JP3345366B2 - Injection device and its injection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection device and an injection method.

[0002]

2. Description of the Related Art Conventionally, in an injection molding machine, a resin heated and melted in a heating cylinder is injected at a high pressure to fill a cavity space of a mold apparatus.
A molded product can be obtained by cooling and solidifying in the cavity space.

For this purpose, the injection molding machine has a mold clamping device and an injection device. The mold clamping device has a fixed platen and a movable platen, and a mold clamping cylinder advances and retreats the movable platen to form a mold device. Close, close and open the mold. The injection device includes a heating cylinder that heats and melts the resin supplied from the hopper, and an injection nozzle that injects the melted resin, wherein a screw is rotatable in the heating cylinder and moves forward and backward. Arranged freely. Then, by driving the first driving means connected to the rear end of the screw to advance the screw without rotating it, the resin is injected from the injection nozzle, and the resin is similarly connected to the rear end of the screw. The resin is metered by driving the second driving means to rotate and retreat the screw.

FIG. 2 is a sectional view of a main part of a conventional injection device. In the figure, reference numeral 12 denotes a heating cylinder, and an injection nozzle 13 is provided at a front end (left end in the figure) of the heating cylinder 12.
A screw 22 is provided in the heating cylinder 12 so as to be rotatable and advance and retreat.
The screw 22 has a screw head 22a at the front end, and the screw head 22a is screwed to a rear (right side in the figure) metering portion 22b. Further, the screw 22 is connected to the heating cylinder 1.
2 and is connected to first and second driving means (not shown) at a rear end (right end in the figure). A spiral (helical) flight 23 is formed on the outer periphery of the metering portion 22b, and a groove 26 is formed by the flight 23.

A resin supply port (not shown) is formed at a predetermined location of the heating cylinder 12, and a hopper is fixed to the resin supply port. The resin supply port is a screw 2
2 is formed at a position corresponding to the rear end (the right end in the figure) of the groove 26 in a state where the 2 is located at the forefront (the left side in the figure) in the heating cylinder 12.

Next, the operation of the injection device having the above configuration will be described. In the weighing step, when the screw 22 is moved backward (moved to the right in the drawing) by rotating the screw 22 by driving the second driving means, the resin in the hopper falls and enters the heating cylinder 12. Enter,
The heating cylinder 12 is advanced (moved to the left in the drawing).

A heater (not shown) is provided around the heating cylinder 12 so that the heating cylinder 12 can be heated by the heater and the resin in the heating cylinder 12 can be melted. Therefore,
When the screw 22 is rotated backward by a predetermined distance, one shot of the melted resin is stored in front of the screw head 22a.

Next, in the injection step, when the screw 22 is advanced without rotating by driving the first driving means, the screw head 22
The resin stored in front of “a” is injected from the injection nozzle 13 and is filled in a cavity space of a mold device (not shown). By the way, in the injection step, the check ring 16 is provided so that the resin stored in front of the screw head 22a does not flow backward.

For this purpose, the screw head 22a
Has a conical (conical) head body 14 at the front (left part in the figure) and a small diameter part 15 at the rear part (right part in the figure). An annular check ring 16 is provided on the outer periphery of the small diameter portion 15, and a resin flow path is formed between the small diameter portion 15 and the check ring 16. The metering unit 2
A seal ring 17 is disposed at the front end of 2b so as to be able to freely contact and separate from the rear end of the check ring 16.

Therefore, in the above-described injection step, if the screw 22 is advanced without rotating, the resin stored in front of the screw head 22a moves rearward and tends to flow backward. Due to the pressure of the resin, the check ring 16 moves rearward relative to the screw 22 so that the rear end of the check ring 16
Abut on the front end of the seal. As a result, the resin stored in front of the screw head 22a can be prevented from flowing backward.

On the other hand, in the measuring step, the screw 22
Is rotated back, the check ring 16 moves forward relative to the screw 22 by the pressure of the resin, and the front end of the check ring 16 is
However, since the notch (not shown) extending in the axial direction is formed at a plurality of locations around the head main body portion 14, the movement of the resin is not hindered.

