JPS63297019A - Mold of extruder - Google Patents

Abstract

PURPOSE:To easily prevent ununiform thickness from developing in an extrudate with simple constitution by a method wherein a die is made possible to control by shifting in the radial direction of a die port. CONSTITUTION:A first annular gap 16 is formed between a mold main body 4 and the fore part of a mandrel 9. In addition, a die port 21, which connects to the inner port 5 of the mold main body 4, in a die 20 provided on the front end side of the mold main body 4. The front end of the mandrel 9 locates in the die port 21. A second annular gap 22, which connects to the first annular gap 16, is formed between the mandrel 9 and the die 20. Material to be formed, which is pushed in the first annular gap 16 by an extruder main body 1, is forced in the second annular gap 22 so as to be formed into a circular pipe at the second annular gap 22 in order to be extruded outside a mold 2 in such a manner as to cover a core material by passing through the second annular gap 22. In this case, by shifting the die 20 for controlling, ununiform thickness can be prevented from developing in the circular pipe P.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a mold for an extrusion molding machine that prevents uneven thickness from occurring in an extruded product.

(Prior Art) Conventionally, molds for extrusion molding machines for extruding a material to be molded, such as a resin, into, for example, a circular tube product, have the following configuration.

That is, a die is attached to one end side of a mold body in which an inner hole is formed, and a die hole coaxial with the inner hole is formed in this die. A mandrel is disposed coaxially with these inner holes and the die hole. When the material to be formed is pushed into the first annular gap between the other end of the mold body and the mandrel, the material to be formed is pushed into the second annular gap between the die and the mandrel.
It passes through an annular gap where it is formed into a circular tube, from where it is extruded out of the mold.

(Problems to be Solved by the Invention) By the way, in an extrusion molding machine, the amount of the molded material supplied to the first annular gap between the other end of the mold body and the mandrel is as follows:
It is usually non-uniform in the pharmacopoeial content of the first annular gap. For this reason, the flow rate of the material to be formed flowing through the second annular gap between the die and the mandrel tends to be uneven at each circumferential portion, and as a result, the extruded circular tube product has uneven thickness. There is an inconvenience that this occurs.

(Object of the Invention) This invention was made in view of the above-mentioned circumstances, and provides an object to easily and with a simple structure prevent uneven thickness from occurring in an extruded product extruded from a mold. The purpose is to

(Structure of the Invention) A feature of the present invention for achieving the above object is that the second annular gap between the die and the mandrel can be adjusted by moving the die in the radial direction of the die hole. The gap size in the radial direction is adjusted to FA so that the amount of flow of the material to be formed flowing through the second annular gap is uniform at each circumferential portion.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

1 is an extruder body of an extrusion molding machine, and 2 is a mold. A material to be molded, such as a resin, is pushed into the mold 2 from the extruder body L, thereby forming a circular tube P for covering the core material M. Extruded. Further, an arrow Fr in the figure indicates the front of the mold 2 in the extrusion direction.

The mold 2 has a cylindrical connecting fitting 3, and this connecting fitting 3
has a first tapered hole 6 as its inner hole. The rear part of the mold body 4 is tapered fitted into the [1 taper hole 6, and the mold body 4 is fitted with the first nut 7.
is screwed to the rear surface of the connecting fitting 3. The mold body 4 has an inner hole 5 having a circular cross section. Reference numeral 8 denotes a first bolt for positioning, which positions the mold body 4 at a predetermined position in the circumferential direction with respect to the connecting fitting 3.

A mandrel 9 is disposed within the mold body 4 coaxially with the inner hole 5. This mandrel 9 includes a first cylindrical body 10 and a second tapered hole 12 formed at the front end side of the first cylindrical body 10.
The second cylindrical body 11 is tapered fitted to the second cylindrical body 11. On the other hand, this inner hole 5 is located at the front and back midway of the inner hole 5 of the mold body 4.
A third tapered hole 14 is formed coaxially with. This third
The first cylindrical body 10 of the mandrel 9 is tapered fitted into the tapered hole 14 at the front and rear midpoints thereof.
is screwed to the rear surface of the mold body 4 by a second nut 15.

A first annular gap 16 is formed between the mold body 4 and the front part of the mandrel 9. A communication groove 17 is formed on the rear outer surface of the mold body 4 toward the rear end of the first annular gap 16 for supplying the molded material from the extrusion hole 1a of the extruder body 1. This communication groove 17 extends over the entire circumference of the mold body 4, and the front end of this communication groove 17 and the rear end of the first annular gap 16 are connected to each other in a plurality of communication grooves formed in the circumferential direction of the mold body 4. The holes 18 communicate with each other. And extrusion hole 1
The material to be formed extruded from a is connected to the communication groove 17 and the communication hole 18.
and into the first annular gap 16.

On the other hand, a die 20 is provided on the front end side of the mold body 4, and a die hole 21 communicating with the inner hole 5 of the mold body 4 is formed in the die 20. The front end of the mandrel 9 is located in the die hole 21, and the first ridge-like gap 1 is provided between the mandrel 9 and the die 20.
A second annular gap 22 is formed which communicates with the second annular gap 6 . The die 20 is detachably screwed to the mold body 4 by a third nut 24.

