JPH10113962A - Screw for injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate irregular melting of resin and to obviate complexity of a screw shape, a decrease in processability and an increase of a cost by ensuring smooth and stable movement without obstructing natural movements of molding material and molten resin. SOLUTION: A screw thread root Vc in a pitch Pc of a compression zone Zc is continued in the same depth from a screw thread root Vf of a feed zone Zf. A first screw thread root Vca formed in a predetermined depth and a second thread root Vcb continued in the same depth from a screw thread root Vm of a metering zone Zm and formed in a predetermined depth are formed of a directly aligned shape. Further, the thread root Vcb is disposed at a rear side of the thread root Vca, and formed so that a longitudinal width Wcb is gradually broadened toward a forward direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw for an injection molding machine which is incorporated in a heating cylinder and plasticizes and melts a molding material.

[0002]

2. Description of the Related Art Generally, a screw for an injection molding machine is provided in a heating cylinder and has a function of plasticizing and melting a molding material together with the heating cylinder by rotating the screw. For this reason, it usually has a front metering zone, a middle compression zone, and a rear feed zone, and the depth of the screw valley is formed shallower on the metering zone side than on the feed zone side. Have been.

In this type of screw, it is necessary to sufficiently plasticize and melt the molding material in the heating cylinder.
-507.

In the screw proposed in the publication, a screw groove (screw valley) of a compression section (compression zone) is provided with a solid resin transport groove located on a measuring section (metering zone) side and a supply section (feed zone). ) Side and a shear portion located in the middle of the melt resin transport groove, and the solid resin transport groove gradually decreases in groove depth and groove width toward the measuring portion, and the melt resin transport groove is The groove depth and the groove width gradually increase, and the groove depth and the groove width in the shearing portion gradually increase, and the groove of the solid resin and the groove of the molten resin transporting the groove depth of the shear portion on both sides. It is formed shallower than the depth.

[0005]

However, the conventional screw described above has the following problems to be improved.

[0006] First, since a shear portion is provided between the solid resin transport groove and the melt resin transport groove, and both the depth and the width of the groove of the solid resin transport groove gradually decrease toward the measuring portion, the molding is performed. Natural movement of materials and molten resin,
In particular, uniform and smooth movement of the molten resin is hindered, and uneven melting of the resin is likely to occur.

Second, since all of the groove depth and groove width of the solid resin transport groove, the melt resin transport groove, and the shearing portion change in the front-rear direction of the screw, the screw shape becomes extremely complicated, and the processability is increased. And cost increase.

The present invention has been made to solve the problems existing in the prior art, and ensures uniform and smooth movement of the molding material and the molten resin without hindering the natural movement of the resin. An object of the present invention is to provide a screw for an injection molding machine that eliminates unevenness and that can reduce a decrease in workability and an increase in cost due to a complicated screw shape.

[0009]

SUMMARY OF THE INVENTION The present invention has a metering zone Zm at the front, a compression zone Zc at the middle, and a feed zone Zf at the rear, and the depth of the screw valley V is reduced. When configuring the screw 1 for an injection molding machine in which the metering zone Zm is formed shallow relative to the feed zone Zf,
The screw valley portion Vc in the pitch Pc of the compression zone Zc is continuously formed at the same depth from the screw valley portion Vf of the feed zone Zf and formed at a constant depth, and the first valley portion Vca of the metering zone Zm. The second valley Vcb, which is continuous at the same depth from the screw valley Vm and is formed at a constant depth, is formed in a directly arranged shape, and the second valley Vcb is formed after the first valley Vca. And the width Wcb in the front-rear direction is formed so as to gradually increase as going forward.

