JPS63128919A - Injection molding equipment - Google Patents

Abstract

PURPOSE:To make the physical properties of a product nearly homogeneous as a whole and realize the uniform enlargement of the whole even when the product is expanded at molding or vulcanization by a structure wherein a disc-shaped material passage, the whole outer edge of which is open to the upper end of a mold space, is formed between an upper mold and a middle mold under the state that the molds are closed. CONSTITUTION:Under the state that an upper mold and a lower mold are closed, a middle mold 26 is housed within the upper and lower molds 21 and 22. At the same time, a nearly cylindrical upright mold space 27 is formed between the outer periphery of the middle mold and the inner peripheries of the upper mold 21 and of the lower mold 22. Within the middle mold 26, an annular hollow space 28 is formed so as to feed with steam for vulcanization or water for cooling through a passage 29. A fluid jetting path 45 is formed in the middle mold 26 and its upper end is open at the center of a material passage 36 and its lower end is connected through a passage provided in a center post 25 to a fluid source such as air source or the like. Rubber is injected from a feeding means through an injection passage 40 and an injection path 38 into the material passage 26 and the mold space 27 in order to fill the material passage 20 and the mold space 27 with the rubber. The rubber poured in the mold space 27 can be almost simultaneously vulcanized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an injection molding apparatus suitable for molding tires, vulcanizing bladders, and the like.

As a conventional injection molding apparatus, one shown in FIG. 6, for example, is known. This thing.

Upper and lower molds 1 and 2 that can be moved toward and away from each other, and these upper and lower molds 1. When 2 is closed, these upper and lower gold y! 11, 2, and forms a substantially cylindrical mold space 3 between the upper and lower molds 1, 2.
A middle metal mold JJ14, a vertical movement f stage 5 for vertically moving the first middle mold 4 independently of the upper and lower molds 1 and 2, and the upper and lower molds.
1. 2 is closed, the second middle mold 4 is disposed between the upper mold l and the first middle mold 4, and forms a material passage 6 between which the plastic material passes. With the middle mold 7,
A vulcanizing heater 8 is installed in the first inner mold 4, and an injection passage is provided in the second inner mold yfIi, 7 for injecting the plastic material into the mold space 3 through the material passage 6. lO
has been established. When molding, for example, a tire or a vulcanizing bladder using such an injection molding apparatus, the upper and lower molds are first molded.

2 are closed close to each other, the mold space 3 is injected and filled with ti7.1 material 1, for example unvulcanized rubber, through the injection passage 10. At this time, the rubber is heated and vulcanized by the heater 3. When this vulcanization is completed, the lower mold 2 is lowered while holding the first middle mold 4 in its current position. As a result, the lower half of the bladder 11 is exposed. Next, the first middle metal 114 is inserted into the lower metal y! 12, but at this time, as shown in FIG. 7, the upper end of the bladder 11 is held by the upper mold 1 and the second middle mold 7.
The middle mold 4 is gradually pulled out while slidingly contacting the bladder 11.
At this time, air is supplied from the pipe 12 between the first and second middle molds 4 and 7 to form a layer of air between the brush II and the first middle mold 4, and the first middle mold 4. Next, insert the second middle mold 7 into the bladder 1! After lowering the second middle mold 7 with the bladder! 1, and the bladder 11 is transported to the next process.

However, in such an injection molding apparatus, the material passage 8 connects the disk portion 13 located in the center, the outer edge of this disk portion 13, and the upper end of the mold space 3. Since it is composed of a plurality of small-diameter injection holes [] 14 that are connected and spaced apart from each other at a predetermined angle, the unvulcanized rubber gradually spreads from each injection port 14 and fills the entire mold space 3, and as a result, The degree of vulcanization differs between the vicinity of the injection port 14 and the intermediate position of the injection port 14. As a result, the physical properties of the product become non-uniform in the circumferential direction, resulting in non-uniform expansion during molding or vulcanization, which poses a problem in that it adversely affects the uniformity of the tire. Moreover, since the middle mold is divided into two parts, the first and second middle molds 3 and 7, the structure becomes complicated, and as mentioned above, the vulcanized bladder 1
1 from wSl, the second middle mold 3', and 7 is required, which poses a problem in that work efficiency decreases.

, J Zhan ・ 1-1 Such a problem arises when the upper and lower molds can be moved close to each other and separated from each other.
When the upper and lower molds are closed, they are housed within the upper and lower molds, and a nearly cylindrical mold space is formed between them, which is unique to the upper and lower molds. With the mold inside can be moved.

An injection molding apparatus comprising: a disc-shaped material passage whose entire outer edge opens at the upper end of the mold space between the upper mold and the middle mold when the mold is closed; A plastic material injection path opening in the center of the passage is formed in the upper mold,
In addition, the problem can be solved by forming a fluid ejection passage that opens into the material passageway in the middle mold.

