JPH0584793A - Device for preventing backflow in preplasticating injection molding machine - Google Patents

Abstract

PURPOSE:To recognize the abrasion state with the lapse of time in a valve body from the outside while surely preventing the backflow of plasticated molten material and to enhance the replacement workability of the valve body and also to inhibit the great advance of cost. CONSTITUTION:Plasticated molten material 27 is supplied to the reservoir part 29 of a plunger cylinder 21, via a supply passage 33 from the inside of a preplasticating cylinder 31. This plasticated molten material 27 is injected into a mold by an injection plunger 25. The preplasticating injection molding machine is constituted so that the valve body 38 of a shutter valve 36 is vertically slid and moved through a gap part 35 present between the slit both end parts 34a, 34b of a supply passage pipe 34 and thereby the supply passage 33 is opened and closed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backflow preventive device for a pre-plastic injection molding machine in which plasticizing and injection of a plastic material are carried out in separate processes.

[0002]

2. Description of the Related Art As is well known, by performing plasticizing and injection of a resin material or a rubber material in separate processes, a pre-plastic injection molding is possible under the optimum conditions to achieve consistent quality without variation. Machine, one example of which is JP-A-3-97
Some are disclosed in Japanese Patent No. 518, etc.

The outline will be described with reference to FIG. 7. Reference numeral 1 is an injection molding machine main body, 2 is a pre-plasticizing mechanism connected to the main body 1, and the injection molding machine main body 1 has a band heater 3 on its outer periphery.
Is provided with a plunger cylinder 4 and an injection plunger 6 whose base is slidably housed in an injection cylinder 5 and whose tip moves forward and backward in the plunger cylinder 4. On the other hand, the prepla mechanism 2 is connected to the tip of the plunger cylinder 4 in an inclined manner, and has a prepla cylinder 8 having a band heater 7 on the outer periphery, and a prepla screw 9 provided in the prepla cylinder 8 so as to be capable of advancing and retracting. I have it.

When the molten material 10 plasticized by the pre-plastic mechanism 2 is supplied from the pre-plastic cylinder 8 through the supply passage 11 to the resin reservoir 12 at the front of the plunger cylinder 4, the plasticized molten material 10 is supplied. The injection plunger 6 moves backward with the increase of. When the injection plunger 6 retracts to the initial position, the supply of the plasticized molten material 10 to the resin reservoir 12 is stopped. That is, a single injection amount of the plasticized molten material 10 is measured by the retracted amount of the injection plunger 6, and the supply is stopped at this initial position. Next, the injection plunger 6 advances to pressurize the plasticized molten material 10,
It is designed to be injected into the cavity of a mold (not shown) through the nozzle 13.

In the figure, 14 is a hopper provided at the upper end of the pre-plastic cylinder 8, and 15 is a pre-plastic screw 9
Actuator 16 for driving the injection plunger 16
Is a control mechanism for driving the.

By the way, in the above-mentioned pre-plastic type injection molding machine, when the injection plunger 6 advances and the plasticized molten material 10 in the reservoir 12 is pushed out at a high pressure during the injection step, the plasticized molten material 10 is There is a possibility that a part of the gas may flow back into the pre-plastic cylinder 8 via the supply passage 11. For this reason,
During the injection process, the pre-plastic screw 9 is moved forward to move the screw head 9a so that the supply passage 11 has one end opening edge 11a.
The supply passage 11 is closed by pressing it to prevent backflow.

[0007]

However, in the above-mentioned conventional pre-plastic injection molding machine, in order to prevent the back flow of the plasticized molten material 10, the screw head 9a is pushed against the one opening edge 11a of the supply passage 11 each time. The screw head 9a and the opening edge 1 at one end are designed to come into contact with each other for sealing.
1a wears over time, and this wear state cannot be recognized from the outside. As a result, the wear deterioration progresses and the pre-plastic cylinder 8 and the pre-plastic screw 9 as a whole must be replaced, and the replacement work is complicated, and
This causes a large rise in work costs.

As another means for preventing the backflow of the plasticized molten material, a check valve that slides freely in the axial direction is provided at the base end of the screw head of the pre-plastic screw,
When the internal pressure in the reservoir rises as the plasticized molten material is filled, the check valve retracts and hits the sealing surface of the screw, closing the tip side of the pre-plastic cylinder to prevent backflow. However, also in this case, the check valve and the seal surface are worn, and the wear state cannot be recognized from the outside, which causes the same problem as described above.

