JPH086851B2 - Manufacturing method of plastic pipe fittings - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a plastic pipe joint, and more particularly to an improvement in a method for manufacturing a plastic pipe joint having a retaining function.

[Conventional technology]

BACKGROUND ART Conventionally, as a pipe joint for a plastic pipe, a plastic pipe joint having a structure in which an insertion port is inserted into a receiving port and a rubber ring is inserted between an outer surface of the receiving port and an inner surface of the receiving port is known.

This kind of pipe joint has an advantage that the connecting work is easy and there is a certain degree of freedom even if an external force is applied to the connected pipe in the axial direction or the bending direction.

However, in the case of the pipe joint of the above-mentioned type, there is a risk that the insertion opening may easily come out of the receiving opening when an external force is applied in the direction in which the pipe comes out.

As a measure for preventing this slip-out, a groove is formed in the circumferential direction that tapers shallower from the rubber ring insertion portion of the socket toward the socket opening end side, and a C-shaped ring is mounted in this groove so that the outer surface of the socket can contact.
When the withdrawal force is applied to the insertion opening, the C-shaped ring is wound around the insertion opening by the radial component force generated by the taper-shaped groove that becomes shallow with the axial movement, and the locking force causes the insertion opening to move. A pipe joint for preventing slipping out has been proposed (for example, Japanese Patent Laid-Open No. 4-39488 or Sho 63-42991).

[Problems of conventional technology]

However, in the above-mentioned slip-out prevention structure, a concave groove whose inner surface becomes shallower in the taper direction in the receiving opening than the rubber ring mounting groove of the receiving opening has to be formed by a separate means. In the case of mold molding, in addition to the convex part for the rubber ring mounting groove, it is necessary to provide a convex part on the mold for molding the groove where the inner bottom surface becomes shallower in taper shape, which complicates the mold shape. Moreover, there is a drawback that the obtained molded product is considerably troublesome and difficult to demold.

In particular, in the case of a socket formed by so-called secondary molding in which a plasticized plastic tube is press-fitted on a mold for expanding diameter, the socket part is formed by expanding and deforming the original tube to form a rubber ring mounting groove. After that, there is a drawback that it becomes very difficult to expand the diameter of the tapered groove as described above and perform accurate molding.

[Problems to be Solved by the Invention]

In view of the above problems, the present invention can easily form a mounting groove for a slip-out prevention C-shaped ring in addition to the rubber ring mounting groove by using a conventional mold, and has a slip-out prevention effect. Another object of the present invention is to provide a method for easily molding an excellent plastic pipe joint.

[Technology that has solved the problem]

That is, the method for manufacturing the plastic pipe joint according to claim 1 is
In the method of molding the plastic pipe joint 8 having the rubber ring mounting groove 6 on the inner surface near the opening end 7, the outer periphery is formed on the surface 3B on the receiving opening 7 side of the rubber ring mounting groove 6 forming expanded portion 3A of the mold 3. By setting the convex mold 4 whose diameter is tapered toward the receiving opening end 7 side coaxially with the expanding metal mold 3, and molding the metal mold 3 with plastic as an inner metal mold, An annular groove 9 which becomes shallower in a taper shape from the inner wall 6A on the receiving opening end 7 side of the rubber ring mounting groove 6 toward the opening end 7 is formed continuously and integrally, and then the mold 3 is demolded, and the taper is removed. The present invention is characterized in that a plastic pipe joint 8 is formed in which a C-shaped ring 10 for preventing slipping out can be fitted in the annular ring groove 9 so that the diameter can be reduced.

