JPH0939059A - Injection mold equipment - Google Patents

Abstract

(57) [PROBLEMS] To accurately control the pressure and amount of resin filled in a cavity when forming a cylindrical body having a tapered portion. A fixed die has a movable body that is movable with respect to a base. The mold is closed with a weak mold clamping force, and the resin is filled in the cavity 34. When the resin is continuously supplied from the molding machine, the base body 38, the moving body 46 and the movable die 33 are slightly opened due to the pressure of the resin. This absorbs the variation in the amount of resin from the molding machine and makes the pressure of the resin in the cavity 34 constant. Next, the mold is closed with a strong mold clamping force, and the base 38
And the moving body 46 are closed. Along with that, the resin in the cavity 34 returns to the molding machine side. When the convex portion 58 of the base body 38 is fitted into the concave portion 81 of the movable die 33 and the gate 87 is closed, the cavity 34 is formed.
A certain amount of resin remains inside. Then, the resin in the cavity 34 is compressed. [Effect] By compressing after filling, a thin taper portion can be reliably molded without defects.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding die apparatus for molding a cylinder having a tapered portion with a molding material such as resin.

[0002]

2. Description of the Related Art Consider forming a cylindrical body P as shown in FIG. This cylindrical body P has a cylindrical main body P1 in the lower part, a step P2 bent inward in the radial direction from the upper end of the main body P1, and an upper part from the inner peripheral part of the step P2. It has a thin-walled cylindrical taper portion P3 protruding inward. Further, inside the tapered portion P3, there is a bridge portion P4 that crosses the tapered portion P3 in the radial direction.

In conventional injection molding, a cavity having the same shape as the cylindrical body P is formed between a fixed die and a movable die of the die device.
Molding is performed by filling the resin injected from the molding machine into the cavity. However, if the resin is simply filled into the cavity of a certain shape, it is especially difficult to taper the thin portion.
With P3 etc., insufficient filling tends to occur. Then, due to contraction due to cooling, especially in the portion where the bridge portion P4 is connected,
There is a sink mark on the outer surface of the tapered portion P3.

Moreover, since the volume of the cavity is constant, the pressure and amount of the resin filled in the cavity are basically determined by the control on the molding machine side. Therefore, if there is an error in the control on the molding machine side, an error will occur in the pressure and amount of the resin filled in the cavity as it is. In order to eliminate this error, it is conceivable to make the control of the injection screw of the molding machine precise, but there are various factors that cause the error, such as temperature and variations in the properties of the resin itself. For example, there is a long resin passage from the screw to the cavity, but if there is an error that occurs in this resin passage, even if the screw control is precise, there will be an error in the pressure and amount of resin filled in the cavity. It will be. That is, it is difficult to eliminate the error generated in the cavity only by controlling the molding machine.

Further, conventionally, after the cavity is filled with the resin, the volume of the cavity itself is reduced by moving some component parts of the mold or switching the mold clamping force. Injection compression molding is known in which the resin is compressed, and this injection compression molding can solve the problem of insufficient filling, but compressing the resin by reducing the volume of the cavity is It does not have the effect of eliminating the error in the pressure and amount of the resin that has been removed.

[0006]

As described above, when a tubular body having a thin taper portion is to be molded, it is not necessary to fill a molding material such as resin into the cavity of a constant shape as in the conventional case. However, there is a problem that insufficient filling is likely to occur in the tapered portion and the like. At the same time, in the conventional injection molding, since the pressure and amount of the molding material filled in the cavity are controlled by the control of the molding machine side, there is a problem that it is difficult to accurately control the pressure and amount of this molding material. Even if injection compression molding can solve the former problem of insufficient filling, the latter problem cannot be solved.

The present invention is intended to solve such a problem, and when molding a cylindrical body having a thin taper portion, the pressure and amount of the molding material filled in the cavity can be accurately controlled. In this way, the purpose is to obtain a high-precision product with stable quality.

