JPH0541416B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a screw-type injection device, which is a device for injecting raw materials in an injection molding machine for molding plastic or synthetic rubber.

[Conventional technology]

Inside an injection molding machine that molds synthetic rubber, etc.
There is a screw-type injection device in which a screw is used as a mechanism for supplying the raw material to a molding die, and the raw material is injected by a plunger.

In the conventional vertical type of this type of screw-type injection device, a plunger is loosely inserted into a cylinder barrel whose axis is in the vertical direction so as to be able to move up and down, and this plunger is formed into a cylindrical shape and rotates inside it. The structure allows the screw to be freely inserted. A nozzle is provided at the end of the cylinder barrel, through which the raw material is injected into the mold.

The raw material is fed into the upper part of the screw by a hopper. The screw rotates within the plunger, and the raw material descends while being pushed by the screw along the inner peripheral surface of the plunger and is sequentially sent to the nozzle. Since the nozzle is blocked by the raw material that was previously used for molding the product, the raw material fed by the screw will accumulate at the top of the nozzle, and when the appropriate amount is fed, the plunger will move into the cylinder barrel. The material rises against the plunger and accumulates below the plunger. Further, as the plunger rises, the screw also rises.

When a predetermined amount of raw material is accumulated, the plunger is lowered and the raw material below the plunger is injected into the mold from the nozzle.

[Problem to be solved by the invention]

In the conventional screw type injection device described above, the screw is housed inside the plunger, so the outside diameter of the plunger is large and the amount of raw material stored is large, making it suitable for injecting large volumes of raw materials. Therefore, it is not suitable for small volume injection for molding small parts. Furthermore, the outer diameter of the screw is smaller than that of the plunger, and therefore it takes time to store a predetermined amount of raw material. Furthermore, since the screw also rises together with the plunger, the supply port for supplying the raw material to the screw also rises, making the connection structure between the hopper and the raw material supply port complicated. Furthermore, when the raw material is injected, the screw also descends as the plunger descends.
The continuity of the raw material is interrupted at the raw material supply port, and the screw is temporarily operated idly when feeding the raw material for the next product molding, which is undesirable because the load on the hydraulic motor etc. that drives the screw fluctuates.

Furthermore, when injecting raw materials into a mold, the passage between the nozzle and the screw must be blocked to prevent the raw material from flowing backwards toward the screw, but conventional screw-type injection equipment requires this type of blocking. This is done by operating a predetermined member using a hydraulic cylinder or the like. Therefore, a driving device for shutting off is required and the structure is complicated.

Therefore, this invention is suitable for injecting a small amount of raw material, can store a predetermined amount of raw material in a short time, can simplify the connection structure between the hopper and the screw, and can To provide a screw type injection device in which raw material is not interrupted and does not require a device for driving a predetermined member for blocking a passage between a nozzle and a screw during injection.

[Means to solve the problem]

In order to achieve the above object, the screw type injection device according to the present invention includes a nozzle attached to one end of a cylinder barrel, and the raw material is supplied from the other end side of the cylinder barrel to the screw type injection device. In a screw-type injection device in which the raw material is injected from the nozzle into a molding die, a screw is provided in the cylinder barrel so as to be rotatable and slidable as appropriate, and a cylindrical portion is attached to the shaft of the screw. A plunger is housed in the cylindrical portion so as to be slidable in the axial direction of the screw, the tip of the plunger faces the nozzle, and the nozzle-side end of the cylinder barrel is provided with a plunger from the inner diameter of the cylinder barrel. The screw also has a suitably large inner diameter, has a cylinder head equipped with the nozzle at its tip, and has an inner circumferential portion communicating with the cylindrical portion of the screw at the nozzle side end of the screw, and an outer circumferential portion of the screw. A closing member that is appropriately larger than the outer diameter and located inside the cylinder head is fixed, and the outer circumference of the closing member and the surface on the opposite nozzle side is attached to and detached from the nozzle side end surface of the cylinder barrel, and the screw When the raw material is supplied by the method, the screw appropriately slides toward the nozzle side with respect to the cylinder barrel to separate the closing member from the nozzle side end of the cylinder barrel. Further, a biasing means is provided for sliding the screw in a direction in which the closing member is pressed against the nozzle side end surface of the cylinder barrel,
When the raw material is supplied by the screw, the screw appropriately slides toward the nozzle side with respect to the cylinder barrel against the restoring force of the biasing means, thereby moving the closing member toward the nozzle side of the cylinder barrel. Another feature is that it can be removed from the end.

