JPH0270416A - Preplunging type injection molding machine - Google Patents

Abstract

PURPOSE:To prevent an injection plunger from generating a dragging section by inserting an injection plunger through an injection line, connecting a feeding cylinder with a side opening, disposing a plasticization device on a side section of a feeding block, setting a top force, an adiabatic plate and a mold mounting plate into a projected section to be set on the lower side of the feeding block and providing a pot opening of the top force in an injection line. CONSTITUTION:An injection line 33 communicating with a side opening 32 is provided through in the centration section of a feeding block 27, into which an injection plunger 29 is inserted, and a top force 46 is fitted by an insulating plate 45 on a mold mounting plate 44. When the injection plunger 29 is lowered by driving an injection device 26 until its tip reaches the lower section of a pot opening 47 of the top force 46, a material 51 is injection filled into a cavity 50, the temperature of which is controlled to the vulcanizing temperature. At that time, as the tip of a feeding cylinder 37 is closed, the material is immediately metered on a plasticization device 35 side. During vulcanizing the material 51, pressing force of the injection plunger 29 is released to release gas, and a mold is opened after the completion of vulcanization. At the time of mold opening, the injection plunger 29 is further lowered downward, and a molded product 52 and a cull 53 are released securely from the top force 46.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plastic injection molding machine used for molding rubbers such as natural rubber and synthetic rubber.

[Prior Art] In the molding of the above-mentioned rubbers, the material is plasticized in a plasticizing chamber without being vulcanized, and then injected into a high-temperature mold to be vulcanized and solidified.

Transfer molding and injection molding are known molding methods, but in transfer molding, it is necessary to preform the material into a tablet, and in injection molding, the inside of the tip of the injection tube that comes into contact with the mold is There was a problem that the mold temperature could not be raised because there was a risk that the raw rubber would be vulcanized, and vulcanization took a long time.

An injection molding machine that solves such problems (Japanese Patent Laid-Open No. 42-8
228) was developed. This molding machine uses a screw to plasticize the raw material, eliminating the need for preforming tablets.Also, since injection is performed using an injection plunger, all of the material transferred into the injection cylinder is discharged during each material cycle. Since there is no residual vulcanized rubber, it has the advantage of increasing the mold temperature and shortening the vulcanization time.

A screw transfer molding machine is similar to such a molding machine. As shown in FIG. 6, this molding machine has a mold clamping cylinder 3 connected to tie bars 4.4 above a fixed platen 2 of a machine base 1, and a transfer pot 5 in the center of the fixed platen 2. It is a through-hole. This transfer bot 4 has an injection cylinder 6 installed inside the machine.
An injection plunger 7 is inserted from the lower end, and a supply cylinder 10 of a plasticizing device 9 having a screw 8 installed therein is connected to the side. The lower mold 11 is fitted into the upper end of the transferbot 5 and attached to the upper surface of the fixed plate 2, and the upper mold 1
2 is attached to a movable platen 14 connected to a mold clamping ram 13.

In this molding machine, the material 15 that is plasticized by the rotation of the screw 8 and accumulated in front of the screw is fed into the transfer robot 4 by the advancement of the screw 8, and is then injected and filled into the cavity 16 of the mold by the injection plunger 7. .

[Problems to be Solved by the Invention] The molding machine described in JP-A-42-8228 has a configuration in which a split mold is opened and closed by a pair of cylinders,
In addition, the injection device is connected to the mold by inserting the tip of the injection cylinder into the parting part of the mold.
If the mold closing position shifts even slightly, bending stress will be applied to the tip of the cylinder, which will deform the connection part with the mold, causing problems such as material leakage and mold damage. Opening and closing of the mold by actuation also has the problem that the mold closing position is likely to shift.

There is no problem with the molding machine shown in Fig. 6 above, but since the transfer bot protrudes from the stationary platen, the lower mold must be fitted into the protruding end of the transfer bot. The work is troublesome and setup takes time, and since the supply cylinder is directly connected to the transferbot, the transferbot may bend due to the reaction force of material feeding due to the advance of the screw, which makes it difficult to use the injection plunger. There was a problem that the injection of material lacked smoothness due to the occurrence of friction.

