JPS5818890B2 - plastic magarican no seikeihouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of forming a bent plastic tube.

When molding a bent plastic tube, a heated fluid is sealed inside the plastic tube, the plastic tube is bent and deformed along a bending die, and the heated fluid is cooled together with the plastic tube to create a shape sufficient for the bent plastic tube. The fluid within the plastic may be drained after imparting retention properties.

As mentioned above, in this forming method, the cross-sectional shape of the bent plastic tube is maintained by the filling fluid in the plastic tube until the bent plastic tube exhibits sufficient shape retention. In other words, the bending stress of the plastic tube is Preventing flattening is an essential requirement, and the heating fluid is not allowed to be withdrawn until the plastic tube has cooled to a certain extent and therefore the heating fluid has cooled to a certain extent.

Cooling of the plastic tube and heating fluid usually requires relying on natural cooling, which takes a long time, and as a result, there is a drawback that it takes a considerable amount of time to mold the above-mentioned bent plastic tube.

Another problem is that as a result of compressive strain occurring inside the bent portion of the plastic tube, wrinkles are unavoidable.

The method for forming a bent plastic tube according to the present invention can solve the above-mentioned difficulties and disadvantages, and is capable of solving the above-mentioned difficulties and disadvantages. Bending and deforming along the mold, then
The heating fluid is discharged while the cover mold is inverted and the bending deformation is maintained, and the cooling fluid is injected into the plastic pipe after the discharge.

The present invention will be explained below with reference to the drawings.

In FIG. 1, P is a plastic pipe, and for example, a plastic joint with a socket S already molded at one end is used.

C1 is a seal plug fitted into a socket S at one end of the plastic tube, and C2 is a seal plug fitted into the other end of the plastic tube, both of which are provided with fluid flow passages.

Ml and M2 are traction chucks tied to both ends of the plastic tube P.

To carry out the present invention, after sealing both ends of the plastic pipe P as described above, a heated fluid such as heated oil is injected into the plastic pipe P from the passage P of the lower sealed plug C2, and the heated oil is used to seal the plastic pipe P. After filling the inside of the pipe P, the lower and upper sealing plugs C2 and C1 seal the passageway.

Next, the chuck M19M2 is pulled by an appropriate pulling means to apply tension to the plastic tube P in the tube axis direction, and as shown in FIG. 2, the plastic tube P is bent and deformed along the bending die B1. .

During this bending deformation, the plastic pipe P is not flattened due to the filling oil.

In addition, the compressive bending stress generated on the inner side P1 of the bending portion of the plastic pipe P is canceled out by the tensile stress as the plastic pipe P is bent and deformed under the tensile tension.

Therefore, wrinkles do not occur on the inner side P1 of the bent portion of the plastic pipe P.

After bending and deforming the plastic pipe P in this way, as shown in FIG. 3A, the bending mold B is
Close 1.

As shown in FIG. 3B, this cover mold B2 has a semicircular groove C2 that forms a zero-shaped groove with the semicircular groove C1 of the bending mold B1, and the outer peripheral surface of the plastic pipe P is These types B1. It is held without any gaps by B2.

After setting the cover mold B2, open the passage of the seal plug C2 at the lower end of the plastic pipe P to drain the heated oil, and open the passage of the seal plug C1 at the upper end of the plastic pipe P, and remove the plastic pipe from which the heated oil has been discharged. Cooling fan air is injected into the pipe P.

In this case, the inside of the plastic pipe P is communicated with the outside air and is in a non-pressurized state, but the plastic pipe P is of type B1. Since the shape is maintained by B2, it will not become flattened.

Furthermore, since the heated fluid is replaced with cooling air, the plastic pipe P is rapidly cooled and solidified.

After discharging the heated fluid, cooling water can also be injected from the passageway of the upper sealing plug C1. In this case, the plastic pipe P
The cooling solidification of can be carried out even more rapidly.

After the plastic pipe P is cooled and solidified, the mold B1. B2
This completes the work.

The method for forming a bent plastic tube according to the present invention involves bending and deforming a plastic tube filled with a heating fluid along a mold under tension, so that the compressive stress generated inside the bend during bending deformation is As a result of being eliminated by the tension, the generation of wrinkles can be prevented.

Furthermore, after being bent and deformed along the mold, the cover mold can be overturned and the bent shape of the plastic tube, especially the cross-sectional shape, is maintained, so even if the heated fluid is discharged and air is injected into the plastic tube, the plastic tube will remain intact. The tube does not flatten,
It can be cooled and solidified while maintaining the predetermined shape at the time of bending and deformation.

Therefore, the heated bent plastic tube can be quickly cooled and solidified, and the bent plastic tube can be molded in a sufficiently short time.

Therefore, according to the present invention, it is possible to efficiently manufacture a plastic bent pipe with a good appearance.

[Brief explanation of the drawing]

1 to 3 show the working procedure of the forming method according to the present invention, in which FIG. 1 is before bending deformation, FIG. 2 is after bending deformation, and FIG. 3 is after bending deformation.
Figure A shows each state during cooling after bending deformation, and Figure 3B is a sectional view taken along line bb in Figure 3A. In the figure, P is a plastic pipe, C1 and C2 are sealed plugs,
M19M2 is a plastic pipe tensioning clamp, B1 is a bending mold, and B2 is a covering mold.

Claims (1)

[Claims] 1 A heating fluid is sealed in a plastic tube, and the plastic tube is bent along a bending mold with tension applied in the tube axis direction, and then a covering mold is placed to maintain the bending deformation. A method for forming a bent plastic tube, which comprises discharging the heated fluid and injecting a cooling fluid into the plastic tube after the discharge.