JPH0612014U - High kneading screw - Google Patents

Abstract

(57) [Summary] [Purpose] A highly kneading screw with little temperature difference of the discharged resin and good plasticizing ability. [Structure] A high kneading screw 1 having a main flight 4 and a sub-flight 2a having a height lower than the height of the main flight 4.
5, the sub-flight 2a has a non-parallel portion 16 branched from the main flight 4 at the formation start point 3, a parallel portion 17 following the non-parallel portion 16, and a non-parallel portion 18 following the parallel portion 17. The depth of the solid groove 7 is gradually increased toward the downstream side in the non-parallel portion 16 on the upstream side.
7 and the following non-parallel portion 18 are gradually shallower, and gradually deeper from the portion following the main flight 4 in parallel to the screw axis of the sub-flight 2a and continuing to the final groove 21, and the depth of the melt groove 8 is , The non-parallel portion 16 following the formation start point 3 of the sub-flight 2a is formed to be gradually shallower toward the downstream side, is gradually deeper in the parallel portion 17, and is the same as the maximum depth of the parallel portion 17 in the non-parallel portion 18 on the downstream side. Of the non-parallel portion 18, and is formed so as to be gradually shallower than a predetermined position before the end point 19 of the non-parallel portion 18 and continues to the final groove 21.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a screw of a molding machine for molding a thermoplastic resin.

[0002]

[Prior art]

 Conventionally, the following two screws are mainly known as a screw having a main flight and a sub flight. The first example will be described with reference to FIG.

The sub-flight 2 of the screw 1 branches from the main flight 4 at a formation start point 3 of the sub-flight 2 as shown in FIG. It is formed by 5. The height differences between the main flight 4 and the sub-flight 2 are all constant. Further, as shown in FIG. 6B, the depth of the solid groove 7 is formed so as to be gradually shallower than the formation start point 3 of the sub flight 2, and the depth of the melt groove 8 is formed. Is gradually shallower than the formation start point 3 and gradually deeper than the predetermined position, and then gradually becomes shallower from the point where it becomes the same depth as the solid groove 7 to the end point 9 of the sub-flight 2. Is formed in.

Next, a second example will be described with reference to FIG.

As shown in FIG. 7 (a), the sub-flight 2 branches off from the main flight 4 at the formation start point 3 of the sub-flight 2 in a non-parallel manner, and then at a parallel portion 10 parallel to the main flight 4. Has been formed. The height differences between the main flight 4 and the sub-flight 2 are all constant. Further, as shown in FIG. 7B, the depth of the solid groove 7 is gradually deeper than the formation start point 3 of the sub-flight 2, and is gradually shallower than the formation start point 12 of the parallel portion 10. It is formed so as to become gradually deeper from a predetermined position toward the end point 9 of the sub-flight 2. In addition, the depth of the melt groove 8 is gradually shallower than the formation start point 3 of the sub-flight 2 and gradually deeper than the formation start point 12 of the parallel part 10, and the end point of the sub-flight 2 from the predetermined position of the parallel part 10. It is formed so that it gradually becomes shallower toward 9.

Since the screw 1 is configured as described above and thus melts while always separating the melt pool and the solid bed, it is possible to perform the melting more efficiently than the screw without the sub-flight 2.

[0007]

[Problems to be solved by the device]

 However, in the screw 1 of the first example among the above-mentioned screws 1, the solid groove 7 gradually decreases in contact area with the barrel 14 toward the downstream, so that the melting rate of the resin decreases, and therefore the plasticizing ability is increased. Will fall. Further, in the screw 1 of the second example, the melt groove 8 has a constant width and the depth becomes deeper as it goes to the downstream side, so that the plasticizing ability is the screw 1 of the first example. It is more excellent, but resin stagnation occurs at the deepest part, resin change, color change failure, and resin deterioration due to stagnation easily occur, and since the melt groove 8 near the last part is deep, melting in the melt groove There was a weak point that the resin could not receive the external heating uniformly, and the temperature variation of the discharged resin became large.

In view of this, the present invention has been made for the purpose of providing a highly kneading screw having a small variation in the temperature of the discharged resin and a good plasticizing ability.

