JP2010052322A - Injection molding machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To exactly remove a molded article having a thin-walled part from a fixed mold while the constitution of the fixed mold is kept as it is. <P>SOLUTION: A fixed-side plate 16 movable along a movement direction (arrow P) of a movable mold 7 is housed in a fixed mold attachment board 2 to which the fixed mold 3 is attached, and a plurality of fixed-side protruding pins 17 are protrusively mounted to the surface opposite to the fixed mold 3. These fixed-side protruding pins 17 can penetrate the fixed mold 3 and protrude from the cavity surface 3a. An air cylinder 19 is attached to the back of the fixed mold attachment board 2, and the fixed-side plate 16 is advanced and made to retreat by advancing and making the piston 21 retreat. When the fixed mold 3 and the movable mold 7 are opened, the molded article is compulsively removed from the fixed mold 3 by operating the air cylinder 19 to make the piston 21 advance and make the fixed-side protruding pins 17 eject the molded article (belt clamp 110) attached to the cavity surface 3a of the fixed mold 3. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an injection molding machine, and more particularly to an injection molding machine in which a protruding means for a molded product is provided on the fixed mold side.

  A normal injection molding machine includes a fixed mounting plate for mounting a fixed mold and a movable mounting plate for mounting a movable mold. The fixed mold mounting plate is fixed to the frame of the injection molding machine, and the movable mold mounting plate can approach and separate from the fixed mold mounting plate. In a normal injection molding machine, the movable mold mounting plate is brought close to the fixed mold mounting plate, and the molten resin is injected into the cavity formed between the fixed mold and the movable mold in the mold closed state, and the pressure is maintained for a predetermined time. To solidify the molten resin to form a molded product. Then, the mold opening is performed by separating the movable mounting plate from the fixed mounting plate. At this time, the molded product is released from the fixed mold by moving while adhering to the movable mold. The molded product is released from the movable mold by the protruding means provided on the movable mold side. However, if the digging of the fixed mold (depth from the parting line to the cavity surface) is larger than the digging of the movable mold, the molded product will not be released from the fixed mold when the mold is opened. It may remain attached.

  When the next injection molding is performed in this state, a molding defect called “double strike” occurs, and in the worst case, the mold (fixed mold or movable mold) is damaged.

  In order to prevent this, not only a movable mold but also a fixed mold is provided with a mold provided with a protruding means for projecting a molded product (see, for example, Patent Document 1). However, by providing the protruding means on the fixed mold, the structure of the fixed mold becomes complicated and expensive, or the fixed mold becomes large and an injection molding machine of one class is required.

  In addition, the injection molding machine monitors the propulsive force of the movable mold mounting plate during the mold closing operation, and if the value exceeds a preset upper limit value, it is determined that some abnormality has occurred and the The forward movement of the mold mounting plate is stopped (low pressure mold protection device). Here, in the conventional protruding means in the fixed mold, the protruding pin is protruded by the urging force of the compression spring. If the urging force of the compression spring is increased in order to ensure that the molded product is released from the fixed mold, the molding die will mistake the thin part of the molded product (for example, a portion having a thickness of about 0.1 to 0.3 mm). Even if it is pinched, the low-pressure mold protection device may not operate. This is because the mold closing force of the mold must be increased in order to resist the biasing force of the compression spring of the protruding means.

Further, in this type of mold, it is difficult to store the fixed mold and the movable parting line in close contact with each other due to the urging force of the compression spring. For this reason, there exists a possibility that a foreign material may enter into the cavity surface when the mold is stored.
JP 2001-347546 A

  In view of the above-described problems, an object of the present invention is to reliably release a mold from a fixed mold even if it is a molded product having a thin portion, with the structure of the fixed mold as it is.

Means for Solving the Problems and Effects of the Invention

The present invention for solving the above problems is as follows.
In order to attach the fixed mold, it is provided with a fixed mold mounting board that is fixedly attached to the frame, and a movable mold mounting board that is attached to the movable mold and approaches / separates from the fixed mold mounting board,
The movable mounting plate is moved close to the fixed mold mounting plate, molten resin is injected into a cavity formed by bringing the movable mold into close contact with the fixed mold, and the movable mounting plate is separated from the fixed mold mounting plate. An injection molding machine that, when opening the fixed mold and the movable mold, attaches the molded product formed by solidifying the molten resin to the movable mold and releases it from the fixed mold,
When the fixed mold and the movable mold are opened, the molded product solidified in the cavity is projected, and a protruding means for forcibly releasing the fixed mold from the fixed mold is provided on the fixed mold mounting plate, and from the start of the protruding in the protruding means It is characterized by a constant protruding force until the end of protruding.

