JP2010179623A - Stationery platen for injection molding machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce deformation of a stationary platen when clamping a molding die, and to prevent a burr from being generated in a molding, in an injection molding machine for molding a plastic product. <P>SOLUTION: This stationary platen 12 is provided with a strength rib having a nozzle insertion hole 12d of a size capable of inserting only a long nozzle 41 into an inside, in an injection device side of a cylindrical member. The long nozzle is formed into a length not contacting with a component attached to the stationary platen and a barrel head 42, under the condition where a tip of the long nozzle contacts with the molding die. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a stationary platen that holds a fixed mold and a shape of a nozzle that fills a mold with molten resin in an injection molding machine that molds plastic products.

  As shown partially in FIG. 4, the injection molding machine applies heat to a mold clamping device 100 that opens and closes a mold and applies a mold clamping force, and a pellet-shaped (rice granular solid) resin. It comprises an injection device 101 that melts and injects and fills the mold at high pressure.

The mold clamping device 100 is provided with a stationary platen 110 to which a fixed mold 31 is mounted by a mounting bolt 33 and a moving platen 20 to which a movable mold 32 is mounted. Tie bars 22 are inserted into the four corners of the stationary platen 110 and are fixed by tie bar nuts 23. The tie bar 22 extends in the left direction of the drawing, passes through the four corners of the moving platen 20, and is connected to a mold clamping housing (not shown) via a tie bar nut. A large mold clamping cylinder is mounted on the mold clamping housing, and the mold clamping ram 21 which is a movable part thereof operates to operate the moving platen 20 and the movable mold 32 connected thereto. By this operation, the mold is opened and closed and the mold is clamped.
Although not shown in the drawing, there is a toggle type mold clamping device as another mold clamping mechanism. In this mechanism, a link mechanism is provided between the moving platen and the mold clamping housing, and the opening and closing of the moving platen and the load of the mold clamping force can be performed by the operation.

The injection apparatus 101 includes a barrel 43, a barrel head 142, a nozzle 141, and the like. The barrel head 142 is fixed to the barrel 43 by mounting bolts 44. Further, the barrel head 142 and the nozzle 141 may be attached as an integral part or may be attached by screw connection of separate parts. Inside the barrel 43, a screw 47 is incorporated so as to be able to rotate and move forward and backward, and is operated by a driving device (not shown). A screw head 46 is attached to the front end portion of the screw 47. Although not shown, a heater is wound around the barrel 43, the barrel head 142, and the nozzle 141, and can be melted by applying heat to the resin.
The pellets that have entered the barrel 43 are transferred forward (left side in the figure) while being melted by the rotational operation of the screw 47 and stored in front of the screw head 46. When the screw 47 and the screw head 46 move forward, the molten resin is injected and filled into the mold through the flow path in the nozzle 141.

  In the mold, a cavity 36 that is a product-shaped space is formed on a mating surface (parting surface) between the fixed mold 31 and the movable mold 32. A plastic product can be molded by injecting and filling molten resin into the cavity 36 through the runner 37 with the mold clamping force applied, and opening and removing the mold after cooling and solidification.

FIG. 5 shows details of the shape of the stationary platen 110. The right side of FIG. 5 represents a front view of the stationery platen 110 viewed from the injection side, and the left side represents a cross sectional view of the A section indicated by the two-dot chain line viewed from the direction of the arrow.
In the front view, tie bar holes 110 b are provided at four corners of the stationary platen 110. A nozzle insertion hole 110e is opened in the center, and a cylindrical member 110f exists around the injection side. From the periphery of the cylindrical member 110f, vertical ribs, horizontal ribs, and diagonal ribs extend outward, and are connected and integrated with members surrounding the periphery. A cast portion 110c, which is a space portion, is provided between the vertical rib, the horizontal rib, and the oblique rib.