This invention was devised to solve the above problems, and its purpose is to prevent the raw rubber inside the tip of the supply tube from being vulcanized even when the mold temperature is raised, and to prevent damage to the mold due to opening and closing of the mold. To provide a new pre-plastic injection molding machine that does not leak, allows easy mounting of a mold, and prevents the injection plunger from being damaged.

[Means for Solving the Problems] This invention according to the above object includes a fixed plate supported and fixed above the machine base by a tie bar, and a fixed plate that is vertically movable through the tie bar and connected to a mold clamping ram on the machine base side. A movable platen, an injection device installed on the upper side of the fixed plate with the injection plunger facing downward, and at least a protrusion on the lower side of the center, through which an injection path communicating with a side hole of a required diameter is provided. a plasticizing device having a screw rotatable and movable in the supply cylinder, a lower mold attached to the upper surface of the movable plate via a heat insulating plate, and an upper mold having a pot hole in the center. The supply block is fixed to the lower side of the stationary plate through a heat insulating plate, the injection plunger is inserted into the injection path, and the supply cylinder is connected to the side hole to form the plasticizing device. is placed on the side of the supply block, the upper mold, the heat insulating plate and the mold mounting plate are fitted into the protrusions and fixed to the lower side of the supply block, and the pot hole of the upper mold is positioned in the injection path. I'll let you.

In addition, the tip of the supply tube is inserted into the side hole and bolted to the supply block in a detachable manner, and is connected to a horizontal screw shaft provided on the support member on the side of the stationary plate and to the receiving plate at the rear. The injection plunger communicates the injection path with the supply cylinder side in the raised position, and in the lowermost position, the tip of the plunger is supported by the parting surface of type 1. Consists of a protruding length.

[Function] In the above configuration, when the upper mold is placed over the lower mold on the fixed plate and the upper mold is raised together with the lower mold toward the supply block, the pot hole fits into the protrusion on the lower side of the supply block. At the same time, the upper mold reaches the mold mounting plate via the heat insulating plate, and the injection path and the pot hole communicate with each other.

When the upper mold is bolted to the mold mounting plate in this state, the upper mold is closed with the lower mold as a fixed mold. Furthermore, when the upper mold and the mold mounting plate are unfastened, the upper mold also comes off from the mold mounting plate and descends as the lower mold descends. Therefore, the upper die can be attached and detached by moving the die up and down.

The material is extruded into the injection path of the supply block by the advancement of the screw of the plasticizing device, and is then injected and filled into the cavity of the mold clamped by the injection plunger.

[Embodiment] In FIGS. 1 to 5, 21 is a machine base, and a fixed platen 22 is supported and fixed by tie bars 21a above. Further, a movable platen 25 connected to the mold clamping ram 24 of the mold clamping cylinder 23 on the machine stand side is inserted through the tie bar 21a so as to be vertically movable.

An injection device 26 is installed on the upper side of the stationary plate 22, and a supply block 27 is fixed on the lower side. This injection device! 26 is provided with an injection plunger 29 at the lower end of an injection ram 28 in a hydraulic cylinder, and is mounted on a fixed plate with the injection plunger 29 facing downward.

The supply block 27 has protrusions 3 at the center of the upper and lower sides.
It has 0.31. In addition, an injection path 33 that communicates with the side hole 32 is provided in the center, and installation on the lower side of the fixed plate is as follows.
After installing the heat insulating plate 34 on the upper side, insert the injection plunger 29 that was attached first and protrudes from the hole in the center of the fixed mold.
This is done by inserting the upper protrusion 30 into the hole in the center of the fixed platen 22 while inserting it into the injection path 33, and fixing it with a bolt or the like.

Further, on the side of the supply block 27, a plasticizing device 35 inserts a tip of a supply cylinder 37 having a screw 36 thereinto into the side hole 3.
2 and are connected removably.

The plasticizing device 35 includes a receiving plate 3 provided at the rear end of the supply cylinder 37.
A pair of hydraulic cylinders 40 for advancing the screw, to which a piston rod 39 is connected to the 8, and a motor 41 for rotating the screw.
A nut-shaped guide member 42 connected to the receiving plate 38 is attached to a side support member 22a provided on the fixed plate 22.
It is screwed onto a rotatable screw shaft 43 provided horizontally, and is attached to the support member 22H so as to be movable forward and backward.

