JP3509791B2 - Backflow prevention device for in-line screw injection molding machine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a backflow prevention device in an inline screw type injection molding machine.

[0002]

2. Description of the Related Art Similar to the present invention, Japanese Patent Application Laid-Open No. 9-174629 discloses a backflow preventing device for the purpose of preventing fluctuations in the timing at which sealing is started, and consequently fluctuations in the amount of resin injected from an injection nozzle. JP-A-9-262877 and JP-A-4-86232 have been proposed.

[0003]

However, in the configuration of the invention of JP-A-9-174629, first, the first ring (31) having the valley portion (37) to be the first resin flow path and the second resin By engaging the former pin (39) and the latter long groove (49) with each other, two types of the second ring (47) in which the valley portion (47) to be a flow path is processed are relatively aligned. It must be controlled so that it can swing freely, and must be kept in a state where it does not rotate with the screw head (14).
Since the rings (31) (32) and these screw heads (14) are assembled in a very complicated and specialized manner, the versatility cannot be exhibited.

Next, in the case of the invention of Japanese Unexamined Patent Publication No. 9-262877, even if a single check ring (31) is sufficient, the outer peripheral surface of the small diameter portion (19) of the screw head (14) is axially extended. A plurality of extending grooves (35) must be machined and corresponding arc-shaped protrusions (36) (37).
It is also necessary to form the non-return ring (31) so that the resin flow path (38) can be opened and closed, so that the screw head (14) and the non-return ring (31) are complicated and expensive special products. Therefore, it is inferior in versatility.

Further, even in the structure of the invention of JP-A-4-86232, a single check ring (32) is sufficient, but either one of the check ring (32) and the screw head assembly shaft (4) is sufficient. It is necessary to engage the projection (33) provided on the other side and the groove (31) notched on the other side as an inclined lead, and the machining and assembly are complicated and specialized, so that versatility is still demonstrated. I can't let you do it.

Further, in any of the above-mentioned known inventions, while the counterclockwise rotation is normally performed during the measurement and is retreated, the counterclockwise rotation and the forward movement are performed once before the injection process after the completion of the measurement. Screw (12) (2), because the structure is premised on the screw (12) (2)
A special drive source and a transmission mechanism for rotating the machine normally and reversely are indispensable, and so to speak, it cannot be applied to the conventional general-purpose in-line screw type injection molding machine that only performs normal rotation.

Also, after the measurement is completed, the screws (12) (2)
During the operation of rotating the screw in the reverse direction, it is difficult to avoid reverse flow of the resin, and there is also the problem that the measurement completion position is likely to change each time. Strokes must be controlled and managed, which is very annoying.

[0008]

DISCLOSURE OF THE INVENTION The present invention is intended to solve these problems, for which purpose a screw incorporated into the inside of the heating cylinder so as to be rotatable and forward / backward movably, and a screw for said screw are provided. A check valve seat ring, which is pressed and fixed to the front end surface of the screw by a small-diameter mounting shaft of the screw head, and a relational state that exists between the front and rear of the screw head and the seat ring facing each other. A check valve loosely fitted on the mounting shaft,

In the backflow prevention device of the inline screw type injection molding machine, which is defined so as to open and close the molten resin flow passage extending from the screw side to the front of the screw head by the action of the check valve with respect to the seat ring.

A recessed groove that opens rearward is cut out in the screw head, and a spring material and a slide ring that is constantly biased by the spring material toward the front end surface of the check valve are incorporated therein.

It is characterized in that a radial communication path with the molten resin flow path is defined between the slide ring and the check valve in front of and behind each other.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The specific constitution of the present invention will be described in detail below with reference to the drawings. FIGS. 1 to 3 show the state during measurement in the present invention, and FIG. Each is shown, and (10) is a heating cylinder by a heater (not shown), which is provided with an injection nozzle (11) at its front end.

(12) is a screw incorporated in the heating cylinder (10), the rear end of which is a drive source (not shown) such as an electric motor or a hydraulic motor.
It is connected to the power transmission, which enables rotation and forward / backward movement. The rotation of the screw (12) means counterclockwise so-called normal rotation, and does not rotate in the reverse direction, so a special transmission mechanism for the reverse rotation is not required. The hopper for charging the pelletized resin into the heating cylinder (10) is not shown.