[0009]

The present invention has been devised in view of the problems of the above-mentioned respective prior art examples, and has a supply passage having a plastic molten material in a pre-plastic cylinder at the tip side of the pre-plastic cylinder. In the pre-plastic injection molding machine in which the plastic molten material in the reservoir is injected into the mold by the injection plunger in the plunger cylinder, A shutter valve that forms a gap along the radial direction and that opens and closes the supply passage by a valve body sliding inside the gap is provided on the way.

[0010]

According to the present invention having the above-described structure, when the plasticized molten material is supplied from the pre-plastic cylinder into the reservoir, the valve body of the shutter valve slides in the gap in one direction and has the valve body. Both supply passages sandwiching the gap are communicated with each other through the passage hole to secure a flow passage for the plasticized molten material.

On the other hand, when the plasticized molten material in the reservoir is injected into the mold by the injection plunger, the valve body slides in the other direction and the passage closing portion of the valve body closes the middle of the supply passage. .. This surely prevents the plasticized molten material in the reservoir from flowing back to the pre-plastic cylinder.

Moreover, when the valve body of the shutter valve slides in one direction as described above, the passage closed portion of the valve body is exposed to the outside, and therefore the wear state of the passage closed portion is recognized from the outside. It will be possible.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

1 and 2 show an embodiment of a pre-plastic injection molding machine according to the present invention, in which 21 is an injection molding machine main body,
Reference numeral 22 is a pre-plasticizing mechanism connected to the main body 21 of the injection molding machine.

The injection molding machine main body 21 has a plunger cylinder 24 around which a plurality of band heaters 23 are wound.
And an injection plunger 25 that moves back and forth in the plunger cylinder 24. The plunger cylinder 2
No. 4 has a hydraulic cylinder 26 for driving the injection plunger 25 at the upper end, and a nozzle 28 for injecting the plasticized molten material 27 into the cavity in the mold (not shown) at the lower end. Further, inside the lower end side of the plunger cylinder 24, a reservoir portion 29 for temporarily retaining the plasticized molten material 27 is formed. The injection plunger 25
Has a substantially columnar shape and is connected to the drive rod 26a of the hydraulic cylinder 26.

On the other hand, the pre-pla mechanism 22 is connected to the side wall of the tip end portion of the plunger cylinder 24 in the direction perpendicular to the axis and has a band heater 30 on the outer periphery.
And a pre-plastic screw 32 provided inside the pre-plastic cylinder 31 so as to be movable back and forth. The pre-plastic cylinder 31 has a supply passage 33 connected to the side wall of the plunger cylinder 24 at the front end thereof to connect the inside of the pre-plastic cylinder 31 and the reservoir 29, and the pre-plastic screw 32 is rotated at the rear end thereof. A hydraulic motor is provided. The hydraulic motor is drive-controlled by an electromagnetic switching valve and an electronic control circuit (not shown).

Further, the supply passage pipe 34 forming the supply passage 33 is divided in the middle, a gap 35 is formed between the divided opposite end portions 34a, 34b, and the supply passage 33 is formed. A shutter valve 36 that opens and closes is provided.

The shutter valve 36 includes a guide frame 37 fixed to the main body 21 of the injection molding machine and the guide frame 37.
And a hydraulic cylinder 39 that moves the valve body 38 up and down. The guide frame 37 has a vertically long and slender rectangular shape with the gap 35 as the center, and has split end portions 34a,
The front and back of the 34b side are open.

The valve element 38 has an elongated rectangular plate shape,
The length is such that the upper piece 37a and the lower piece 37b of the guide frame 37
The length is set shorter than the length between the inner surfaces of and, and both side surfaces are slidably guided along the inner surfaces of the both side pieces 37c and 37d. Further, as shown in FIG. 3, the valve body 38 has a through passage 38a formed at a predetermined position in the upper end portion along the axial direction of the supply passage 33, and a holding groove 38b parallel to the through passage 38a at the lower end portion. Has been formed. Further, the through passage 38a
The passage forming member 40 is screwed to the internal thread cut on the inner peripheral surface of the passage, while the sealing member 41 for closing the passage is screwed to the internal thread cut on the inner peripheral surface of the holding groove 38b. ..
The passage constituting member 40 has a substantially cylindrical shape, has an external thread formed on the outer peripheral surface thereof, a passage hole 40a is formed therethrough in the central axis direction, and a flange portion 40b is provided at the outer end edge. The seal member 41 has a substantially columnar shape, has an outer peripheral surface with an external thread, and has an outer end edge having a front surface 41a.
A flange portion 41b serving as a sealing surface is provided.