Further, a stepped portion 25 is provided on the front end side of the inner hole 5 of the mold body 4.
The die 20 is sandwiched between the stepped surface 26 of the stepped portion 25 and the third nut 24.

Then, by loosening the third nut 24, the die 20 becomes movable in the radial direction within the stepped portion 25. On the other hand, four bolt holes 28 extending in the radial direction of the inner hole 5 and communicating the inside and outside of the stepped portion 25 are formed through the mold body 4 at equal intervals in the circumferential direction. A second port 29 is screwed into each of these bolt holes 28, and the die 20 in the stepped portion 25 is supported by the mold body 4 by each of the second bolts 29.

The die 20 is composed of a cylindrical die body 31 having a die hole 21 and a cylindrical die support 32 that supports the die body 31 on the mold body 4.

A fourth taper hole 33 coaxial with the die hole 21 is formed in the inner hole of the die support 32, and the die main body 31 is tapered fitted into the fourth taper hole 33. 34 is a heater.

Then, the material to be formed that has been pushed into the first annular gap 16 by the extruder main body 1 is press-fitted into the second annular gap 22, and is formed into a circular pipe P in this second annular gap 22 while passing through this second annular gap 22. It passes through and is extruded out of the mold 2 so as to cover the core material M.

In the above case, by adjusting the movement of the die 20, uneven thickness of the circular tube P can be prevented.

That is, after loosening the third nut 24,
If 9 is loosened, the die 20 is allowed to move in the radial direction,
Next, by turning each second bolt 29, the die 20 is moved to a desired position in the radial direction. Then, by screwing in each second bolt 29, the die support 32 of the die 20 can be fixed to the mold body 4, and then, by screwing in the third nut 24, the die body 31 can be fixed to the die support 32. can be fixed. This allows the second
The gap size in the radial direction of the annular gap 22 can be adjusted to a predetermined value at each location in the circumferential direction, and the flow rate of the material to be formed passing through the second annular gap 22 can be adjusted at each location in the circumferential direction to make it uniform. can.

As a result, uneven thickness can be prevented from occurring in the circular pipe P extruded from the second annular gap 22.

In this case, since the die 20 is located at the front end of the mold 2 and faces the outside, the movement of the die 20 can be adjusted while visually checking it. Therefore, the second annular gap 22 can be easily adjusted.

Furthermore, by loosening and removing the third nut 24 from the above-mentioned state and removing the die body 31 from the die support 3z, it is possible to change the size of the mandrel 9 and the die 20, and to clean the mold 2. In this case, the die main body 31 is fixed to the mold main body 4 by the second four-piece bolt 29, so even if the die support 32 and the mandrel 9 are removed, the die main body 31 remains fixed. ing. Therefore, even if the removed parts are reinstalled, the die main body 31, the die support 32, and
Since the mold body 4 and the mandrel 9 fit each other in a tapered manner, the dimensions between these parts can be maintained accurately. Therefore, once the die 20 is moved and adjusted, the mandrel 9 and the die body 31 of the die 20 are moved as described above.
Even if the tube is attached and detached, a circular tube P without uneven thickness can be reliably obtained again.

(Effects of the Invention) According to the present invention, since the die can be moved and adjusted in the radial direction of the die hole, by adjusting the movement of the die, the gap dimension in the radial direction of the second annular gap can be adjusted to a predetermined value.

Therefore, even if the material to be formed that has been pushed into the first annular gap is uneven at each location in the circumferential direction of the first annular gap, the material to be formed will not be uniform when passing through the adjusted second annular gap. The flow rate is adjusted to be uniform at each location in the circumferential direction, thereby preventing uneven thickness from occurring in the extruded product extruded from the mold through the second annular gap.

Further, when adjusting the movement of the die as described above, since the die faces the outside of the mold, the movement adjustment of the die can be performed while visually checking the die. Therefore, the second annular gap can be easily adjusted.

Furthermore, since the above-mentioned prevention of uneven thickness can be achieved simply by making it possible to adjust the movement of the die itself in the radial direction, there is no need to provide a separate means for preventing uneven thickness in the mold. It can be done.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which FIG. 1 is a side sectional view of a mold of an extrusion molding machine, and FIG. 2 is a sectional view taken along the line ■-■ in FIG. 2... Mold, 4... Mold body, 5... Inner hole, 9... Mandrel, 16... First annular gap, 20-... Die, 21
...Dice hole, 22...Second annular gap.

Claims (1)

[Claims] 1. A mold body with an inner hole is provided, a die with a die hole communicating with the inner hole is provided on one end side of the mold body, and a die is provided coaxially with the inner hole in the inner hole and the die hole. A mandrel is disposed above the mold body, and the material to be formed is pushed into the first annular gap between the other end of the mold body and the mandrel, and the material to be formed is passed through the second annular gap between the die and the mandrel. A mold for an extrusion molding machine adapted for extrusion, characterized in that the die is movable and adjustable in the radial direction of a die hole.