A mold mounting plate 44 is bolted to the lower side of the supply block 27, a heat insulating plate 45 is provided on the mold mounting plate 44, and an upper mold 46 is fixed with bolts. This upper mold 46 has a bottom hole 47 having the same diameter as the injection path 33 in the center,
The mold mounting plate 44, the insulation plate 45, and the upper mold 46 are closed with a lower mold 49 attached to the upper surface of the movable platen 26 via a heat insulation plate 48 to form a cavity 50 communicating with the bottom hole 47. The hole provided in the center of each is fitted into the lower protrusion 31 of the supply block 29 to be attached to the supply block, so that the injection path 33 and the bot hole 47 communicate with each other, and the tip is raised at the lowest point. The injection plunger 29, which has a length protruding from the parting surface of the mold 46, enables injection and filling of the material into the cavity 50.

In the above structure, the upper mold 46 with the heat insulating plate 45 attached to the upper surface is placed on the lower mold 49 on the movable platen, and the mold clamping ram 25 is raised at low speed and under low pressure to remove the upper mold together with the lower mold 49. 46 toward the supply block side, the hole at the top of the pot hole fits into the lower protrusion 31 of the supply block 29, and the upper mold 4
6 reaches the mold mounting plate 44 via the heat insulating plate 45, and the injection path 3
3 and the bot hole 47 communicate with each other. In this state, the upper mold 46
When the upper mold 46 is bolted to the mold mounting plate 44, the upper mold 46 is thereafter closed with the lower mold 49 as a fixed mold.

Also, when the upper mold 46 and the mold mounting plate 44 are unfastened, the lower mold 4
9, the upper mold 46 also lowers the lower protrusion 31 and the mold mounting plate 4.
It deviates from 4 and descends.

Next, molding will be explained.

First, the injection device is hydraulically driven to lower the injection plunger 29 to a position that closes the tip of the supply cylinder, and then the motor is driven to rotate the screw 36. As a result, the material supply port 37a
A material such as ribbon-shaped rubber supplied to the screw groove is plasticized and transferred to the front of the screw, and as the material accumulates, the screw 36 retreats. Furthermore, by controlling the pressure of the pressure oil discharged from the hydraulic cylinder 40 when the screw is retracted, back pressure control is generated and the materials are kneaded uniformly.

When the screw 36 reaches a preset metering stop position, the rotation of the motor 41 is stopped and the injection device 26 is stopped.
is re-driven to raise the injection plunger 29 and open the injection path 33.
and the supply tube 37 are communicated with each other.

Then, pressure oil is supplied to the hydraulic cylinder 40 and the screw 36 is
move forward. All of the material 51 metered in front of the screw is extruded into the injection path 33, as shown in FIG.

Next, the injection device 26 is driven to lower the injection plunger 28 at a speed and pressure of II@ until the tip reaches the lower part of the pot hole of the upper mold 46. As a result, as shown in FIG. 3, the material 51 is injected and filled into the cavity 50 of the mold in a clamped state, the temperature of which has already been adjusted to the vulcanization temperature of the material. At this time, the tip of the supply cylinder is closed by lowering the injection plunger 29, so that the material is immediately measured on the plasticizing device side.

During vulcanization of the material 51, the pressing force of the injection plunger 29 is released as needed to vent gas, and the mold is opened after vulcanization is completed. At the initial stage of mold opening, the injection plunge t29 is further lowered in synchronization with the mold opening speed to reliably release the molded product 52 and cull 53 from the upper mold 46, as shown in FIG.

After the mold is opened, the ejecting pin 54 is ejected from the lower mold 49 by a protruding device (not shown) built into the movable plate, and the mold is released as shown in FIG. Injection bag after demolding! 26 to raise the injection plunger 29 to the position where the tip of the supply cylinder is opened, and at the same time, hydraulically drive the mold clamping cylinder 24 to raise the mold clamping ram 25 to clamp the mold. begins the molding process.

