JPH0567411B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an apparatus for molding the end of a synthetic resin pipe to obtain an enlarged diameter socket having an annular bulge.

(Prior Art) As one of the means for connecting a front resin pipe body made of vinyl chloride resin or the like, there is a means shown in FIG. 1.

That is, an enlarged diameter socket 2 is provided at the end of one tube body 1.
A connection is made by inserting the other pipe body 1' into this enlarged diameter socket part 2. This socket part 2 is formed with an annular bulging part 3 having a storage groove 3a on the inner periphery, and an annular rubber seal member 4 accommodated in this storage groove 3a creates a gap between the tube bodies 1 and 1'. A seal has been made. In addition, at the end of the tube body 1, the diameters A, B, C, and D of each part are A<D<B<
It is in the relationship of C.

A conventional forming apparatus for obtaining the enlarged diameter socket 2 of the tube body 1 is constructed as shown in FIG. This device includes a front mold 11, a rear mold 12, and an intermediate split mold 13 provided between these molds 11 and 12 and capable of expanding and contracting the diameter. Front type 11
The rear part has a taper 11a, and the diameter gradually increases toward the rear end. As shown in the figure, the intermediate split mold 13 has a larger diameter than the front mold 11 and the rear mold 12 in its most expanded state, and has a taper 13 continuous with the taper 11a of the front mold 11 at its front part.
a, and has an annular protrusion 13b for forming the annular bulge 3 of the tubular body 1 at the rear. Further, gaps are formed between each of the molds 11, 12, 13 to form intake passages 14, 15, and a plurality of intake passages 16 are formed radially inside the intermediate split mold 13 as well. A main air intake passage 17 is formed in the center of the intermediate split mold 13 and the rear mold 12, and is connected to the air intake passages 14, 15, and 16.

Then, with the intermediate split mold 13 expanded to its maximum diameter, the end of the preheated tube body 1 is inserted into the front mold 11.
When inserted from above, this end portion passes through the taper 11a of the front mold 11 and the taper 13a of the intermediate split mold 13, expands in diameter, and then passes over the annular projection 13b to reach the rear mold 12. Thereafter, air is taken in from the air intake passages 14, 15, and 16 through the main air intake passage 17, thereby forming the tube body 1 into the final shape shown in FIG.

(Problems to be Solved by the Invention) However, the above molding apparatus had the following drawbacks.

(1) Since the taper 11a and the taper 13a are continuous and constitute an almost integral taper, the tube body 1 contacts over the entire area at the taper 13a, but only in a narrow area (at E in the figure) at the taper 11a. (range shown) and cannot be contacted.

(2) Since the intermediate split mold 13 is composed of a large number of divided pieces, it is difficult to produce a perfect circular cross-sectional shape, and furthermore, the cross-sectional shape becomes distorted after long-term operation. While the front mold 11 has a perfect circular cross-sectional shape, the intermediate split mold 13 has a cross-sectional shape that is not a perfect circle, so the tube body 1 cannot be brought into close contact with the taper 11a, resulting in gaps being formed here and there.

As a result, airtightness cannot be ensured between the tubular body 1 and the front mold 11, so that the intake air does not work effectively and it is difficult to accurately mold the inner shape of the tubular body 1 to a predetermined dimension. In particular, the storage groove 3a of the annular bulge 3 of the tube body 1 requires high precision in order to store the seal member 4 and obtain a predetermined watertightness, which cannot be achieved with the above-mentioned device.

For this reason, in reality, an outer mold is placed around the above device, and this outer mold is used to mold the tube body 1 into the intermediate split mold 13.
A predetermined inner shape is obtained by pressing it against the surface. However, in this case, marks of the outer mold may be left on the outer circumferential surface of the tube body 1, reducing its commercial value. The disadvantage is that the minute processing cycle becomes longer.
Various proposals have been made in the past regarding means for obtaining the inner surface shape of a tube body with high accuracy by effectively utilizing intake air without using an outer mold. For example, there is a device in which a rubber ring is installed on the outer peripheral surface of the front mold and, if necessary, on the outer peripheral surface of the rear mold, and the rubber ring ensures airtightness between the mold and the tube body.

However, in such devices, the rubber ring deteriorates each time it comes into contact with the heated tube, so the service life of the rubber ring is short, and the rubber ring has to be replaced with a new one frequently. be.

(Means for Solving the Problems) The present invention aims to eliminate the above-mentioned drawbacks, and the gist thereof is to provide a front type having a taper at the rear, and a front type having a taper at the front and a rear side. It is equipped with an intermediate split mold having an annular projection capable of expanding and contracting the diameter, and a rear mold, into which the end of the heated synthetic resin tube is inserted, and at least through the air intake passage formed between each mold. In an apparatus for forming an enlarged-diameter socket portion having an annular bulge portion for housing an annular seal member by taking air into the device,
A feature is that a step is provided at the border between the front mold and the middle split mold in the most expanded diameter state, and at this boundary, the front end of the middle split mold in the most expanded diameter state is made smaller in diameter than the rear end of the front mold. The present invention relates to an apparatus for forming an enlarged diameter socket of a synthetic resin pipe body.