[0008]

In order to achieve the above-mentioned object, a first aspect of the present invention is an injection molding die device for a cylindrical body having a thin taper portion, which is opened / closed with each other and is closed when the mold is closed. A pair of mold bodies that form the cylindrical cavity is provided therebetween, and the opening and closing directions of these mold bodies are made to coincide with the axial direction of the cylindrical body. One mold body is a base body, a moving body is movably supported by the base body in the opening / closing direction of both mold bodies, and abuts against the other mold body to close the movable body body. And a compression portion integrally provided on the base body. Further, the gate from the material passage to the cavity is configured to be closed by the compression unit as the moving body of the one mold body closes to the base body. The compression portion forms the outer surface of the tapered portion of the cylindrical body.

According to a second aspect of the present invention, in the injection molding die apparatus according to the first aspect of the present invention, the cylindrical body has a bridge portion that traverses the inside of the taper portion, while the other mold body is provided. The projection has a projection that penetrates the inside of the tapered portion of the cylindrical body and projects from the tip end opening of the tapered portion, and has a slit portion in which the bridge portion fits. Further, the compression portion of the one mold body has a hole portion into which the protruding portion of the other mold body is removably fitted, and is removably fitted into the slit portion of the other mold body. It has a projecting piece.

[0010]

In the injection molding die apparatus according to the first aspect of the present invention, first, the pair of molds are closed by a weak clamping force, and the moving body of one mold and the other mold are closed, and In the state where the moving body of the mold body and the base body are opened, the filling step of supplying the molding material to the material passage and filling the cavity is performed.

Subsequent to this filling step, the molding material is continuously supplied to the mold apparatus, and the moving body and the other mold body are displaced with respect to the base body of one mold body, and the molding material in the mold machine By balancing the pressure and the mold clamping force, a pressure adjusting step for adjusting the pressure of the molding material in the cavity is performed. That is, in this pressure adjusting step, the base of one mold body and the movable body and the other mold body are opened against the mold clamping force by the pressure of the molding material in the mold device, but the opening amount is It is determined by the balance between the pressure of the molding material in the mold device and the mold clamping force, and the larger the amount of the molding material supplied to the mold device, the larger. In other words, even if there is an error in the amount of the molding material supplied from the material supply device such as the molding machine, the error is absorbed by the change in the opening amount, and the pressure of the molding material in the cavity becomes constant.

After the pressure adjusting step, the mold clamping force is increased to close the base body and the moving body of the one mold body, and the measuring process is performed.
In this measuring step, the molding material in the cavity returns to the material supply device side, but as the base body and the moving body are closed, the compression part integrated with the base body closes the gate, and at this point the inside of the cavity is closed. A certain amount of molding material remains. That is,
Although the amount of the molding material in the cavity is not constant when the pressure adjusting step is completed, the molding material in the cavity is made constant by the subsequent measuring step. Thus, the pressure adjusting step and the measuring step accurately control the pressure and amount of the molding material filled in the cavity.

After the measuring step, that is, after the gate is closed, the base body and the moving body of one mold are closed until they abut each other, and the compression step of compressing the molding material in the cavity is performed. As a result, the shrinkage of the molding material due to solidification is compensated, and it is not necessary to perform the pressure-holding step on the material supply device side for this compensation. And in the compression process,
The compression portion forming the outer surface of the tapered portion of the tubular body compresses the molding material of the tapered portion.