The above explanation is about molding rubber, but it can of course be applied to molding general thermoplastic resins. The mold can be left to cool.

To replace the screw 36, after releasing the connection between the supply block 27 and the supply tube 37, the screw shaft 43 of the support member 22a is rotated to move the plasticizing device 35 backward, and the receiving plate 38 and guide It can be pivoted about the pivot of the member 42 (not shown).

As described above, this invention includes an injection device and a supply block provided above and below on a fixed plate above the machine base, a plasticizing device connected to the side of the supply block, and material from the plasticizing device being transferred into the supply block. From the injection path, the injection plunger can be used to inject and fill the mold that is placed between the supply block and the movable plate via a heat insulating plate, so when the injection device is connected to the parting part of the mold. This problem does not occur, and since the temperature of the mold does not extend to the supply block side due to the heat insulating plate, materials such as rubber do not vulcanize before injection filling, and therefore the metal The vulcanization time can be shortened by raising the mold temperature.

In addition, since the injection path is provided through the supply block, even if a plasticizing device is connected to the side, the injection path will not bend due to the reaction force when the screw advances, and even after long-term use, the injection path will not be bent. Injection filling using a plunger can be performed smoothly.

Furthermore, a protrusion is provided at the center of the lower side of the supply block, and the center part of the upper mold having a pot hole is fitted into this protrusion to attach the upper mold to the supply block. When set on the lower mold, simply raise the supply block until it touches the bottom side of the supply block, and the injection path and pot hole can be aligned and the upper mold's retaining tube can be aligned, which saves time and effort when installing the mold. Not only does it not hang and is easy to remove, but the screw can be easily replaced by connecting the plasticizing device so that it can move forward and backward, and the molded product and cull can be reliably released from the upper mold using the injection plunger. It has many advantages that cannot be compared with conventional structures.

[Brief explanation of the drawing]

Figures 1 to 5 show one embodiment of the pre-plastic injection molding machine according to the present invention, in which Figure 1 is a longitudinal sectional view in a mold line state, and Figures 2 to 5 show the molding process in order. FIG. 6 is a vertical cross-sectional view of the supply block and mold portion to be described, and FIG. 6 is a vertical cross-sectional view of a conventional screw transfer molding machine. 21... Machine base 21a... Tie bar 25... Movable plate 27... Supply block 29... Injection plunger 31... - Lower protrusion 33... Injection path 35... Plasticizing device 37... Supply tube 42... Guide member 45, 48...・Insulation board 47... Pot hole 50... Cavity 52... Molded product

Claims (3)

[Claims] (1) A fixed plate supported and fixed with tie bars above the machine base, a movable plate inserted through the tie bars so as to be able to move vertically and connected to the mold clamping ram on the machine base side, and an injection plunger above the fixed plate. an injection device installed with the injection device facing downward, a supply block having a protrusion at least on the lower side of the center and an injection passage through the center that communicates with a side hole of a required diameter, and a screw in the supply cylinder. It consists of a material plasticizing device that can rotate and move forward and backward, a lower mold that is attached to the upper surface of the movable plate via a heat insulating plate, and an upper mold that has a pot hole in the center, and the supply block is insulated. It is fixed to the lower side of the stationary block via a plate, the injection plunger is inserted into the injection path, and the supply cylinder is connected to the side hole, and the plasticizing device is arranged on the side of the supply block. , wherein the upper mold, the heat insulating plate, and the mold mounting plate are fitted into the protrusion and fixed to the lower side of the supply block, and the pot hole of the upper mold is located in the injection path. type injection molding machine. (2) In the pre-plastic injection molding machine according to item 1, the supply tube has its tip inserted into the side hole and is detachably bolted to the supply block, and is attached to a support member on the side of the stationary plate. A pre-plastic injection molding machine characterized in that a guide member connected to a rear receiving plate is screwed onto a horizontal screw shaft provided so that the guide member can move forward and backward. (3) In the pre-plastic injection molding machine described in item 1, the injection plunger communicates the injection path with the supply cylinder side at the raised position, and at the lowest position, the tip protrudes from the parting surface of the upper mold. A pre-plastic injection molding machine characterized by a length.