[0009]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems of the prior art, the present invention provides a high-mixing screw having a main flight and a sub-flight formed at a height lower than the height of the main flight, wherein the sub-flight is a starting point of formation of the sub-flight. , The non-parallel portion that is branched from the main flight and is not parallel to the main flight and has no melt groove, the parallel portion that is parallel to the main flight and the parallel portion that is parallel to the main flight It has a non-parallel part that is non-parallel to the flight and is connected to the main flyt in parallel with the screw axis in the non-parallel part, and the depth of the solid groove gradually increases toward the downstream side in the non-parallel part on the upstream side. The depth of the melt groove, which is deeper and gradually shallower in the parallel part and the following non-parallel part, and gradually deeper from the part following the main flight parallel to the screw axis of the sub-flight, and continuing to the final groove. In the non-parallel part following the formation start point of the sub-flight, it is formed shallower toward the downstream side, gradually deeper in the parallel part, and at the same depth as the maximum depth of the parallel part in the non-parallel part on the downstream side. Further, the high-mixing screw is characterized in that it is formed so as to be gradually shallower than a predetermined position before the end point of the non-parallel portion and continues to the final groove. Then, the height difference between the main flight and the sub-flight is formed to be a constant height difference in the parallel portion of the main flight and the sub-flight, and in the non-parallel portion on the downstream side, The height of the ridge gradually approaches the height of the main flight, and then the height of the ridge is formed with a certain difference so as to have a constant height.

[0010]

[Action]

 In the high-kneading screw, the resin that has started melting is gently separated from the unmelted resin in the non-planar portion on the upstream side of the melt groove and sent to the parallel portion. The molten resin sent to the parallel section is sent to the non-parallel section on the downstream side while absorbing the increased amount by the melt groove depth. In the non-parallel portion, the increased amount of molten resin is absorbed by the melt groove width and passes through the melt groove where the groove depth does not increase, so there is little stagnation and it is sufficiently kneaded and melted and discharged from the melt groove to the downstream side. .

Further, the unmelted resin in the solid groove of the upstream non-parallel portion is sent to the parallel portion without flowing into the melt groove, and is sent to the non-parallel portion of the downstream side while transporting the molten resin to the melt groove at any time. . The unmelted resin in the non-parallel portion undergoes compression in the groove width direction and groove depth direction to accelerate melting, and complete melting at the solid groove end point.

[0012]

【Example】

 Hereinafter, the present invention will be described with reference to the embodiments shown in FIGS. 1 to 3 by using the same reference numerals for the same components as those of the prior art.

As shown in FIG. 1A, the high kneading screw 15 is composed of a main flight 4 and a sub flight 2 a, and a solid groove 7 and a melt groove 8 are formed therein.

As shown in FIGS. 1A and 2, the sub-flight 2a diverges from the main flight at the formation start point 3 of the sub-flight 2a on the upstream side (right side in the figure) of the high-mixing screw 15 and A non-parallel portion 16 that is non-parallel to the flight 4, a parallel portion 17 that follows the non-parallel portion 16 and that is parallel to the main flight 4, and a parallel portion that follows the parallel portion 17 and that is non-parallel to the main flight again. It has a parallel part 18 and its end is connected to the main fly 4 in parallel with the screw shaft. In the non-parallel portion 16, the sub-flight 2a is in close contact with the main flight 4 to form a melt groove, but since the solid groove is reduced by the width of the sub-flyt 2a and its cross-sectional area is reduced, It is designed to give compression support to the resin.

As shown in FIG. 1B, the depth of the solid groove 7 is gradually deeper than the barrel 14 in the non-parallel portion 16 of the sub-flight 2 a, and continues to the parallel portion 17 and the parallel portion 17. The non-parallel portion 18 is formed so as to be gradually shallower, gradually deeper from the end point 19 of the non-parallel portion 18, and continue to the final groove 20. The depth of the melt groove 8 is gradually shallower in the non-parallel portion 16 of the sub-flight 2a with respect to the barrel 14 as shown in FIG. 1 (c), and gradually deeper in the parallel portion 17 and at the downstream side. The non-parallel portion 18 is formed to have the same depth as the maximum depth of the parallel portion 17. Then, it is gradually shallower than a predetermined position before the end point 19 of the non-parallel portion 18 and continues to the final groove 20.