In the cross-sectional view, there is a plate-like member 110g on the left side, and the left side surface is a mold mounting surface 110a. A locate ring 15 is attached to the nozzle insertion port 110e at the center. By aligning the inner diameter portion of the locating ring 15 with the convex portion of the mold, it is possible to perform alignment. As a result, the outlet of the molten resin at the tip of the nozzle 141 coincides with the inlet of the runner 37 of the mold, and the molten resin flow path can be ensured in a straight line.
A barrel opening 110d is provided inside the cylindrical member 110f, and a space in which the barrel head 141 can enter is secured. This is because if the nozzle 141 is lengthened, the narrow resin flow path inside is also lengthened, and the resistance when the molten resin is injected and filled into the mold is increased. As described above, generally, the stationary platen 110 is provided with the barrel opening 110d so that the barrel head 142 is placed therein, and the nozzle 141 is made as short as possible.

In the injection molding machine as described above, when a clamping force is applied to the mold, the stationary platen 110 is deformed as shown in FIG. 4, and a deflection amount of α0 is generated. This is because a large bending force is generated in the stationary platen when force is received from the die and the tie bar nut 23 because the tie bar 22 must be disposed outside the die.
Further, in this state, when the molten resin is injected and filled into the mold cavity 36 at a high pressure by the injection device 101, the parting surface is opened due to the pressure of the molten resin, and a burr 36a is generated. . This is because the stationary platen 110 is deformed, and a large amount of mold clamping force acts on the outside of the mold, and the force for aligning the parting surfaces is not transmitted to the central portion.

In particular, the barrel opening 110d provided in the central portion of the stationary platen 110 is opened by a bending force when a mold clamping force is applied, and the rigidity against the bending force of the stationary platen 110 is reduced, so that it is bent. This is a cause of increasing the amount α0.
When the burr 36a is generated, the molded product becomes a defective product, which greatly reduces the production efficiency.

In order to solve such a problem, in Patent Document 1, a V-shaped or arch-shaped support wall is provided between a mold wall (a plate-like member on the mold side) and an end wall (a plate-like member on the injection side). A stationary stationery platen is disclosed.
Further, Patent Document 2 discloses a method in which a mold mounting plate is provided between a stationary platen and a mold, and a convex portion is provided on the stationary platen to apply a clamping force directly behind the mold.

JP 09-38984 A JP 2002-192567 A

However, in the stationary platen of Patent Document 1, the internal shape becomes very complicated. Normally, the stationary platen is a cast product of a steel material, but it is difficult to cast such a large part having a complicated shape, and there is a problem that the probability of a defective product increases.
Further, in Patent Document 2, there is a problem that the number of parts of the mold clamping device is increased and the structure is complicated by providing the mold mounting plate.

In order to solve the above problems, in the first invention of the present invention,
A mold clamping device that applies a clamping force to the stationary platen with a fixed mold and a moving platen with a movable mold through four tie bars, and the tip of the nozzle attached to the barrel head to the fixed mold In an injection molding machine equipped with an injection device that injects and fills molten resin into a mold, the stationary platen is sized so that only a long nozzle can be inserted inside the cylindrical device on the injection device side. A strength rib having a nozzle insertion hole is provided, and the long nozzle has such a length that the stationary platen and the parts attached to the barrel head do not come into contact with each other when the tip is in contact with the mold.
In the second invention, the stationary platen includes a nozzle insertion hole having a substantially constant inner diameter through which only a long nozzle can be inserted.

  Since the deformation (deflection) of the stationary platen is reduced, it is difficult to open the parting surface of the mold, and the occurrence of burrs can be reduced. Therefore, it is possible to improve the yield rate of molded products and improve productivity.

It is a figure showing the metal mold | die, a part of clamping device, and a part of injection device based on the Example of this invention. It is a figure showing the shape of the stationery platen based on the 1st Example of this invention. It is a figure showing the shape of the stationery platen based on the 2nd Example of this invention. It is a figure showing the conventional metal mold | die, a part of clamping device, and a part of injection device. It is a figure showing the shape of the conventional stationary platen.

Embodiments according to the present invention will be described below with reference to the drawings.
FIG. 1 shows a mold, a part of a mold clamping device, and a part of an injection device according to a first embodiment of the present invention. The difference from the conventional example shown in FIG. 4 is the internal shape of the stationary platen 10 and the length of the long nozzle 41, and only the difference will be described here.

