axis of the nozzle receiving portion 35 of the hot runner unit 10. In this state (the state shown in FIG. 6), the injection nozzle 34 can be accurately pressed against the nozzle receiving portion 35. Accordingly, it is possible to surely form a pressure contact state that can be injected between the injection nozzle 34 and the nozzle receiving portion 35 and between the hot runner 14 and the fixed mold 12.

  Further, the forward drive in the same direction as the forward direction of the hot runner unit 10 is achieved by performing the forward movement operation of the hot runner unit 10 and the operation of applying the nozzle touch force by separate drive means (advance / retreat drive means 28, drive device). The force can be applied by the advance / retreat driving means 28. Therefore, the advance operation of the hot runner unit 10 can be accurately performed also by this. Further, since the injection unit 13 can be moved forward in a single direction, the injection nozzle 34 is accurately pressed against the nozzle receiving portion 35 of the hot runner unit 10 while avoiding complication of the moving mechanism including the driving device. It becomes possible.

  Further, the drive means (drive device 28) used to advance the hot runner unit 10 and the drive means (drive device) used to apply the nozzle touch force by the injection unit 13 are separated and attached to the hot runner unit 10. The advance / retreat driving means 28 can be reduced in size. Further, since the output corresponding to the nozzle touch force is not required for the advancing / retreating drive means 28, it is not necessary to use a high output for the advancing / retreating drive means 28, so that the advance / retreat drive means 28 can be downsized. Become.

  In this embodiment, the mold clamping direction gap d is provided between the fixed platen 11 and the hot runner unit 10 in a state where the hot runner unit 10 is advanced and the hot runner 14 is in contact with the fixed mold 12. At the same time, the size of the gap d is detected, and the quality of the contact state between the hot runner 14 and the fixed mold 12 is determined by comparing the detected value with a preset reference value. Thereby, for example, when the size of the detected clamping direction gap d is equal to or less than the reference value, it is considered that a good contact state is formed between the hot runner 14 and the fixed mold 12. In addition, it is possible to form a pressure contact state by the forward movement of the injection unit 13. On the other hand, when the detected size of the mold clamping gap d exceeds the reference value, some foreign matter is interposed between the nozzle portion 20 of the hot runner 14 and the nozzle receiving portion 25 of the fixed mold 12. For this reason, it is considered that a good contact state is not formed, and the injection operation can be interrupted. Therefore, it is possible to accurately determine whether the hot runner unit 10 is positioned with respect to the fixed mold 12 before actually pressing the injection nozzle 34 against the nozzle receiving portion 35 of the hot runner unit 10. Only when accurately positioned, the nozzle unit can be reliably touched by driving the injection unit 13 forward. This can be expected to improve yield. In addition, by determining whether the contact state is good or not in this manner, the advance drive of the hot runner unit 10 by the advance / retreat drive means 28 does not have to be performed with high accuracy. In other words, simple control is sufficient to advance the hot runner unit 10 to a position where it abuts against the fixed mold 12. Also by this, the positioning control of the hot runner unit 10 can be performed with an easy and simple mechanism.

  As mentioned above, although one Embodiment of this invention was described, the injection molding method which concerns on this invention can take arbitrary forms within the scope of the present invention, without being limited to the form of the said illustration.

  For example, in step S3, whether or not the contact state is good may be determined based on whether or not the detected size of the clamping direction gap d is included in a preset numerical range. That is, when the size of the mold clamping direction gap d detected in step S2 is included in the preset numerical range, a good contact state is formed between the hot runner 14 and the fixed mold 12. As a result, it is possible to form a pressure contact state by the forward operation of the injection unit 13 (perform the subsequent injection operation). Further, when the detected size of the clamping direction gap d is smaller than the lower limit of the preset numerical range (out of the set range), the tip of the hot runner 14 (nozzle portion 20) is worn, etc. The injection operation can be interrupted assuming that a good contact state is not formed with the fixed mold 12. Therefore, the injection unit 13 is advanced only when the hot runner unit 10 is accurately positioned with respect to the fixed mold 12 in consideration of wear of the hot runner 14 due to continuous use as well as when foreign matter is mixed. It is possible to reliably perform nozzle touch by driving.

  Moreover, in the above embodiment, the case where three injection units including the illustrated injection unit 13 are arranged is illustrated, but of course not limited to this, one or two, or four or more injections It is also possible to apply to an injection molding machine equipped with a unit.

  Of course, other specific forms can be adopted for matters other than the above as long as the technical significance of the present invention is not lost.

DESCRIPTION OF SYMBOLS 10 Hot runner unit 11 Fixed platen 12 Fixed mold 13 Injection unit 14 Hot runner 15 Guide pin 16 Guide plate part 17 Runner holding part 18a, 18b Fastening member 19 Runner main part 20 Nozzle part 21 Through-hole 22 Band heater 23 Guide part 24 Sleeve portion 25 Nozzle receiving portion 26 Insertion hole 27 Sliding contact hole 28 Advance / retreat driving means 29 Recess 30 Fixing plate 31 Flange portion 32 Ring portion 33 Runner block 34 Injection nozzle 35 Nozzle receiving portion 36 First annular portion 37 Second annular portion 38 Cooling Water passage 39 Gap detection part 40 Opposite concave part 41 Control part 42 Gap (between guide plate part and runner block)
43 Receiving member d Clamping direction clearance (between guide plate and fixed platen)

Claims (2)

By pressing the injection nozzle of the injection unit from a direction inclined with respect to the mold clamping direction against a hot runner unit that has a hot runner integrally and is configured to be able to advance and retreat toward the fixed mold, the hot runner is In the injection molding method to press against a fixed mold,
With the advance / retreat driving means provided separately from the drive unit for the injection unit, the hot runner unit is advanced along the clamping direction and the hot runner is brought into contact with the fixed mold,
The drive unit advances the injection unit in a direction inclined with respect to the mold clamping direction, and presses the injection nozzle against the hot runner unit in contact with the fixed mold, whereby the hot runner An injection molding method using a hot runner unit, characterized in that is pressed against the fixed mold with a nozzle touch force. With the hot runner in contact with the fixed mold, a clamping direction gap is provided between the fixed platen to which the fixed mold is attached and the hot runner unit, and the size of the gap is detected. ,
The injection molding method using a hot runner unit according to claim 1, wherein the quality of the contact state between the hot runner and the fixed mold is determined based on the detected size of the mold clamping direction gap.

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