JPS62225322A - Molding of rubber ring type socket - Google Patents

Abstract

PURPOSE:To obtain a rubber ring type socket, provided with a smooth inner peripheral surface and a high water-tightness, by a method wherein an inner mold is forced into the end of a synthetic resin tube to expand it and a rubber ring mounting groove is formed by an annular projection, thereafter, the annular projection is provided with a taper surface, inclined toward reverse direction, on the outer peripheral surface of the annular projection. CONSTITUTION:One end of a synthetic resin tube 5 is softened by heating and an inner mold 1 is forced into the end part of the tube to form a socket 51 by an enlarged diametral section 11 through expanding the diameter of the tube while a rubber ring mounting groove 52, inflated outwardly, is formed by an annular projection 12. Subsequently, outer molds 21, 22 are pushed against the outer peripheral surface of the socket 51 to regulate the configuration of the socket, then, the tip end of the socket at the tip end side of the rubber ring mounting groove 52 near the side wall 521 of an opening is heated by heaters 3a, 3b accommodated in the inner mold 1 and the outer mold 21 to melt the tip end part of the socket. Then, the side wall 521 of the opening of the rubber ring mounting groove 52 is opened and expanded by the annular projection 12, thereafter, it is restored elastically and the configuration of the side wall 521 coincides substantially with the annular projection 12. The annular projection 12 is extracted out of the rubber ring mounting groove 52, thereafter, the inner peripheral surface of the tip end of the socket is cooled by applying it against the enlarged diametral section 11 of the inner mold 1 for a predetermined period of time.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method of molding a rubber ring type socket having an undercut portion using an inner mold having no expansion/reduction mechanism.
JA'Tjru.

(Prior Art and its Problems) As a conventional method for forming this type of rubber ring type socket by force, there is a forming method proposed in Japanese Patent Application Laid-open No. 126115M/1983.

This molding method is convenient when molding a groove for attaching a rubber ring with a roughly semicircular cross section, but the cross section is roughly trapezoidal, and the inner surface of the bottom wall of the groove is parallel to the tube axis. When molding a groove for attaching a rubber ring, there is a problem in that a desired shape cannot be obtained.

For example, as shown in the cross-sectional views in FIGS.
When molding, first, as shown in the figure (a), the inner mold 1 is press-fitted into the end of the heated and softened synthetic resin pipe 5, and an enlarged diameter socket is formed, and an annular shape with a trapezoidal cross section is formed. A groove 52 for attaching a rubber ring is bulged with the protrusion 12. And outer mold 21.
22 presses and shapes the outer peripheral surface of the socket, and the heating devices 3a and 3b built into the inner mold 1 and the outer mold 21 melt the tip of the socket. Next, as shown in FIG. I (After drilling, the tip of the socket elastically restores its original shape, and (c) the groove 52 for attaching the rubber ring shown in the figure is formed.

However, in this molding method, when the outer peripheral surface of the annular projection 12 is made parallel to the tube axis, the inner surface of the groove bottom wall of the rubber ring mounting groove 52 tapers toward the opening end of the socket. There was a problem in that the tube was tilted at an angle θ with respect to the tube axis.

This may be due to the fact that (a) the opening side wall 521 heated to a molten state in the heating process shown in the figure shrinks more than other parts, or (b) the unreasonable This may be due to poor return of the opening side wall portion 521 during the opening process, resulting in a small inclination angle α, but if the inner surface of the groove bottom wall of the rubber ring mounting groove 52 is inclined,
There is a problem in that when a rubber ring of a standard size and shape is attached to the rubber ring 52, a gap is created and the watertightness is reduced.

The present invention solves these problems, and provides a method for molding a rubber ring type socket in which a groove for attaching a rubber ring is obtained in which the inner surface of the groove bottom wall is parallel to the tube axis. It is.

(Iζth Means for Solving the Problems) The present invention press-fits an inner mold into the end of a heated and softened synthetic resin pipe, forms an enlarged diameter socket with the enlarged diameter part of the inner mold, and When forming a groove for attaching a rubber ring with an annular projection protruding from the diameter part, the inner surface of the groove bottom wall is parallel to the tube axis. A taper is expanded and inclined at a desired angle, and a J-cut is formed, and the annular protrusion is used to form a groove for attaching a rubber ring, and then an outer mold is applied to the outer peripheral surface of the socket to shape it, and then a groove for attaching a rubber ring is formed. After heating the tip of the socket, which is located on the tip side of the opening side wall of the groove, to the melting temperature of the resin, the outer mold is opened and the inner mold is forcibly removed from inside the socket. This is characterized in that the mold is cooled by being held in contact with the outer circumferential surface of the enlarged diameter part of the inner mold for a predetermined period of time.

EMBODIMENT OF THE INVENTION Hereinafter, the specific structure of this invention is demonstrated in detail based on an Example.

(Example) Fig. 1 is a longitudinal sectional view showing an outline of the molding process of the present invention, Fig.
The figure is a sectional view of a main part showing another embodiment of a rubber ring type socket obtained by the molding method of the present invention.

In the figure, group @1 is an inner mold, 2 is an outer mold, and 5 is a synthetic resin tube made of thermoplastic resin such as vinyl chloride resin.