Further, in the injection molding die apparatus of the second aspect of the present invention, when the mold is closed, the projecting portion of the other mold body is fitted into the hole of the compression portion of the one mold body, and the projecting portion of this mold body is projected. The projecting piece of the compression section fits into the slit section of the section. The projecting portion forms the inner surface of the tapered portion of the tubular body, both side surfaces of the bridge portion, and one end edge, and the projecting piece portion forms the other end edge of the bridge portion. Since the protruding portion is integral with the compression portion, the molding material of the bridge portion is also compressed in the compression process.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below.
This will be described with reference to the drawings. The molded product is the cylindrical body P shown in FIG. 9 described above. This embodiment is applied to injection molding using a thermoplastic resin as a molding material, and uses an inline screw type injection molding machine as shown in FIG. In FIG. 8, 1 is a heating cylinder device which is a material supply device. The heating cylinder device 1 includes a cylinder body 2 having a substantially cylindrical shape.
have. A heater 3 for heating is provided on the outer periphery of the cylinder body 2, and a nozzle 4 is provided at the tip portion (left portion in the drawing). A hopper 5 is provided on the upper rear side of the cylinder body 2.
The screw 6 is housed in the cylinder body 2 so as to be rotatable and axially movable (left and right in the drawing). A piston rod 12 of a hydraulic cylinder 11 is fixedly connected to the rear side of the screw 6. That is, the hydraulic cylinder 11 drives the screw 6 in the axial direction. The screw 6 is driven to rotate by an electric servomotor 13. In order to transmit rotation from the servo motor 13 to the screw 6, a gear 15 for rotation transmission is spline-fitted to a spline cylinder 14 fixed to the outer circumference of the piston rod 12. That is, the gear 15 is prevented from rotating with respect to the screw 6, but can freely move in the axial direction.

Further, 21 is a direct pressure type mold clamping device, and this mold clamping device 21 has a fixed side platen 22 and a movable side platen 23. The movable platen 23 is movable in the left-right direction in the drawing along a tie bar 24, and is driven by a hydraulic cylinder 25 via a mold clamping ram 26. The drive of the hydraulic cylinder 25 is controlled by a drive control device 27 including a servo valve and the mold clamping force can be adjusted. Then, the fixed mold 32 of the mold device 31 is attached to the fixed platen 22, and the movable platen
The movable mold 33 is attached to the 23. The mold clamping device 21 and the heating cylinder device 1 are comprehensively controlled by a control device such as a computer.

Next, the structure of the mold device 31 will be described with reference to FIGS.
It will be described in detail based on. It should be noted that FIGS. 1 and 4 for explaining the operation are simplified for easy understanding, and there are some points that do not correspond to other drawings. Moreover, FIG. 1 to FIG.
In the figure, the resin is shown by thick line hatching. The fixed mold 32, which is one mold body, and the movable mold 33, which is the other mold body, are opened and closed by the movement of the movable side platen 23, and when the molds are closed, a cavity 34 having the shape of the cylindrical body P is formed between them. To do. The cylindrical body P to be molded
The axial direction of is matched with the mold opening / closing direction of the fixed mold 32 and the movable mold 33.

The fixed die 32 has a fixed side mounting plate 36 attached to the fixed side platen 22 and a fixed side receiving plate 37 fixed to the surface of the fixed side mounting plate 36 on the movable die 33 side. The fixed-side mounting plate 36 and the fixed-side receiving plate 37 form a base 38. Further, a locating ring 39 and a sprue bush 40 are fixed to the fixed side mounting plate 36. The sprue bush 40, to which the nozzle 4 of the heating cylinder device 1 is connected, has a sprue 41 which is a material passage inside, and penetrates through the fixed side receiving plate 37 and projects toward the movable die 33 side. .

On the movable die 33 side of the fixed side receiving plate 37,
A movable plate 46, which is a movable body, is supported so as to be movable within a predetermined range in the mold opening / closing direction. For this support, a guide pin 47 fixed to the fixed side mounting plate 36 and the fixed side receiving plate 37 and protruding toward the movable die 33 penetrates the moving plate 46 slidably. Along with this, the sleeve fixed to the movable die 33 side of the fixed side receiving plate 37 together with the stopper 48 by the bolt 49.
50 slidably penetrates the moving plate 46. The stopper 48 limits the maximum gap between the movable plate 46 and the base body 38, that is, the maximum opening amount by hitting the movable plate 46 from the movable die 33 side. Further, the moving plate 46 is biased toward the movable die 33 with respect to the base body 38 by the spring 51 which is a biasing means sandwiched between the fixed side mounting plate 36 and the moving plate 46 in a compressed state. There is. The tip end of the sprue bush 40 is slidably fitted in a through hole 52 formed in the moving plate 46. The moving plate 46 is a frame 46.
and a block 46b fixed to the inside of the frame 46a.

