JPH04115629U - Screw for injection molding - Google Patents

Abstract

(57) [Summary] [Purpose] To provide an injection molding screw that can perform appropriate kneading and quickly supply resin to the metering section, thereby shortening the metering time. be. [Structure] The ratio of the screw pitch P ₃ in the supply section 4 to the screw pitch P ₁ in the metering section 2 is set to 1.
05 or more and less than 1.50.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention relates to screws, especially screws used in injection molding machines for resin etc. It is something that

0002

[Conventional technology]

BACKGROUND ART Conventionally, the following types of screws have been generally used in injection molding machines for resins, etc. That is, as shown in FIGS. 2 and 3, the screw 11 is comprised of a metering section 12, a compression section 13, and a supply section 14 in order from the tip (left side in FIG. 2). The groove M ₃ in the supply section 14 is formed deeper than the groove M ₁ in the metering section 12, and the compression ratio of the resin is usually about 2 to 3 times. As the screw 11 rotates, pellet-shaped resin is supplied from the supply section 14, compressed and melted through the compression section 13, and sent to the measuring section 12 at the tip.

0003 On the other hand, the screw pitch P (distance between adjacent peaks) is Therefore, the screw pitch P for the channel inner diameter D has a constant value. The ratio P/D is also constant and usually has a value of 0.8 to 1.0.

0004

[Problem that the idea aims to solve]

However, the screw 11 had the following problems. i.e. , let's send the resin to the tip (measuring part 12) as quickly as possible to shorten the measuring time. In this case, it is conceivable to increase the rotational speed of the screw 11. death However, in such a case, abnormal heat generation of the resin itself and damage to the screw 11 may occur. This sometimes caused problems in kneading. As a result, the rotational speed of the screw 11 It was not possible to easily adopt the method of increasing the

[0005] This invention was made to solve the above problems, and its purpose is to In addition to being able to perform precise kneading, the resin can be quickly supplied to the metering section. We provide an injection molding screw that can shorten measurement time. There are many things.

[0006]

[Means to solve the problem]

In order to achieve the above purpose, the present invention has a measuring section, a compression section, and a supply section starting from the tip. A screw for injection molding, which has a screw pitch in the measuring section. The ratio of the screw pitch in the supply section to 1.05 or more and less than 1.50. The gist of this invention is an injection molding screw that is characterized by:

[0007]

[Effect]

The screw pitch in the supply section is larger than the screw pitch in the metering section. Due to the large size, the resin is quickly sent from the supply section to the metering section.

[0008]

【Example】

Hereinafter, embodiments embodying the present invention will be described based on the drawings. Figure 1 shows this example. Injection molding machine A showing an injection molding screw (hereinafter referred to as screw) 1 in FIG. As shown in the figure, the screw 1 has a constant inner diameter D. The metering section 2, compression section 3, and and a supply section 4. A hopper 5 is arranged above the supply section 4. The raw material resin is quantitatively supplied from this hopper 5 to the vicinity of the supply section 4 in the flow path F. is being supplied to.

[0009] The depth of the groove in the supply section 4 is formed deeper than that in the measuring section 2. The compression ratio is about 2 to 3 times the same as before. And the screen By rotating Liu 1 in a certain direction, the resin, which was initially in the form of pellets, becomes From the supply part 4, it is compressed and melted through the compression part 3, and sent to the measuring part 2 at the tip, and then the flow path It is designed to be stored near the measuring section 2 in F.

0010 A nozzle 6 and a mold 7 are provided at the left end of the flow path F in the figure. molten When a predetermined amount of resin is stored near the metering section 2, the screw 1 is turned to the left in the figure. By moving the liquid in this direction, the liquid is injected into the mold 7 through the nozzle 6. ing. Next, the screw 1 will be explained in detail. Screw in the supply section 4 -Pitch (distance between adjacent peaks) P₃is the screen in the measuring section 2 and the compression section 3. Leupitch P₁,P₂It is formed larger than. For the above-mentioned flow path inner diameter D screw pitch P₁,P₂,P₃ratio P₁/D,P₂/D,P₃/D using To explain in more detail, in the measuring section 2 and the compression section 3, P₁/D and P₂/D are both 0.88. On the other hand, in the supply section 4, P₃/D is 1.08. That is, the screws in the metering section 2 and the compression section 3 Pitch P₁,P₂Screw pitch P in the supply section 4 for₃ratio P₃/P ₁ ,P₂/P₁is approximately 1.23.

In the present invention, the ratio P ₃ /P ₁ of the screw pitch P ₃ to the screw pitch P ₁ must be 1.05 or more and less than 1.50. P ₃ /P ₁ is 1. If P 3 /P 1 is less than 0.05, the effect of increasing the resin supply rate, which is the purpose of the present invention, will be impaired. On the other hand, if P ₃ /P ₁ is 1.50 or more, although the supply rate will increase, the thermal history for the resin will be insufficient. This is because it becomes difficult to knead the resin completely. In order to be able to increase the supply rate appropriately and to provide a sufficient thermal history, the most preferable range of P ₃ /P ₁ is about 1.1 to 1.3. Note that the ratios P ₁ /D, P ₂ /D, and P 3 /D of the screw pitches P ₁ , P ₂ , and _{P 3} to the inner diameter D of the flow path are not particularly limited, but values that provide a more appropriate thermal history may be used. In order to do so, it is preferably about 0.8 to 1.0.

Next, the function and effect of the screw 1 of this embodiment will be explained. Since the screw 1 in this embodiment has a large P ₃ /D of 1.08 in the supply section 4, the thrust force applied to the resin toward the tip of the screw 1 can be reduced without increasing the rotational speed of the screw 1. The supply speed increases accordingly. On the other hand, in the measuring section 2 and the compressing section 3, both P ₁ /D and P ₂ /D were set to 0.88, so the kneading function is almost the same as in the past, and a sufficient thermal history is provided. In fact, as a result of comparing the conventional screw 11 and the screw 1 of this embodiment, it was possible to increase the metering speed by about 1.5 times.

[0013]The present invention is not limited to the above embodiments, and may be configured as follows, for example, without departing from the spirit of the invention. That is, in the above embodiment, the value of P ₂ /D in the compression section 3 was set to 0.88, which is the same as the value of P ₁ /D in the measuring section 2, but it was set to be larger than 0.88 and 1.08. It may be set smaller than . In this case, the resin flows more smoothly than in the previous embodiment.

[0014]

[Effect of the idea]

According to the injection molding screw of the present invention, appropriate kneading can be performed. In addition, the resin can be quickly supplied to the measuring section, which in turn shortens the measuring time. It has the effect of being able to

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part of an injection molding machine showing a screw of this embodiment.

FIG. 2 is a plan view showing a conventional screw.

FIG. 3 is a partial cross-sectional view showing a screw in a resin flow path.

[Explanation of symbols]

1... Screw for injection molding, 2... Measuring section, 3... Compression section,
4...supply section, _P1 ...screw pitch in measuring section,
P ₃ ...Screw pitch in the supply section.

Claims (1)

[Scope of utility model registration request] 1. An injection molding screw (1) comprising a metering section (2), a compression section (3) and a supply section (4) from the tip, the screw pitch (P) in the metering section (2).
An injection molding screw characterized in that the ratio of the screw pitch (P ₃ ) in the supply section (4) to the pitch ₍ P 3 ) in the supply section (4) is 1.05 or more and less than 1.50.