The invention of claim 2 heats the pipe end portion 2 of the plastic straight pipe 1 to a plasticizing temperature, and forcibly pushes the heating end 2 into the diameter-expanding die 3 to form a rubber ring on the inner surface near the opening end 7. In a method of molding a plastic pipe joint 8 having a mounting groove 6, a peripheral diameter of the rubber ring mounting groove 6 of the diameter-expanding die 3 on the surface 3B on the side of the receiving opening end 7 side of the expanding portion 3A for forming the receiving opening. A convex mold 4 having a tapered diameter toward the end 7 is set coaxially with the expanding metal mold 3, and a plastic straight pipe 1 is plasticized on the convex mold 4.
The rubber ring mounting groove 6
The annular groove 9 which becomes shallower in a taper shape from the inner wall 6A of the receiving opening end 7 side toward the opening end 7 is continuously and integrally formed, and then the diameter expansion die 3 is demolded to form the tapered annular groove. It is characterized in that a plastic pipe joint 8 to which a C-shaped ring 10 for preventing slipping out can be attached so as to be able to reduce its diameter is formed in 9.

[Action]

The method for manufacturing a plastic pipe joint according to claim 1 is based on the premise of injection molding or cast molding.

That is, in forming the tapered annular groove 9 in which the C-shaped ring 10 for preventing the escape of the opening 5 is mounted so that the diameter can be reduced,
The outer peripheral diameter is tapered toward the receiving opening end 7 side on the surface 3B on the receiving opening end 7 side of the expanded diameter portion 3A for rubber ring mounting groove 6 provided in the injection molding or casting molding die 3 The convex mold 4 having a reduced diameter is set coaxially with the mold 3, and the mold 3 is used as an inner mold and molded with plastic.

Therefore, the tapered groove can be formed by simply setting the convex mold 4 coaxially in a conventional injection or casting mold. Further, the convex mold 4 is the expanded diameter portion for molding the rubber ring mounting groove 6.
Since it is placed in a continuous state with 3A, it acts to mitigate unevenness changes.

The invention of claim 2 is based on a so-called secondary molding method in which the pipe end portion 2 of the plastic straight pipe 1 heated to the plasticizing temperature is forcibly pushed into the diameter-expansion die 3.

That is, when the plastic pipe joint 8 having the rubber ring mounting groove 6 on the inner surface in the vicinity of the opening end 7 is molded by this secondary molding method, the taper for mounting the C-shaped ring 10 for preventing the slip-out of the insertion opening 5 from being contracted is possible. When molding the circular annular groove 9, the outer peripheral diameter is tapered toward the opening end 7 on the surface 3B of the expanding portion 3A for forming the rubber ring mounting groove of the expanding die 3 on the side of the receiving opening end 7 side. A diametrical convex mold 4 is set coaxially with the diameter-expanding mold 3, and a plasticized plastic straight pipe 1 is laid on this and molded.

Therefore, similarly to the invention of claim 1, the tapered groove can be formed by simply setting the convex die 4 coaxially in the conventional die for secondary molding without requiring a complicated die.

Moreover, in the case of this secondary molding method, the rate of change in diameter reduction in the radial direction of the plastic pipe 2 along the diameter-expanding mold 3 from the diameter-expanding portion 3A to the receiving opening end 7 side depends on the convex mold 4. Since it is alleviated, the molding can be performed quickly and precisely.

When the pipes are joined by the plastic pipe joint 8 obtained by the method of the invention of claim 1 or 2,
As shown in the figure, the rubber ring 6B is inserted into the rubber ring mounting groove 6, and the insertion hole 5 is inserted into the tapered annular groove 9 with the C-shaped retaining ring 10 attached.

At this time, since the inner bottom surface 9A of the annular groove 9 is tapered so that the diameter thereof increases as it goes deeper, the C-shaped ring 10 does not move to the large diameter portion and obstruct the insertion of the insertion port 5.

After joining the pipes, when an external force is applied in the pipe axial direction and the insertion opening 5 tries to come out, the C-shaped ring 10 moves in the annular groove 9 toward the receiving opening 7 and together with the insertion opening 5, and the tapered inner bottom surface 9A. It is reduced in diameter by the radial component force generated by the contact with and winds around the outer surface of the insertion slot 5, and at the same time, increases the axial frictional force with the tapered inner bottom surface 9A and exerts a withdrawal resistance.