[Effect]

The raw materials supplied from Hotupa to the above-mentioned Skrill are:
It is forced along the inner circumferential surface of the cylinder barrel to the nozzle by the screw. At this time, since the raw material is pushed by the rotation of the screw, a force in the direction of the nozzle acts on the blades of the screw. As a result, the screw slides in the nozzle direction, the closing member separates from the end of the cylinder barrel, a gap is formed between the closing member and the end of the cylinder barrel, and the raw material flows through the gap. is fed into the cylinder head. When the nozzle is closed, the plunger is moved back in a direction opposite to the nozzle by the pushed raw material, and the raw material is stored in the cylindrical portion. When a predetermined amount of raw material is stored, the plunger moves forward and is injected from the nozzle into the mold. At this time, the raw material is pressurized by the forward movement of the plunger, and this pressure acts on the inner surface of the cylinder head of the closing member. For this reason,
The screw to which the closing member is fixed slides slightly in the direction opposite to the nozzle, and the closing member and the nozzle side end face of the cylinder barrel are pressed together to close the gap.

Further, the biasing means is provided depending on the viscosity of the resin that is the raw material. In other words, when a resin with low viscosity is used as a raw material, there is a risk that the closing member may not sufficiently close the end face of the cylinder barrel during injection. This closure is ensured by applying force.

〔Example〕

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The screw type injection device according to the present invention will be explained in detail below based on the preferred embodiments shown in the drawings. In this example, a case is shown in which this injection device is used in a vertical injection molding machine.

FIG. 3 shows a schematic front view of a vertical injection molding machine, in which raw materials are fed from a raw material tank (not shown) to a hopper 1 attached above the rear of the injection molding machine. A cylinder barrel 11 (shown in the first diagram) of an injection device 10 is disposed at the lower end of the hopper 1, and this cylinder barrel 11 is housed in a heating cylinder 12. A molding section 2 is located below the cylinder barrel 11, and a main cylinder 3 for mold clamping is disposed below this molding section 2. A movable platen 4 is attached to the rod of the main cylinder 3, and the movable platen 4 rises and the lower die of the molding die fixed to the movable platen 4 is pressed against the upper die to perform mold clamping. The movable platen 4 is lowered and the mold is opened.

The discharge port of the hopper 1 is the cylinder barrel 1.
1, and this raw material supply port 13 penetrates into the inside of the cylinder barrel 11, as shown in FIG.
As shown in FIG. 1, a cylinder head 14 is attached to the lower end of the cylinder barrel 11, and a nozzle 15 is attached to the lower end of the cylinder head 14. As shown in FIG. Further, a seat ring 16 having an inner diameter approximately equal to that of the cylinder barrel 11 is removably fitted in the vicinity of the connection between the cylinder barrel 11 and the cylinder head 14, that is, on the end face of the cylinder barrel 11 on the nozzle 15 side.

The inner diameter of the cylinder head 14 is appropriately larger than the inner diameter of the cylinder barrel 11.

A screw 17 is loosely inserted into the cylinder barrel 11 and has a spirally wound blade portion 17a having an appropriate outer diameter and pitch. A drive gear 18 is fitted to the upper part of the screw 17, and the screw 17 is rotated within the cylinder barrel 11 by rotating the drive gear 18 by a hydraulic motor or the like (not shown). Also, Skrillyu 17
A flange portion 17b having an appropriate diameter is formed at a position above the upper end of the cylinder barrel 11, and between this flange portion 17b and the upper end of the cylinder barrel 11, a push-up member made of a compression coil spring is provided as a biasing means. A spring 19 is interposed so as not to interfere with the rotation of the screw 17. The restoring force of the push-up spring 19 is applied so that the screw 17 moves upward with respect to the cylinder barrel 11.