(Function) As described above, in the socket molding device of the present invention, a step is provided at the boundary between the front mold having a taper at the rear and the intermediate split mold having the taper at the front and in the most expanded diameter state. Since the front end of the middle split mold, which is at its most expanded diameter at this boundary, is made smaller in diameter than the rear end of the front mold, the inner circumferential wall of the tube enters into the step, allowing the tube to taper over a wide range of the front mold. It can be firmly attached over the entire area. As a result, airtightness between the tube body and the front mold can be ensured, and air intake can be made to work effectively. Furthermore, an outer mold is not required.

(Embodiment) Hereinafter, an embodiment of the enlarged-diameter socket forming apparatus of the present invention will be described with reference to FIG. 3. In the molding apparatus used in this embodiment, parts corresponding to the conventional molding apparatus shown in FIG. 2 are designated by the same reference numerals in the figure, and detailed explanation thereof will be omitted.

In FIG. 3, the intermediate split mold 13 is shown in its most expanded state. The taper 11a of the front mold 11 and the taper 13a of the intermediate mold 13 have approximately the same taper angle, but are not continuous with each other, and a step F is formed at the boundary. That is, the diameter of the front end of the intermediate split mold 13 in its most expanded state is smaller than the diameter of the rear end of the front mold 11. Note that this step F is approximately 0.5 mm.

The rear mold 12 is tapered so that its diameter gradually increases from the front end to the rear end. This taper angle Θ
is approximately 2 degrees. The diameter of the front end of the rear mold 12 is the same as the diameter of the rear end of the front mold 11, but is slightly smaller.

Next, the operation of the molding apparatus having the above structure will be explained. As shown in FIG. 4, the end of the preheated tube 1 is inserted from the front mold 11 with the middle split mold 13 in its most expanded diameter state. The ends of the tube body 1 have a taper 11a formed at the rear of the front mold 11 and a taper 13a formed at the front of the intermediate mold 13.
The diameter of the intermediate mold 13 is expanded, and the rear mold 1 passes over the annular protrusion 13b formed at the rear of the intermediate mold 13.
Reach 2.

In this state, a step F is formed at the boundary between the front mold 11 and the intermediate split mold 13 in the most expanded state, so that the inner circumferential wall of the tube body 1 is
It enters the depression on the side of the intermediate split mold 13 created by the above process, and also tightly adheres to the taper 11a of the front mold 11 over a wide range (range indicated by G in the figure).

As mentioned above, since airtightness is ensured between the pipe body 1 and the front mold 11 and rear mold 13, when air is taken from the air intake paths 14, 15, and 16 through the main air intake path 17, the air is It works effectively and allows the tubular body 1 to be accurately molded into a predetermined inner shape.

After that, the intake is stopped, water is poured on the tube body 1 to solidify it, and then the intermediate split mold 13
The diameter of the tube is reduced and the tube body 1 is removed.

In the device of the present invention, the step F may be obtained by forming an annular convex portion 20 at the rear end of the front mold 11 as shown in FIG. 5, or as shown in FIG. An annular recess 30 is formed at the front end of the intermediate split mold 13.
The step F may be obtained by forming the step F.

Further, the intermediate split mold 13 may be configured by being divided into a split mold having an annular projection 13b and a split mold having a taper 13a.

(Effects of the Invention) As described above, according to the socket molding device of the present invention, the boundary between the front mold having a taper at the rear and the intermediate split mold having the taper at the front and in the most expanded diameter state. A step is provided, and the front end of the middle split mold, which is at its most expanded diameter at this boundary, is made smaller in diameter than the rear end of the front mold, so that the inner circumferential wall of the tube enters the step, allowing the tube to become the front end of the front mold. Since it is possible to securely adhere to the taper over a wide range and ensure airtightness between the tube and the front mold, the intake air works effectively and the inner shape of the tube can be accurately molded to predetermined dimensions.

Moreover, since there is no need to use an outer mold, the inconvenience of leaving marks of the outer mold on the outer circumferential surface of the tube can be eliminated, and the time for cooling the tube can also be shortened.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the connecting structure of the pipe body, Fig. 2 is a side view of the upper half showing the process of forming the enlarged diameter socket of the pipe body using a conventional device, and Fig. 3 is a side view of the upper half of the pipe body using the present invention. A side view of the upper half showing a molding device constituting an embodiment of the present invention, No. 4
The figure is a side view of the upper half showing the process of forming the enlarged diameter socket of the tube using the same device, and Figures 5 and 6 are the upper half of the main parts showing other embodiments of the present invention. FIG. 1... Synthetic resin pipe body, 2... Expanded diameter socket, 3...
...Annular bulge, 4...Sealing member, 11...Front mold, 11a, 13a...Taper, 12...Rear mold, 13...Intermediate split mold, 13b...Annular projection,
F...step.

Claims (1)

[Claims] 1. A heated synthetic resin tube comprising a front mold with a taper at the rear, an intermediate split mold with a taper at the front and an annular protrusion at the rear that can expand and contract the diameter, and a rear mold. By inserting the end of the mold and drawing air through the air intake passage formed between at least the molds, an enlarged-diameter socket portion with an annular bulge for accommodating the annular seal member is formed. In this device, a step is provided at the border between the front mold and the middle split mold in the most expanded diameter state, and at this boundary, the front end of the middle split mold in the most expanded diameter state is made smaller in diameter than the rear end of the front mold. An apparatus for forming an enlarged diameter socket of a synthetic resin pipe body, which is characterized by: