JPH07304065A - Ejector pin protecting device of injection mold - Google Patents

Abstract

PURPOSE:To prevent the damage of an ejector pin or the inner peripheral surface of a product molding cavity by certainly retracting the ejector pin. CONSTITUTION:In an injection mold consisting of the matrix 2 attached to an injection molding machine and the mold attached to the matrix and forming a product molding cavity, the matrix 2 is constituted of a movable unit 29 and a fixed unit 23 mutually brought to a separate and contact state. An ejector pin demolding the molding product molded in the product molding cavity is provided to either one of the movable and fixed units 29, 23 in an advancing and receding state. A cooperation mechanism allowing the ejector pin to advance and recede with respect to the molding surface of the product molding cavity in cooperation with the movement of the movable unit 29 at the time of the connection of both units 29, 23 is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding die used for injection molding of plastics, and more particularly to protecting an ejector pin of an injection molding die provided with an ejector pin for releasing a molded product of a product molding cavity. It relates to the device.

[0002]

2. Description of the Related Art Injection molding is a method of manufacturing a molded product by injecting heat-plasticized plastic into a cavity of a mold at a high pressure to solidify it, and a molding metal used in this injection molding method. The mold generally has, as its main components, a spool bush that forms a spool, a runner plate that forms a runner, and a fixed side (nozzle side) and a movable side (counter nozzle side) that form a product forming cavity. It is equipped with a mold plate and a protruding mechanism for ejecting the product from the mold, and the plastic injected from the nozzle of the injection molding machine is injected into the cavity through the spool and runner, and is solidified in the cavity. After forming the molded product, both mold plates are separated, that is, the mold is opened, and the ejector pin in the projecting mechanism projects to release the product from the mold. It is made as to the cause.

[0003]

However, in the injection molding die of the above-mentioned conventional injection molding machine, the ejector pin is thin and the sliding surface is also manufactured with extremely high precision. The ejector pin may become stuck in the cavity's injection molding surface and may not return as it gets caught or gas enters, and if the movable mold plate moves in the direction in which the product molding cavity is formed in this state. However, there is a problem that the ejector pin is bent or the inner peripheral surface of the expensive product molding cavity is damaged.

In order to cope with such a problem, after detecting a state in which the ejector pin is retracted from the injection molding surface of the cavity by, for example, a limit switch or a proximity switch, the movable side mold plate is formed into a product molding cavity. Although it has been proposed to move the limit switch and the proximity switch and the control device for controlling the limit switch and the proximity switch, they are vulnerable to heat and are not practical because of many malfunctions. Therefore, the present invention has been proposed in view of the above problems, and an object of the present invention is to reliably retract the ejector pin to prevent damage to the inner peripheral surface of the ejector pin or the product molding cavity. is there.

[0005]

In order to achieve the above object, an ejector pin protection device for an injection molding die according to the present invention comprises a mother die attached to an injection molding machine and a product attached to this mother die. In an injection molding die comprising a molding die forming a molding cavity, the mother die is composed of a movable side unit and a fixed side unit which are separable from each other, and either the movable side unit or the fixed side unit. On one side, an ejector pin for releasing the molded product molded in the product molding cavity is provided so that it can move forward and backward, and when the movable unit and the fixed unit are joined, the ejector pin is linked to the movement of the movable unit It is characterized in that an interlocking mechanism for retracting from the molding surface of the molding cavity is provided.

Further, when the interlocking mechanism erects the protective rod from the base end portion for advancing and retracting the ejector pin or the mounting member connected to the base end portion, when the movable side unit and the fixed side unit are joined, Another feature is that the tip of the protective rod is operated so that the ejector pin retracts from the product molding surface of the product molding cavity.

[0007]

According to the above construction, when the resin is press-fitted into the product molding cavity for molding and the movable side mold plate is moved to open the product molding cavity, the ejector pin is moved from the product molding surface of the cavity. Advance to the protruding state and knock out the molded product. Next, in the injection molding machine in which the product is taken out from the product molding cavity, the movable side template moves in the direction of closing the product molding cavity in order to mold the next product. The interlocking mechanism causes the ejector pin to retreat from the product molding surface of the product molding cavity in association with the movement of the movable mold plate. At this time, the interlocking mechanism erects the protective rod from the base end portion for advancing and retracting the ejector pin or the mounting member connected to the base end portion,
When the movable side unit and the fixed side unit are joined together, the tip of the protective rod is operated to move the ejector pin from the product molding surface of the product molding cavity. The cavity can be reliably retracted from the product molding surface.