In this case, according to a preferred embodiment, the width Wc in the front-rear direction including the first valley portion Vca and the second valley portion Vcb within the pitch Pc of the compression zone Zc is the same at all pitches Pc. Form. The diameter Da of the first valley Vca is selected to be 0.60 to 0.74 times the diameter Do of the screw flight part F, and the diameter Db of the second valley Vcb is larger than the diameter Do. 0.78
It is desirable to select a size of about 0.92 times. On the other hand, the pitches P1, P2, P3,... Of the screw flight portion F in the front portion Zff of the feed zone Zf are gradually increased as going forward, while the resin kneading portion K, for example, a regular Between the screw flight portions F of the subflight portion F having a different pitch Pd from the pitch Pf of the screw flight portion F
In place of the double flight section Ka or the regular screw flight section F formed with s, an inverted lead section Kb composed of a plurality of lead strips N formed in the opposite direction is provided.

Thus, the compression zone Zc
Is formed as a section in which the front side of the feed zone Zf and the rear side of the metering zone Zm overlap in shape rather than independently configuring the compression zone Zc. That is, the compression zone Zc has a screw valley Vf (first valley Vca) of the feed zone Zf in which the width in the front-rear direction gradually narrows as going forward, and a metering zone in which the width in the front-rear direction gradually narrows as going backward. Screw valley Vm of Zm (second valley Vc
It is configured as a combination of b).

Therefore, the solid molding material Ax is transported forward by the feed zone Zf, and further transported forward by the first valley Vca in the compression zone Zc. At this time, since the first valley portion Vca gradually narrows in the front-rear direction width Wca as it goes forward, it is plasticized and melted without increasing frictional resistance.
The molten resin Ay enters the second valley Vcb where the solid molding material Ax is hard to enter. In the second valley Vcb, the width Wcb in the front-rear direction gradually increases as going forward, and is continuous with the screw valley Vm of the metering zone Zm.
The molten resin Ay is transferred forward through the second valley Vcb and the metering zone Zm. With such a screw shape, natural movement of the molding material Ax and the molten resin Ay,
In particular, uniform and smooth movement of the molten resin Ay is ensured, and the screw shape is not complicated. The molten resin Ay is kneaded by the resin kneading section K in the metering zone Zm, and is further homogenized.

[0013]

Next, preferred embodiments according to the present invention will be described in detail with reference to the drawings.

First, the overall structure of the screw 1 for an injection molding machine according to this embodiment will be described with reference to FIG.

The screw 1 integrally has a front metering zone Zm, a middle compression zone Zc, and a rear feed zone Zf.
A spiral screw flight portion F is provided on the outer peripheral surfaces of c and Zf.
Are continuously formed. As a result, a screw valley V is formed between the screw flights F in the axial direction. In this case, the depth of the screw valley Vm of the metering zone Zm is equal to the screw valley Vf of the feed zone Zf.
Shallower than the depth of.

The pitches P1, P2, P of the screw flight portion F at the front portion Zff of the feed zone Zf.
3, P4 gradually increases as going forward. Specifically, when the diameter of the screw flight portion F is Do, P1 / Do is about 0.8 to 0.9 at the pitch P1,
At the pitch P4, P4 / Do is formed with about 1.00 as a guide.

On the other hand, a resin kneading section K is provided in the metering zone Zm. That is, a subflight portion Fs having a pitch Pd different from the pitch Pf of the screw flight portion F is formed between the regular screw flight portions F, thereby forming a double flight portion Ka.

On the other hand, the rear end of the screw 1 is connected to a screw drive (not shown). Thus, the screw 1 is rotated and moved forward and backward by the screw driving unit. The virtual line indicates a part of the injection device 10, and the injection molding machine M is configured by the injection device 10 and a mold clamping device (not shown). Also, 11
Denotes a heating cylinder, 12 denotes an injection nozzle, and 13 denotes a hopper for supplying a molding material (pellet).

Next, the configuration of the compression zone Zc, which is a main part of the present invention, will be described with reference to FIG.

