JPS643656B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a die position adjustment device for an extruder crosshead that adjusts the position of the die in order to prevent uneven thickness of extruded material extruded onto a wire rod within the extruder crosshead. be.

Generally, an extruder crosshead consists of a crosshead body, a nipple fixed within the crosshead body through which the wire to be coated with the extruded material passes, and a die attached to the crosshead body. If the die is eccentric with respect to the center axis of the nipple, the thickness of the extruded coating on the wire will be uneven, so the die must be accurately aligned with the nipple.

One prior art technique involves direct displacement and adjustment of the die, usually by means of a screw drive. However, since a large load is applied to the screw driving means due to the reaction of the pressing force of the screw, it is difficult to adjust the position of the die smoothly, and the structure is complicated, making it large and expensive, and the adjustment accuracy is low. Ta. Other conventional techniques use a double eccentric die holder to adjust the position of the die, but this technique also has the drawbacks of not being able to smoothly adjust the position of the die, low accuracy, and a complicated structure. .

In order to eliminate these drawbacks, the present applicant has proposed a device for adjusting the position of the die by combining a fluid ram and a position adjustment bolt that pushes the fluid ram (Japanese Patent Application No. 58-10470, Japanese Unexamined Patent Publication No. 59-137114). Publication No.). However, with this device, the position of the die is adjusted by pushing opposing fluid rams that push the dies relative to each other with position adjustment bolts, so if there is an error in the pitch of the opposing position adjustment bolts, the position of the die will change. In addition to not being able to guarantee accuracy, the load from the die is applied to the position adjustment bolt during adjustment, making it impossible to accurately adjust the position. In addition, since position adjustment bolts are required for all fluid rams, there is a drawback that the number of parts is large and a corresponding number of drive sources are required, making the device expensive.

SUMMARY OF THE INVENTION An object of the present invention is to provide an extruder crosshead position adjustment device that has a simpler structure and is capable of adjusting the position of a die with higher precision.

Embodiments of the present invention will be described in detail with reference to the drawings. FIGS. 1 and 2 show an extruder crosshead 12 equipped with a die position adjusting device 10 according to the present invention.
As usual, this extruder crosshead 12 has an inlet 14a that receives a thermoplastic molten resin 2 such as PVC or PE, which is an extruded material, from an extruder main body (not shown).
A nipple 18 is fixed in the crosshead body 14 via a nipple holder 16 and passes through which the wire 1 made of a highly conductive material for an electric wire to be extruded and coated is passed, and a die 20 is attached to the front of the crosshead body 14. It consists of The molten resin 2 enters the crosshead body 14 from the inlet 14a, passes through the extrusion passage around the nipple 18, and enters the die 2.
0 as a coating on the wire 1.

The die position adjusting device 10 of the present invention includes a frame 22 fixed to the front of the crosshead main body 14 by appropriate means, and a die 20 disposed within the frame 22.
4, such as a hydraulic ram that presses radially from 4 directions.
It consists of two fluid rams 24A to 24D. The dice position adjustment device 10 of the present invention further includes:
Two opposing fluid rams 24A and 24B and 24
Two position adjustment bolts 26A, 26C are screwed into the frame 22 so as to push one of C and 24D, for example 24A and 24C, from the outside, and a joint 2 is attached to the frame 22 and attached to each position adjustment bolt 26A, 26C.
Drive sources 30A and 30C, such as step motors, are connected to each other via bolts 8A and 28C to rotate respective position adjustment bolts 26A and 26C. As can be seen from the drawing, the fluid rams 24A and 24C pushed by the position adjustment bolts 26A and 26C are slidable in the radial direction of the die 20 within the space 23 in the frame 22, but the position adjustment bolts 26A and 26C The fluid rams 24B and 24D, which do not have the same structure, are fixed to the frame 22.
Further, the fluid rams 24A, 24C pushed by the position adjustment bolts 26A, 26C have dies 20.
When fixing the plunger 24 as shown in the figure.
Fluid is supplied so that a and 24c are always pushed to their full stroke. Therefore, as will be described later, when the position of the die 20 is adjusted by the position adjustment bolts 26A, 26C, the plungers 24b, 24d of the corresponding fluid rams 24B, 24D, which do not have position adjustment bolts,
A and 26C change the fluid supply amount of the fluid rams 24B and 24D so that the die 20 is displaced by a stroke corresponding to the amount to be displaced. The fixing bolt 32 is a stop plate 3 fixed to the front surface of the frame body 22.
The die 20 is screwed into the crosshead body 1.
The die 20 is fixed by pressing it against the front of the die 4.