[0012]

However, in the above-described conventional injection device, if the clearance δ between the inner circumference of the heating cylinder 12 and the outer circumference of the screw 22 is large, in the injection process, the resin is removed via the clearance δ. Backflow occurs, and the filling amount of the resin into the cavity space fluctuates. In addition, since the check ring 16 advances as the screw 22 advances, the timing at which the check ring 16 and the seal ring 17 come into contact may slightly change. And seal ring 1
The amount of the resin flowing backward before contact with 7 also changes.

Therefore, when molding a small molded product, the quality of the molded product is deteriorated only by a slight change in the filling amount or the reverse flow amount of the resin. In addition, the dimensions, quality, and the like of the molded product vary, and the molded product cannot be formed stably. Therefore, the clearance δ
Heating screw 12 and screw 2 so that
However, when the clearance δ is reduced, as the screw 22 advances and retreats,
Galling occurs between the screw head 22a and the heating cylinder 12, or between the check ring 16 and the heating cylinder 12, and the screw head 22a, the check ring 16 or the heating cylinder 12 is damaged.

The present invention solves the above-mentioned problems of the conventional injection device, and can stably mold a molded product, and does not damage a screw head, a check ring or a heating cylinder. An object of the present invention is to provide an injection method.

[0015]

For this purpose, in the injection apparatus of the present invention, a heating cylinder, a rotatable and reciprocatingly disposed inside the heating cylinder, and a screw head at the front end are provided. It has a screw, first driving means for moving the screw forward and backward, second driving means for rotating the screw, and a check ring disposed on the screw head. The clearance between the outer circumference of the check ring and the inner circumference of the heating cylinder at the measuring position set in the heating cylinder is equal to the outer circumference of the screw and the inner circumference of the heating cylinder behind the measuring position. Is smaller than the clearance between. The measuring position is a position where one shot of resin is stored in front of the screw head. Then, in the measuring step, the screw is rotated in a state of stopping at the measuring position without being retracted.

In another injection apparatus according to the present invention, the measuring position is such that the screw is retracted by a predetermined distance from the forward limit position to be at the retract limit position, and is slightly advanced from the retract limit position. Sometimes, a gap is formed between the check ring and the screw head and between the check ring and the seal ring. In still another injection device of the present invention, the clearance between the outer periphery of the check ring and the inner periphery of the heating cylinder is formed over a distance from a forward limit position of the screw to the metering position. You. In still another injection device of the present invention, the heating cylinder further comprises:
It has a cylinder head, a cylinder middle, and a cylinder body. The cylinder intermediate portion is removably attached to the cylinder body, and the cylinder head portion is detachably attached to the cylinder intermediate portion. In still another injection device of the present invention, the clearance between the outer periphery of the check ring and the inner periphery of the heating cylinder is 5 to 10 [mm].

In the injection method of the injection device according to the present invention,
A heating cylinder, a screw provided rotatably and advancing and retreating in the heating cylinder, and having a screw head at a front end, and a check ring provided at the screw head; The clearance between the outer circumference of the check ring and the inner circumference of the heating cylinder at the measuring position set in the clearance between the outer circumference of the screw and the inner circumference of the heating cylinder behind the measuring position. Applies to smaller injection devices. Then, a suck-back step of retracting the screw to the measurement position, a measurement step of rotating the screw at the measurement position and stopping the screw to store the resin in front of the screw head, and moving the screw forward And performing an injection step. In the injection method of another injection device of the present invention, further, in the measuring position, the screw is retracted by a predetermined distance from the forward limit position, is placed in the retract position, and is slightly advanced from the retract position. Sometimes, a gap is formed between the check ring and the screw head and between the check ring and the seal ring.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a sectional view of a main part of an injection device according to a first embodiment of the present invention.
FIG. 4 is a view for explaining the operation of the injection device according to the first embodiment of the present invention, FIG. 4 is a first view showing a state of the check ring in the first embodiment of the present invention, and FIG. First
FIG. 6 is a second diagram showing a state of the check ring in the embodiment, and FIG. 6 is a third diagram showing a state of the check ring in the first embodiment of the present invention.

