JPH0585615U - Injection mold - Google Patents

Abstract

(57) [Summary] [Purpose] To provide an injection mold in which the core does not bend in the cavity and uneven thickness does not occur in the tube. [Structure] Sliding hole 1 facing both sides of the cavity 13 corresponding to the outer circumference of the tube and orthogonal to the cavity 13.
7 and 18 were formed. The sliding bodies 21 and 22 are inserted into the sliding holes 17 and 18, and the cores 15 are moved by the springs 29 and 30.
Urge towards. Supporting portions 37 and 38 are provided on the side of the cavities 13 of the sliding bodies 21 and 22.
Pressing surfaces 41, 4 for preventing the bending by pressing the core 15 to the 8
2 and the support portion 3 under the action of the pressure of the thermoplastic resin 50.
Pressure receiving surface 45 for pressing 7, 38 into the sliding holes 17, 18,
46 and.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an injection mold for injecting a thermoplastic resin under pressure to form a tube.

[0002]

[Prior Art]

 To form a tube by pressure-injecting a thermoplastic resin, insert a long core that forms the hollow part of the tube into the cavity that corresponds to the outer circumference of the tube, and insert the cavity and the cavity. A viscous thermoplastic resin is injected under pressure, and when the thermoplastic resin is cooled and hardened, the tube formed between the cavity and the core is taken out. At this time, in the conventional injection mold, the long core is supported only at the end of the cavity.

[0003]

[Problems to be solved by the device]

 However, in the conventional injection mold, the long core is not supported inside the cavity, and there is a case where the mold is bent due to its own weight inside the cavity. As described above, when the thermoplastic resin is injected under pressure into the cavity while the core is flexed in the cavity, uneven thickness is generated in the formed tube. As described above, when uneven thickness occurs in the tube, the thin wall portion easily breaks and the performance deteriorates.

Therefore, the present invention has an object of solving the above-mentioned problems, and an object thereof is to provide an injection mold in which the core does not bend in the cavity and uneven thickness does not occur in the tube.

[0005]

[Means for Solving the Problems]

 In order to solve the above problems, the present invention has the following configuration as means for solving the problems. That is, a long core is inserted into the cavity formed by abutting a pair of mold bodies formed by dividing the cavity corresponding to the outer circumference of the tube into two in the longitudinal direction, and the thermoplastic resin is inserted into the cavity. In a die for injection in which is injected under pressure to form a tube, sliding holes orthogonal to the cavity are formed in the die body so as to oppose each other on both sides of the cavity, and slide into the sliding hole. A slide body is movably inserted into each of the slide holes, a biasing body that biases the slide body toward the core is housed in the slide hole, and the slide body has a support projecting into the cavity. And a pressure receiving surface that pushes the core by the urging of the urging member and a pressure receiving surface that receives the action of the pressure of the thermoplastic resin injected under pressure in the opposite urging direction. Specially formed This is the composition of the injection mold to be collected.

[0006]

[Action]

 The biasing bodies housed in the sliding holes formed facing each other on both sides of the cavity urge the sliding bodies inserted in the sliding holes toward the core. Then, the sliding body slides in the sliding hole toward the core, and the supporting portions thereof respectively project into the cavity. At that time, the pressing surface of the supporting portion presses the core while facing it from both sides. When the thermoplastic resin is injected under pressure into the cavity, the pressure receiving surface of the support receives the pressure of the thermoplastic resin, and the sliding body overcomes the biasing force of the biasing body and slides toward the sliding hole. , The support part is pushed into the sliding hole.

[0007]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. As shown in FIGS. 1 and 2, the injection mold 1 of the present embodiment includes a pair of mold bodies 3 and 5 which are divided into two in the longitudinal direction. The abutting surfaces thereof are provided with grooves 10 and 11 having the same shape and recessed in a semicircular shape. Then, the grooves 10 and 11 become a cavity 13 which becomes a circular hollow portion corresponding to the outer circumference of the tube to be formed when the abutting surfaces are butted. An elongated core 15 forming a hollow portion of the tube is inserted in the cavity 13. The core 15 has a cylindrical shape corresponding to the inner circumference of the tube, and the core 15 is supported by the mold bodies 3 and 5 at the end of the cavity 13.

Sliding holes 17 and 18 orthogonal to the cavity 13 are formed in the mold bodies 3 and 5 so as to face each other on both sides of the cavity 13. Each of the sliding holes 17 and 18 has a narrow rectangular shape at the entrance portion on the side of the cavity 13 and is widely formed in a circular shape from the middle, and the widely formed portion is opened to the outside of the mold bodies 3 and 5. .. Cylindrical slide bodies 21 and 22 slidable in the front-rear direction toward the cavity 13 are inserted into the widely formed portions. Cylindrical projections 25 and 26, which are thinner than the slide bodies 21 and 22, are formed at one ends of the slide bodies 21 and 22, and the slide bodies 21 and 22 face the core 15 on the outer circumferences of the projections 25 and 26. The springs 29 and 30 for urging the springs are fitted. The springs 29 and 30 are pressed into the slide holes 17 and 18 from the outside of the mold bodies 3 and 5 by the pressing portions 33 and 34.

On the other hand, on the side opposite to the convex portions 25, 26 of the sliding bodies 21, 22, there are formed support portions 37, 38 projecting into the cavity 13 by the urging force of the springs 29, 30. The supporting portions 37 and 38 are formed in a plate shape so as to fit into the inlet portions of the sliding holes 17 and 18 on the cavity 13 side. Further, the end portions of the supporting portions 37 and 38 on the cavity 13 side have a curved surface that fits a part of the outer periphery of the core 15, and the core 15 is pushed by the biasing force of the springs 29 and 30 in the fitted state. The pressing surfaces 41, 42 and the core 15 have a flat shape that does not fit onto the outer circumference of the core 15 and spreads out from the outer circumference into a brim shape. The pressure receiving surfaces 45 and 46 for receiving are formed.

The number and position of the sliding holes 17 and 18 orthogonal to the cavity 13 of the mold bodies 3 and 5 and the sliding bodies 21 and 22 inserted therein depend on the length and material of the core 15. The number and position at which the core 15 is not bent may be appropriately selected. The operation of the injection mold 1 configured as above will be described.

First, the core 15 is inserted into the cavity 13, and its ends are supported by the mold bodies 3 and 5. The insertion method is such that the supporting portions 37 and 38, which are provided facing each other in the cavity 13 portion of the one mold body 3 which is divided into two parts and which have already protruded into the cavity 13 portion, are widened. After fitting 15 and supporting the end, the other mold body 5 is butted. At this time, the slide bodies 21 and 22 inserted into the slide holes 17 and 18 are urged toward the core 15 by the springs 29 and 30, but the narrow inlet portions of the slide holes 17 and 18 are provided. It does not project into the cavity 13. Then, the support portions 37, 38 of the slide bodies 21, 22 project into the cavity 13 from the inlet portions of the slide holes 17, 18, and the pressing surfaces 41, 42 push the core 15 from both sides so as to face each other. The deflection of the child 15 is prevented. In this way, the core 15 is inserted into the cavity 13 and is pressed against the pressing surfaces 41 and 42 of the supporting portions 37 and 38 from both sides so as to be viscous thermoplastic from the end of the cavity 13. Resin 50 is injected under pressure as shown in FIG. At this time, the injection mold 1 is heated to about 150 ° C. When the thermoplastic resin 50 flows into the cavity 13 and reaches the pressure receiving surfaces 45, 46 of the support portions 37, 38, the pressure receiving surfaces 45, 46 receive the pressure of the thermoplastic resin 50 and become integrated with the support portions 37, 38. The sliding bodies 21 and 22 are slid in the directions of arrows A and B in FIG. Then, when the thermoplastic resin 50 fills the inside of the cavity 13, the supporting portions 37 and 38 are completely pushed into the sliding holes 17 and 18 from the inside of the cavity 13 as shown in FIG. In this way, after the thermoplastic resin 50 fills the cavity 13, the injection mold 1 is cooled to cure the thermoplastic resin 50. After the thermoplastic resin 50 is cured to form a cylindrical tube, the mold bodies 3 and 5 are divided, and the tube integrated with the core 15 is removed from the mold bodies 3 and 5. Finally, the tube is taken out by pulling out the core 15.

Therefore, in this embodiment, since the core 15 is pressed in the cavity 13 from both sides of the cavity 13 by the pressing surfaces 41 and 42 of the supporting portions 37 and 38, the core 15 is pushed into the cavity 13. The tube formed in the cavity 13 does not bend and uneven thickness does not occur.

The present invention can be variously modified without departing from the gist thereof.

[0014]

[Effect of the device]

 As described above in detail, according to the injection mold of the present invention, the core does not bend in the cavity, and the uneven thickness does not occur in the tube formed in the cavity. can do.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an embodiment of an injection mold.

FIG. 2 is an AA in FIG. 1 of an injection mold.
FIG.

FIG. 3 is a cross-sectional view showing a state where a thermoplastic resin is injected under pressure into the cavity of FIG.

FIG. 4 is a cross-sectional view showing a state where the cavity of FIG. 3 is filled with a thermoplastic resin.

[Explanation of symbols]

1 ... Injection mold, 3, 5 ... Mold body, 13 ...
Cavity, 15 ... Core, 17, 18 ... Sliding hole, 21,
22 ... Sliding body, 29, 30 ... Spring, 37, 38 ... Support part, 41, 42 ... Pressing surface, 45, 46 ... Pressure receiving surface, 50 ...
Thermoplastic resin

Claims (1)

[Scope of utility model registration request] 1. A long core is inserted into the cavity formed by abutting a pair of mold bodies formed by dividing a cavity corresponding to the outer circumference of the tube into two in the longitudinal direction, and inserting the elongated core into the cavity. In an injection mold for injecting a thermoplastic resin under pressure to form a tube, sliding holes orthogonal to the cavity are formed in the mold body so as to face each other on both sides of the cavity. A sliding body is slidably inserted therein, and a biasing body that biases the sliding body toward the core is housed in the sliding hole, and the sliding body projects into the cavity. A supporting surface is formed, and a pressing surface that presses the core by the biasing of the biasing member and a pressure receiving surface that receives the action of the pressure of the thermoplastic resin injected under pressure in the anti-biasing direction. That they formed Injection mold for the butterflies.