〔Example〕

 Next, an embodiment of the present invention will be described.

1 is a sectional view showing an inner mold for carrying out the method according to the invention of claim 1, FIG. 2 is a sectional view showing a mold for carrying out the method according to the invention of claim 2, and FIG. 2 is a cross-sectional view showing a step of secondary molding with the mold of FIG. 4, FIG. 4 is a cross-sectional view showing a state of removing the mold for secondary molding, and FIG. 5 is a plastic pipe joint obtained by the method of the present invention. And FIG. 6 is a sectional view showing the usage state.

[Embodiment 1] As shown in FIG. 1 in the inner mold 3 for injection molding, an annular groove in which the outer peripheral diameter is tapered toward the opening end 7 side in the expanded diameter portion 3A for forming the rubber ring mounting groove. After setting the convex mold 4 for forming 9 coaxially, a plastic was cast, cooled and cured, and then demolded to obtain a plastic pipe joint 8.

[Embodiment 2] As shown in FIG. 1 in the inner mold 3 for casting, an annular shape in which the outer peripheral diameter is tapered toward the opening end 7 side in the enlarged diameter portion 3A for forming the rubber ring mounting groove. After setting the convex mold 4 for forming the groove 9 coaxially, plastic was injected, and after cooling and hardening, the mold was removed to obtain a plastic pipe joint 8.

[Embodiment 3] As shown in FIG. 2, in the diameter-expanding die 3 for the secondary molding, the outer diameter of the diameter-increasing portion 3A for forming the rubber ring mounting groove is tapered toward the opening end 7 side. The convex mold 4 for forming the annular groove 9 was set coaxially.

Then, the pipe end 2 of the straight plastic pipe 1 was heated to a plasticizing temperature, and the heating end 2 was forcedly pushed into the diameter-expanding mold 3 to form a receptacle as shown in FIG.

At this time, the plastic straight pipe 1 heated to the plasticizing temperature is smoothly expanded and deformed along the expanded diameter portion of the expanded diameter die 3 and has passed over the expanded diameter portion 3A for forming the rubber ring mounting groove. After that, by the restoring elastic force of the plastic straight pipe 1, the convex mold 4
The diameter was reduced along the surface and was expanded and deformed into the shape of the mouth.

Hold the plastic tube in this state to cool it,
Thereafter, as shown in FIG. 4, the diameter of the mold 3 was reduced and the mold was removed to mold the plastic pipe joint 8.

The plastic pipe joints 8 obtained in Examples 1 to 3 are
As shown in FIG. 5, the inner wall of the rubber ring mounting groove 6 on the opening end 7 side
Annular groove 9 that tapers shallower from 6A toward the opening end 7
Has a shape integrally formed in the rubber ring mounting groove 6 continuously in the axial direction (arrow X).

Then, as shown in FIG. 6, a rubber ring 6B for sealing is mounted in the rubber ring mounting groove 6 and a C-shaped ring 10 for preventing slipping out is mounted in the tapered annular groove 9 so as to be capable of reducing its diameter.
When the insertion port 5 was inserted to connect the pipes and the withdrawal force was applied to the insertion port 5, the tapered inner bottom surface 9A of the tapered annular groove 9
The pull-out was prevented by the tightening force of the C-shaped link 10 that is deformed by reducing the diameter along the direction.

〔effect〕

As described above, in the method for manufacturing the plastic pipe joint according to claims 1 and 2, the tapered groove 9 in which the ring 10 for preventing the slip-out is mounted is integrated with the rubber ring mounting groove 6 in a continuous state. Since it is continuously molded into, it is possible to use injection molding or cast molding that has been conventionally used, and also a diameter-expanding mold for secondary molding as it is by simply attaching the convex mold 4 coaxially. Can be cheap.