In the figure, reference numeral 32 denotes a heating cylinder as an injection cylindrical body, which includes a cylinder head 33 having a length L1; a cylinder intermediate portion 36 having a length L3; The cylinder head 33 has a length L4, and the cylinder head 33 is detachably attached to a cylinder intermediate part 36 by a bolt 35 as a first fixing means. It is detachably attached to the cylinder body 34 by a bolt as a fixing means of 2. An injection nozzle 13 is attached to a front end (left end in the figure) of the cylinder head 33, and a screw 2 as an injection member is provided in the heating cylinder 32.
2 is disposed rotatably and freely forward and backward.

The screw 22 has a screw head 22a at the front end, and the screw head 22a
Is screwed to the rear (right side in the figure) metering portion 22b. The screw 22 extends rearward in the heating cylinder 32 and has a rear end (right end in the figure).
Are connected to first and second driving means (not shown). A spiral flight 23 is formed on the outer periphery of the metering portion 22b, and a groove 26 is formed by the flight 23. The screw 22, the heating cylinder 32 and the first and second driving means constitute an injection device, and the injection device and a mold clamping device (not shown) constitute an injection molding machine. Then, a control device (not shown) is provided, and the control device controls the injection device and the mold clamping device.

A resin supply port (not shown) is formed at a predetermined position of the heating cylinder 32, and a hopper is fixed to the resin supply port. The resin supply port is a screw 22
Is rotated backward by a predetermined distance so that the resin that is advanced in the groove 26 when it is rotated is sufficiently melted before reaching the front end of the metering portion 22b.

In the injection step, a check ring 16 is provided to prevent the resin stored in front of the screw head 22a from flowing backward. For this purpose, the screw head 22a is located at the front (left in the figure).
And a small-diameter portion 15 at a rear portion (right portion in the figure). An annular check ring 16 is provided on the outer periphery of the small diameter portion 15, and a resin flow path is formed between the small diameter portion 15 and the check ring 16. The check ring 16 is provided at the front end of the metering portion 22b.
A seal ring 17 is disposed so as to be able to freely contact with and separate from the rear end.

Therefore, in the above-mentioned injection step, if the screw 22 is advanced without rotating, the resin stored in front of the screw head 22a moves rearward and tries to flow backward. Due to the pressure of the resin, the check ring 16 moves rearward relative to the screw 22 so that the rear end of the check ring 16
Abut on the front end of the seal. As a result, it is possible to prevent the resin stored in front of the screw head 22a (leftward in the figure) from flowing backward.

On the other hand, in the measuring step, the screw 22
Is rotated at a measuring position described later, the check ring 16 moves forward relative to the screw 22 by the pressure of the resin, and the front end of the check ring 16 contacts the rear end of the head main body 14. Although not in contact, notches (not shown) extending in the axial direction are formed at a plurality of locations around the head main body portion 14, so that the movement of the resin is not hindered.

In the injection step, when the resin flows backward through the clearance between the outer periphery of the check ring 16 and the inner periphery of the heating cylinder 32, the amount of resin filling the cavity space varies. In addition, since the check ring 16 advances as the screw 22 advances, the timing at which the check ring 16 and the seal ring 17 come into contact may slightly change. The amount of resin flowing backward until the resin and the seal ring 17 come into contact also changes. Therefore, when molding a small molded product, the quality of the molded product is deteriorated by only slightly changing the filling amount or the amount of the resin flowing backward. In addition, the dimensions, quality, etc. of the molded products vary,
It is not possible to stably mold molded products.

Therefore, it is conceivable to design the heating cylinder 32 and the screw 22 so as to reduce the clearance. However, when the clearance is reduced, the screw head 22a and the heating cylinder 32 are connected with each other as the screw 22 advances and retreats. Ring or check ring 16
Galling occurs between the screw head 22a, the check ring 16 and the heating cylinder 32.
Will be damaged.