The base 38 has a fixed side mounting plate.
The first pin 56 as a compression part is fixed by being sandwiched between the 36 and the fixed side receiving plate 37. The first pin 56 is
Penetrating the fixed side receiving plate 37 and protruding to the movable mold 33 side,
The tip side of the first pin 56 is a through hole formed in the moving plate 46.
It is slidably fitted to 57. And the first pin 56
The tip portion of the convex portion 58 is formed so that it can project to the movable die 33 side from the moving plate 46.
A product forming surface 59 that forms the outer surface of the tapered portion P3 of the tubular body P is formed inside the tip end side of 56. In addition, inside the first pin 56, a hole portion 60 is formed to connect to the product forming surface 59. Further, a second pin 61 as a compression portion is fixed to the base 38 by being sandwiched between the fixed side mounting plate 36 and the first pin 56. A projecting piece 62 is formed at the tip of the second pin 61.
Enter the hole 60 of the first pin 56.

The movable die 33 includes a movable side mounting plate 71 attached to the movable side platen 23 and a movable side receiving plate fixed to a surface of the movable side mounting plate 71 on the fixed die 32 side via a spacer block 72. 73 and a movable side mold plate 74 fixed to the surface of the movable side receiving plate 73 on the fixed mold 32 side. The movable side mold plate 74 is composed of a frame body 74a and a block 74b fixed to the inside of the frame body 74a. Also,
The movable die 33 is provided with a guide bush 75 through which the guide pin 47 of the fixed die 32 slidably passes. Also,
The movable side mold plate 74 abuts against the movable plate 46 of the fixed mold 32 and closes it. However, in order to guide the movable side mold plate 74 and the movable plate 46 to each other, the movable plate 46 has a guide pin 76.
Is fixed, and a through hole 77 into which a guide pin 76 is slidably fitted is formed in the movable side mold plate 74.

The fixed mold 32 is attached to the movable mold plate 74.
A concave portion 81 into which the convex portion 58 is removably fitted is formed. Further, the protrusion 83 formed in the insert 82 fixed by being embedded in the movable side mold plate 74 coaxially penetrates the inside of the recess 81 and protrudes toward the fixed mold 32. The projecting portion 83 forms the inner surface of the cylindrical body P including the taper P3 by the outer surface thereof. The tip of the protrusion 83 is the first of the fixed mold 32.
It is a fitting portion 84 that is fitted in the hole 60 of the pin 56 so as to be freely inserted and removed. Further, a slit portion 85 is formed on the tip end side of the protruding portion 83 including the fitting portion 84. This slit part
85 is pulled out to both side surfaces and the tip surface of the protruding portion 83,
The projecting piece portion 62 of the second pin 61 of the fixed die 32 is removably fitted. Thus, the protruding portion 83 penetrates the inside of the tapered portion P3 of the cylindrical body P to be molded, and the tapered portion P3
Is projected from the opening at the tip of the. The fitting surface between the convex portion 58 and the concave portion 81, the fitting surface between the hole portion 60 and the fitting portion 84, and the fitting surface between the protruding piece portion 62 and the slit portion 85 are parallel to the mold opening / closing direction. There are almost no gaps between them so that they form pillar surfaces and that no burr is generated in the molded cylinder P.

Further, the movable plate 46 of the fixed mold 32 and the movable mold which are closed.
A runner 86 and a gate 87, which are material passages for communicating the sprue 41 with the cavity 34, are formed between the 33 and the movable side mold plate 74. This gate 87
Is to be closed by fitting the convex portion 58 of the fixed die 32 into the concave portion 81 of the movable die 33. The force of the spring 51 for urging the moving plate 46 is set to the force that keeps the moving plate 46 and the movable die 33 closed against the pressure of the resin inside the runner 86.

