JP3345360B2 - Injection equipment - 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.

[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. On the other hand, 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, the resin is injected from the injection nozzle by moving the screw forward by the first driving means connected to the rear end, and the resin is measured by moving the screw backward by the second driving means.

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.
Is attached. A screw 22 is disposed in the heating cylinder 12 so as to be rotatable and advance / 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. The screw 22 extends rearward in the heating cylinder 12 and is connected at a rear end (right end in the figure) to first and second driving means (not shown). A spiral flight 23 is formed on the outer periphery of the metering portion 22b.
Is formed.

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. First, in the weighing step, when the screw 22 is rotated backward (moved to the right in the drawing) by driving the second driving means, the pellet-shaped resin in the hopper falls down. It enters the heating cylinder 12 and moves forward (moves to the left in the drawing) in the heating cylinder 12.

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 retracted by a predetermined distance while rotating, 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 resin stored in front of the screw head 22a does not flow backward,
A backflow prevention device is provided.

That is, 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, when the screw 22 is advanced in the injection step, the screw head 22
The resin stored in front of a moves backward and tends to flow backward, but the check ring 16 moves relatively backward with respect to the screw 22 due to the pressure of the resin, and the check ring 16 moves backward. The end abuts on the seal ring 17 to perform sealing. 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 retracted, the check ring 16 moves relatively forward with respect 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 portion 14. A plurality of notches (not shown) extending in the axial direction are formed at a plurality of places around the resin 14, so that 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 in the cavity space fluctuates. As a result, when a small molded product is molded, the influence of the fluctuation of the filling amount becomes large, and the molded product cannot be molded stably.

Further, even when a molded article having a normal size is molded, if the speed control of the screw 22 is switched to the pressure control of the screw 22 in the injection step, the pressure of the resin increases, and the resin pressure increases through the clearance δ. Flows backward, and the filling amount of the resin in the cavity space fluctuates.
Therefore, it is conceivable to design the heating cylinder 12 and the screw 22 so that the clearance δ becomes small.
As the screw 2 is advanced and retracted, galling occurs between the screw head 22a or 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.

[0014] The present invention solves the above-mentioned problems of the conventional injection device, and provides an injection device capable of stably forming a molded product without damaging a screw head, a check ring or a heating cylinder. The purpose is to provide.

[0015]

For this purpose, in the injection apparatus of the present invention, a heating cylinder and a screw which is disposed rotatably and advancing and retracting in the heating cylinder and has a screw head at a front end. And first driving means for moving the screw forward and backward, and second driving means for rotating the screw. Then, a portion in front of the Vp switching point where the speed control is switched from pressure control to pressure control when the screw in the heating cylinder is advanced is defined as a predetermined region, and a portion behind the predetermined region is defined as another region. Then, the clearance between the outer periphery of the metering portion of the screw and the inner periphery of the predetermined region in the heating cylinder is defined by the outer periphery of the metering portion and the inner periphery of the other region in the heating cylinder. The clearance between is made smaller. In the measuring step, the rotation of the screw is performed in the other area.

In another injection device of the present invention, a heating cylinder, a screw rotatably and advancing and retracting in the heating cylinder and having a screw head at a front end, and advancing and retreating the screw are provided. It has a first driving means and a second driving means for rotating the screw. Then, a portion in front of a point where the pressure of the resin when the screw in the heating cylinder is advanced forward suddenly increases due to the shape of the cavity space is a predetermined region, and a portion behind the predetermined region is another region. When, and the outer periphery of the metering portion of the screw,
The clearance between the outer periphery of the metering portion and the inner periphery of the other region of the heating cylinder is smaller than the clearance between the inner periphery of the predetermined region in the heating cylinder. In the measuring step, the rotation of the screw is performed in the other area. In still another injection device of the present invention, the heating cylinder further comprises:
A cylinder head is provided at the front and a cylinder body is provided at the rear. The predetermined region is formed in the cylinder head. In still another injection device of the present invention, the cylinder head is detachably attached to the cylinder body.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a cross-sectional view of a main part of an injection device according to an embodiment of the present invention, and FIG. 3 is a diagram illustrating an operation of the injection device according to the embodiment of the present invention. In the figure, reference numeral 32 denotes a heating cylinder. The heating cylinder 32 includes a cylinder head portion 33 at a front portion (left portion in the drawing) and a cylinder body portion 34 at a rear portion (right portion in the drawing). 33 is a bolt 35
Thus, it is detachably attached to the cylinder body 34. The injection nozzle 13 is attached to the front end (left end in the figure) of the cylinder head 33. In the heating cylinder 32, the screw 22 is rotatable,
And it is arranged so that it can move 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.