Therefore, the inside diameter of the heating cylinder 32 is reduced in a predetermined area in the front, that is, in the cylinder head 33, and the area behind the measuring position, that is, in the cylinder head 33,
The cylinder intermediate portion 36 and the cylinder body 34 are made larger. In the present embodiment, the clearance between the forward limit position of the screw 22 and the metering position, that is, the clearance between the outer circumference of the check ring 16 and the inner circumference of the cylinder head 33 at the distance L1 is δ1
(Approximately 5 to 10 μm), and the clearance between the outer periphery of the screw 22 and the inner periphery of the cylinder intermediate portion 36 and the cylinder body 34 is δ2 (approximately 20 to 30 μm).
, The clearances δ1 and δ2 are set to δ1 <δ2. In the present embodiment, the clearance δ1 is reduced by reducing the inner diameter of the cylinder head 33, but by increasing the diameter of the check ring 16 while keeping the inner diameter of the cylinder head 33 unchanged. The clearance δ1 can be reduced.

Next, the operation of the injection device having the above configuration will be described. FIG. 1 shows a state in which the injection step has been completed, and the screw 22 is located at the forward limit position in the heating cylinder 32. When the injection step is completed, first, suck back is performed in the suck back step, and by driving the first driving means, the screw 22 is not rotated, and the screw 22 is rotated for a predetermined distance as shown in FIG. It is moved backward (moved to the right in the figure) by L5 and placed at the retreat limit position. Then, when the screw 22 is placed at the retreat limit position, the check ring 16 and the screw head 22a come into contact as shown in FIG. Next, as shown in FIG. 5, when the first driving means is driven to slightly advance the screw 22 to the metering position, a gap is formed between the check ring 16 and the screw head 22a. The gap a is between the check ring 16 and the seal ring 1
7, a gap b is formed. In this case, the clearance δ1 between the outer circumference of the check ring 16 and the inner circumference of the cylinder head 33 is extremely small. Therefore, the check ring 16 does not move even if the screw 22 advances slightly. During this time, the screw 22 is not rotated, so that no resin is stored in front of the screw head 22a. The retracted position is the position of the seal ring 1.
7 is set so as to be slightly behind the front end surface of the cylinder intermediate portion 36, and the measuring position is set such that the front end surface of the seal ring 17 and the front end surface of the cylinder intermediate portion 36 substantially coincide with each other. Is done.

Next, in the measuring step, when the screw 22 is rotated in a stopped state at the measuring position by driving the second driving means, the resin in the hopper drops and is heated. It enters the cylinder 32 and moves forward (moves to the left in the figure) in the groove 26. During this time, the screw 22 rotates, but the check ring 16 hardly rotates. Further, the gap a,
Since b is formed, the check ring 16 is hardly worn even when the screw 22 rotates. Since the clearance δ1 is extremely small, the check ring 16 hardly moves even under the pressure of the resin.

A heater (not shown) as heating means is provided around the heating cylinder 32 so that the heating cylinder 32 can be heated by the heater and the resin in the heating cylinder 32 can be melted. Has become. Therefore, when the screw 22 is rotated, the resin is advanced in the groove 26 by a predetermined distance L2,
One shot is stored in front of the screw head 22a.

Next, in the injection step, when the first driving means is driven to advance the screw 22 without rotating, the check ring 16 is moved relative to the screw 22 as shown in FIG. The check ring 16 and the seal ring 17 come into contact with each other, and the resin stored in front of the screw head 22a is injected from the injection nozzle 13 and enters the cavity space of a mold device (not shown). Will be filled.

As described above, in the present embodiment, the clearance between the outer periphery of the check ring 16 and the inner periphery of the cylinder head 33 is set to δ1, so that the resin is removed via the clearance δ1 in the injection step. Backflow can be prevented. Therefore, the filling amount of the resin in the cavity space can be made constant. In addition, after the screw 22 is placed at the retreat limit position, the screw 22 is slightly advanced by the time the injection process is started.
With the check ring 16 stopped, place the check ring 1
A gap a can be formed between the check ring 6 and the screw head 22a, and a gap b can be formed between the check ring 16 and the seal ring 17. Therefore, when the injection step is started, it is possible to prevent the timing at which the check ring 16 and the seal ring 17 come into contact from changing. As a result, the amount of resin flowing backward until the check ring 16 and the seal ring 17 come into contact can be made constant.