Further, in the case of the invention of claim 2, in addition to the above effect, the stepwise deformation of the plastic straight pipe at the time of the secondary molding is alleviated, so that the pipe joint 8 can be easily molded and can be molded into a quick and accurate shape. Becomes

Further, since the pipe joint 8 obtained in claim 2 is not subjected to excessive diameter reduction deformation due to the interposition of the convex mold 4 at the time of molding, the strength of the tapered groove 9 portion is not significantly reduced and the insertion opening is securely prevented. It has an effect such as

[Brief description of drawings]

1 is a sectional view showing an inner mold for carrying out the method according to the invention of claim 1, FIG. 2 is a sectional view showing a mold for carrying out the method according to the invention of claim 2, and FIG. 2 is a cross-sectional view showing a step of secondary molding with the mold of FIG. 4, FIG. 4 is a cross-sectional view showing a state of removing the mold for secondary molding, and FIG. 5 is a plastic pipe joint obtained by the method of the present invention. And FIG. 6 is a sectional view showing the usage state. 1 ... Plastic straight pipe, 2 ... Pipe end, 3 ... Expanding die, 3A
... Rubber ring mounting groove forming expanded part, 4 ... Convex, 5 ... Insert, 6
… Rubber ring mounting groove, 6A… Inner wall of rubber ring mounting groove on the opening side of the receiving port, 6B… Rubber ring for sealing, 7… Reception port opening end, 8… Plastic pipe joint, 9… Toward the receiving port opening end side Tapered annular groove, 9A ... inner bottom surface of taper, 10 ... C-shaped ring to prevent slipping out

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kazutaka Takada 64 Ishizukita-machi, Sakai City, Osaka Kubota Vinyl Pipe Factory Co., Ltd. (56) References JP 54-43314 (JP, A) (JP, U) Japanese Patent Publication Sho 53-17323 (JP, B2)

Claims (2)

[Claims] 1. A method for molding a plastic pipe joint 8 having a rubber ring mounting groove 6 on the inner surface in the vicinity of the opening end 7, wherein the rubber ring mounting groove 6 forming expanded portion 3A of the mold 3 is located on the side of the receiving opening end 7 side. On the surface 3B of the above, a convex mold 4 whose outer diameter is tapered toward the receiving opening end 7 side is set coaxially with the expanding metal mold 3, and the mold 3 is made of plastic as an inner metal mold. By molding, the annular groove 9 that becomes shallower in a taper shape from the inner wall 6A of the rubber ring mounting groove 6 on the side of the receiving opening end 7 side toward the opening end 7 is formed continuously, and then the mold 3 is removed. A method for manufacturing a plastic pipe joint, characterized by molding and molding a plastic pipe joint 8 in which the C-shaped ring 10 for preventing the slip-out can be fitted in the tapered annular groove 9 in such a manner that the diameter can be reduced. 2. A rubber ring mounting groove is formed on the inner surface in the vicinity of the open end 7 by heating the pipe end 2 of the straight plastic pipe 1 to a plasticizing temperature and forcibly pushing the heated end 2 into a diameter expansion mold 3. In a method of molding a plastic pipe fitting 8 having
The rubber ring mounting groove 6 of the diameter-expanding die 3 has a convex shape 4 in which the outer diameter of the diameter-expanding portion 3A of the diameter-expanding portion 3A on the side of the receiving opening 7 is tapered toward the receiving opening 7 side. Is set coaxially with the diametrical expansion mold 3, and the plasticized plastic straight pipe 1 is laid on the mold to form the plastic mold. The annular groove 9 which becomes shallower in a taper shape in the 7-direction is formed continuously and integrally, and then the diameter-expanding die 3 is demolded, and the C-shaped ring 10 for preventing slipping out is tapered in the tapered annular groove 9. A method for manufacturing a plastic pipe joint, characterized in that a plastic pipe joint 8 that can be mounted is molded.