JPS59224322A - Method and apparatus for vertically molding thrmoplastic resin tubular body - Google Patents

Abstract

PURPOSE:To provide a thin tubular body with a high dimensional accuracy when the tubular body is molded vertically by a cross-head die by providing a fluidized cooling water film between the outer circumferential surface of the tubular body and the inner circumferential surface of a sizing hole. CONSTITUTION:A tubular body a of thermoplastic resin molded by a cross-head die 2 is extruded in the downward direction. Then, said tubular body (a) is passed through an upper and a lower sizing hole 13, 20 provided on both upper and lower end of a sizing member 12 positioned under the tubular body (a) to be taken up by a take-up unit. At this time cooling water is supplied upward from a water supply hole 19 to provide a water film beteen the outer circumferential surface of the tubular body (a) and the inner circumferential surface of the sizing hole 13, while cooling water is supplied downward from a water supply hole 19' to provide a water film between the outer circumferential surface of the tubular body (a) and the inner circumferential surface of the sizing hole 20. In this manner, while the tubular body (a) is not brought into contact with the sizing hole wall, molding, sizing and cooling are carried out simultaneously in the tubular body.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for forming a tubular body such as a pipe or tube made of a thermoplastic resin into a vertical shape.

An example of a conventional device of this type is shown in FIG.

The conventional example shown in FIG.
6-194815, a thermoplastic resin material fed by an extruder 51 to a cross-bed die 52 is extruded from the die 52 into a tubular body a' and connected to a vacuum source by a vacuum vibrator 53. A cooling water supply pipe 55 is connected to the lower part of the vacuum sizing former 54, and a vacuum pipe 56 connected to a vacuum source is connected to the upper part to form a vacuum chamber 57. A cooling water supply pipe 59 is provided at the bottom and a cooling water discharge pipe 6o is provided at the top.
The water passes through the second water tank 61 to which the water is connected, and is taken by a taking machine (not shown). In this case, since the vacuum sizing former 54 is used, the tubular body a
It has the advantage of excellent dimensional accuracy and less dimensional variation, but when molding thin-walled, small-diameter tubular bodies,
In addition, when feed fat from a specific vertebrate is used, dimensional accuracy decreases and molding becomes difficult. For example, in the case of a tubular body with an outer diameter of 6 fins or less and a wall thickness of 0.1 mm or less, when passing through the former 54, the decompression effect causes the outer peripheral surface of the tubular body a' and the surface of the former 54 opposite to this to This causes friction between the former 54 and the former 54 due to the resistance.
The tubular body a' is elongated in the middle between it and the take-up machine, resulting in variations in dimensions, and it becomes difficult for a tubular body made of urethane resin or the like with low external slipperiness to pass through the former section 54.

The present invention eliminates the drawbacks of the conventional examples described above, and provides a method and apparatus for vertically forming a thermoplastic resin tubular body, which has high dimensional accuracy even for a small-diameter, thin-walled tubular body, and does not cause dimensional variations. The purpose is to provide the following.

In order to achieve the above-mentioned object, the present invention includes a thermoplastic resin tubular body formed by a cross-head die, which is supplied with gas and moves downward, and a sizing member installed below the head die. By lowering the inside of the upper and lower sizing holes formed at both the upper and lower ends of the cooling water, and moving the cooling water downward through the cooling water flowing upward in the upper sizing hole and the cooling water flowing downward in the lower sizing hole. , a molding method in which a water film of flowing cooling water is formed between the outer circumferential surface of the tubular body and the inner circumferential surface of the sizing hole, and the tubular body is formed and the dimensions are adjusted at the same time as cooling, and the tubular body is formed using a thermoplastic resin material. At the same time as molding, there is a cross rad die that supplies gas to the inside, and is placed below it, and has upper and lower sizing holes on the top and bottom, and a cavity between the sizing holes, and a cooling water supply member is installed in this cavity. The gist of the apparatus is a molding device equipped with a sizing member to which the sizing member is connected, and a machine for taking up the tubular body coming out of the sizing member. Embodiments of the present invention will be described with reference to FIG. 2 and subsequent figures.

1 shows an extruder that supplies a thermoplastic resin material to a cross to a RAD die 2, and the cross head and the extrusion port of the die 2 are
As shown in the figure, a die ring 4 is attached to the outlet of the die body 3 so that its position can be adjusted in the radial direction by an adjustment screw 5, and the center of the mandrel 6 disposed inside the die body 3 is connected to a proar 7. A ventilation hole 8 is provided.

A basin-shaped water tank 9 is installed below the cross-head radish 2, and a first weir body 19 is provided concentrically in this water tank 9, and a large number of water holes 11 are provided in this weir body 1o. It is perforated.

A sizing member 12 is connected to the water tank 9, and the upper part of the sizing member 12 penetrates the opening of the water tank 9 and protrudes upward. An upper sizing hole 13 is bored, a second weir body f4 is established in the top layer iK of the sizing member 12, and a selt 21 is installed in the water tank 9 as shown in FIG.
An overflow water pipe 22 having a head whose position can be adjusted vertically is attached.