A guide portion 10 having an outer diameter approximately equal to the inner diameter of the synthetic resin tube 5 is provided at the tip of the inner mold 1, and an enlarged diameter portion 11 with an enlarged outer diameter is provided continuously with the guide portion 1o. There is. An annular projection 12 having a substantially trapezoidal cross section is provided on the outer peripheral surface of the enlarged diameter portion 11, and the outer peripheral surface of the annular projection 12 tapers toward the distal end side of the inner mold 1. A taper is provided that is inclined at a desired angle θ with respect to the tube axis. Also,
A heating tool @3a is located at the rear adjacent to the annular projection 12.
! +! It's being crotched.

On the other hand, the outer mold 2 includes an outer mold 21 located on the outer peripheral side of the annular projection 12 and an outer mold 22 located on the outer peripheral side of the annular projection 12. These outer molds 21 and 22 are connected to a cylinder device (not shown) and can be moved in the X and Y directions shown by arrows in FIG.
1 has a built-in heating device 3b.

The mold device used in the present invention has the above-mentioned configuration, and the process of molding a socket using this device will now be explained.

As shown in the upper half of FIG. 1, one end of the synthetic resin pipe 5 is heated and softened, and the inner mold 1 is press-fitted into the end of the pipe, and the diameter of the socket 51 is expanded and molded using the enlarged diameter part 11. , a groove 52 for attaching a rubber ring is formed by the annular protrusion 12 and bulges outward. Next, the outer molds 21 and 22 are pressed against the outer peripheral surface of the socket 51 to shape the socket, and heating devices 3aJj and 3b built into the inner mold 1 and the outer mold 21 are used to heat the opening side wall of the rubber ring mounting groove 52. 5
The tip of the socket on the distal side from 21 is heated to melt the entire tip of the socket without alternating layers.

Therefore, as shown in the lower half of FIG.
Open the mold and remove the inner mold 1 from inside the socket 51! Make a friend.

In this "impossible" process, as explained in the molding process of FIG.
After being pushed open by the annular projection 12 and expanded, it elastically returns to a shape that almost matches the annular projection 12.

After the annular projection 12 is fired from the rubber ring attachment groove 52, the inner circumferential surface of the tip of the socket is applied to the enlarged diameter portion 11 of the inner mold 1 for a predetermined period of time to cool it. By this cooling II, the opening side wall portion 521 of the rubber ring mounting groove 52 is cooled and contracted, and a rubber ring mounting groove 52 having an inner surface of the groove bottom wall parallel to the tube axis is obtained.

In the above embodiment, a rubber ring mounting inlet having a substantially trapezoidal cross section was molded. However, as shown in FIG. !
The present invention can also be suitably used when forming the A-wearing groove.

(Operations and Effects of the Invention) As described above, the present invention includes press-fitting an inner mold into the end of a synthetic resin pipe to expand the diameter thereof, and forming a groove for attaching a rubber ring with an annular projection. In order to force the diameter without reducing the diameter, taking into consideration the amount of deformation due to this force and the shrinkage deformation m due to cooling, a tapered surface inclined at a desired angle in the opposite direction is provided on the outer periphery of the annular protrusion in advance. It is something that

Therefore, there is no TfJ! When widened, when the tip of the socket deforms by a predetermined angle, this deformation is offset and the inner surface of the groove bottom wall of the rubber ring mounting groove becomes a plane parallel to the pipe axis, making the inner circumferential surface smooth and watertight. A highly durable rubber ring socket can be obtained.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the molding process of the present invention;
FIG. 2 shows another embodiment of the lζ rubber ring type socket obtained by the present invention. ! A sectional view of the main part, Figure 3 shows a conventional example, (a) a cross-sectional view of the diameter expansion/heating process, and (b) a sectional view of the diameter expansion/heating process.
The figure is a cross-sectional view of the main part of the forced punching process, and the figure (c) is a cross-sectional view of the main part of the molded rubber ring type socket. 1... Inner mold 10... Guide section 11.
...... Expanded diameter part 12 ...... Annular projection 2 (
21, 22)...Outer mold 3a, 3b...
・Heating device 5...Synthetic resin pipe 51...
...Diameter expansion socket 52...Groove for installing rubber ring 52
1...Opening side wall patent applicant Mitsubishi Plastics Co., Ltd. agent Patent attorney Hisashi Kondo Mikani 1 area 1'3rg2

Claims (1)

[Claims] An inner mold is press-fitted into the end of the synthetic resin pipe that has been softened by heating, and the enlarged diameter part of the inner mold forms an enlarged diameter socket, and an annular projection protruding from the enlarged diameter part makes the inner surface of the groove bottom wall into a pipe. When forming a groove for attaching a rubber ring parallel to the shaft by bulging, the outer peripheral surface of the annular protrusion is provided with a tapered surface that widens toward the opening of the socket and is inclined at a desired angle. After forming a groove for attaching a rubber ring with an annular protrusion, the outer mold is applied to the outer circumferential surface of the socket to shape it.
Next, after heating the tip of the socket located on the tip side of the opening side wall of the groove for attaching the rubber ring to the melting temperature of the resin, the outer mold is opened and the inner mold is forcibly removed from inside the socket, and the tip of the socket is heated. A method for molding a rubber ring type socket, characterized in that the inner circumferential surface of the inner mold is kept in contact with the outer circumferential surface of the enlarged diameter part of the inner mold for a predetermined period of time and cooled.