The hydraulic cylinder 39 is mounted and fixed in the center of the upper piece portion 37a of the guide frame 37, and the tip of the drive rod 39a is connected to the upper surface of the valve body 38. Further, in the hydraulic cylinder 39, the valve body 38 is moved up and down via the drive rod 39a by a hydraulic control mechanism (not shown), and the center of the flange portion 41b of the seal member 41 is located at the axis of the supply passage 33 at the maximum upward movement position. In the mind, the passage component 40 at the maximum down position
The center of the passage hole 40a is controlled so as to be located at the axis of the supply passage 33.

Further, as shown in FIGS. 1 and 3, a turning mechanism 42 is provided at the divided end portion 34a on the side of the pre-plastic screw 32.
An advancing / retreating member 43 is provided to be brought into contact with or separated from the valve element 38 via the. The advancing / retreating member 43 has a substantially cylindrical shape, has a passage portion 43a formed continuously with the supply passage 33 on the inner periphery thereof, and has a male screw 34c formed on the inner peripheral surface of the divided end portion 34a on the outer peripheral surface thereof. The mating male screw 43b is cut and is formed so as to be able to move forward and backward through the female and male screws 34c and 43b.

As shown in FIG. 2, the rotating mechanism 42 is connected to a large-diameter flange 44 integrally provided on the outer periphery of the front end portion of the advancing / retreating member 43, and a protrusion 44a on the outer peripheral edge of the large-diameter flange 44. The hydraulic actuator 46 is connected via the bracket 45. The connecting bracket has a distal end rotatably supported by a protrusion 44a via a pivot pin 47, and a proximal end connected and fixed to a distal end of a drive rod 46a of a hydraulic actuator 46. The hydraulic actuator 46 is vertically disposed at an upper position on a side portion of the large-diameter flange 44, and expands and contracts the drive rod 46a via a control mechanism (not shown) to rotate the large-diameter flange 44. The advancing / retreating member 43 is moved forward / backward.

The operation of this embodiment will be described below.
That is, when the plasticized molten material 27 in the pre-plastic cylinder 31 is supplied into the reservoir portion 29 via the pre-plastic screw 32, first, the drive rod 4 of the hydraulic actuator 46 is driven.
6a rises to rotate the large-diameter flange 44 in the direction of the broken line arrow (clockwise direction) in FIG. Therefore, the advancing / retreating member 43
Rotates in the same direction and retreats, and as shown in FIG.
With a distance. In this state, when the valve body 38 is slid downward in the guide frame 37 by the hydraulic cylinder 39 and reaches the maximum lowered position, the passage hole 40a and the supply passage 33 are positioned coaxially. Next, the hydraulic actuator 4
The drive rod 46a of 6 descends to rotate the large-diameter flange 44 in the direction of the solid arrow in FIG. 2 (counterclockwise direction). Therefore, the advancing / retreating member 43 advances as shown in FIG. 4B, and the tip end surface 43c comes into pressure contact with the front surface 40c of the flange portion 40b of the passage forming member 40. As a result, each divided end 34a,
34b is reliably connected via the valve element 38, and the entire supply passage 33 communicates with each other to secure a flow passage for the plasticized molten material 27.

Therefore, after that, the pre-plastic screw 3
2 rotates, and the plasticized molten material 27 can be smoothly supplied from the supply passage 33 to the reservoir 29.

Next, when injecting the plasticized molten material 27 in the reservoir portion 29 by the injection plunger 25, the advancing / retreating member 43 is first retracted to be separated from the passage forming member 40 as shown in FIG. 4C. Subsequently, the valve element 38 is slid upward as shown in FIG. 4D. And the valve body 38
When reaches the maximum rising position, the seal member 41 and the supply passage 33 will be positioned coaxially from now on. Large diameter flange 4
4 is rotated so that the advancing / retreating member 43 advances as shown in FIG.
b While being pressed against the front surface 41a, the other end 34
One side 38c of the valve element 38 is brought into pressure contact with b. As a result, the supply passage 33 is reliably closed by the seal member 41, and backflow of the plasticized molten material 27 into the pre-plastic cylinder 31 during injection is prevented.