Further, a protruding plate 91 is supported between the movable side mounting plate 71 and the movable side receiving plate 73 so as to be movable in the mold opening / closing direction. On the ejecting plate 91, product ejecting pins 92 and 93 for ejecting the molded cylindrical body P and runner ejecting pins for ejecting the resin solidified in the runner 86.
94 and are fixed.

Next, the injection molding method will be described. In the heating cylinder device 1, the plasticizing step and the injection step are repeated. In the plasticizing step, the thermoplastic resin supplied from the hopper 5 into the cylinder body 1 is melted and plasticized by heating by the heater 3 and kneading by rotation of the screw 6. With this plasticization, the resin is sent forward by the rotation of the screw 6 and is accumulated on the tip side in the cylinder body 1. Along with that, the screw 6 retracts due to the pressure of the resin. Even during the plasticizing process, the hydraulic cylinder 11
A suitable back pressure is applied to the screw 6 in the forward direction. When it is detected that the screw 6 has retracted to a predetermined position, the screw 6 is moved forward by driving the hydraulic cylinder 11, and the resin on the tip end side in the cylinder body 1 is moved to the nozzle 4
And is supplied to the sprue 41 of the mold device 31.
When it is detected that the screw 6 has advanced to a predetermined position, or when the screw 6 has advanced to the forward limit,
The plasticizing step is again performed.

The mold clamping device 21 first closes the fixed mold 32 and the movable mold 32 with a weak constant mold clamping force F1. At this time, FIG.
As shown in (a), the movable plate 46 of the fixed die 32 and the movable die 33 abut against each other and close. On the other hand, the base body 38 of the fixed mold 32 and the movable plate 46 are opened with the initial opening amount A1, but the stopper 48 is not in contact with the movable plate 46. That is, mold clamping force
F1 and the force G of the spring 51 are in balance. Further, the convex portion 58 of the fixed die 32 is not fitted in the concave portion 71 of the movable die 33,
The open gate 87 connects the runner 86 and the cavity 34. On the other hand, the protruding portion 83 of the movable die 33 is fitted into the hole 60 of the fixed die 32, and the fixed die 32 is fitted into the slit portion 85 of the movable die 33.
The protruding piece portion 62 of is fitted. In this state, the resin is injected from the heating cylinder device 1 to the sprue 41. This resin is filled from the sprue 41 through the runner 86 and the gate 87 into the cavity 34 (filling step).

Subsequent to this filling step, the mold clamping force remains F1 and the screw 6 is used in the heating cylinder device 1.
The injection process is continued until it is detected that the screw has advanced to a predetermined position, or until the screw 6 advances to the forward limit. That is, although the resin is still supplied from the heating cylinder device 1 to the mold device 31, the hydraulic pressure is closed by the pressure of the resin in the mold device 31 as shown in FIG. 1 (b). The movable plate 46 against the base 38 of the fixed mold 32 against the mold clamping force F1 given by the mold clamping device 21.
And the movable die 33 is displaced in the opening direction. As a result, the generated internal pressure is released. The expanded opening amount A2 between the base 38 and the moving plate 46 is determined by the balance between the pressure of the resin in the mold device 31 and the mold clamping force. More specifically, mold clamping force
The opening amount A2 is determined by the balance between F1 and the force G of the spring 51 and the force H of the resin in the mold device 31 that causes the moving plate 46 and the movable mold 33 to retract. This opening A2 is the mold device
The larger the amount of resin supplied in 31, the larger the size. In other words, even if there is an error in the amount of resin supplied from the heating cylinder device 1, the error is absorbed by the change in the opening amount, and the pressure of the resin in the cavity 34 is adjusted and becomes constant (pressure adjustment). Process). In this way, the pressure of the resin in the cavity 34 can be accurately controlled.