The compression zone Zc has a pitch Pc
The screw valley Vc inside the first valley Vca and the second valley V
cb. In this case, the first valley portion Vca and the second valley portion Vcb are directly arranged, and one of the first valley portions Vca is formed at the same depth from the screw valley portion Vf of the feed zone Zf and has a constant depth. At the same time, the other second valley Vcb is the screw valley Vm of the metering zone Zm.
From the same depth and at a constant depth. Further, the second valley portion Vcb is disposed on the rear side of the first valley portion Vca, and is formed so that the width Wcb in the front-rear direction is gradually increased as going forward, and the second valley portion Vcb is formed with the first valley portion Vca within the pitch Pc. The width W in the front-back direction including the second valley Vcb
c is formed so as to be the same for all pitches Pc. Thereby, the front-rear width Wcb of the second valley portion Vcb in the compression zone Zc gradually increases as going forward, and the width Wca in the front-rear direction of the first valley portion Vca gradually decreases as going forward.

The diameter Da of the first valley portion Vca is selected to be 0.60 to 0.74 times the diameter Do of the screw flight portion F, preferably near the center value of the same size range. At the same time, the diameter Db of the second valley portion Vcb is selected to be 0.78 to 0.92 times the diameter Do, preferably near the center value of the range of the same size. The second valley Vcb
Is desirably slightly deeper than the screw valley Vm located in front of the resin kneading section K.

Next, the function of the screw 1 for an injection molding machine according to the present embodiment will be described with reference to FIGS.

First, a solid molding material Ax (pellet) is supplied from the hopper 13 into the heating cylinder 11. Heating cylinder 11
The molding material Ax supplied into the inside is transferred forward by the screw valley Vf of the feed zone Zf in the screw 1. At this time, the pitches P1, P2, P3, P of the screw flight portion F in the front portion Zff of the feed zone Zf
4 gradually increases in the forward direction, so that the load of the molding material Ax in the softened region is reduced. Further, as shown in FIG. 2, the molding material Ax is transferred forward by the first valley portion Vca in the compression zone Zc. At this time, since the width Wca in the front-rear direction of the first valley portion Vca gradually decreases, the molding material Ax is plasticized and melted without increasing frictional resistance.

On the other hand, a plasticized and molten molding material, that is,
The molten resin Ay enters the second valley Vcb where the solid molding material Ax is difficult to enter. In the second valley Vcb, the width Wcb in the front-rear direction gradually increases as going forward, and is continuous with the screw valley Vm of the metering zone Zm.
The molten resin Ay is transported forward by the second valley Vcb and the screw valley Vm of the metering zone Zm. In this case, since the molten resin Ay moves in the second valley Vcb, which has a constant depth and is relatively shallow, uniform and smooth movement is secured, the transfer efficiency is enhanced, and the break-up phenomenon of the solid bed is avoided. In addition, uniformity of the molten resin Ay is ensured.

The molten resin Ay sent from the compression zone Zc is mixed with the resin kneading portion K in the metering zone Zm, that is, by the interaction between the screw flight portion F and the subflight portion Fs constituting the double flight portion Ka. It is further uniformly kneaded.

Next, a modified embodiment of the screw 1 for an injection molding machine according to the present invention will be described with reference to FIG.

In the modified embodiment, the resin kneading portion K in the metering zone Zm is changed, and instead of the regular screw flight portion F, a plurality of (three) lead strips N are formed in the opposite direction. An inverted lead portion Kb was provided.
Also in this case, the molten resin Ay sent from the compression zone Zc is kneaded by the reverse lead portion Kb and is made more uniform. The other configuration is the same as that of the embodiment shown in FIG. Therefore, in FIG. 4, the same parts as those in FIG.
Detailed description is omitted.

The embodiment has been described in detail above.
The present invention is not limited to such an embodiment,
The configuration, shape, quantity, material, numerical value, etc. of the details can be arbitrarily changed without departing from the gist of the present invention. For example, the width in the front-rear direction including the first valley portion and the second valley portion in the pitch of the compression zone is desirably formed to be the same at all pitches, but this does not exclude the case where they are not the same. Further, the resin kneading portion can be replaced with another configuration having the same function.