The difference in mountain height between the main flight 4 and the sub-flight 2a is formed to be constant in the parallel portion 17 as shown in FIG. 3, and the downstream side in the non-parallel portion 18 before the end point of the sub-flight 2a. The height of the mountain of the secondary flight is approached to the height of the main flight toward, and then it is formed to a constant height.

Next, the operation of the high kneading screw 15 will be described.

The resin supplied from the hopper (not shown) is heated by the heat from the barrel 14 and sent to the right side in FIG. 1 or 2 through the feed zone of the screw (not shown). The resin which has started to be melted is gently separated from the unmelted resin by the non-parallel portion 16 having no melt groove and is transported to the parallel melt groove 8. The unmelted resin is sent to the parallel solid groove 7. Since the contact area between the unmelted resin and the barrel is always constant in the parallel solid groove 7, heat can be efficiently exchanged. As a result, the melted resin is transported to the parallel melt groove 8 at any time, and while the parallel solid groove 7 is always filled with the unmelted resin, the melted resin is compressed in the depth direction toward the downstream. . The parallel melt groove 8 corresponding to the parallel solid groove 7 moves downstream while absorbing the increase in the amount of molten resin transported from the parallel solid groove 7 at the groove depth. In the non-parallel solid groove 7a following the parallel solid groove 7, compression in the width direction is mainly applied to the unmelted resin to relax the compression in the depth direction. This relaxation prevents the unmelted resin from becoming excessively thin, reduces the migration resistance of the unmelted resin, and prevents the unmelted resin from being divided (mixed with the molten resin). In the non-parallel portion solid groove 7a, the contact area with the barrel decreases as it goes downstream, but it is not possible to reduce the melting rate of the unmelted resin that has received sufficient latent heat in the parallel portion solid groove 7a. Absent. Further, since the sub-flight 2a is non-parallel in the non-parallel portion solid groove 7a, the transport force of the molten resin to the melt groove is increased, and the adverse effect of this is that the unmelted resin flows into the melt groove. Although this occurs, the difference in height between the main flight 4 and the sub-flight 2a is gradually shallowed from the starting point of the solid groove 7a in the non-parallel portion, and is then made constant to solve this problem and the resin melted sufficiently is transported to the melt groove. The unmelted resin is completely melted by the end point 9 of the non-parallel portion. In the non-parallel part melt groove 8a corresponding to the non-parallel part solid groove 7a, unlike the parallel part melt groove 8, the increase in the amount of molten resin transported from the solid groove is absorbed by the increase in the width direction, and the groove depth is set to the parallel part. Since the final depth of the melt groove 8 is the same as the final depth, the thickness of the molten resin does not become thick, and the heat supplied from the barrel can be uniformly received by the molten resin. Furthermore, since the groove depth is relatively shallow, a pump action is generated by the rotation of the screw, and a stable and uniform molten resin that is strong against back pressure is discharged. Also, there is little resin retention at the bottom of the groove, which is excellent for resin color change.

Next, an experimental example of the high kneading screw according to the present invention will be described with reference to FIGS. 4 and 5.

4A shows a high kneading screw according to the present invention, FIG. 4B shows a second example of the prior art, and FIG. 4C shows a screw of the first example of the prior art. The figure shows a case where low melt index (low fluidity) propylene is used as the resin by rotating at.

Here, the discharge resin temperature of the screw of the first example is 264.3 ° C. to 267.0 ° C. and the temperature variation is 2.7 ° C., and the discharge resin temperature of the screw of the second example is 249. The temperature variation between 6 ° C and 256.3 ° C is 6.7 ° C. The discharge resin temperature of the high kneading screw according to the present invention is 256.1 ° C to 258.7 ° C, and the temperature variation is 2.6 ° C. That is, the polypropylene kneaded and melted by the highly kneading screw of the present invention has a relatively high temperature rise and is uniformly melted without any variation in the temperature.

FIG. 5 shows a comparison of the plasticizing ability of a high kneading screw having a diameter of 100 and a polypropylene having a low melt index measured at a rotation speed of 128 rpm. The screw of the present invention has a plasticizing ability equivalent to that of the conventional second example screw, and shows an improvement in plasticizing ability of 10% over the screw of the first example.