1. First, bring the upper and lower molds close to each other and close them.
Zero-order, which forms a mold space between the upper and lower molds and the middle mold,
Plastic material is injected from the injection path into the mold space through the material passage, and the mold space is filled with the plastic material. At this time,
The injection path opens at the center of the material passage, and the entire outer edge of the material passage opens at the upper end of the mold space.
The plastic material flows uniformly in any circumferential position of the mold space, so that the physical properties of the product are uniform throughout. Moreover, since the entire outer edge of the material passage is open to the upper end of the mold space, the injection time can be shortened, and plastic materials with good wave properties can be used. Moreover, the injection pressure can be reduced. When a product is molded in this way, the inner mold is lowered after the lower metal mold has been lowered. At this time, fluid is ejected from the fluid ejection path. Here, the upper end of the product is covered by the disc-shaped plastic material that filled the material passage, so
The fluid presses the integrated product, the disc-shaped plastic material, against the upper mold to prevent it from falling, and a part of it passes between the product and the middle mold and escapes to the outside, causing the product to fall. This will help the middle mold come out. When the inner mold is extracted from the product in this manner, the product is transported to the next process. here,
Since the medium mold is not divided into two parts, the work of extracting the medium mold from the product becomes easy and work efficiency is improved.

extension 1 Hereinafter, one embodiment of the present invention will be described based on the drawings.

In FIG. 1, 21 and 22 are upper and lower molds that can be moved closer to each other and separated from each other. fixed on the top. The movement plate 24 is raised and lowered by a hydraulic drive means (not shown).

A vertical center post 25 is slidably inserted into the center of the movable platen 24 and the lower mold 22.
5 is raised and lowered by a hydraulic drive means (not shown).
2 It moves independently with respect to the lower mold 21 and 22.

A middle mold 26° is removably attached to the upper end of the center post 25, and this middle mold 26 includes upper and lower molds 21.2.
2 is housed in the upper and lower molds 21 and 22, and the outer periphery and the upper and lower molds 21 and 2 are closed.
An upright, substantially cylindrical mold space 27 is formed between the mold space 27 and the inner periphery of the mold. An annular cavity 28 is formed in this middle mold 2B, and steam for vulcanization or cooling water for cooling is supplied to this cavity 28 through a passage 28. This passage 29
is connected to a steam source or a cooling water source via a passage (not shown) provided in the center post 25.

Further, 30 is a vacuum passage formed in the lower mold 22, and one end of the vacuum passage L and the passage 30 is connected to the lower end of the mold space 27, and the other end is connected to a vacuum source (not shown). Further, a disc-shaped material passage 36 is formed between the inner surface of the upper mold 21 and the upper end surface of the middle mold 28 when the upper and lower molds 21 and 22 are closed. The entire circumference of the outer end in the radial direction is the mold space 27.
It is open at the top end. The material passage 36 has at its outer edge a narrowed part 37 as shown in FIG. Again, in FIG. 1, 38 is an injection path formed in the upper mold 21, and the lower end of this injection path 38 is located at the center of the material passage 36, that is, at a position away from the upper end of the mold space 27. It's open.

The upper end of the injection passage 38 communicates with an injection passage 40 of an injection nozzle 38 connected to the upper mold 21, and this injection passage 40 has a throat portion 41 having a small diameter in the middle thereof. The injection passage 4
0 is connected to a supply means for supplying a plastic material 1 such as rubber (not shown), and the rubber fed under pressure from this supply means is injected into the injection passage 40. The mold space 27 is injected and filled through the injection path 38 and the material path 36. Reference numeral 45 denotes a fluid ejection passage formed in the middle mold 2B, the upper end of this fluid ejection passage 45 opens at the center of the material passage 3B, and the lower end thereof is provided in the center post 25 (not shown). It is connected to a fluid source, such as an air source, via a passageway.

Next, the operation of one embodiment of the present invention will be explained.

First, the lower mold 22 is activated by operating the hydraulic drive means. Middle mold 26
is raised to approach the upper mold 21. And lower mold 2
2 comes into contact with the upper mold 21 and the upper mold 21 and the lower mold 22 are closed, and the lower mold 22 and the middle mold 28 stop rising.

At this time, between the middle mold 2B, the upper mold 21, and the lower mold 22, there is a disc-shaped material passage 3B and a substantially cylindrical mold space 2.
7 is formed. Next, rubber is injected from the supply means into the injection passage 4.
0, the rubber is injected into the material passage 36 and the mold space 27 through the injection passage 38, filling the material passage 3B and the mold space 27 with rubber. At this time, the injection path 38 opens at the center of the material path 3B, and the entire outer edge of the material path 36 opens at the upper end of the mold space 27, so the rubber injected from the injection path 3 The mold space 27 is supplied evenly and at the same time to any position in the circumferential direction of the space 27.
The injected rubber can be vulcanized almost simultaneously.

As a result, the physical properties of the bladder 51 when it becomes a product are substantially uniform throughout, and even when expanded during molding or vulcanization, the entire bladder 51 expands evenly.