A cylindrical portion 17d is formed in the shaft portion 17c of the screw 17 along the axial direction of the screw 17. The lower end of the screw 17 faces the nozzle 15 and is located at approximately the same height as the lower end of the cylinder barrel 11, and a bush 20, which is a closing member, protrudes from the lower end.
It is detachably attached by screwing to the cylindrical portion 17d. The outer diameter of the bush 20 is suitably larger than the inner diameter of the cylinder barrel 11, and its upper peripheral edge abuts against the seat ring 16. The bush 20 is therefore located within the cylinder head 14. Further, the inner peripheral surface of this bush 20 is continuous with the surface of the cylindrical portion 17d of the screw 17.

Then, in the cylindrical portion 17d of the screw 17,
A plunger 21 that is slidable in the axial direction of the cylindrical portion 17d is inserted, and this plunger 21
The tip end faces the nozzle 15. In addition,
This sliding movement of the plunger 21 is performed by a drive device (not shown).

Further, the cylinder head 14 and nozzle 15 are also covered by the heating cylinder 22.

The operation of the embodiment of the screw type injection device constructed as above will be explained below.

The drive gear 1 is driven by a hydraulic motor (not shown) or the like.
8 in a predetermined direction, the screw 17 rotates within the cylinder barrel 11. The raw material fed to the hopper 1 is dropped from the raw material supply port 13 at the lower end of the hopper 1 and supplied to the screw 17. The raw material is supplied between the outer peripheral surface of the shaft portion 17c and the inner peripheral surface of the cylinder barrel 11, and is pushed down by the blade portion 17a and sent downward by the rotation of the screw 17. At this time, the downward force applied to the raw material acts on the blade portion 17a of the screw 17, so the screw 17 moves slightly downward against the restoring force of the push-up spring 19, and the bush 20 The upper peripheral edge of the seat ring 1
There is a gap between them apart from 6. Therefore, the raw material fed by the screw 17 passes through the gap and is fed into the cylinder head 14 and the nozzle 15.

At this time, since the nozzle 15 is blocked by the raw material from the last time the product was molded, the nozzle 1
The raw material fed into the nozzle 5 is stored in the upper part of the nozzle 15, and as the raw material is fed sequentially, it is also stored in the cylinder head 14. When the cylinder head 14 is filled with raw materials and further raw materials are supplied, the reaction force of the raw materials causes the plunger 21 to move toward the cylindrical portion 17 as shown in FIG.
The raw material is also stored below the plunger 21 by rising inside the plunger 21. When a predetermined amount of raw material is supplied, the plunger 21 rises to a predetermined height, and this is detected and a drive device (not shown) applies pressure to the plunger 21 to push it down. By the operation of this plunger 21, the raw material is transferred to the nozzle 1.
It will be ejected from 5.

Further, when the plunger 21 is operated, pressure is also applied to the lower end of the screw 17 via the bush 20, so the screw 17 rises slightly, and the upper peripheral edge of the bush 20 is pressed against the seat ring 1.
6 and the space between them is closed. Therefore, the raw material does not flow back inside the screw 17 due to the pressure caused by the operation of the plunger 21.

Note that if the viscosity of the raw material is low, the pressure applied to the raw material during injection alone cannot
6 and the bush 20 may not be sufficiently closed, and the raw material may flow back into the screw 17. However, since the restoring force of the push-up spring 19 acts in the direction of pushing up the screw 17 and presses the bush 20 against the seat ring 16, the space between them is closed and the backflow of the raw material is reliably prevented. .

In this embodiment, the bushing 20 for preventing the backflow of raw material during injection comes into contact with the seat ring 16 and tends to wear out, but since the bushing 20 is attached to the lower end of the screw 17, it can be easily replaced. can do.

〔Effect of the invention〕

As explained above, according to the injection device according to the present invention, since the outer diameter of the plunger can be made smaller than the outer diameter of the screw, a small volume of raw material can be injected, and small parts can be molded efficiently. can. Further, since the outer diameter of the screw is larger than the plunger diameter, a predetermined amount of raw material can be stored in a short time, and the time for the molding operation can be shortened.

Moreover, by changing the combination of the plunger and screw and changing the diameter of the plunger, injection conditions such as the injection amount can be easily changed.