[0023]

[Effect of device]

 As described above, in the high-mixing screw according to the present invention, the auxiliary flight diverges from the main flight at the formation start point, and the non-parallel portion with respect to the main flight, the parallel portion that follows this non-parallel portion, and the non-parallel portion that follows this parallel portion. The non-parallel portion has a parallel portion and is connected to the main flight in parallel with the screw axis, and the depth of the solid groove is gradually increased toward the downstream side in the non-parallel portion on the upstream side. It is gradually shallower in the non-parallel part that follows, and gradually deeper from the part that follows the main flight parallel to the screw axis of the sub-flight and continues to the final groove, and the depth of the melt groove follows the formation start point of the sub-flight. In the non-parallel part, it is formed gradually shallower toward the downstream side, gradually deeper in the parallel part, and at the same depth as the maximum depth of the parallel part in the non-parallel part on the downstream side. Position in front Since it was formed to be shallower gradually and continued to the final groove, it was connected from the non-parallel portion on the upstream side, which has no melt groove, to the melt groove in the parallel portion without causing a sudden change in cross-sectional area, and The high melting efficiency of the secondary flight and the narrowing effect of the non-parallel secondary flies in the width direction of the solid bed promotes the melting of the solid bed. Further, by making the deepest part of the melt groove in the non-parallel portion on the downstream side shallow, the heat transfer from the barrel is improved, so that the retention of the molten resin is reduced and the plasticizing ability is improved. Furthermore, by providing a constant groove depth in the non-parallel portion on the downstream side of the melt groove in the axial direction, a high peripheral velocity due to the rotation of the screw is continuously formed, and the molten resin discharge effect is improved. It has an excellent effect that it can

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of a high kneading screw of the present invention.

FIG. 2 is a development view of a main flight and a sub flight.

FIG. 3 is an explanatory diagram showing a height relationship between a main flight and a sub flight.

FIG. 4 is an explanatory view showing a state of discharge resin temperature of a high kneading screw of the present invention and a conventional screw.

FIG. 5 is an explanatory view showing the plasticizing ability of the high kneading screw of the present invention and the conventional screw.

FIG. 6 is an explanatory view of a conventional screw.

FIG. 7 is an explanatory view of a conventional screw.

[Explanation of symbols]

 1 screw 2 secondary flight 2a secondary flight 4 main flight 7 solid groove 8 melt groove 14 barrel 15 high kneading screw 16 non-parallel part 17 parallel part 18 non-parallel part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ken Katsu Suzuki 2068 Ooka, Numazu City, Shizuoka Prefecture Toshiba Machine Co., Ltd. Numazu Office

Claims (2)

[Scope of utility model registration request] 1. A high-kneading screw having a main flight and a sub-flight formed at a height lower than the height of the main flight, wherein the sub-flight branches from the main flight at a formation start point of the sub-flight, A non-parallel part that is not parallel to the main flight and has no melt groove, a parallel part that follows this non-parallel part and that is parallel to the main flight, and a non-parallel part that follows this parallel part and that is not parallel to the main flight again. The non-parallel portion has a parallel portion and is connected to the main flight parallel to the screw axis in the non-parallel portion, and the depth of the solid groove is gradually deeper toward the downstream side in the non-parallel portion on the upstream side. It is gradually shallower in the non-parallel part, and gradually deeper from the part following the main flight parallel to the screw axis of the sub-flight, and then to the final groove.The depth of the melt groove is non-parallel to the starting point of the sub-flight formation. In the gradually shallower toward the downstream side, gradually deeper and the non-parallel portion of the downstream side are formed in the same depth and the maximum depth of the parallel portion is parallel portion, further,
A high-kneading screw, which is formed so as to be gradually shallower than a predetermined position before the end point of the non-parallel portion and continues to the final groove. 2. The height difference between the main flight and the sub-flight is formed to be a constant height difference in a portion where the main flight and the sub-flight are parallel, and in the non-parallel portion on the downstream side. 2. The high kneading screw according to claim 1, wherein the height of the flight peak gradually approaches the height of the main flight, and then is formed to have a constant height with a certain difference.