Reference numeral (13) is a screw head mounting shaft having a constant length (L), the rear end screw shaft portion (13a) of which is screwed and fastened to the screw (12) from the front side, and the mounting thereof. The intermediate portion (13b) of the shaft (13) causes the check valve seat ring (14) to move to the screw (1
It is clamped and fixed to the front end of 2).

Further, (15) is a screw head (torpedo) shaped into a substantially bullet-shaped taper, which is independent of the mounting shaft (13) and has a diameter smaller than this. The front end screw shaft portion (13c) is detachably screwed and fastened in a crowned state from the front. It goes without saying that the spiral directionality of the front end screw shaft portion (13C) is the directionality in which the screw head (15) is tightened by the rotation of the screw (12).

Moreover, a plurality of (four in total in the illustrated example) notches (16) are formed on the outer peripheral surface of the screw head (15).
However, in addition to the overall radial symmetric distribution type, a recessed groove (17) that opens rearward is cut out in the center of the screw head (15) as well. (G) shows the notch depth of the concave groove (17), and (S) shows the notch opening diameter larger than the mounting shaft (13).

(18) is a substantially cylindrical check valve interposed between the front and rear of the screw head (15) and the seat ring (14) facing each other, and the mounting shaft (1)
3) By being loosely fitted upward, the mutual gap between the outer peripheral surface of the mounting shaft (13) and the inner peripheral surface of the check valve (18) is formed as a flow passage (P1) for the molten resin.

In this case, as is apparent from FIGS. 5 to 7, the rear end surface of the check valve (18) forms a flat surface which can be brought into close contact with the front end surface of the seat ring (14). From the front end face of the check valve (18), a plurality of (four in total in the figure) projections (19) are provided so as to project in a generally radial symmetrical distribution type, and the projections (19) are adjacent to each other. A matching mutual gap can be secured as a radiation communication path (P2) with the molten resin flow path (P1).

Pitch Circle Diameter of convex child (19)
As suggested from FIGS. 1 and 2, (D) is almost equal to the opening diameter (S) of the concave groove (17) cut out in the screw head (15), and the protrusion (19) of the concave groove is Groove (1
There is a positional relationship that directs the inside of 7).

(20) is the screw head (15)
The slide ring (21) fitted over the mounting shaft (13) for the screw head in the assembled state facing the inside of the concave groove (17) of the check valve (1).
8) A spring member which is pressed against the convex element (19) of FIG. 8 and urges backward, and is composed of one compression coil spring and is incorporated in the concave groove (17).

That is, the flat rear end face of the slide ring (20) which receives the pressing biasing force of the spring member (21) has a flat front end face of the protrusion (19) protruding from the check valve (18). And the check valve (18) is prepared so that the check valve (18) receives a rearward biasing force capable of closely contacting the seat ring (14) on the screw (12) side. Is there.

The pressing biasing force of the spring member (21) is set to be weaker than the back pressure of the screw (12), and the check valve (18) is reliably separated from the seat ring (14) during measurement. Thus, the molten resin can be smoothly circulated to the flow passage (P1).

When the measurement is completed, the pressing force of the spring material (21) is added to the reaction force from the molten resin stored in front of the screw head (15), so that the check valve (18) is Upon receipt of the increased pressing force, the seat ring (14) is automatically and instantly brought into close contact with and integrated with the seat ring (14), and backflow of the molten resin and deviation of the measurement completion position in the process are prevented.

Even if the slide ring (20) that receives the biasing force of the spring member (21) can move forward and backward, the outer peripheral surface of the slide ring (20) and the recessed groove. The molten resin is sealed between the inner peripheral surface of (17) and the inner peripheral surface of the slide ring (20) and the outer peripheral surface of the screw head mounting shaft (13). It goes without saying that the molten resin is kept so as not to enter the inside of the groove (17).

Since the present invention is constructed as described above, first, in the measuring step, the screw (12) is rotated counterclockwise and then retracted by a predetermined amount, so that the resin fed from the hopper is screwed (12). ) Kneading and plasticizing, and moving forward, from the screw (12) side through the molten resin flow path (P1) and its radial communication path (P2) to the screw head (15) as shown by the arrows in FIGS. It reaches the front, and one shot of molten resin is stored in front of it.