[0008]

Embodiments of an ejector pin protection device for an injection molding die according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is a perspective view showing the whole of the cassette type injection molding die according to the present embodiment. As shown in FIG. 1, this cassette type injection molding die 1 is basically an injection molding machine. It is composed of a mother die 2 to be attached and a round cassette 3 which is set in the mother die 2 to form a cavity for molding a product. First, the round cassette 3 will be described. The cassette 3 is composed of a fixed-side cassette portion 4 and a movable-side cassette portion 5, which are circular in plan view, as shown in FIGS. 2 and 3. And both cassette parts 4,
A cavity 6 is formed at the mating portion of 5.

Here, the fixed side cassette portion 4 is formed with an upper half portion 6a of the cavity, a runner 7 and a hot water pool 8 which communicate therewith, and the hot water pool 8 and the runner 7 are formed.
A molten resin as a molding material is supplied to the cavity 6 via the. On the other hand, the movable cassette unit 5
A circular first plate 9, a second plate 10 having a diameter smaller than that of the first plate 9, and a sleeve 11 having a diameter smaller than that of the second plate 10 are sequentially connected, and an upper surface side of the first plate 9 The cavity forming member 12 forming the cavity upper half portion 6b is attached to the lower surface of the sleeve 11, and the sleeve back plate 13 is fixed to the lower surface of the sleeve 11 to form an assembly. Further, the assembly is provided with the ejector mechanism 14. Is.

The ejector mechanism 14 has an ejector back plate 15 slidably fitted in the sleeve 11, an ejector plate 16 connected to the upper surface of the plate 15, and an ejector plate 16 penetrating the ejector plate 16. The ejector pin 17 for releasing the molded product, the lower end of which is in contact with the ejector back plate 15, the ejector lock plate 18 coupled to the lower surface side of the ejector back plate 15, the bottom portion 18a of the plate 18 and the sleeve back. The spring 19 is interposed between the plate 13 and the plate 13 and constantly urges the plate 13 in the backward direction (downward in FIG. 3), and the ejector cylinder 49 raises the plate 13. (See Figure 6). Then, the sleeve 11 and the ejector lock plate 18
The portion between the bottom portion 18a and the bottom portion 18a is an engagement small diameter portion 18b, and the engagement portion of the locking means described later can be engaged with this small diameter portion 18b. In addition, this round cassette 3
In the above, when the ejector lock plate 18 is pushed by the ejector cylinder 49 against the spring 19 toward the assembly side, the tip of the ejector pin 17 is projected from the lower half 6b of the cavity and the molded product is formed. It is configured to be released from the mold.

Next, the matrix 2 will be described. As shown in FIG. 4, the mother die 2 includes a fixed-side unit 23 mainly composed of a fixed-side attachment plate 20, a runner plate 21, and a cavity plate 22, which are sequentially stacked from the top, and a core plate 24 in the same order from the top. And a core back plate 25, a block 26, and a movable side mounting plate 27, which are superposed on each other and connected by bolts 28 ... 28. The mating surface between the cavity plate 22 and the core plate 24 is a PL surface (part line surface). The PL surface serves as a boundary surface, and the units 23 and 29 are separated or brought into intimate contact with each other to form a mold. It is designed to be opened and closed.

As shown in FIGS. 4 to 6, the fixed side unit 23 penetrates through the cavity plate 22 and the fixed side mounting portion 30 to which the fixed side cassette portion 4 of the round cassette 3 is mounted. A plurality of support pins 31 each projecting downward and four taper guide insertion holes 32 ... 32 each having a tapered surface 32a below are arranged at predetermined positions. Of these, the fixed-side mounting portion 30 is formed in a shape corresponding to the cassette portion 4 so that the fixed-side cassette portion 4 of the round cassette 3 can be stored in a predetermined state therein, and the lower end thereof is the cassette portion. The insertion port 30a is provided with a pair of openable and closable pressing plates 33, which are opposed to each other at the edge of the insertion port 30a.

As shown in FIGS. 5 and 7, each of the pressing plates 33, 33 is formed with an operation recess 33a so that it can be easily operated by hooking a finger, and both side parts 33b, 33b thereof. Is engaged with the guide plates 34, 34 and is slidable in the radial direction of the mounting portion 30.
When the fixed side cassette part 4 of the round cassette 3 is inserted from the insertion port 30a and set in the mounting part 30 in a predetermined state, as shown by a chain line in FIG.
The end portion of the fixed side mounting portion 30 side of the above is located outside the insertion opening 30a, but after the fixed side cassette portion 4 is set, the end portion of the holding plate is the insertion opening 3 as shown by the solid line in FIG.
0a is slid to a position projecting inward by a predetermined amount, and the lower surface of the fixed side cassette part 4 is received at the projecting position to prevent the cassette part 4 from coming off from the fixed side mounting part 30. It has become.