An intermediate cavity 17 communicating with the sizing hole 13 is formed inside the sizing member 12, and a distributor 16 is housed in the cavity 17. A pair of upper and lower annular flanges 18, 18 of the distributor 16 ' has multiple water holes 19.19'
is drilled, and an intermediate sizing hole 15 is drilled in the center concentrically with the sizing hole 13. The lower part of the sizing member 12 is attached to the pusher belt 3 as shown in FIG.
The lid member 30 has a lower sizing hole 2o that communicates with the cavity 17 and is arranged concentrically with the sizing hole 15. It is perforated. FIG. 6 shows a distributor 16' having a structure different from that of FIG. The outer periphery of the central rising portion of the lid member 30 comes into sliding contact with the inner periphery of the lid member 30 .

Two first and second water supply pipes 24 and 25 are branched from a water supply main pipe 23 connected to a cooling water supply source (not shown), and the first water supply pipe 24 opens above the water tank 9, and the second water supply pipe 25 opens into the cavity 17 in the middle of the flange 18, 18'.

Both water supply pipes 24.25 have first and second valves 26.2, respectively.
7 is provided, 28 is a flow meter, and 29 is a pressure gauge.

The operation of forming the tubular body a using the above-mentioned material will be explained. This work is broadly divided into start-up operation and normal operation.

In the start-up operation, the thermoplastic resin material is melted and kneaded in the extruder 1, shaped into a tubular body in the RAD die 2, and extruded downward into the cross. At this time, cooling water is supplied to the water tank 9 by the first water supply pipe 24, and this cooling water passes through the water passage hole 11 of the first weir body 10, further exceeds the second weir body 14, and reaches the top of the sizing member 12. il'' and then flows down through the sizing hole 13.15.20 and the water passage hole 19.19' and is then discharged. The above-mentioned tubular body usually has a low melt viscosity, strong adhesion to metal, and is not stiff. Since it exists as a water film between the surrounding surface and the sizing hole 13.15.2
Forming without contacting the inner peripheral wall of 0 (forming)
And sizing will be performed together with cooling. Formation of such a water film is performed by adjusting the opening degree of the first valve 26 and the height of the overflow water pipe 22'.

At the end of such a start-up operation, the tip of the tubular body a passes through a turnwheel (not shown) and is gripped and taken off by a pulling machine, whereby a predetermined pulling force is applied to the tubular body a, and the start-up operation ends. do.

When the start-up operation is completed as described above, steady operation will start, but in this steady operation,
The blower 7 is operated to supply air or a gas such as nitrogen gas at a required pressure into the tubular body a from the vent hole 8 of the mandrel 60, and at the same time, the second valve 27 is opened and the first valve 26 is opened. Closed or close to closed. Through such operations, the cooling water supplied from the second water supply pipe 25 into the cavity 17 between the seventh flange 18 and 18' is transferred to the second water supply pipe 25.
As shown by the arrows in the figure, the water is distributed vertically by the distributor 16 and flows.

The cooling water flowing upward in this way reaches the upper sizing hole 13 through the water passage hole 19, flows upward through the hole in a countercurrent relationship with the tubular body a, and here, the cooling water reaches the upper sizing hole 13 through the water passage hole 19. A water film is formed between the sizing hole 13 and the inner peripheral surface of the sizing hole 13. On the other hand, the cooling water flowing downward reaches the lower sizing hole 20 through the water passage hole 19', flows downward through the hole in parallel flow relationship with the tubular body a, and here, the cooling water passes through the water passage hole 19' and reaches the lower sizing hole 20. A water film is formed between the hole 20 and the inner circumferential surface of the hole 20 .

In this way, molding, size adjustment, and cooling are simultaneously performed at 1° C. in each sizing hole.

In the above case, the outer diameter d of the tubular body S, the outer diameter am of the lower sizing hole 20 (see Fig. 2 above), the inner diameter dO1 of the outlet of the die 2, the inner diameter d1 of the upper sizing hole 130, and the inner diameter of the intermediate sizing hole 15. d.

(Figure 7 above) When considering K, do > d, ≧
The formulas ds>d and >d are set to hold, and the ratio depends on various extrusion molding conditions such as the extrusion amount of the type of resin material, resin temperature, melt viscosity, dimensions of the tubular body, and molding speed. Be changed.

In addition, the air volume adjustment from Proa 7 and the first and second valves 26.2
The valve adjustment in step 7 may be set in advance to match the various extrusion molding conditions as described above.

Alternatively, a solenoid valve or a switching valve may be used, and an appropriate automatic control member may be used to automatically operate the valve.