The force G of the spring 51 is slightly weakened by increasing the opening amount from A1 to A2, and the mold clamping force given by the hydraulic cylinder 25 is also returned by the movable mold 33 and the mold clamping ram 26 being pushed back. Although it may change slightly, the change in the force G and the mold clamping force of the spring 51 is so small that it can be ignored. That is, the variation in the pressure of the resin that balances the force G of the spring 51 and the mold clamping force, which changes according to the displacement of the moving plate 46 and the movable die 33, occurs when the cavity of a constant volume is filled with different amounts of the resin. It is much smaller than the variation in pressure.

In the pressure adjusting step, the pressure of the resin acting to open the base body 38 of the fixed die 32, the movable plate 46 and the movable die 33 is set in the direction parallel to the die opening / closing direction for the fixed die 32. Is the pressure exerted on the substrate 38 at. This is the pressure related to pressure regulation. On the other hand, in the mold apparatus 31 of the above-described embodiment, since the runner 86 is formed between the movable plate 46 and the movable die 33 of the fixed die 32, the base 38, the movable plate 46 and the movable die 33 are opened. The pressure of the resin acting in this way is exerted on the base body 38 (more precisely, including the sprue bush 40) only in the cavity 34. Therefore, the pressure is adjusted based on the cavity 34. On the other hand, the pressure of the resin inside the runner 86 acts to open the moving plate 46 and the movable die 33, but the pressure of the resin inside the runner 86 is affected by the spring 51.
Against, the movable plate 46 and the movable die 33 are kept closed. This is the same in the next measuring step.

After the pressure adjusting step is completed, the mold clamping device 21 increases the mold clamping force to F2. As a result, the base body 38 of the fixed die 32 and the movable plate
46 and are closing. Accordingly, the excess resin in the cavity 34 returns from the gate 87, which is still open, to the runner 86, and the resin in the mold device 31 returns to the cylinder body 2 of the heating cylinder device 1. The screw 6 retracts accordingly. Then, as shown in FIG. 2A, when the convex portion 58 of the fixed die 32 starts to fit into the concave portion 81 of the movable die 33, the gate 87 is closed, and at this point, a certain amount of resin is stored in the cavity 34. It will remain (measurement process).

After the weighing process, as shown in FIG.
The base 38 of the fixed die 32 and the moving plate 46 are closed until they abut each other, and accordingly, the resin in the cavity 34 is pressed and compressed (compression step). The compression amount B is equal to the opening amount A3 between the base 38 and the moving plate 46 at the end of the measuring process.

At the end of the pressure adjusting step, the volume of the cavity 34, that is, the amount of resin in the cavity 34 is not constant. However, in the subsequent measuring step, the resin in the cavity 34 returns to the runner 86 as described above, and at the moment the gate 87 is closed, a certain amount of resin remains in the cavity 34. Thus, by the pressure adjustment process and the measurement process,
The pressure and amount of resin filled in the cavity 34 will be accurately controlled.

By the way, in the mold apparatus 31, the runner is
By forming 86 between the movable plate 46 of the fixed die 32 and the movable die 33, the volume of the runner 86 does not change in the weighing process. Therefore, the resin smoothly returns from the cavity 34 whose volume is decreasing to the runner 86, and the cavity 34
It ensures that the pressure of the resin inside is kept constant. Along with this, the mold closing operation can be speeded up.

After the gate 87 is closed due to the mold closing, a compression step is performed and the resin in the cavity 34 is compressed, but in the metering step, a certain amount of resin is left in the cavity 34 at a certain pressure. As a result, the compression is smoothly performed.
Then, the compression compensates for the shrinkage that accompanies the solidification due to the cooling of the resin. Therefore, for this compensation, it is not necessary to perform the pressure holding step on the heating cylinder device 1 side.

As described above, the first pin of the fixed die 32
The product forming surface 59 of 56 forms the upper surface of the stepped portion P2 and the outer surface of the tapered portion P3 of the cylindrical body P that is the product, and the projecting piece portion 62 of the second pin 61 of the fixed die 32 is the upper end edge of the bridge portion P4. The concave portion 81 of the movable die 33 forms the outer surface of the main body portion P1, and the protruding portion 83 of the movable die 33 forms the inner surface of the tubular body P, both side surfaces of the bridge portion P4, and the lower end edge.