On the other hand, in the movable unit 29, as shown in FIGS. 4 and 8, each of the fixed unit 29 and the movable side mounting unit 35 on which the movable cassette unit 5 of the round cassette 3 is mounted. 36 for guiding the support pins 31 respectively, and the respective taper guide insertion holes 3 when the mold is closed.
2 into each of the fixed side and movable side units 23,
29 and four taper guides 37 ... 37 for positioning the cassettes 4 and 5 in a predetermined close contact state are respectively arranged. Of these, the movable side mounting portion 35 is formed in a shape corresponding to the cassette portion 5 so that the movable side cassette portion 5 can be stored in a predetermined state, and the upper end thereof serves as a cassette portion insertion port 35a. And the insertion port 35a
This is a configuration in which a pair of pressing plates 33, 33 that can be opened and closed as in the case of the fixed-side mounting portion 30 are provided at the rim portion of the pair so as to face each other.

Further, the taper guides 37 have the taper guide insertion holes 3 in the fixed side unit 23 when the mold is closed.
2, a guide shaft portion 37a that rushes into 2, and a taper portion 37b that comes into close contact with the tapered surface 32a of the insertion hole 32 when rushing in.
A support shaft portion 37c slidably inserted into a holding bush 38 provided on the core plate 24, and a support shaft portion 37 is attached to a bolt 39 inserted from a lower side of the holding bush 38.
This is a configuration in which the c side is connected. Then, in the mold open state, the heads of the bolts 39 are placed on the lower surface of the holding bush 38 by the plurality of disc springs 40 interposed between the lower surface of the support shaft portion 37c and the bottom surface of the holding bush 38. A predetermined gap is formed between the lower surface of the large-diameter end portion of the tapered portion 37b and the upper surface of the holding bush (upper surface of the core plate, that is, the PL surface) at the position of contact.

Further, in the injection molding die 1 of the present invention, a predetermined space a is formed in the block 26 of the movable unit 29 of the mother die 2, and the lock for the movable cassette portion 5 is formed in the space a. Means 41 are provided. This locking means 41, as shown in FIGS.
The plate member 42 has a and a protruding portion 42b extending laterally from the base end portion thereof, and an operation handle 44 connected to the tip of the protruding portion 42b of the plate member 42 via a connecting member 43. . Of these, the bifurcated portion 42a of the plate member 42 has a substantially U-shaped cutout in a plan view, and the cutout portion has the engagement small diameter portion 18b (FIG. 2, FIG. 2) of the movable cassette portion 5. (See FIG. 3), and the long holes 42d and 42d are formed in each of the branched portions forming the forked portion 42a, and the long holes are formed. A rod 46 formed by externally fitting a flanged bush 45 penetrates through 42d and 42d.
As shown in FIG. 10, one end of each of these rods 46 is supported by the core plate 24 and the other end thereof is supported by the fixed-side mounting plate 27.

The flange 45a of the bush 45 is also provided.
Is located on the upper surface side of the plate material 41, the flange 45
A compression spring 47 is interposed between a and the core plate 24, and is constantly pressed by the spring force acting through the flange 45a so that the plate member 41 is in close contact with the upper surface of the movable side mounting plate 27. Has been done. And
When the operating handle 44 is pulled in the direction of arrow A in the state where the plate member 42 is at the solid line position in FIG.
Is disengaged from the engaging small diameter portion 18b of the movable side cassette portion 5, and the engagement is released. Conversely, from the position indicated by the chain line in FIG.
When the locking means 41 is pushed to the position indicated by the solid line in the figure by pushing 4, the engaging portion 42c engages with the engaging small-diameter portion 18b of the movable side cassette portion 5, thereby allowing the cassette portion 5 to move.
Is fixed in a predetermined storage position.

In this case, the projecting portion 42b of the locking means 41 is provided with an elongated hole-shaped guide hole 42e in the longitudinal direction thereof (that is, the sliding direction of the locking means 41), and penetrates this guide hole 42e. As described above, the pin 48 is provided, and both ends of the pin 48 are supported by the core back plate 25 and the fixed side mounting plate 27, respectively. Is guided in the engagement or disengagement direction (counter A direction or A direction in FIG. 9).