As described above, since the filling amount and the amount of the resin flowing backward can be made constant, the quality of the molded product can be improved. Further, since it is possible to suppress the occurrence of variations in the dimensions, quality, and the like of the molded article, it is possible to stably mold the molded article. Also, screw 2
2 does not need to be retracted at the metering position, so that galling between the screw head 22a and the heating cylinder 32 or between the check ring 16 and the heating cylinder 32 can be prevented. Therefore, the screw head 22a, the check ring 16 or the heating cylinder 3
2 is not damaged.

Further, since the cylinder head portion 33 can be separated from the cylinder body portion 34 and the cylinder intermediate portion 36, the clearance δ1 can be easily changed, and the cylinder head portion 33, the cylinder body portion 34 or When the cylinder intermediate portion 36 is damaged, it can be easily replaced. Further, when the type of the molded article is changed and the amount of resin for one shot required for molding is changed, the cylinder head 33 is replaced, and the effective distance is set to a value necessary for molding the molded article. It can be changed according to the amount of resin.

When the amount of resin for one shot changes, the cylinder head portion 33 and the cylinder intermediate portion 36 can be replaced by using the cylinder body portion 34 as it is. For example, when it is desired to increase the amount of resin for one shot, the cylinder head portion 33 is lengthened and the cylinder intermediate portion 36 is shortened accordingly. Therefore, the distance L1,
L3 and L4 are as follows: L1 + L3 + L4 = C (constant) L1 + L3 = K (constant)

Next, a second embodiment of the present invention will be described. In addition, about what has the same structure as 1st Embodiment, the description is abbreviate | omitted by attaching the same code | symbol. FIG. 7 is a sectional view of a main part of an injection device according to a second embodiment of the present invention. In this case, in the cylinder head 33, the inner diameter of the portion P1 facing the check ring 16 when the screw 22 is placed at the measurement position is reduced, and the inner diameters of the other portions are slightly increased.

Next, a third embodiment of the present invention will be described. In addition, about what has the same structure as 1st Embodiment, the description is abbreviate | omitted by attaching the same code | symbol. FIG. 8 is a sectional view of a main part of an injection device according to a third embodiment of the present invention. In this case, as the inner diameter of the cylinder head portion 33 is made larger than the inner diameters of the cylinder body portion 34 and the cylinder intermediate portion 36, the outer diameter of the check ring 16 is increased accordingly.

Therefore, since the inner diameter of the cylinder head 33 is large, the amount of resin stored in front of the screw head 22a can be increased. It should be noted that the present invention is not limited to the above-described embodiment, but can be variously modified based on the gist of the present invention, and they are not excluded from the scope of the present invention.

[0039]

As described above in detail, according to the present invention, in the injection device, the heating cylinder and the heating cylinder are rotatably and reciprocally disposed within the heating cylinder, and the screw is provided at the front end. A screw with a head,
The screw drive includes a first drive unit for moving the screw forward and backward, a second drive unit for rotating the screw, and a check ring disposed on the screw head. The clearance between the outer circumference of the check ring and the inner circumference of the heating cylinder at the measuring position set in the heating cylinder is equal to the outer circumference of the screw and the inner circumference of the heating cylinder behind the measuring position. Is smaller than the clearance between. The measuring position is a position where one shot of resin is stored in front of the screw head. And in the measuring step, the screw is
It is rotated without stopping at the measuring position without being retracted.

In this case, the clearance between the outer periphery of the check ring at the measuring position and the inner periphery of the heating cylinder is equal to the clearance between the outer periphery of the screw and the inner periphery of the heating cylinder in a region behind the measuring position. Since it is smaller than the clearance, it is possible to prevent the resin from flowing backward through the clearance in the injection step.