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 2
2 is located at the forward limit position in the heating cylinder 32, and the rear end of the groove 26 (the right end in the figure)
Is formed at a location corresponding to. 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 process is completed, the injection nozzle 1
First, suckback is performed to prevent the resin from leaking from the screw 3, and the screw 22 is retracted by a predetermined distance L1 without being rotated by the first driving means (moving to the right in the drawing). ) And placed in the weighing start position shown in FIG.

During this time, since the screw 22 is not rotated, no resin is stored in front of the screw head 22a (left side in the figure). Next, in the weighing process,
When the screw 22 is further moved backward by rotating the screw 22 by driving the second drive unit, the pellet-shaped resin in the hopper falls and the heating cylinder 32
And advance in the groove 26 (moving to the left in the figure)
Let me do.

A heater (not shown) 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. Therefore, when the screw 22 is rotated backward by a predetermined distance L2, 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 drive unit, the screw head 22a
Is injected from the injection nozzle 13 and charged into a cavity space of a mold device (not shown). At the Vp switching point, the speed control of the screw 22 is switched to the pressure control of the screw 22.

In the injection step, a backflow prevention device is provided so that the resin stored in front of the screw head 22a does not flow back. That is, the screw head 22a has a conical head body 14 at the front and a small diameter portion 15 at the rear. 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.
A seal ring 17 is provided at the front end of the metering portion 22b so as to be able to freely contact and separate from the rear end of the check ring 16.

Therefore, in the injection step, when the screw 22 is advanced, the screw head 22
The resin stored in front of a moves backward and tends to flow backward, but the check ring 16 moves relatively backward with respect to the screw 22 due to the pressure of the resin, and the check ring 16 moves backward. The end abuts on the seal ring 17 to perform sealing. 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 retracted, the check ring 16 moves relatively forward with respect 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 portion 14. A plurality of notches (not shown) extending in the axial direction are formed at a plurality of places around the resin 14, so that the movement of the resin is not hindered.

By the way, when molding a small molded product,
If the clearance between the inner circumference of the heating cylinder 32 and the outer circumference of the screw 22 is large, the resin flows backward through the clearance in the injection step, and the filling amount of the resin in the cavity space fluctuates. As a result, the molded product cannot be molded stably. In addition, even when molding a molded product having a normal size, when the speed control of the screw 22 is switched to the pressure control of the screw 22 in the injection process, the pressure of the resin increases, and the resin flows backward through the clearance, The filling amount of the resin in the cavity space varies.

In this case, 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 or the check ring Galling occurs between the heating cylinder 16 and the heating cylinder 32, and the screw head 22a, the check ring 16, or the heating cylinder 32 is damaged.

Therefore, a predetermined area in front of the heating cylinder 32, for example, a portion in front of the Vp switching point, a portion corresponding to the amount of resin required for molding a small molded product, and a pressure of the resin. The inner diameter of the heating cylinder 32 is reduced at a portion in front of a point where the height suddenly increases due to the shape of the cavity space, and the inner diameter of the heating cylinder 32 is increased in another region behind the heating cylinder 32.

In the present embodiment, the screw 22 in the predetermined region, that is, the portion of the distance L1
When the clearance between the outer circumference of the heating cylinder 32 and the inner circumference of the heating cylinder 32 is δ1, and the clearance between the outer circumference of the screw 22 behind the predetermined area and the inner circumference of the heating cylinder 32 is δ2, δ1 <δ2 To be. Then, suckback is performed in the predetermined area.
When the suckback is completed, the distance L1 is set so that the portion of the screw head 22a having the maximum diameter slightly enters the cylinder main body 34.

In the present embodiment, the effective distance within which the screw 22 can be moved in the cylinder head 33 is equal to the distance L1.
The clearance between the outer circumference of the screw 22 and the inner circumference of the cylinder head 33 is set to δ1, and the clearance between the outer circumference of the screw 22 and the inner circumference of the cylinder body 34 is set to δ2.

As described above, the clearance .delta.2 of the portion to be moved while rotating the screw 22 is increased, and the clearance .delta.1 of the portion to be moved without rotating the screw 22 is reduced. , Δ2, the backflow of the resin can be suppressed. Therefore, it is possible to suppress a change in the filling amount of the resin in the cavity space, and it is possible to stably mold the molded product.

