JPH02281918A - Method and mold for molding cylindrical body - Google Patents

Abstract

PURPOSE:To shorten one cycle time of molding without making the structure of a mold more complicated and surely prevent the deformation at releasing from occurring by a method wherein a gas conducting path forming member, by which outside gas is introduced in a space formed between the mold and a molded cylindrical body at releasing, is moved relative to the mold. CONSTITUTION:An air introducing path is provided between a core block 3 and a pin 6 so as to introduce air from outside in a space 15, which is formed between a core part 4 and a container main body 14B during the transferring course of the container main body 14B. Further, the pin 6 is interlocked with a stripper 7 so as to be moved until the pin 6 comes into contact with the bottom wall 14Bb of the container main body 14B. As a result, a molded tubular body is sound at all times, resulting in enhancing the yield of the tubular body, shortening one cycle time of molding and consequently enhancing the productivity of the tubular body and, in addition, the structure of the mold does not become more complicated.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a method for molding a cylindrical body and a mold used for this molding.

BACKGROUND OF THE INVENTION Photographic 135 film is generally stored in a cartridge, and is commercially available along with the cartridge in a cartridge storage container. The cartridge storage container consists of a container main body and a cap. After the cartridge is stored in the container main body, the cap is placed over the cartridge entrance/exit of the container main body, and the cap is fixed to the container main body. The container body consists of a cylindrical peripheral wall and a bottom wall, is made of plastic, and is molded by injection molding.

The container body is formed in the following steps, as will be explained later in the Examples section. That is, a molten molding material is press-fitted into a cavity formed between a fixed cavity plate and a movable core block.
This solidifies to form the container body, and then the core block moves together with the molded body and separates from the cavity plate.
Next, the stripper plate moves, thereby releasing the molded body from the core block.

Fig. 13 shows how the molded container main body is released from the core block; Fig. 13 (a) is a cross-sectional view immediately after it is released from the core block, and Fig. 13 (b) is a cross-sectional view of the molded container body after it has been released from the core block; FIG. 3 is a cross-sectional view of the main body in the middle of being released from the core block.

As shown in FIG. 13(a), immediately after molding, the stripper plate 47 is in close contact with the core block 43 and the movable mold mounting plate 48 that supports it, and the molded container body 54 is in close contact with the core block 43. 43 and the radially inner end of the stripper plate 47. Next, as shown in FIG. 13(b), the stripper plate 4
7 moves in the direction of the arrow, the radially inner end of the stripper plate 47 presses the opening side end surface of the container body 54 to release the container body 54 from the core portion 44 .

At this time, if an attempt is made to release the container body 54 before it is completely solidified, the space 55 inside the portion of the container body away from the core block becomes depressurized, and the peripheral wall is constricted into an annular shape due to atmospheric pressure. Or the bottom wall becomes depressed and deformed. Both of the above variants may occur together.

If the container body is released from the core after it has completely solidified, the above deformation will not occur, but this will take time for complete solidification.
This becomes an obstacle to shortening the time for one molding cycle and improving productivity.

As a method to solve the above problems, JP-A-62-
The methods described in Japanese Patent No. 62721 and Japanese Patent No. 63-193142 have been proposed.

The former is an injection mold that includes a cavity plate that forms the outer surface of a bottomed cylindrical injection molded product and a core that forms the inner surface of the molded product, in which a recess is formed on the tip surface of the core. a columnar nesting mold having a plurality of clearance parts on its outer peripheral surface is fitted and fixed, and each of the clearances is provided in the vicinity of the distal end surface of the core of at least one of the core and the nesting mold. The present invention relates to an injection mold, characterized in that a chamber is formed in the core and a communicating hole is formed in the core to introduce outside air into the chamber.

In the latter case, three or more inner surfaces from the bottom of the peripheral wall are at least one
This invention relates to a container body for a photographic film cartridge, characterized in that it is formed on a rough surface having a height difference of gm.

However, in the former case, the structure of the mold becomes complicated, which leads to an increase in manufacturing costs. In the latter case, (a) if the dimensions of the irregularities on the rough surface are not appropriate, an inverted tapered portion will be formed when the mold is released, and the container body will be chewed. (b) Due to repeated use, the uneven surface provided on the core block is worn out and the desired rough surface is no longer formed. (c) An attempt is made to prevent the above deformation by collecting air on the rough surface and supplying this air, but since the amount of air stored is small, the problem is that a sufficient effect cannot be obtained. be.

Object of the Invention The present invention provides a method for forming a cylindrical body that does not complicate the structure of the mold, can shorten the molding cycle time, and can reliably prevent deformation during mold release, and a method for this molding. The purpose is to provide a type to use.

21. Constitution of the Invention The first invention includes, when molding a cylindrical body, (a) a step of supplying a molding material into a molding space; and (b) a step of solidifying the molding material to form a cylindrical molded body. and (c) forming the gas conduction path so that an external gas is introduced into the space formed between the mold and the cylindrical molded body by a gas conduction path forming member provided on the mold when the mold is released. The present invention relates to a method for molding a cylindrical body, the method comprising a step of moving a member relative to the mold.

The second invention is a mold used for molding a cylindrical body,
Relating to a mold for forming a cylindrical body, which is provided with a gas conduction path forming member, and wherein the gas conduction path forming member is movable relative to the mold when the molded cylindrical body is released from the mold. .

E, Example The present invention will be explained in detail below.

FIGS. 1(A) to 1(E) are sectional views of main parts showing the procedure for molding the container body of the cartridge storage container.

First, a fixed cavity plate 1, a movable core block 3 attached to a movable plate 8, and a stripper plate 7 are set as shown in FIG. 1(A). A hot runner 12 is installed inside the cavity plate 1. The core block 3 is provided with a through hole reaching the tip, and a bottle 6 is fitted into this through hole so as to be able to reciprocate. Bin 6 will be detailed later. Thus, a cavity 10 is formed by the cavity plate 1, the core portion 4 of the core block 3, and the radially inner end of the stripper plate 7. In the figure, 11
is a gate, and 13 is a sprue.

Cooling water W is passed through the water passage 5, and as shown in FIG. 1 (Sunday), a melt molding material (polypropylene in this example) 14A is press-fitted from the hot runner 12. This press fit is
This is done with a conventional in-line screw injection device (not shown). Thus, hot runner 12, gate 1
1, the molding material 14A is filled into the cavity 10.

After the molding material has solidified to a certain extent by cooling, the core block 3 and stripper plate 7 are moved back as shown by the arrows, as shown in FIG. 1(c).

The container body 14B formed by solidifying the molding material is separated from the cavity plate 1 together with the core block 3.

Next, as shown in FIGS. 1(D) and 1(E), the stripper plate 7 is moved forward, and its radially inner end pushes the container body 14B to remove it from the core part 4 of the core block 3.
Release from the mold. The container body 14 moves while its peripheral wall 14 a slides in contact with the core portion 4 .

The following two points should be noted here. One of them is that an air conduction path is provided between the core block 3 and the bottle 6, and in the process of moving the container body 14B in FIG. Air is introduced from the outside into the space 15 that is formed. Another is that the bottle 6 moves in conjunction with the stripper plate 7 so as to come into contact with the bottom wall of the container body 14. These are shown in FIG. 2, which is an enlarged sectional view taken along the line ■-■ of FIG. 1(D), FIG. This will be explained with reference to Figure 5.

4 is an enlarged half sectional view of the bottle 6 seen from the front, and FIG. 5 is a sectional view taken along the line V--V in FIG. 4. The cross-sectional shape of the bottle 6 is a circular shape with thin arcuate cutouts 6a provided at four locations. The cutout portion 6a is provided over the entire length of the bottle 6. The bottle 6 is inserted into the through hole (
(Circular cross section) 3b without any play.
As shown in the figure, an air guide path 17 is formed. When the container body is released from the core part 4 on the 14th day, air A flows from the outside into the air conduction path 1, as shown in FIGS. 1(D) and 3.
The space 1 between the core part 4 and the container body 148 via 7
5 will be introduced. Therefore, in the process of FIG. 1(D), the space 15 is maintained at approximately atmospheric pressure without being depressurized, and the
Deformation of the container body as explained in FIG. 3 does not occur. Furthermore, the air guide passage 17 discharges the air inside the cavity 10 outside the mold during injection molding (FIG. 1 (Sun)) to ensure molding. The depth d of the cutout portion 6a shown in FIG.
0.01 so that the air is conductive and the molding material does not block the air conduction path 15 during injection molding (Fig. 1 (B)).
It is preferable to set it to about 0.02M.

Even if the tip of the air guide path 15 were to be blocked during injection molding, the bottle 6 would move in conjunction with the stripper plate 7, and the tip would protrude from the core 4, preventing air from being introduced. It won't happen. In the figure, 14th day C is an annular projection formed on the outer periphery of the opening side end of the container main body, and is for fitting into the annular groove of the cap (not shown) to fix the cap.

The bin may have the shape shown in FIGS. 6 and 7. FIG. 6 is an enlarged half sectional view of the bottle seen from the front, and FIG. 7 is a sectional view taken along the line ■--■ in FIG.

The cross-sectional shape of the pin 16 is cross-shaped, with cutout portions 16a close to quarter circles provided at four circular locations.

However, a small portion 16b at the tip of the pin 16 has a circular cross section. The cutout portion 16a forms an air conduction path similarly to the above example. In this example, during injection molding, the air guide path is closed by the circular end portion 16b of the pin 16, so the molding material does not enter the air guide path, and therefore burrs are not generated. do not have. Furthermore, when the container body is released from the core part, the pin 16 moves in conjunction with the stripper plate, so that the air conduction path formed by the cutout part 16a is immediately exposed from the tip of the core part by this movement, and the core part Air is introduced into the space between the container body and the container body. In addition, in this example, the cut portion 16
The total cross-sectional area of a can be made large, and therefore the cross-sectional area of the air passage can be made large, and pressure reduction in the space can be particularly effectively prevented. Even in the case of the pin 6 shown in FIG. 4, the occurrence of burrs can be prevented by providing a circular bow portion 6b shown by a virtual line at the tip.

As described above, the molded container body can be smoothly released from the core part without deformation, so there is no need to add a draft angle to the mold for mold release, and there are fewer restrictions on the design of the container body. Become. In the example in Figure 1, pin 6 (or 16
) is moved in conjunction with the stripper plate 7 until the mold release is completed as shown in (D) and (E) of the same figure, but the pin 6
(or 16) may be moved by a small amount until the air guide passage 17 (see FIGS. 2 and 3) communicates with the space 15 after the mold release starts. Also, pin 6 (or 1
6) and the stripper plate 7 may be fixed and the core block 3 may be moved leftward in FIG. 1 to release the mold. It is advantageous for the mold design to provide the gate in contact with the flat bottom wall, and it may be provided in contact with the center of the bottom wall, but it can also be provided in a position eccentric from the center as shown in Figure 1. . By setting the gate position in this way, when injecting the molten molding material into the cavity, the final filling portion can be limited to a specific location.

Even if a short shot occurs for some reason, it is always at a fixed location, so it can be easily detected by a separately provided inspection device, and has the effect of preventing defective products from being sent to the next process.

FIG. 8 shows an example in which a convex portion 4a is provided at the tip of the core portion 4 at the pin 6 (or 16) insertion portion of the core block 3, and a cavity concave portion 10a is formed in the cavity 10 by the convex portion 4a. As shown in FIG. 9, the molded container body 1
A recess 18 is formed inside the bottom wall 14Bb on the fourth day, corresponding to the cavity recess 10a shown in FIG. Suppose there is a slight gap between the pin 6 (or 16) and the core part 4 in FIG. 8, and the molding material enters this gap or air passage, resulting in a slight gap as shown in FIG. Even if the burr 19 is generated, the burr 19 can be stored in the recess 18, and the burr 19 does not get in the way of storing the object (patrone) even if the burr 19 is not removed regularly, which is convenient.

The air passage can also be provided in a fixed cavity plate. FIG. 10 is an example of the cold runner method, and is an enlarged sectional view showing the process of releasing the molded container body from the cavity plate configured as described above, and FIG. 11 is an enlarged sectional view taken along the line XI-XI in FIG. Cross section, 1st
FIG. 2 is also a sectional view taken along the xn-xn line.

The core portion of the core block (not shown) has a draft angle, and when the core block retreats, the molded container body 34 is released from the core portion and left behind on the cavity plate 21. In the figure, 34a is the peripheral wall of the container body 34;
b is the bottom wall, 34c is the annular convex portion at the opening end,
34d is an unnecessary part formed within the runner. A protruding pin 27 is reciprocatably fitted into the three through holes of the cavity plate 21, and a pin 26 similar to the pin 6 shown in FIGS. 4 and 5 (FIGS. 6 and 7) is inserted into another through hole. A pin similar to the pin 16 shown in FIG. An air guide path 37 is formed by the cutout 26a of the pin 26.

Move the ejecting pin 27 in the direction of the arrow to remove the container body 34.
is released from the cavity plate 21, and the bottle 26 is moved in the direction of the arrow so as to come into contact with the bottom wall 34b. At this time, the container main body 3
4 and the cavity plate 21
Air A is introduced into the space 35 from the outside to prevent the space 35 from being depressurized.

Thus, as in the above example, the bottom wall 34b is not deformed by atmospheric pressure (deformation that swells toward the space 35), and mold release is not inhibited by the reduced pressure in the space 35, so that mold release is not possible. done smoothly. In this example, the protruding pin 27 has the same shape as the pin 6 in FIGS. 4 and 5 or the bottle 16 in FIGS. 6 and 7, so that the pin 27 has the function of air conduction, and the bottle 26 can be omitted. can.

The mold release using the ejector pin shown in FIG. 10 can also be applied to the example shown in FIG. That is, an ejector pin is provided on the core block 3 in place of the stripper plate 7 shown in FIG. 1, and the ejector pin is used to press the bottom wall 14 of the cylindrical molded body (container body) 14B to release it from the mold. The rest is the same as in the example of FIG.

The present invention has been described in detail above, but in addition to the above examples, various modifications can be made based on the technical idea of the present invention. For example, in addition to injection molding, the cylindrical body may be molded by compression molding or other molding methods, and the cylindrical body may be used for various purposes other than the main body of the cartridge storage container. In addition to the cylindrical shape, the peripheral wall shape may be a peripheral wall with other cross-sectional shapes, and the present invention is also applicable to molding a cylindrical body without a bottom wall (such as when retracting the core block from the cavity plate). In addition to air, the external gas may be other atmospheric gas. Furthermore, in addition to the method of forming a cavity by combining a female mold and a male mold, the present invention can also be applied to molding a cylindrical body using a single mold. For example, when molding a cylindrical body that requires high dimensional accuracy on the inner circumferential surface, a male die is heated and molding material is supplied to it, and the heat solidifies the cylindrical body along the die surface. Form the body.

When molding a cylindrical body that requires high dimensional accuracy on the outer circumferential surface, a female mold is heated and the molding material is injected into it, and the cylindrical body is solidified along the inner surface of the female mold by the heat. After forming a mold, turn it upside down and discharge excess molding material. In these cases, a pin for forming an air conduction path as shown in FIG. 4, FIG. 5, FIG. 6, or FIG. 7, for example, is arranged in the male mold or female mold in the same manner as above, and the mold is released. By doing so, the same effects as described above can be achieved. In these methods,
Powdered molding materials can preferably be used.

5. Effects of the Invention The present invention provides a gas conduction path forming member that introduces external gas into the space formed between the mold and the molded cylindrical body during mold release. Since it is moved relative to the mold, the space does not become depressurized due to the introduction of the external gas. Therefore, even if the cylindrical molded body is released from the mold before it is completely solidified, the cylindrical molded body will not be deformed, and the mold release will be performed smoothly without being prevented from being released by reduced pressure.

Further, due to the above-mentioned movement of the gas conduction path forming member, even if the tip of the gas conduction path is blocked during supply of the molding material, the gas conduction path will be able to communicate with the space after the gas conduction path formation member is moved. The above-mentioned external gas introduction is carried out without any delay. As a result, the molded cylindrical body is always sound, improving the yield, shortening the time for one molding cycle and improving productivity, and the structure of the mold does not become complicated. .

[Brief explanation of drawings]

1 to 12 show examples of the present invention, and FIGS. 1(A), (B), (c), (D), and (E) show the molding of the main body of the cartridge storage container. Figure 2 is an enlarged cross-sectional view of the main parts shown in Figure 1 (D). Figure 3 is an enlarged cross-sectional view of the same <m-m line. Figure 4 is a pin (air conductor). FIG. 5 is an enlarged half-sectional view taken from the front of a bottle according to another example; FIG. 5 is an enlarged half-sectional view taken from the front of a bottle according to another example; FIG. The figure is a cross-sectional view taken along the line ■-■ in Figure 6, Figure 8 is an enlarged partial cross-sectional view of a mold according to another example, and Figure 9 is an enlarged cross-section of the patrone storage container body formed by the mold shown in Figure 8. Figure 10 is an enlarged partial cross-sectional view showing a state in which the main body of the cartridge storage container is released from the mold according to still another example, Figure 11 is a cross-sectional view taken along the line XI-XI of Figure 10, and Figure 12 is the same < It is a sectional view taken along the xn-xn line. Fig. 13 shows a conventional example, in which Fig. 13 (a) is a sectional view of the main part immediately before releasing the cartridge storage container body from the core block, and Fig. 13 (b) shows the main part of the cartridge storage container main body removed from the core block. FIG. 3 is a cross-sectional view of a main part in the middle of being released from the mold. In addition, in the symbols shown in the drawings, 1.21...Cavity plate 3...
......Core block 4...Core part 6.16.26...Bin 6a, 16a,
26a......Resection part 7...
Stripper plate 10...Cavity 14A...Molding material 14th, 34...Patrone storage container body 14Ba, 34a... ... Peripheral wall 14Bb,
34b...Bottom wall 27...
It is a protruding bottle. Agent Patent Attorney Hiroshi Osaka 1 “0 Yu Figure 13 Area ■ Area

Claims (1)

[Claims] 1. When molding a cylindrical body, (a) a step of supplying a molding material into a molding space; (b) a step of solidifying the molding material to form a cylindrical molded body; c) When releasing the mold, the gas conduction path forming member is installed in the mold so that external gas is introduced into the space formed between the mold and the cylindrical molded body through the gas conduction path forming member provided on the mold. A method for molding a cylindrical body, the method comprising: moving it relative to a mold. 2. A mold used for molding a cylindrical body, which is provided with a gas conduit forming member, and when the molded cylindrical body is released from the mold, the gas conduit forming member is relative to the mold. A mold for molding a cylindrical body that is movable.