Next, a method of adjusting the position of the dice 20 using the dice position adjusting device 10 of the present invention will be explained. FIGS. 1 and 2 show a state in which the dice 20 are fixed. If you want to move the die 20 from this state, for example, in the vertical direction in FIG.
Remove the force from 6A, turn the drive source 30A, and turn the position adjustment bolt 26A by the amount you want to move the dice 20.
move up or down. In this case, since the fluid has been removed from the fluid rams 24A and 24B, the load necessary to displace the die is not applied to the position adjustment bolt 26A, so the position adjustment bolt 26A is small due to only engagement with the frame 22. It only receives the load and therefore the position adjustment bolt 2
6A can be displaced with high precision. Thereafter, fluid is supplied to the fluid ram 24A to push the plunger 24a of the fluid ram 24A to its full stroke, and then fluid is supplied to the fluid ram 24B to fix the die 20. In this case, fluid ram 2
4B is supplied with fluid so that the plunger 24b is displaced by a stroke corresponding to the amount of displacement of the position adjustment bolt 26A. Fluid rams 24A, 24
For the thrust forces PA and PB generated at B, the fluid pressure or ram diameter is set so that PB>PA>P, where P is the force required to move the die 20. Also,
It will be appreciated that the stroke of the fluid rams 24B, 24D is required to be greater than the stroke of the positioning bolts 26A, 26C. That is, in order to guarantee the position of the die 20 at the position of the position adjustment bolts 26A, 26C, the relationship of stroke of the position adjustment bolt ≦ stroke of the fluid rams 24B, 24D is required, and if the stroke of the fluid ram is equal to the position of the position adjustment bolt If the stroke is smaller than the stroke, the die 20 may not move the required amount. Therefore, the stroke of the fluid rams 24B, 24D actually needs to be greater than the stroke of the position adjustment bolts 26A, 26C. When it is desired to move the die 20 in the left-right direction in FIG. 2, the above operation is performed on the fluid rams 24C and 24D.

In the above embodiment, the die 20 is fixed by the fixing bolt 32, so when adjusting the position of the die 20, the crosshead body 14 and the die 2
Loosen the fixing bolt 32 to the extent that the molten resin 2 does not leak from between the bolt and the bolt. Note that this fixing bolt 32 may be replaced with a small ram.

According to the present invention, as described above, the position adjustment of the dice is performed using the position adjustment bolt, so the accuracy is high, and since a pressing force is always applied to the position adjustment bolt, the die position can be adjusted due to play such as crushing. There is no positional deviation, and when adjusting the position of the die, the fluid is removed from the fluid ram so that no load from the die is applied to the positioning bolt, so the positioning bolt can be adjusted with little force and with high precision. Furthermore, the movement of the die is carried out by a fluid ram, so the overall structure is simple, and the number of position adjustment bolts and their driving sources is small, making it compact and inexpensive. There are practical benefits that can be achieved.

[Brief explanation of drawings]

1 and 2 are a longitudinal cross-sectional view and a cross-sectional view of a main part of an extruder crosshead equipped with a die position adjusting device according to the present invention. 10...Dice position adjustment device, 12...Extruder crosshead, 14...Crosshead main body, 18
...Nipple, 20...Dice, 24A to 24
D...Fluid ram, 26A, 26C...Position adjustment bolt, 30A, 30C...Drive source.

Claims (1)

[Claims] 1. A die position adjustment device for an extruder crosshead that adjusts the position of the die of an extruder crosshead, which is comprised of a nipple attached to a crosshead body and a die attached to the crosshead body, with respect to the nipple; a plurality of fluid rams that push in the radial direction but from which fluid is removed when adjusting the position of the die; a position adjustment bolt that is screwed into the frame so as to push one of the opposing fluid rams from the outside; and the position adjustment bolt. The fluid ram that is pushed by the position adjustment bolt is supplied with fluid up to its full stroke, and the stroke of the fluid ram that is not pushed by the position adjustment bolt is equal to the stroke of the position adjustment bolt. A die position adjustment device for an extruder crosshead, characterized by being set larger.