When injecting the rubber, air in the mold space 27 and material passage 36 is sucked from the vacuum passage 30 and discharged to the outside;
A passage 29 is then removed from the steam source to prevent air pockets from forming within or on the product, e.g. bladder 51.
Steam is supplied to the cavity 28 via the mold space 27. The rubber injected into the material passage 3B is vulcanized to form a bladder 51 and a disk-shaped rubber 52, respectively.Next, the lower mold 22 and the middle mold 26 are slightly lowered together. Thereby, after the vulcanized rubber is cut at the throat 41, the lower mold 22 is lowered by a predetermined amount by the hydraulic drive means. At this time, the upper half of the bladder 51 is in agreement q2 with the upper mold 21.
Since it is sandwiched between B and B, it does not descend, and its lower half is exposed to the outside, as shown in FIG.

Air is supplied between the disc-shaped rubber 52 and the middle mold 2B from a fluid source through the fluid ejection path 45. As a result, the disc-shaped rubber 52 and the bladder 51 are pressed against the upper mold 21. In this state, when the center post 25 and the middle mold 26 are lowered together by the hydraulic drive means, the bladder 51,
The disk-shaped rubber 52 is pressed against the upper mold 21 and does not fall, and only the middle mold 26 descends. Here, a part of the air passes between the middle mold 2B and the bladder 51 and escapes to the outside, so a thin air layer is formed between the middle mold 2B and the bladder 51, and the bladder 51 The middle mold 26 can be easily removed from the mold. When the inner mold 28 is extracted from the bladder 51 in this manner, the bladder 51 is taken out and conveyed to the next process.

In the next step, the disc-shaped rubber 52 is transferred from the bladder 51 to the narrow part 3.
Cut out the place corresponding to 7.

Next, a test example will be explained. In this test, first,
A comparative bladder molded using the conventional injection molding apparatus described above and a test bladder molded using the injection molding apparatus described in this example were prepared, and then the axial center portions of both bladders were molded with a ring. After cutting out the bone fragments, a rectangular bone fragment was obtained by cutting at specified points.Next, a test piece with a thickness of about 2 cm was cut out from each bone fragment using a slicer, and these tests were conducted. A tensile test was conducted on the piece according to the vulcanized rubber testing method specified in JIS6301. Among the characteristics obtained in this test, the results of 300% modulus are shown in Figure 4. Here, in the comparison bladder, an injection molding device having eight injection ports 14 was used. Therefore, as shown in FIG. 4, there are eight peaks and eight valleys, and it can be seen that the directionality of the physical properties is different near the injection port and in the middle of the injection port. On the other hand, in the test bladder, there is no such variation in physical properties, and the physical properties are uniform in the circumferential direction.

Furthermore, for the comparison mentioned above, the sample bladder was mounted on a uniformity machine and the uniformity (diameter at the center in the axial direction was 2
The results are shown in Figure 5.As is clear from the figure, the comparison tire had a small amount of runout corresponding to the number of injection ports, but the test tire had less runout. It can be seen that no such deflection occurs, and the uniformity is improved.

In the above-mentioned embodiment, the upper mold 21 was kept stationary and the lower mold 22 was moved to move the upper and lower molds 21 and 22 toward and away from each other, but in this invention, the lower mold 21 was kept stationary. The upper mold may be moved, or both the upper and lower molds may be moved so that they come into contact with or move away from each other.

As explained below, according to the present invention, the structure is simplified, it is possible to mold a product with uniform physical properties in the circumferential direction, and the efficiency of the molding work is also improved. .

[Brief explanation of the drawing]

Fig. 1 is a front sectional view showing an embodiment of the present invention, Fig. 2 is a front sectional view near the material passage, Fig. 3 is an explanatory drawing explaining its operation, and Fig. 4 shows the results of a tensile test. 5 is a graph showing the results of a uniformity test, FIG. 6 is a front cross-sectional view showing a conventional injection molding device, and FIG. 7 is an explanatory diagram explaining the operation of the conventional injection molding device. 21... Upper mold 22... Lower mold 2B...
・Inner mold 27... Mold space 3B... Material passage 38... Injection path 45... Fluid ejection path Patent applicant Brideston Co., Ltd. Agent Patent attorney Ta 1) Toshio Figure 1 21...・Upper mold 22...Lower mold 26...Middle mold 27...Mold space 36...
・Material passage 38... Injection passage 45... Fluid ejection passage Fig. 2 Fig. 3 Fig. 4 Fig. 5 Circumferential direction position j Pit Fig. 6 Fig. 7 n

Claims (1)

[Claims] The upper and lower molds are able to approach and separate from each other, and when the upper and lower molds are closed, they are housed in the upper and lower molds, and a substantially cylindrical mold space is created between the upper and lower molds. an injection molding apparatus, comprising: a middle mold that can independently move relative to the upper and lower molds; A disc-shaped material passage whose entire circumference opens at the upper end of the mold space is formed, and a plastic material injection passage which opens at the center of the material passage is formed in the upper mold, and which opens into the material passage. An injection molding device characterized in that a fluid ejection path is formed in a middle mold.