  The injection molding machine according to the present invention is configured as described above, and the protruding means for the molded product, which has been conventionally provided in the fixed mold, is provided in the fixed mold mounting plate of the injection molding machine. Therefore, the molded product attached to the fixed mold can be reliably released without complicating the structure of the fixed mold or increasing the size of the fixed mold (in other words, leaving the fixed mold as it is). . As a result, the next injection molding is performed with the molded product attached to the fixed mold, thereby avoiding the problem of damaging the molding mold.

  Since the protruding force in the protruding means from the start of protruding to the end of protruding is made constant, the injection power of the molten resin and the holding pressure of the mold can be the same as in the case where the protruding means is not provided. For this reason, even if it is a case where the thin part is provided in the molded article, the low-pressure mold protection device of the injection molding machine can be operated normally.

  Specifically, the protruding means includes a pneumatic cylinder attached to a surface of the fixed mold mounting plate opposite to the fixed mold mounting surface along the axis of the piston along the moving direction of the movable mold mounting plate. A plate mounted on the fixed mounting plate so as to be movable along a moving direction of the movable mounting plate, and moving as the piston of the pneumatic cylinder moves forward and backward, and a cavity surface of the fixed mold from the plate And a projecting pin that projects from the cavity surface of the fixed mold when the piston of the pneumatic cylinder moves forward.

  The pneumatic cylinder is inexpensive, has a simple configuration, and is easy to operate. Of course, other protruding means such as a hydraulic cylinder or an electric motor may be used.

  An intermediate pin is disposed between the piston of the pneumatic cylinder and the plate, and the pneumatic cylinder can move the plate via the intermediate pin.

  The protrusion stroke can be adjusted by simply changing the intermediate pin.

  Furthermore, it is preferable that the area of the portion of the plate where the protruding pin protrudes is larger than the projected area of the cavity surface so as to include the cavity surface of the fixed mold.

  Thereby, since the protruding pin can be arranged over the entire cavity surface of the fixed mold, it can protrude over the entire molded product.

  Examples of the present invention will be described. 1 is a front cross-sectional view of the main part of an injection molding machine 100 according to an embodiment of the present invention, FIG. 2 is a side view of the same, FIG. 3 is a cross-sectional view taken along the line XX of FIG. 110 is a front view of 110, and FIG. 5 is a front view of the fixed mold 3.

  As shown in FIGS. 1 and 2, a fixed mold mounting plate 2 is fixed to the frame 1 of the injection molding machine 100 of this embodiment. A fixed mold 3 is attached to a fixed mold mounting surface 2 a of the fixed mold mounting board 2. Four tie bars 4 protrude from the four corners of the fixed mold mounting board 2 in a direction perpendicular to the fixed mold mounting surface 2a. These tie bars 4 are inserted through guide bushes 6 attached to the four corners of a movable mounting plate 5 disposed on the frame 1 so as to face the fixed mounting plate 2. The movable mold mounting board 5 is supported by each tie bar 4 by a mold clamping mechanism (not shown) and approaches and separates from the fixed mold mounting board 3. In FIG. 1, the moving direction of the fixed mounting board 3 is indicated by an arrow P.

  As shown in FIG. 1, a movable die 7 is attached to a surface of the movable attachment plate 5 that faces the fixed mold attachment plate 2. The movable mold 7 is provided with movable-side protruding means 8. That is, a recess 9 is provided on the back surface of the movable mold 7 (the surface attached to the movable mounting board 5), and in this recess 9, the approaching / separating direction of the movable mounting board 5 (the direction of the arrow P). ) Is movable along the movable side plate 11. The movable side plate 11 is provided with a plurality of movable side protruding pins 12 projecting toward the fixed mounting plate 2. Each movable-side protruding pin 12 is inserted through a through hole 13 provided in the movable mold 7 correspondingly to each of the movable-side protruding pins 12, and the tip surface thereof reaches the cavity surface 7 a of the movable mold 7. The movable plate 11 is moved along the direction of the arrow P in the concave portion 9 of the movable mold 7 by a driving means (not shown). When the movable side plate 11 moves forward (when moving toward the fixed mold mounting plate 2), each movable side protruding pin 12 protrudes from the cavity surface 7a of the movable mold 7.

  A fixed-side protruding means 14 is built in the fixed mounting board 2. That is, a recessed portion 15 is provided in the mounting surface 2a of the fixed mold 3 in the fixed mold mounting plate 2, and the recessed portion 15 extends along the approaching / separating direction (direction of arrow P) of the movable mounting plate 5. A movable fixed side plate 16 is accommodated. The fixed side plate 16 is provided with a plurality of fixed side protruding pins 17 protruding toward the movable mounting plate 5. Each fixed-side protruding pin 17 is inserted through a through hole 18 provided in the fixed mold 3 corresponding to them, and the tip end surface thereof reaches the cavity surface 3 a of the fixed mold 3.

  As shown in FIG. 1 to FIG. 3, a plurality of (in the case of the injection molding machine 100 of the present embodiment) are provided on the back surface portion of the fixed mold mounting plate 2 (surface opposite to the mounting surface 2 a of the fixed mold 3). Four) pneumatic cylinders 19 are attached, and an intermediate pin 22 is interposed between the piston 21 and the stationary plate 16 of each pneumatic cylinder 19. When each pneumatic cylinder 19 is actuated to advance the piston 21, the fixed plate 16 is moved via the intermediate pin 22. When the fixed mold plate 16 moves forward (when moving toward the movable mounting plate 5), each fixed-side protruding pin 17 protruding from the fixed mold plate 16 protrudes from the cavity surface 3a of the fixed mold 3.

  A conical hole 23 that communicates with the recess 15 is provided on the back surface of the fixed mounting plate 2. At the time of injection molding, the nozzle 24 enters the portion of the hole 23 and is brought into close contact with a locating ring (not shown) of the fixed mold 3 to inject molten resin.

  Next, a molded product molded by the injection molding machine 100 of the present embodiment will be described. This molded product is, for example, a belt clamp 110 shown in FIG. The belt clamp 110 is made of a resin material. For example, when the belt clamp 110 is inserted into a through hole (not shown) of a vehicle body, the belt clamp 110 is pressed against the inner peripheral surface, and is elastically restored when the through hole is exceeded. A clamp body 27 including a pair of claw portions 25 and a stabilizer 26 and an elongated belt 28 extending from the surface of the clamp body 27 opposite to the claw portions 25 are integrally provided. For example, a plurality of wire harnesses (not shown) are wound around the belt 28, and the tip portion thereof is passed through a lock hole 29 provided at a connection portion between the stabilizer 26 and the belt 28. As a result, the protrusion 28 a provided on the belt 28 is engaged with the lock piece 29 a provided on the lock hole 29, and is held in a retaining state.

  In this belt clamp 110, the clamp body 27 is thick and the belt 28 is thin. The thinnest part of the belt 28 is 0.1 to 0.3 mm.

  Next, the fixed mold 3 for forming the belt clamp 110 will be described. As shown in FIG. 1 and FIG. 2, a plurality of belt clamps 110 (14 in this embodiment) are formed at a time. That is, as shown in FIG. 5, a runner forming portion 31 is dug in the center of the fixed mold 3 in the height direction along the left-right direction. A branch runner forming portion 32 extends vertically at a certain interval. A clamp body forming portion 34 and a belt forming portion 35 that form the clamp body 27 of the belt clamp 110 are provided from each branch runner forming portion 32 via the gate 33. A sprue hole 36 is provided at a substantially central portion in the left-right direction of the runner forming portion 26. The clamp body forming part 34 and the belt forming part 35 are each provided with a through hole 18 for protruding the fixed side and allowing the pin 17 to pass therethrough. The belt forming portion 35 is provided with a plurality of (three in this embodiment) through holes 18 at a predetermined interval. The configuration of the movable mold 7 is substantially the same as the configuration of the fixed mold 3 except that the concave portion 9 is provided and the movable plate 11 is internally provided.

  The operation of the injection molding machine 100 of this embodiment will be described. As shown in FIG. 1, the movable mold mounting board 5 to which the movable mold 7 is attached approaches toward the fixed mold mounting board 2, and the movable mold 7 comes into close contact with the fixed mold 3 and is closed. A cavity 37 is formed between the cavity surface 3 a of the fixed mold 3 and the cavity surface 7 a of the movable mold 7. In this state, for example, polypropylene molten resin (not shown) is injected from the nozzle 24 of the injection molding machine 100. This molten resin enters the runner forming portion 31 through the sprue hole 36 of the fixed die 3, and the cavity of the fixed die 3 and the movable die 7 from the runner forming portion 31 through each branch runner forming portion 32 and the gate 33. 37 is injected.

  The fixed mold 3 and the movable mold 7 in the mold closed state are held for a predetermined time, and the molten resin is solidified. Then, the movable mounting board 5 moves in a direction away from the fixed mold 3. In a normal case, the solidified molded product adheres to the cavity surface 7 a of the movable mold 7, moves integrally with the movable mold 7, and is released from the fixed mold 3. However, since the thickness of the clamp body 27 is much thicker than the thickness of the belt 28 as in the assembly of the belt clamp 110 which is a molded product of this embodiment, the excavation of the fixed mold 3 is the excavation of the movable mold 7. If the depth is greater than the depth, the resistance for releasing from the fixed mold 3 increases, and there is a possibility that the fixed mold 3 remains attached. Further, when the belt 28 is thin, the low-pressure mold protection device may not operate normally even if the movable mold 7 approaches during the next injection molding cycle.

  In order to prevent the above-mentioned problems, the fixed-side protruding means 14 for forcibly releasing the solidified molded product (the assembly of the belt clamps 110) on the fixed mold mounting plate 2 of the injection molding machine 100 of the present embodiment. Is provided. For this reason, as shown in FIG. 6, when the movable mounting plate 5 moves in a direction away from the fixed mold mounting plate 2, mold opening of the fixed mold 3 and the movable mold 7 starts. At this time, the pneumatic cylinders 19 are operated almost simultaneously with the separation of the movable mounting plate 5 and the pistons 21 move forward. Since the fixed side plate 16 moves forward via each intermediate pin 22, each fixed side protruding pin 17 protruding from the fixed side plate 16 pushes out the molded product attached to the cavity surface 3 a of the fixed mold 3. Thereby, the molded product is released from the fixed mold 3. The molded product released from the fixed mold 3 adheres to the cavity surface 7a of the movable mold 7 and moves.

  Each fixed-side protruding pin 17 of the fixed-side plate 16 is accommodated in the fixed mold 3 by releasing the molded product from the fixed mold 3 and then retracting the piston 21 of each pneumatic cylinder 19.

  As shown in FIG. 7, when the mold opening of the fixed mold 3 and the movable mold 7 is completed (the movable mold 7 is separated from the fixed mold mounting plate 2 to the maximum), the driving means (for example, a hydraulic cylinder) not shown The movable side plate 11 housed in the movable die 7 moves forward, and each movable side protruding pin 12 protruding from the movable die plate 11 pushes out the molded product attached to the cavity surface 7a of the movable die 7 so that it can move. Release from the mold 7. The molded product released from the movable mold 7 is dropped by separating the belt clamps 110 and the runners 38 by a molding machine (not shown), sorted, and stored in a product box (not shown).

  The movable side plate 11 is retracted, and each movable side protruding pin 12 is accommodated in the movable mold 7. Then, the movable mounting plate 5 moves toward the fixed mounting plate 2 and the above-described steps are repeated.

  Since the conventional fixed-side protruding means is provided in the fixed mold, the structure of the fixed mold becomes complicated or the fixed mold becomes large. On the other hand, in the case of the injection molding machine 100 of the present embodiment, the fixed-side protruding means 14 is provided on the fixed mold mounting plate 2 of the injection molding machine 100. For this reason, it is only necessary to process the through holes 13 for passing through the respective fixed-side protruding pins 17 with respect to the fixed mold 3, and the configuration of the fixed mold 3 is almost the same. Moreover, the size of the fixed mold 3 is unchanged. Furthermore, storage of the fixed mold 3 and the movable mold 7 is easy.

  The present applicant conducted an experiment and obtained a protruding force for releasing the molded product attached to the cavity surface of the fixed mold from the fixed mold at a predetermined mold opening position. Then, as shown in FIG. 8, it was found that a protruding force of about 2500 N was required when the mold opening position was 5 mm. Here, in the case of the conventional fixed-side protruding means, the drive mechanism of the fixed-side protruding means is a compression spring. In the case of a compression spring having a protruding force of about 2500 N when the mold opening position is 5 mm because the elastic restoring force (protruding force) of the compression spring is maximized when the deflection amount is maximum (that is, the mold is closed). The protruding force at the mold closing position is about 4500N. In FIG. 8, the displacement of the protruding force of the compression spring is indicated by a straight line 39. For this reason, it is necessary that the molten resin injected into the fixed mold and movable mold cavities should be injected with a force of about 4500 N compared to the case where no protruding means is provided so as to resist the protruding force. is there. The holding pressure in the mold closed state must be increased by about 4500 N force.

  On the other hand, in the case of the injection molding machine 100 of the present embodiment, the driving mechanism of the fixed-side protruding means 14 is the pneumatic cylinder 19. For this reason, the protruding force is constant from the protruding start to the protruding end. In FIG. 8, the displacement of the protruding force of the pneumatic cylinder 19 is indicated by a straight line 41. As a result, the injection power of the molten resin and the holding pressure in the mold-closed state are the same as when the fixed-side protruding means 14 is not present. Thereby, even if the molded product has a thin portion, the low-pressure mold protection device operates normally.