Then, by the reaction force from the stored molten resin, the screw (12) is further retracted while controlling the back pressure, and when the screw (12) is retracted to the predetermined measurement completion position, the screw (12) is retracted. To stop the rotation of.

By doing so, the check valve (18), which was at a so-called intermediate position between the screw head (15) and the seat ring (14) during the measurement, is replaced by the spring member (21).
The slide ring (2
0), it is pushed rearward toward the seat ring (14), and when the weighing process is completed, the pressure is applied to the seat ring (14) shown in FIG.
As described above, a sealed state in which the seat ring (14) and the seat ring (14) are instantly brought into close contact with and integrated with each other can be obtained.

Then, at the time point when the injection start timing is reached after the measurement step is completed, the screw (1
If 2) is rapidly advanced, its screw head (1
The molten resin in the reservoir is injected from the injection nozzle (11) in front of 5) and is filled in the cavity (not shown) of the mold.

As a result, it is not necessary to rotate the screw (12) counterclockwise in order to prevent backflow, and the check valve (18) is urged by the pressing force of the spring member (21) and the slide ring (20). The backflow can be immediately prevented from the time when the measurement is completed, the injection amount in the subsequent injection process can be always kept constant, and excellent start-up response characteristics can be obtained.

In the basic embodiment shown in FIGS. 1 to 7, one compression coil spring is adopted as the spring material (21), but as is apparent from the modified embodiment shown in FIG. 8 corresponding to FIG. It is also possible to adopt a conical disc spring of No. 1 and install them in the groove (17) of the screw head (15) in parallel.

8 and 9, a plurality of projections (19) forming a radiation communication path (P2) with the molten resin flow path (P1) are connected to the check valve (18). Instead of projecting from the front end face, it is also possible to project from the rear end face of the slide ring (20) as an overall radial symmetrical distribution type.

Further, in the above-described basic embodiment and modified embodiment, the flat rear end surface of the slide ring (20) and the flat front end surface of the check valve (18) have a plurality of protrusions (19).
The slide ring (20) and the check valve (18) form a radiation communication path (P2) with the molten resin flow path (P1) between the slide ring (20) and the check valve (18). As long as it happens, it is okay to keep the two in bite condition.

The other constructions of the modified embodiments of FIGS. 8 and 9 are substantially the same as those of the basic embodiment of FIGS. 1 to 7, and therefore FIGS. 8 and 9 correspond to FIGS. Only the reference numerals are entered, and the detailed description thereof is omitted.

[0034]

As described above, according to the present invention, the screw (12) operably incorporated into the heating cylinder (10) for rotation and forward / backward movement, and the screw (1)
A seat ring (14) for a check valve, which is pressed and fixed to the front end face of the screw (12) by a small-diameter mounting shaft (13) of the screw head (15) with respect to 2);
The screw head (15) and seat ring (14)
The check valve (18) loosely fitted on the mounting shaft (13) under the relationship of being interposed between the front and the rear facing each other.
With and

Due to the action of the check valve (18) on and off the seat ring (14), the screw (12) is moved.
In the backflow prevention device of the inline screw type injection molding machine, which is defined to open and close the molten resin flow passage (P1) from the side toward the front of the screw head (15),

A recessed groove (17) opening rearward is cut out in the screw head (15), and a spring member (21) and by this is constantly urged toward the front end face of the check valve (18). Slide ring (20) with

The slide ring (20) and the check valve (1
Since the radiation communication path (P2) with the molten resin flow path (P1) is defined between the front and the rear of (8), there is an effect that the problems of the prior art described at the beginning can be alleviated.

That is, according to the above configuration of the present invention, the check valve (18) causes the reaction force from the molten resin stored in front of the screw head (15) at the completion of the measurement and the spring member ( 21) It receives a strong pressing force with the seat ring (14) and automatically and instantly comes into close contact with the seat ring (14). Therefore, it is not necessary to reversely rotate the screw as in the prior art and move it forward. The completion position can be constantly kept constant without deviation, and it is possible to prevent the variation of the amount of resin continuously injected.

Moreover, the slide ring (20) which receives the pressing biasing force of the spring member (21) causes the check valve (1) to operate continuously.
Even if the slide ring (20) and the check valve (18) are in pressure contact with the molten resin flow passage (P1), a radiation communication passage (P2) is formed between the slide ring (20) and the check valve (18). Therefore, the resin measuring process can be performed without any trouble.