Details of the shape of the stationary platen 10 are shown in FIG. The right side of FIG. 2 represents a front view of the stationary platen 10 as viewed from the injection side, and the left side of FIG. 2 represents a cross-sectional view as viewed from the direction of the arrow.
Mostly the same as the conventional example of FIG. 5, but the strength rib 10g is integrally attached to the injection device side inside the cylindrical portion 10h, and the barrel opening 110d in the conventional example is closed. ing. The inner diameter of the nozzle insertion hole 10f, which is the inner diameter portion of the strength rib 10g, is desirably as small as possible so that the heat of the heater wound around the nozzle can be dissipated and the inner diameter portion is not thermally affected.
Further, the length of the long nozzle 41 is set such that the head of the mounting bolt 44 of the barrel head 42 does not interfere with the stationary platen 10 in a state where the tip touches the mold. At this time, the long nozzle 41 and the barrel head 42 may be either an integrated product or a separate screwed product.

  Thus, the rigidity against the bending force of the stationery platen 10 as a whole is greatly increased by adding the strength rib 10g to the inside of the cylindrical member 10h. Therefore, even when the mold clamping force is applied, the deflection amount α1 of the stationary platen can be kept small. Since the mold clamping force can be applied evenly to the entire mold and even to the center, it is possible to prevent the occurrence of burrs without opening the parting surface even when the mold is filled with molten resin at high pressure. .

3 shows another shape of the stationary platen 12 according to the present invention.
The central nozzle insertion hole 12d has a cylindrical shape with a substantially constant inner diameter, and the size thereof should be as small as possible so that the heat of the heater wound around the nozzle can be radiated and does not affect the inner diameter part thermally. desirable.
Thus, the barrel opening existing in the conventional example is eliminated, the rigidity against the bending force of the stationary platen 12 as a whole is increased, and the generation of burrs can be prevented.
In addition, the size of the inner diameter portion may change within a range where the rigidity does not significantly affect, for example, a conical shape or a cut-off shape.

The deflection amount α1 when the stationary platens of the first and second embodiments are employed is sufficiently small compared to α0 in the case of the conventional example, and a great effect can be achieved.
In addition, since the shape of the stationary platen in the first and second embodiments is not greatly changed as compared with the conventional example, no problem occurs in casting the stationary platen.

  The above embodiment is an example of the present invention, and the present invention is not limited by the embodiment, and is defined only by the matters described in the claims, and other embodiments are also possible. It can be implemented.

  The present invention can be easily applied to a normal injection molding machine simply by changing the internal shape of the stationary platen and the length of the nozzle, and can be fully utilized in a production machine.

10 Stationary Platen 10a Mold Mounting Surface 10b Tie Bar Hole 10c Casting Part 10d Nozzle Casting Hole 10e Mold Side Nozzle Insertion Hole 10f Nozzle Insertion Hole 10g Strength Rib 10h Cylindrical Member 12 Stationary Platen 12a Mold Mounting Surface 12b Tie Bar Hole 12c Cast hole 12d Nozzle insertion hole 12e Cylindrical member 15 Locating ring 20 Moving platen 21 Mold clamping ram 22 Tie bar 23 Tie bar nut 31 Fixed mold 32 Movable mold 33 Mold mounting screw 36 Cavity 36a Burr 37 Runner 41 Long nozzle 42 Barrel head 43 barrel 44 mounting bolt 46 screw head 47 screw 100 clamping device 101 injection device 110 stationary platen 110a mold mounting surface 110b tie bar hole 110c Cast-out part 110d Barrel opening 110e Nozzle insertion hole 110f Cylindrical member 110g Plate member 141 Nozzle 142 Barrel head

Claims (2)

A mold clamping device that applies a clamping force to the stationary platen with a fixed mold and a moving platen with a movable mold through four tie bars, and the tip of the nozzle attached to the barrel head to the fixed mold In an injection molding machine equipped with an injection device that injects and fills molten resin into a mold with contact,
The stationery platen is provided with a strength rib having a nozzle insertion hole of a size that allows only a long nozzle to be inserted inside, on the injection device side of the cylindrical member,
An injection molding machine according to claim 1, wherein the long nozzle has a length in contact with a stationary platen and a part attached to the barrel head in a state where the tip is in contact with the mold.   2. The injection molding machine according to claim 1, wherein the stationary platen includes a nozzle insertion hole having a substantially constant inner diameter through which only a long nozzle can be inserted.

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