The proar mentioned above is used in a region where the change in wind pressure is small or small with respect to a change in air volume, and it has been found that the region indicated by the arrow in FIG. 8 is the optimal region. Usually, a relief hole is provided between the proa and the connection part of the cross-to-rad die to adjust the air flow, and the cross-sectional area of the ventilation path is changed by adjusting the position of the shield plate, and excess gas is discharged from the relief hole. Good. Normally, when the extrusion amount from the RAD die 2 is increased to increase the production speed and the wind pressure changes, the lip end surface of the lower end of the die ring 4 and the mandrel 6 and the upper sizing The tubular body in the space between it and the top of the hole 13 contracts or expands, causing a change in drawdown rate and a change in wall thickness.To prevent this, the above-mentioned measures are taken to prevent changes in wind pressure even if the air volume increases or decreases. It takes less.

This invention is as described above, in which a tubular body made of thermoplastic resin that is molded by a rad die and moved downward by being supplied with gas inside is moved to both upper and lower ends of a sizing member installed below the rad die. The tubular body is cooled by lowering the cooling water into the upper and lower sizing holes formed in the upper and lower sizing holes, and moving the cooling water downward through the upper sizing holes and the lower sizing holes. A film of flowing cooling water is formed between the outer circumferential surface of the sizing hole and the inner circumferential surface of the sizing hole, and the forming and dimensional control of the tubular body are performed at the same time as cooling. In this case, the downward movement of the tubular body is braked and the drawdown rate is reduced, and as a result, it is possible to form the tubular body with a die size close to the product diameter, resulting in a tubular body with little residual stress. Thickness: 0.3 to 1.0 mm
), it is possible to form a thin-walled tubular body with dimensional accuracy equivalent to that of a vacuum sizing former, and with no dimensional variation. Furthermore, in the lower sizing hole, the cooling water film adhering to the surface of the tubular body that has been cooled to 1/2 crystallization temperature in the upper part is broken, and the cooling efficiency is increased by new cooling water, so that the cooling efficiency is increased again after that. There is no need to provide any cooling equipment. In addition, the water film inside each sizing hole is
Since it functions as a lubricant, it has become possible to use urethane resins with low external lubricity. For example, even if additives are added to polyamide resin and the melting temperature is lowered,
By controlling the temperature, pressure, and flow rate of the cooling water supplied into the sizing member, and adjusting the amount of air flow from the rad die to the cross, roundness can be improved and thin-walled tubular bodies with high dimensional accuracy can be provided. There is an effect that it can be done.

[Brief explanation of the drawing]

FIG. 1 is a partially longitudinal front view of a typical example of a conventional tubular body made of thermoplastic resin, FIG. 2 is a partially longitudinal front view of an embodiment of the present invention, and FIG. 3 is a section A in FIG. Enlarged vertical front view of 4th
The figure is an enlarged longitudinal sectional front view of part B in Fig. 2, Fig. 5 is an enlarged longitudinal sectional front view of part C in Fig. 2, and Fig. 6 is a similar drawing showing a modification of the same part as Fig. 5. FIG. 7 is a longitudinal sectional front view for explaining the dimensional relationship of a part of the one shown in FIG. 2, and FIG. 8 is a diagram showing the relationship between wind pressure and air volume in the proar of the one shown in FIG. 2. 2... Rad die to the cross 7... Floor 12... Sizing member 13... Upper sizing hole 16.16'... Distributor 17... Intermediate cavity 20... Lower sizing hole 24... ... 1st water supply pipe 25 - 2nd water supply pipe 26 ... 1st valve 27 ... 2nd valve helmet 1 figure ff12 Fig. 8 Flash air volume □ min = 98-

Claims (1)

[Claims] 1. A thermoplastic resin tubular body molded by a cross rad die is extruded downward, and the sizing member is inserted into the upper and lower sizing holes formed at the upper and lower ends of the sizing member located below. Due to the water film formed on the inner peripheral surface of the hole,
It is moved downward without contacting the wall of the sizing hole, is taken up by a take-up machine, and gas is supplied into the tubular body from the center of the rad die to the cross, and the air is moved upward and downward into the upper sizing hole. A heating method characterized by continuously supplying cooling water downward into each sizing hole, and using this cooling water to continuously form a water film between the outer circumferential surface of the tubular body and the inner circumferential surface of the sizing hole. A method for forming a tubular body made of plastic resin into a vertical shape. 2. A rad die for molding a tubular body from a thermoplastic resin material and supplying gas into the cross, a sizing member placed below the rad die, and a take-up unit for taking over the tubular body coming out of the sizing member. equipped with a machine,
The sizing member has upper and lower sizing holes arranged concentrically with the outlet of the rad die on the upper and lower sides thereof, and a cavity formed between the upper and lower sizing holes, and a cooling water is supplied to the cavity. 1. A device for vertically forming a tubular body made of thermoplastic resin, characterized in that members are connected. 3. The outer diameter of the product tubular body to be formed is d, and the inner diameter of the exit of the rad die to the cross is d. , the inner diameter of the upper sizing hole is
, when the inner diameter of the lower sizing is ds, the formula d, >
The molding apparatus according to claim 2, wherein d, ≧d3>d.