Furthermore, since the plunger rotates integrally with the screw and there is no relative rotation between them, wear on the plunger can be minimized. In addition, since the cylinder barrel does not move relative to the machine frame of the injection device, the raw material supply port formed in the cylinder barrel is always in a constant position, and the hopper that drops the raw material into the raw material supply port is also constant. Can be set to any position. Therefore, the positional relationship between the raw material supply port and the hopper and the positional relationship between this hopper and the supply device that supplies raw materials to the hopper can be made constant, the interconnection structure of these does not become complicated, and the raw material at the raw material supply port can be kept constant. There is no chance that the sequence will be interrupted.

Furthermore, when the raw material is injected into the mold, the pressure applied to the raw material by the plunger moves the closing member and blocks the passage that communicates the nozzle with the screw, so the raw material flows back toward the screw. I never end up doing it. Furthermore, since the closing member is operated by the pressure applied to the raw material, there is no need to provide a separate means for driving it.

[Brief explanation of drawings]

The drawing shows a case where the injection device according to the present invention is attached to a vertical injection molding machine. Figure 1 is a partial cross-sectional view showing the entire injection device during injection.
The middle part is omitted. FIG. 2 is a partially omitted sectional view showing the injection device during raw material measurement. FIG. 3 is a front view schematically showing the vertical injection molding machine. 1... Hopper, 10... Injection device, 11... Cylinder barrel, 13... Raw material supply port, 14... Cylinder head, 15... Nozzle, 16... Seat ring, 17... Screw, 17a... Vane Department,
17b...Shaft portion, 17d...Cylindrical portion, 19...Pushing spring, 20...Button, 21...Plunger.

Claims (1)

[Scope of Claims] 1. A nozzle is attached to one end of the cylinder barrel, and raw materials are supplied from the other end of the cylinder barrel and sent to the nozzle by a screw, and from the nozzle the material for molding is supplied. In a screw-type injection device in which raw materials are injected into a mold, a screw is provided in a cylinder barrel so as to be rotatable and slidable as appropriate, a cylindrical portion is formed on the shaft of the screw, and a shaft of the screw is formed in the cylindrical portion. A plunger is housed so as to be slidable in the direction, the tip of the plunger faces the nozzle, and the cylinder barrel has an inner diameter suitably larger than the inner diameter of the cylinder barrel at the nozzle side end, A cylinder head equipped with the nozzle is connected to the nozzle, and the nozzle side end of the screw has an inner peripheral part communicating with the cylindrical part of the screw, and the outer peripheral part is suitably larger than the outer diameter of the screw, and the cylinder head is connected to the cylinder head. A closing member located inside is fixed, and the outer circumference of the closing member, which is the surface opposite to the nozzle, is attached to and detached from the nozzle side end surface of the cylinder barrel, and when the raw material is supplied by the screw, A screw type injection device characterized in that the screw slides appropriately toward the nozzle side with respect to the cylinder barrel to separate the closing member from the nozzle side end of the cylinder barrel. 2 A nozzle is attached to one end of the cylinder barrel, the raw material is supplied from the other end of the cylinder barrel and sent to the nozzle by a screw, and the raw material is injected from the nozzle into the mold. In the screw type injection device, a screw is provided in the cylinder barrel so as to be rotatable and slidable as appropriate, a cylindrical portion is formed in the shaft portion of the screw, and a screw is provided in the cylindrical portion so as to be slidable in the axial direction of the screw. A plunger is housed, the tip of the plunger faces the nozzle, the cylinder barrel has an inner diameter suitably larger than the inner diameter of the cylinder barrel at the nozzle side end, and the tip is provided with the nozzle. A closing member that connects the cylinder head, has an inner peripheral part communicating with the cylindrical part of the screw at the nozzle side end of the screw, has an outer peripheral part suitably larger than the outer diameter of the screw, and is located inside the cylinder head. the outer circumferential part of the closing member and the surface on the anti-nozzle side is attached to and detached from the nozzle side end surface of the cylinder barrel, and the screw is moved in a direction in which the closing member is crimped onto the nozzle side end surface of the cylinder barrel. A biasing means for sliding is provided, and when the raw material is supplied by the screw, the screw appropriately slides toward the nozzle side against the cylinder barrel against the restoring force of the biasing means. The screw type injection device is characterized in that the closing member is removed from the nozzle side end of the cylinder barrel.