Even with such a necessary structure of the backflow prevention device, the groove (17) which opens rearward is cut out in the screw head (15), and the spring member (21) is inserted into the groove (17). ) And a slide ring (20) which is pressed and urged by the check valve (18) by this, it is extremely easy to apply to a general-purpose in-line screw type injection molding machine that performs only forward rotation. In addition to the fact that a special drive source for forward / reverse rotation and a transmission mechanism are not required, the versatility and mass production effect are remarkably excellent.

Further, if the structure of claim 2 is adopted, the plurality of protrusions (19) are simply processed into one of the slide ring (20) and the check valve (18), and The radiation communication path (P2) can be easily formed, and the number of parts is small, which further improves the mass production effect.

Further, if the configuration of claim 3 is adopted,
Check valve (1) for the screw head mounting shaft (13)
8), the slide ring (20) and the spring material (21) can be incorporated, and these and the screw head (15) can be replaced quickly, which also has an effect of improving workability.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a state during measurement in a backflow prevention device of the present invention.

FIG. 2 is an enlarged sectional view taken along line 2-2 of FIG.

FIG. 3 is an enlarged sectional view taken along line 3-3 of FIG.

FIG. 4 is a side cross-sectional view corresponding to FIG. 1, also showing a state of completion of weighing.

FIG. 5 is a perspective view showing a check valve extracted.

FIG. 6 is a front view of FIG.

7 is a sectional view taken along line 7-7 of FIG.

FIG. 8 is a side sectional view corresponding to FIG. 1, showing a modified embodiment of the backflow prevention device according to the present invention.

FIG. 9 is a perspective view showing the slide ring of FIG. 8 in an extracted manner.

[Explanation of symbols]

(10) · Heating cylinder (12) · Screw (13) · Mounting shaft for screw head (13c) · Front end screw shaft (14) · Seat rings for check valves (15) ・ Screw head (17) ・ Concave groove (18) · Check valve (19) ・ Convex (20) ・ Slide ring (21) · Spring material (P1) · Molten resin flow passage (P2) -Radial communication passage (L) · Length of mounting shaft for screw head (G) Depth of groove cutout (S) -Notch opening diameter of the concave groove

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-9-272142 (JP, A) JP-A-7-256715 (JP, A) JP-A-7-214616 (JP, A) JP-A-7- 16892 (JP, A) JP-A-52-51450 (JP, A) Actual development 1-175809 (JP, U) Actual development 3-81724 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) B29C 45/52

Claims (3)

(57) [Claims] 1. A screw (12) operably incorporated into a heating cylinder (10) for rotation and forward / backward movement.
A check valve seat ring (14) fixed to the front end surface of the screw (12) by a small-diameter mounting shaft (13) of the screw head (15) with respect to the screw (12); Screw head (15)
The seat ring (14) is provided with a check valve (18) loosely fitted on the mounting shaft (13) under a relational state in which the front and rear faces of the seat ring (14) face each other. Due to the contact and separation action of the check valve (18) with respect to the screw, the molten resin flow path (P) from the screw (12) side to the front of the screw head (15).
1) In a backflow prevention device of an in-line screw type injection molding machine which is determined to open and close, a recessed groove (17) that opens rearward is cut out in the screw head (15), and a spring material (21) is provided therein. As a result, a slide ring (20) which is constantly pressed and urged toward the front end face of the check valve (18) is incorporated, and the melting is performed between the slide ring (20) and the check valve (18) before and after. A backflow prevention device for an in-line screw type injection molding machine, characterized in that a radiation communication path (P2) is defined with a resin flow path (P1). 2. From one of the front end face of the check valve (18) and the rear end face of the slide ring (20) toward the other,
2. A plurality of protrusions (19) are projected in a generally radial symmetrical distribution type so that adjacent mutual gaps of the protrusions (19) are formed as radial communication paths (P2). Backflow prevention device for the inline screw type injection molding machine described. 3. A screw head (15) is formed separately from a screw head mounting shaft (13) having a constant length (L), and a front end screw shaft portion (13) of the mounting shaft (13) is formed.
The in-line screw type according to claim 1, wherein the compression coil spring (21) and the slide ring (20) are fitted onto the mounting shaft (13) while being detachably screwed and fastened to c). Backflow prevention device for injection molding machines.