Further, when the injection step is started, the timing at which the check ring and the seal ring come into contact can be prevented from changing, so that the time until the check ring and the seal ring come into contact with each other can be prevented. The amount of resin flowing backward can be constant. Therefore, the filling amount of the resin into the cavity space and the amount of the resin flowing backward can be made constant, so that the quality of the molded product can be improved. Further, since it is possible to suppress the occurrence of variations in the dimensions, quality, and the like of the molded article, it is possible to stably mold the molded article.

Further, since it is not necessary to retract the screw at the metering position, it is possible to prevent galling between the screw head and the heating cylinder or between the check ring and the heating cylinder. Therefore, the screw head, the check ring or the heating cylinder is not damaged.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of an injection device according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a main part of a conventional injection device.

FIG. 3 is a diagram illustrating an operation of the injection device according to the first embodiment of the present invention.

FIG. 4 is a first diagram showing a state of a check ring according to the first embodiment of the present invention.

FIG. 5 is a second diagram showing a state of the check ring according to the first embodiment of the present invention.

FIG. 6 is a third diagram showing a state of the check ring according to the first embodiment of the present invention.

FIG. 7 is a sectional view of a main part of an injection device according to a second embodiment of the present invention.

FIG. 8 is a sectional view of a main part of an injection device according to a third embodiment of the present invention.

[Explanation of symbols]

 16 Check ring 22 Screw 22a Screw head 32 Heating cylinder δ1, δ2 Clearance

Claims (7)

(57) [Claims] (A) a heating cylinder; and (b) a rotatable and rotatable interior of the heating cylinder.
(C) first drive means for moving the screw forward and backward, (d) second drive means for rotating the screw, and (e) second drive means for rotating the screw. And (f) a clearance between the outer circumference of the check ring and the inner circumference of the heating cylinder at a measuring position set in the heating cylinder, And a clearance between an outer periphery of the heating cylinder and an inner periphery of a region behind the weighing position in the heating cylinder , and (g) the weighing position is located in front of the screw head.
A position one shot of resin is stored in (h) metering process, the screw is retracted
The injection device is rotated without stopping at the weighing position without being rotated . 2. The measuring position includes moving the screw forward.
Backward from the limit position by a predetermined distance and
When slightly advanced from the retreat limit position,
Between the check ring and the screw head, and the reverse
Position where a gap is formed between the retaining ring and the seal ring
The injection device according to claim 1, wherein 3. An outer periphery of the check ring and the heating syringe.
The clearance between the inner circumference of the screw and the screw
Over the distance from the forward end position of the
The injection device according to claim 1 or 2, which is formed. 4. (a) The heating cylinder is connected to a cylinder.
A cylinder portion, a cylinder intermediate portion, and a cylinder body portion. (B) The cylinder intermediate portion is provided with the cylinder body portion on the cylinder body portion.
The cylinder head is detachably mounted on the middle part of the cylinder.
An injection device according to any one of claims 1 to 3, which is attached.
Place. 5. An outer periphery of said check ring and a heating cylinder.
The clearance between the inner circumference and the inner circumference is 5 to 10 mm.
The injection device according to claim 1. 6. A heating cylinder, a screw provided rotatably and advancing and retracting in the heating cylinder, having a screw head at a front end, and a check ring provided at the screw head. Along with the clearance between the outer periphery of the check ring and the inner periphery of the heating cylinder at the measuring position set in the heating cylinder, the outer periphery of the screw and the inner periphery of the heating cylinder in a region behind the measuring position. (A) a suck-back step of retracting the screw to the weighing position; and (b) rotating the screw in a stopped state at the weighing position. Resin in front of the screw head
A measuring step of storing the injection method of the injection apparatus characterized by having an exit step of performing injection by advancing (c) the screw. 7. The measuring position includes moving the screw forward.
Backward from the limit position by a predetermined distance and
When slightly advanced from the retreat limit position,
Between the check ring and the screw head, and the reverse
Position where a gap is formed between the retaining ring and the seal ring
The injection method of the injection device according to claim 6, wherein: