JPH0335541Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a mold for an extrusion molding machine that eliminates the need for uniform thickness unevenness when forming a circular tube as an extrusion product.

Traditionally, the molds of extrusion molding machines have been manufactured by, for example,
There is one shown in Publication No. 49-10256. In this configuration, a die is provided in the mold body, a mandrel is provided in the die hole formed in the die,
This mandrel is screwed to the mold body. The annular gap between the die and the mandrel serves as a circular tube extrusion molding section. Furthermore, the die is movable and adjustable in its radial direction.

To explain the extrusion molding procedure for a circular tube with the above configuration, a material to be molded which has been heated by a heater and fluidized is extruded by a screw. The material to be molded then passes through the extrusion molding section, where a circular tube is molded. By the way, at the beginning of molding,
The positional relationship between the die and the mandrel may not be on the same axis, and in this case, a circular tube with uneven thickness will be formed. While doing so, they changed the position of the die and made adjustments to prevent uneven thickness.

However, in the above-mentioned conventional structure, a large amount of molding material is consumed in order to adjust the unevenness in thickness, which causes problems such as a decrease in yield and an increase in the cost of the product.

This idea was devised in view of these problems, and aims to improve yield by eliminating the need for uneven thickness adjustment for molded products, and also to facilitate the work of fixing and extracting the mandrel from the mold body. The purpose is to do so.

The feature of this invention to achieve the above object is that the rear part of the mandrel is formed into a tapered shape, and the rear tapered part of the mandrel can be freely inserted into and removed from the tapered hole formed in the support body on the above-mentioned axis. The mandrel is fixed to the support by only this fitting, and the support, the spider, and the mold body are integrally molded, and these three are sequentially connected to each other so that the mandrel can be inserted from the rear end of the mandrel. A through hole is formed that extends radially outward to the outside of the mold body.

Examples of this invention will be described below with reference to the drawings.

In the figure, 1 is an extrusion molding machine main body, 2 is a mold, and this mold 2 is detachably fixed to the extrusion molding machine main body 1 by a fixing member 3. This extrusion molding machine main body 1 has a cylinder 4 and a screw 5 rotatably inserted into the cylinder 4, and the screw 5 and the mold 2 are located on the same axis C. .

The mold 2 has a cylindrical mold main body 6, and the mold main body 6 is located in front of the screw 5 in the extrusion direction (indicated by an arrow Fr in the figure). Further, a substantially cylindrical support body 9 is provided in the inner hole 7 of the mold body 6. This support body 9 is also located on the axis C, and is connected to the inner peripheral surface of the inner hole 7 by spiders 8 arranged at equal intervals in the circumferential direction. In this case, the mold body 6, spider 8, and support body 9 are integrally molded. In addition, the inner hole 7
is a breaker plate 1 having a plurality of through holes 10
It communicates with the inside of the cylinder 4 via 1.

A die 12 is removably fitted into a mounting hole 6a formed at the front end of the mold body 6 in the extrusion direction, and is removably fixed with a fastener 13. A die hole 14 tapered toward the front is formed in the die 12, and the die hole 14 and the attachment hole 6a are also located on the axis C.

A mandrel 15 is provided within the die hole 14. This mandrel 15 has tapered parts 15a and 15b at its front and rear parts, respectively, and then the tapered part 15b is removably fitted into a tapered hole 17 formed in the support body 9 on the axis C. There is.

In the above case, the mandrel 15 is then fixed to the support body 9 only by fitting the tapered portion 15b into the tapered hole 17.

The annular gap between the inner circumferential surface of the die hole 14 and the front tapered part 15a of the mandrel 15 serves as a circular pipe extrusion molded part 16, and this extrusion molded part 1
The rear end of the spider 6 communicates with the inner hole 7 through the gap between the spiders 8, 8.

On the other hand, a dovetail groove 18 is formed at the bottom of the tapered hole 17 so as to correspond to the rear end position of the mandrel 15, and this dovetail groove 18 is communicated with the outside through a through hole 19. That is, this through hole 19 sequentially communicates the support body 9, the spider 8, and the mold body 6, and extends from the dovetail groove 18 toward the outside of the mold body 6 in the radial direction of the mandrel 15. ing.

Reference numeral 20 denotes a tool for extracting the mandrel 15 from the tapered hole 17, which is inserted into the through hole 19.
When the mandrel 15 is removably inserted into the mandrel 20, the tip tapered portion 20a of the tool 20 slides and presses the end surface of the rear tapered portion 15b, thereby pulling out the mandrel 15.

Next, the effects of the configuration of the above embodiment will be briefly explained.

When a resin material, which is an example of a material to be molded that has been heated and fluidized by a heater (not shown), is extruded from the extrusion molding machine main body 1 by the screw 5, this resin material is transferred to the breaker plate 11, the inner hole 7, the spider 8, The extrusion molding part 1 is formed by sequentially passing through the gaps between
6, and a circular tube 21 is formed here.

Incidentally, in this case, since the mandrel 15 is fixed to the support body 9 by simply being fitted into the tapered hole 17, it is thought that the mandrel 15 may easily fall out from the tapered hole 17. However, since the front tapered portion 15a of this mandrel 15 receives back pressure from the material to be molded and can easily fit into the taper hole 17, the mandrel 15 is reliably prevented from accidentally falling off from the support body 9.

Although the above example is based on the illustrated example, the present invention may be applied to a mold for covering electric wires, etc.

According to this invention, since the support body 9 for supporting the mandrel 15 is integrally molded with the mold body 6, the tapered hole 17 in this support body 9 can be molded with high precision with respect to the mold body 6. That will happen.
Therefore, the axes of the die hole 14 of the die 12 attached to the mold body 6 and the axes of the tapered hole 17 also match accurately. In the above configuration, when the rear tapered portion 15b of the mandrel 15 is fitted into the tapered hole 17, the mandrel 15 precisely matches the axis of the die hole 14, and therefore the circular tube 21 is formed. This is advantageous because it eliminates the need for adjustment to prevent uneven thickness. As a result, the material to be molded is not consumed in order to make adjustments to prevent thickness deviation, and the yield can be improved.

Moreover, since the mandrel 15 is fixed to the support body 9 only by taper fitting, the work of fixing the mandrel 15 is easy.

In the above case, the fixation of the mandrel 15 is simply due to the taper fitting, but during extrusion molding, the front tapered part 15a of this mandrel 15 receives back pressure from the material to be molded, and the rear tapered part 15a of the mandrel 15 15b is easily fitted into the tapered hole 17, so that the fixed state of the mandrel 15 to the support body 9 is reliably maintained.

By the way, when trying to pull out the mandrel 15 that has been tapered fitted to the support body 9, it is necessary to press the rear end of the mandrel 15 forward.
However, if the screw 5 exists behind the mandrel 15, this will get in the way.
The above work cannot be done easily.

Therefore, in this invention, a through hole 19 is provided that extends from the rear end position of the mandrel 15 toward the outside of the mold body 6 in the radial direction of the mandrel 15. For example, by inserting a rod-shaped tool from outside the mold body 6 and pushing the rear end of the mandrel 15 forward with the tool, the mandrel 15 can be removed from the tapered hole 17.
The rear tapered portion 15b can be extracted.

Therefore, the screw 5 is placed behind the mandrel 15.
Even when the mandrel 15 is located, the work of extracting the mandrel 15 can be easily performed, which is advantageous because the labor for replacing the mandrel 15 is simplified when changing the mandrel 15 to one of a different shape.

Moreover, since the through hole 19 is formed so as to communicate with the integrally molded support body 9, spider 8, and mold body 6, the first effect is as follows.
In addition, there is no risk that the material to be molded that is pressurized within the inner hole 7 or the extrusion molding portion 16 will leak into the through hole 19. Second, when disassembling or assembling the extrusion molding machine, the positions of the through holes 19 located in each part of the support 9, the spider 8, and the mold body 6 will not be misaligned.

Therefore, the through hole 19 for extracting the mandrel 15 can be provided without any problem.

[Brief explanation of the drawing]

The figure is a sectional side view showing an embodiment of this invention. 1... Extrusion molding machine body, 2... Mold, 5... Screw, 6... Mold body, 8... Spider, 9
...Support, 12...Dice, 14...Dice hole, 15...Mandrel, 15a...Front tapered part, 15b...Rear taper part, 16...Extrusion molded part, 17...Tapered hole, 19... ...Through hole, C...
Axial center.

Claims (1)

[Scope of utility model registration request] An extrusion screw, a cylindrical mold body located in front of this screw in the extrusion direction, and a die fixed to the front end of this mold body in the extrusion direction are provided on the same axis, and the die is formed on the die. A mandrel is provided in the die hole, and a support for supporting the mandrel is provided in the mold body, and this support is connected to the inner surface of the mold body by a spider, and the support body is connected to the inner surface of the mold body by a spider, and In the mold for an extrusion molding machine, the annular gap between the inner circumferential surface of the die hole and the front part of the mandrel is formed into a tapered shape as a circular pipe extrusion molding part, and the rear part of the mandrel is tapered. The rear tapered part of the mandrel is removably fitted into the tapered hole formed in the support on the axis, and the mandrel is fixed to the support only by this fitting; The spider and mold body are integrally molded,
A mold for an extrusion molding machine, characterized in that a through hole is formed which sequentially communicates these three parts and extends from the rear end of the mandrel radially outward of the mandrel to the outside of the mold body.