After the resin in the cavity 34 is sufficiently cooled and solidified, the fixed mold 32 and the movable mold are moved by the mold clamping device 21.
33 and die are opened. Along with that, the resin in the cavity 34, that is, the product P and the resin solidified in the runner 86 and the sprue 41, first separates from the fixed mold 32. Then, an unillustrated ejecting rod provided on the mold clamping device 21 side pushes the ejecting plate 91 toward the fixed mold 32, whereby the runner ejecting pin 94 ejects the resin solidified in the runner 86 and the sprue 41. The mold P is released from the movable mold 33, and the cylindrical body P on which the product ejection pins 92 and 93 are formed is ejected and released from the movable mold 33. Further, after the resin solidified in the runner 86 and the sprue 41 and the cylindrical body P are taken out, the mold is closed again, and the above steps are repeated.

As described above, according to the configuration of the above-described embodiment, the pressure and amount of the resin filled in the cavity 34 can be easily and accurately adjusted by the pressure adjusting process and the measuring process performed in the mold device 31. It is possible to control, and it is possible to obtain a highly accurate cylindrical body P with stable quality by performing the compression process and the compression process.

Further, in the mold apparatus 31, since the runner 86 is formed between the movable plate 46 of the fixed mold 32 and the movable mold 33, pressure adjustment is performed with the cavity 34 as a reference, and in the measuring process. By smoothly returning the resin in the cavity 34 to the runner 86, the pressure and amount of the resin filled in the cavity 34 can be controlled more accurately.

Further, since the taper portion P3 of the tubular body P is inclined with respect to the mold opening / closing direction, even if the taper portion P3 to be finally formed is thin, in the filling step and the pressure adjusting step. Means that the surfaces of the fixed die 32 and the movable die 33 that form the tapered portion P3 are largely separated from each other, and therefore the resin smoothly flows into the portion of the cavity 34 that becomes the tapered portion P3, resulting in poor filling. Never. Then, in the compression step, since the first pin 56 compresses the tapered portion P3, the thin tapered portion
P3 can be reliably molded without any defects, and there is no possibility of sink marks on the outer surface of the tapered portion P3 at the portion where the bridge portion P4 is connected. Moreover, the taper portion P3 inclined with respect to the mold opening / closing direction is more strongly compressed than the main body portion P1.

Further, the movable die 33 is provided with a slit portion 85 surrounding the protruding portion 83 penetrating the inside of the tapered portion P3 and the bridge portion P4 from below, and the fixed die 32 is integrally formed with the base 38 thereof.
Since the hole portion 60 into which the protruding portion 83 fits and the protruding piece portion 62 into which the slit portion 85 fits are provided, the entire tapered portion P3 including the bridge portion P4 can be reliably compressed.

The present invention is not limited to the above embodiment, and various modifications can be made. For example,
In the above-mentioned embodiment, the case where an in-line screw type injection molding machine is used has been described as an example, but various types of molding machines such as a plunger type may be used. Also, as the mold clamping device, in addition to the direct pressure type as in the above embodiment, various types such as a toggle type can be used. The drive source of the mold clamping device is not limited to the hydraulic cylinder, but may be an electric motor or the like.

Further, the mold device is not limited to that of the above embodiment. For example, an air cylinder or the like can be used as the urging means for urging the moving body in addition to the spring. Further, in the above embodiment, the runner 86 and the gate 87 are formed between the fixed die 32 and the movable die 33, but the present invention is not limited to this. For example, it is also possible to employ a direct gate which is open in the fixed mold in the mold opening / closing direction toward the movable mold side. In this case, the convex portion provided on the movable die may be fitted to the direct gate to close it. The cylindrical body to be molded is not limited to the one in the above embodiment, and the present invention can be applied to general molding of a cylindrical body having a thin taper portion.