  Further, when the drive mechanism is a compression spring, there is a possibility that the compression spring may be damaged due to repeated loads, or that the fixed side plate may be galled due to variations in deflection. However, when the drive mechanism is the pneumatic cylinder 19, there is little possibility that such a problem will occur. In addition, by changing the pneumatic cylinder 19, it is easy to adjust the protruding stroke and the protruding force.

  In the protruding means 14 of this embodiment, an intermediate pin 22 is interposed between the fixed side plate 16 and the piston 21 of the pneumatic cylinder 19. The protruding stroke can also be adjusted by adjusting the length of the intermediate pin 22.

  And as FIG. 3 shows, the area of the part by which the fixed side protrusion pin 17 is protrudingly provided in the fixed side plate 16 of the cavity surface 3a is included so that the whole cavity surface 3a of the fixed mold | type 3 may be included. It is desirable to make it larger than the projected area. Thereby, since the fixed-side protruding pin 17 can be disposed over the entire cavity surface 3a of the fixed mold 3, it can be projected over the entire molded product, and a part of the molded product is not projected. The problem of remaining attached to the cavity surface 3a of the fixed mold 3 can be avoided.

  In the case of the injection molding machine 100 of the present embodiment, the driving mechanism of the fixed side protruding means 14 is the pneumatic cylinder 19. The pneumatic cylinder 19 has the advantage of being inexpensive and simple in construction. However, a drive mechanism other than the pneumatic cylinder 19 such as a hydraulic cylinder or an electric motor may be used.

It is front sectional drawing of the principal part of the injection molding machine 100 of the Example of this invention. It is a side view similarly. It is the XX sectional view taken on the line of FIG. (A) is a front view of the belt clamp 110, (b) is also a side view. 3 is a front view of a fixed mold 3. FIG. It is action explanatory drawing which shows the state in the middle of mold opening. It is action explanatory drawing which shows the state which the mold opening was complete | finished. 4 is a graph showing displacement of a protruding force of a compression spring and a pneumatic cylinder 19;

Explanation of symbols

100 Injection molding machine 110 Belt clamp (molded product)
DESCRIPTION OF SYMBOLS 1 Frame 2 Fixed mold mounting board 2a Mounting surface 3 Fixed mold 3a Cavity surface 5 Movable mounting board 7 Movable mold 14 Fixed side protrusion means (protruding means)
16 Fixed plate (plate)
17 Fixed side protruding pin (protruding pin)
18 Through hole 19 Pneumatic cylinder 21 Piston 22 Intermediate pin 37 Cavity

Claims (4)

In order to attach the fixed mold, it is provided with a fixed mold mounting board that is fixedly attached to the frame, and a movable mold mounting board that is attached to the movable mold and approaches / separates from the fixed mold mounting board,
The movable mounting plate is moved close to the fixed mold mounting plate, molten resin is injected into a cavity formed by bringing the movable mold into close contact with the fixed mold, and the movable mounting plate is separated from the fixed mold mounting plate. An injection molding machine that, when opening the fixed mold and the movable mold, attaches the molded product formed by solidifying the molten resin to the movable mold and releases it from the fixed mold,
When the fixed mold and the movable mold are opened, the molded product solidified in the cavity is projected, and a protruding means for forcibly releasing the fixed mold from the fixed mold is provided on the fixed mold mounting plate, and from the start of the protruding in the protruding means An injection molding machine characterized by a constant protruding force until the end of protruding.   The protruding means includes a pneumatic cylinder attached to a surface of the fixed mold mounting plate opposite to the fixed mold mounting surface along a piston axis along a moving direction of the movable mold mounting board, and the fixed mold mounting A plate is mounted on the panel so as to be movable along the moving direction of the movable mounting plate, and moves in accordance with the advance and retreat of the piston of the pneumatic cylinder, and projects from the plate toward the cavity surface of the fixed mold The injection molding machine according to claim 1, further comprising a protruding pin that protrudes from a cavity surface of the fixed mold when the piston of the pneumatic cylinder advances.   The injection molding machine according to claim 2, wherein an intermediate pin is disposed between the piston of the pneumatic cylinder and the plate, and the pneumatic cylinder moves the plate via the intermediate pin. .   The area of the portion of the plate where the protruding pin protrudes is larger than the projected area of the cavity surface so as to include the cavity surface of the fixed mold. The injection molding machine described in 1.

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