In the injection molding die 1 of the present invention, the ejector pin protection device 50 is provided on the side portion of the round cassette 3 as the most important feature of the present invention.
As shown in FIG. 6, the ejector pin protection device 50 includes an ejector lock plate 1 that pushes up the ejector plate 16 to raise the ejector pin 17.
A protective rod 51 is erected on the side of the block 26 that supports the lower surface of 8, and a tip 52a of the protective rod 51 is attached to a portion of the cavity plate 22 facing the abutting piece 53 which is detachably provided with a bolt 52. Therefore, the length of the protective rod 51 is the tip 51 of the protective rod 51 when the ejector pin 17 does not project from the surface of the cavity C (state where resin is formed).
The a is in contact with the lower surface of the contact piece 53. Then, the block 26, the protective rod 51, and the contact piece 53.
And the like form the interlocking mechanism 54.

According to the above construction, the portion forming the product molding cavity 6 is constituted by the round cassette 3 consisting of the movable side cassette portion 4 and the fixed side cassette portion 5, and each cassette portion 4 of the cassette 3 is formed. Since 5 can be detachably attached to the fixed unit 23 and the movable unit 29 that form the master block 2, respectively, the fixed unit 23 and the movable unit that form the master block 2 29
In the state where PL and P are separated from each other on the PL surface, first, for the fixed-side unit 23, the pressing plates 33, 33 at the edge of the cassette mounting opening 30a are opened from the closed position shown by the solid line in FIG. When it is slid to the position, the end portions of the pressing plates 33, 33 on the fixed-side mounting portion 30 side are located outside the rim portion of the cassette portion mounting opening 30a. The fixed-side cassette unit 4 can be easily taken out from the inside of the mounting unit 30.

Next, in this way, the fixed side cassette portion 4
When a fixed cassette part of another new round cassette is mounted in the fixed mount part 30 after the removal, the fixed cassette part is fixed from the cassette mounting port 30a contrary to the above case. It is inserted to a predetermined position in the side mounting portion 30 and the pressing plates 33, 33 are slid to the closed position shown by the solid line in the figure. As a result, the fixed-side mounting portion 30
With the lower surface of the new fixed-side cassette portion housed in a predetermined position inside, a part of the cassette-portion mounting opening 30a is closed by both pressing plates 33, 33, so that the cassette portion is fixed-side mounting portion 30a. It will be securely attached and held in a predetermined position inside.

On the other hand, in the movable side unit 29, the movable side cassette portion 5 housed in the mounting portion 35 is locked by the lock means 41. Therefore, in order to unlock the movable side cassette portion 5, first the lock means 41 is moved. The operation handle 44 is pulled in the direction of arrow A in FIG. 9 to move the lock means 41 from the lock position shown by the solid line in FIG. 9 to the lock release position shown by the chain line. In this way, the locking means 41
The engaging portion 42c of the movable side cassette portion 5 is disengaged from the engaging small diameter portion 18b of the movable side cassette portion 5, and the engagement between them is released. The movable side cassette unit 5 can be easily removed.

Thus, when the movable side cassette 5 and the fixed side cassette 4 of the round cassette 3 mounted on the mother die 3 are joined to form the cavity C in both rods, the resin melted in the cavity C is formed. Is press-fitted and molded. Resin is molded and the movable side cassette 5 is separated from the fixed side cassette 4,
When the molded product in the cavity C is exposed, the ejector cylinder 49 of the ejector mechanism 14 extends to raise the ejector pin 17 via the ejector back plate 15 and the molded product in the cavity C is ejected and released. After that, when the pressure fluid to the ejector cylinder 49 is discharged, the ejector lock plate 18 is pushed downward by the spring 19 and the ejector pin 17 is lowered and is retracted from the peripheral surface of the cavity C. At this time, the molded resin residue is not caught in the sliding surface of the ejector pin 17, and the ejector pin 17 is not retracted from the peripheral surface of the cavity C due to carbonized residue or gas due to high heat. Sometimes.