In the above-mentioned embodiment, the injection molding of the thermoplastic resin is taken as an example. However, the present invention is not limited to the injection molding of ceramics using the thermoplastic resin as a binder, the injection molding powder metallurgy method, or the thermoforming method. It can be applied to injection molding of various molding materials such as curable resin injection molding.

[0044]

According to the injection molding die apparatus of the first aspect of the present invention, the moving body and the other die body are displaced with respect to the base body of one die body, and the pressure adjusting step and By performing the measuring process, the pressure and amount of the molding material filled in the cavity can be easily and accurately controlled, and by performing the compressing process after the measuring process, a high-precision cylindrical body with stable quality can be obtained. Can be obtained. Particularly, since the outer surface of the thin taper portion of the cylindrical body is formed by the compression portion integrated with the base body,
This tapered portion can be reliably molded without any defect.

Furthermore, according to the injection molding die apparatus of the second aspect of the present invention, while the tubular body has the bridge portion that traverses the inside of the tapered portion, the other die body penetrates the inside of the tapered portion. Since the slit portion for accommodating the protrusion and the bridge portion is provided, and the compression body of one mold body is provided with the hole portion to which the protrusion is fitted and the projecting piece portion to be fitted to the slit portion, the bridge portion is also included. As a result, the entire taper section can be reliably compressed. Even if there is a bridge portion, it is possible to prevent sink marks from being generated on the outer surface of the tapered portion at the portion where the bridge portion is connected due to the compression.

[Brief description of drawings]

FIG. 1 is a sectional view near a cavity showing an embodiment of an injection molding die apparatus of the present invention, showing a filling step.

FIG. 2 is a sectional view of the vicinity of the cavity in the same manner, showing a pressure adjusting step.

FIG. 3 is a sectional view of the vicinity of the cavity of the same as above, showing a measuring step.

FIG. 4 is a sectional view of the vicinity of the same cavity, showing a compression step.

FIG. 5 is a cross-sectional view of the vicinity of the cavity of the same as above, and FIGS.
And the cross section is changed by 90 °.

FIG. 6 is a front view of the same fixed type.

FIG. 7 is a sectional view of the same as above.

FIG. 8 is a side view showing a cross section of a part of the entire apparatus used for injection molding.

FIG. 9 is a side view, partly in cross section, showing a cylindrical body to be molded, in which the projection directions of (a) and (b) are different by 90 °.

[Explanation of symbols]

 31 Mold device 32 Fixed mold (one mold body) 33 Movable mold (other mold body) 34 Cavity 38 Base material 46 Moving plate (moving body) 51 Spring (biasing means) 56 First pin (compressing portion) 60 Hole 61 Second pin (compressed part) 62 Projected part 83 Projected part 85 Slit part 86 Runner (material passage) 87 Gate P Cylinder P3 Tapered part P4 Bridge part

Claims (2)

[Claims] 1. An injection molding die apparatus for a cylindrical body having a thin taper portion, comprising a pair of mold bodies which are opened and closed to form the cylindrical cavity between them when the mold is closed. The opening / closing direction of the mold body is made to coincide with the axial direction of the tubular body, and one mold body is supported by the base body so as to be movable in the opening / closing direction of both mold bodies, and abuts against the other mold body to close the mold body. A gate from the material passage to the cavity, having a moving body, a biasing means for biasing the moving body toward the other mold body with respect to the base body, and a compression portion integrally provided on the base body. Is configured to be closed by a compression part as the moving body of the one mold is closed to the base body, and the compression part forms an outer surface of a taper part of the cylindrical body. Mold equipment. 2. The cylindrical body has a bridge portion that traverses the inside of the tapered portion, and the other mold body has a protruding portion that penetrates through the tapered portion of the cylindrical body and protrudes from a tip opening of the tapered portion. In addition to having a slit portion in which the bridge portion fits into this protrusion, the compression portion of the one mold body has a hole portion into which the protrusion portion of the other mold body is removably fitted, The mold apparatus for injection molding according to claim 1, further comprising a projecting piece portion that is removably fitted into the slit portion of the other mold body.