[0029]

As described above, in the screw for an injection molding machine according to the present invention, the screw valleys in the pitch of the compression zone are continuously formed at the same depth from the screw valleys of the feed zone and have a constant depth. The first valley formed in the, and the second valley formed continuously at the same depth from the screw valley of the metering zone, and formed at a constant depth, is formed by a directly arranged shape, the second valley Since the portion is arranged on the rear side of the first valley portion and is formed so that the width in the front-rear direction gradually increases toward the front, the following remarkable effects are obtained.

Since the compression zone is configured as a section where the front part of the feed zone and the rear part of the metering zone overlap in shape, the screw shape is not complicated, and the workability is reduced due to the complicated screw shape. And cost increase can be eliminated.

Further, since smooth and stable movement can be ensured without hindering the natural movement of the molding material and the molten resin, uneven melting of the resin can be eliminated.

According to a preferred embodiment, if the width in the front-rear direction including the first valley portion and the second valley portion in the pitch of the compression zone is formed to be the same at all pitches, the workability of the screw can be further improved. it can.

According to a preferred embodiment, if a resin kneading section is provided in the metering zone, the molten resin sent from the compression zone can be made more uniform.

[Brief description of the drawings]

FIG. 1 is a side view showing a main part of a screw for an injection molding machine according to the present invention;

FIG. 2 is a functional explanatory view of the screw for the injection molding machine,

FIG. 3 is an overall side view of the screw for the injection molding machine;

FIG. 4 is an overall side view according to a modified embodiment of the screw for the injection molding machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Screw for injection molding machine Zm Metering zone Zc Compression zone Zf Feed zone Zff Front of feed zone V Screw valley Vc Screw valley Vca First valley Vcb Second valley Vf Screw valley Vm Screw valley Pc Pitch Pf pitch Pd pitch P1... Pitch of screw flight portion Wc longitudinal width Wcb longitudinal width Da diameter of first valley portion Df diameter of screw flight portion K resin kneading portion Ka double flight portion Kb reverse lead portion F screw flight portion Fs sub Flight Department

Claims (8)

[Claims] 1. A metering zone having a front metering zone, a compression zone at an intermediate portion, and a feed zone at a rear portion, and a depth of a screw valley portion is formed so that the metering zone is formed shallow with respect to the feed zone. In a screw for an injection molding machine, a screw valley in the pitch of the compression zone is continuous from the screw valley of the feed zone at the same depth, and a first valley formed at a constant depth, and the meter. The second valley, which is continuous at the same depth from the screw valley of the ring zone and is formed at a constant depth, is formed by a directly arranged shape, and the second valley is formed of the first valley. A screw for an injection molding machine, wherein the screw is disposed on the rear side and is formed so that the width in the front-rear direction gradually increases as going forward. 2. The width in the front-rear direction including the first valley portion and the second valley portion in the pitch of the compression zone is formed to be the same at all pitches. Screw for injection molding machine. 3. The injection molding machine according to claim 1, wherein the diameter of the first valley is 0.60 to 0.74 times the diameter of the screw flight. Screw. 4. The injection molding machine according to claim 1, wherein the diameter of the second valley is 0.78 to 0.92 times the diameter of the screw flight. Screw. 5. The screw for an injection molding machine according to claim 1, wherein a pitch of the screw flight portion at a front portion of the feed zone is formed to be gradually larger as going forward. 6. The screw for an injection molding machine according to claim 1, wherein a resin kneading section is provided in said metering zone. 7. The double flight section according to claim 6, wherein the resin kneading section is a double flight section in which a subflight section having a pitch different from the pitch of the screw flight section is formed between regular screw flight sections. Screw for injection molding machine. 8. The screw for an injection molding machine according to claim 6, wherein said resin kneading part is a reverse lead part comprising a plurality of lead strips formed in opposite directions instead of a regular screw flight part. .