After the injection is completed, the advancing / retreating member 43 is shown in FIG. 4F.
As shown in (3), the valve element 38 is moved backward to allow the sliding movement of the valve element 38 downward.

In this way, the valve body 38 slides up and down in the guide frame 37, and the passage constituting member 40 and the seal member 41 are completely exposed to the outside at the maximum vertical movement position. The wear state of each of the flange portions 40b and 41b of the seal member 41 can be easily recognized from the outside. Therefore, if wear deterioration progresses,
The members 40 and 41 and the valve body 38 can be removed and replaced. Therefore, unlike the conventional case, it is not necessary to replace the entire main parts such as the pre-plastic cylinder and the screw, which is extremely advantageous in terms of cost and the like. In particular, each member 40, 41 can be easily removed from the outside by being completely exposed to the outside, so that the replacement work efficiency is significantly improved.

Further, the passage hole 40a of the passage forming member 40 of the valve body 38 and the passage portion 43a of the advancing / retreating member 43 are connected to each other by the supply passage 3.
Since it is set to the same diameter as the inner diameter of 3, the plasticized molten material 2
No sticking of 7 to the inner peripheral surface of the passage causes clogging, and smooth flow is always obtained.

Since the valve body 38 is forcibly slid by the hydraulic cylinder 39, the supply passage 3
The opening and closing action of 3 becomes reliable.

FIG. 5 shows a second embodiment of the present invention in which a pair of through passages 50, 50 and holding grooves 51, 51 are formed on both sides of the valve body 38, each having an internal thread on its inner peripheral surface. , The through-passages 50, 50, the holding grooves 51, 51 in the divided end portions 34a,
Passage forming members 52, 52 and seal members 53, 53 which are brought into proper pressure contact with the end face of 34b are provided. Therefore, when they are worn and deteriorated, they can be individually replaced, which facilitates the replacement work.

FIG. 6 is based on the configuration of each of the above embodiments.
The shutter valve 36 and a part of the rotating mechanism 42 are provided with a partition wall 60.
The inside of the partition wall 60 is vacuumized by using a vacuum pump to prevent air from entering the supply passage 33, that is, the plasticized molten material 27 when the valve body 38 is switched up and down. Is.

The present invention is not limited to the above-mentioned structure, and for example, the valve element 38 can be formed in a large-diameter disk shape and can be rotationally slid in an eccentric state. Further, it is possible to use air instead of hydraulic pressure for the various drive mechanisms.

[0033]

As is apparent from the above description, according to the backflow prevention device for the pre-plastic injection molding machine according to the present invention, the supply passage is slid in the gap of the supply passage pipe in which the valve body is divided. Since the shutter valve for opening and closing the valve is provided, it is possible to surely prevent the backflow of the plasticized molten material, and it is possible to recognize the time-dependent wear state of the valve body from the outside. As a result, the valve element that has deteriorated due to wear can be replaced independently, so that the workability of replacement can be improved and the increase in cost can be suppressed.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention.

FIG. 2 is a perspective view of a main part of this embodiment.

FIG. 3 is a cross-sectional view of a main part of this embodiment.

FIG. 4 is an explanatory diagram showing the operation of the present embodiment.

FIG. 5 is a cross-sectional view of essential parts showing a second embodiment of the present invention.

FIG. 6 is a sectional view showing another example of the present invention.

FIG. 7 is a cross-sectional view showing a conventional pre-plastic injection machine.

[Explanation of symbols]

21 ... Injection molding machine main body, 22 ... Pre-plastic mechanism, 24 ... Plunger cylinder, 25 ... Injection plunger, 27 ... Plasticizing melt material, 29 ... Reservoir part, 31 ... Pre-plastic cylinder,
32 ... Pre-plastic screw, 33 ... Supply passage, 34 ... Supply passage pipe, 35 ... Gap, 36 ... Shutter valve, 3
8 ... Valve body.

Claims (1)

[Claims] 1. A plastic melt material in a pre-plastic cylinder is supplied to a reservoir portion of a plunger cylinder through a supply passage provided at a tip side of the pre-plastic cylinder, and the plastic melt material in the reservoir portion is supplied in the plunger cylinder. In the pre-plastic injection molding machine for injecting into the mold by the injection plunger of No. 1, in the middle of the supply passage pipe of the pre-plastic cylinder, a gap along the radial direction is formed, and the valve body slides in the gap. A backflow prevention device for a pre-plastic injection molding machine, comprising a shutter valve for opening and closing the supply passage.