In such a case, the protection rod 51 of the ejector pin protection device 50 is not fully lowered and its tip 51
Since "a" is left in the state of being close to the contact piece 53 of the cavity plate 22, when the movable side cassette 5 is joined to the fixed side cassette 4, first, the tip 5 of the protective rod 51 is
1a is received by the contact piece 53 Next, when the movable side cassette 5 moves further to the fixed side cassette 4 side, the tip 51a of the protective rod 51 is received by the contact piece 53, so the ejector pin 17 protects the ejector pin 17. 51
With this, the ejector pin 17 is forcibly retracted from the peripheral surface of the cavity C. As a result, the peripheral surface of the cavity C will not be damaged by the ejector pin 17 even if the movable side cassette 5 moves to the fixed side cassette 4 side and is joined for the next molding.

In this embodiment, as an ejector pin protection device, a protection rod is erected on the side of a block supporting the lower surface of the ejector lock plate, and is provided on a cavity plate portion facing the tip of the protection rod. It is composed of a contact piece, and the block, the protective rod, the contact piece, and the like form the interlocking mechanism, but the invention is not limited to this, and for example, the linking mechanism interlocks with the movement of the movable side cassette,
It suffices that the ejector pin is forcibly prevented from protruding from the surface of the cavity C. Also,
INDUSTRIAL APPLICABILITY The present invention does not reject a device that electrically detects that the ejector pin has retracted, which is conventionally used, but also provides an electrical detection device together to further improve safety. There is an advantage that can be.

[0026]

As described above, the ejector pin protection device for the injection molding die according to the present invention, in order to mold the next product by the injection molding machine in which the product is taken out from the product molding cavity, When the movable side mold plate moves in the direction to close the product molding cavity, the interlocking mechanism interlocks with it to retract the ejector pin from the product molding surface of the product molding cavity, so that it slides like a conventional injection molding machine. The ejector pin can be reliably retracted from the injection-molded surface of the cavity even if debris is caught in the moving surface or gas enters. This has the advantage that it is possible to prevent damage to the inner peripheral surface of the expensive product molding cavity.

Furthermore, since it is possible to prevent the ejector pin from reliably retracting from the injection molding surface of the cavity and to prevent the inner peripheral surface of the expensive product molding cavity from being damaged, the injection molding die can be prevented. There is also an advantage that the durability can be significantly improved and the operation efficiency can be improved by eliminating the stoppage of the operation for repairing the injection molding surface of the cavity.

Further, when the interlocking mechanism stands up the operating rod from the base end portion for advancing and retracting the ejector pin or the mounting member connected to the base end portion, when the movable side unit and the fixed side unit are joined, With a structure in which the tip of the operating rod is operated to retract the ejector pin from the product molding surface of the product molding cavity, a simple structure is sufficient.
There is also an advantage that it can be easily attached to an existing injection molding machine.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a round cassette alone.

FIG. 2 is a partially cutaway side view showing a round cassette alone.

FIG. 3 is an enlarged side view of the upper part of the round cassette with a cutout.

FIG. 4 is a vertical cross-sectional view of a mother die with a cassette set.

FIG. 5 is a vertical sectional side view of a mother die.

FIG. 6 is a vertical sectional front view of a mother die.

FIG. 7 is a plan view of a fixed-side unit of the mother die.

8 is a cross-sectional view taken along the line VIII-VIII in FIG.

FIG. 9 is a plan view of the movable unit of the mother die.

10 is a cross-sectional view taken along line IX-IX in FIG.

FIG. 11 is a central vertical cross-sectional view of a mother die.

[Explanation of symbols]

 1 ... Cassette type injection molding mold 2 ... Mother mold 3 ... Round cassette 4 ... Fixed side cassette part 5 ... Movable side cassette part 6 ... Cavity 23 ... Fixed Side unit 29 ... Movable side unit 42 ... Locking means. 50: ejector pin protection device 54: interlocking mechanism

Claims (2)

[Claims] 1. An injection molding die comprising a mother die attached to an injection molding machine and a molding die attached to the mother die to form a product molding cavity, wherein the mother die can be separated from and contact with each other. The movable side unit and the fixed side unit are provided, and an ejector pin for releasing the molded product molded in the product molding cavity is provided in either of the movable side unit and the fixed side unit so as to move forward and backward. When joining the unit and the fixed side unit, an interlocking mechanism that allows the ejector pin to move in and out of the product molding surface of the product molding cavity in conjunction with the movement of the movable side unit is provided. Ejector pin protection device. 2. When the interlocking mechanism erects the protective rod from the base end portion for advancing and retracting the ejector pin or the mounting member connected to the base end portion, the movable side unit and the fixed side unit are joined together, The ejector pin protector for an injection molding die according to claim 1, wherein the ejector pin is configured to be retracted from the product molding surface of the product molding cavity by operating a tip portion of the protective rod.