Further, since the clearance δ2 of the part to be moved while rotating the screw 22 is increased,
As the screw 22 moves forward and backward, galling between the screw head 22a or the check ring 16 and the heating cylinder 32 can be prevented from occurring. Therefore, the screw head 22a, the check ring 16, or the heating cylinder 32 is not damaged.

Further, since the cylinder head 33 and the cylinder body 34 can be separated from each other, it is not only easy to manufacture the heating cylinder 32 with different clearances δ1 and δ2, but also to make the cylinder head 33 Or, when the cylinder body 34 is broken, it can be easily replaced. 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.

[0035]

As described above in detail, according to the present invention, in the injection apparatus, the heating cylinder, the rotatable and reciprocatingly disposed inside the heating cylinder, and the screw head at the front end are provided. , A first driving unit for moving the screw forward and backward, and a second driving unit for rotating the screw. And
When a portion in front of the Vp switching point where the speed control is switched from pressure control to pressure control when the screw in the heating cylinder is advanced is set as a predetermined region, and a portion behind the predetermined region is set as another region. The clearance between the outer periphery of the metering portion of the screw and the inner periphery of the predetermined region in the heating cylinder is between the outer periphery of the metering portion and the inner periphery of the other region in the heating cylinder. It is made smaller than the clearance. In the measuring step, the rotation of the screw is performed in the other area.

In this case, the clearance between the outer periphery of the metering portion of the screw and the inner periphery of the predetermined region in the heating cylinder is reduced, so that the resin is prevented from flowing back through the clearance in the injection step. can do. Therefore, it is possible to suppress a change in the filling amount of the resin in the cavity space, and it is possible to stably mold the molded product.

[0037]

[0038]

In another injection device of the present invention, the heating cylinder further includes a cylinder head portion at a front portion,
A cylinder body is provided at the rear. The predetermined region is formed in the cylinder head. In this case, since the cylinder head and the cylinder main body can be separated, not only is it easy to manufacture the heating cylinder with different clearances, but also when the cylinder head or the cylinder main body is damaged. Can be easily replaced.

[Brief description of the drawings]

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

[Explanation of symbols]

 22 Screw 22a Screw Head 32 Heating Cylinder 33 Cylinder Head 34 Cylinder Body δ1, δ2 Clearance

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 45/00-45/84

Claims (4)

(57) [Claims] 1. A heating cylinder, (b) a screw rotatably and advancing and retracting in the heating cylinder, and having a screw head at a front end, and (c) advancing and retreating the screw. a first driving means for, and a second driving means for rotating (d) is the screw
And having, advancing the screw in (e) the heating cylinder
V that can be switched from speed control to pressure control
-P The portion in front of the switching point is a predetermined area, and the predetermined area is
When the area behind the area is another area, the outer circumference of the metering portion of the screw and the heating cylinder
The clearance between the inner periphery of the predetermined region, the main
And the outer periphery of Taringu portion, is smaller than the clearance between the inner periphery of the other regions in the heating cylinder, (f) the rotation of the screw in the metering process the other
Injection apparatus is performed in a region characterized by Rukoto. (A) a heating cylinder; and (b) a rotatable and movable head inside the heating cylinder.
Retractably arranged, with a screw head at the front end
Clew; (c) first driving means for moving the screw forward and backward ; and (d) second driving means for rotating the screw.
And having, advancing the screw in (e) the heating cylinder
The pressure of the resin at this time depends on the shape of the cavity space.
The area in front of the point where the height suddenly rises is a predetermined area,
When the portion behind the predetermined area is another area,
To the outer circumference of the metering part of the screw and the heating cylinder
Clearance between the predetermined area and the inner periphery of the predetermined area,
The outer periphery of the metering section and the front of the heating cylinder
Less than the clearance between the inner circumference of the other area
Is, (f) the rotation of the screw in the metering process the other
An injection apparatus characterized in that the injection is performed in an area. Wherein (a) said heating cylinder, a cylinder head portion on the front, provided with a cylinder body portion in the rear, to claim 1 or 2 (b) wherein the predetermined region is formed in the cylinder head portion An injection device as described. 4. The cylinder head according to claim 1, wherein :
The device according to claim 3, which is detachably attached to the body part.
Injection equipment.