JPS582806B2 - Ring installation method and mold on the inner circumferential wall of a thermoplastic resin pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an example of a method for implanting a ring on the inner circumferential wall of a thermoplastic resin pipe and a mold used for the purpose. The present invention relates to a method and mold for implanting a ring having an outer diameter somewhat larger than the inner diameter of a socket.

Various methods of joining pipes have been studied in the past, and even in the case of a so-called single-receiver and single-insertion pipe, in which one end of a long pipe is expanded in diameter and used as a socket, and the other end is used as a socket. , during the secondary molding of the socket part, an enlarged part is further provided in a part of the enlarged diameter part, and a packing, such as a rubber ring for sealing, is attached to the groove groove on the inner peripheral surface side corresponding to the enlarged diameter part, A method is known in which this provides watertightness and prevents the pipe from separating due to the frictional force of the packing.

By the way, in these methods, when joining pipes, packings are installed in the internal grooves in advance, and then the pipes are inserted and joined.

However, since the packings may start to roll due to the frictional force during insertion, there is a risk that safe and reliable joining may be inhibited, and this is still not sufficient.

In addition, these enlarged parts are usually provided by secondary molding, and although special techniques and considerable skill are required during molding, the wall thickness of the abutting enlarged part is equal to that of the non-expanded part. There is a tendency for the wall to become thinner than that of the

Therefore, the expanded portion is susceptible to stress concentration, and not only the strength of the pipes tends to decrease, but also the rigidity of the expanded portion tends to decrease.

The present inventors focused on improving the above-mentioned drawbacks, and as a result of various efforts, they have now completed the present invention.

That is, an object of the present invention is to prevent packings from rolling out of their predetermined positions as much as possible when pipes are inserted and joined, and to suppress as much as possible the tendency of strength and rigidity reduction in enlarged portions. It is an object of the present invention to provide a method and mold that can easily and reliably shape pipes with increased strength and rigidity.

The method of the present invention that achieves this object is a method in which a ring for packing engagement is implanted on the inner circumferential wall of the end of a thermoplastic resin pipe in a plasticized state, and the ring is expanded in a direction along the tapered surface of a tapered core. The ring is housed and held in an annular groove formed by a stepped part cut out in two parts of the rounded surface and end face of a plurality of segment groups having a diameter, and a locking member that abuts the end face of the ring. A thermoplastic resin pipe is covered with the outer peripheral surface protruding from the annular groove, and after the ring is implanted and fixed on the inner peripheral surface of the pipe, the segment group is reduced in diameter and withdrawn from the mold. There is a gist in what you do.

In addition, the ring implantation mold to which this method can be applied is a ring implantation mold that is inserted into the end of a thermoplastic resin pipe in a plasticized state, and a ring for packing engagement is implanted on the inner circumferential wall of the end of the pipe. The mold includes a tapered core, a plurality of segment groups whose diameter expands and contracts in a direction along the tapered surface of the tapered core, and an engagement surface that abuts one end surface of the ring, The segment group has a stepped portion with a portion of its top surface and end surface cut out, and when the diameter of the segment group is expanded, the stepped portion and the engaging surface form a storage portion for the ring, and the storage portion is The gist is that the maximum outer diameter of the constituent members is smaller than the maximum outer diameter of the ring.

By the way, the ring in the ring implantation mold of the present invention is once latched to the stepped portion formed in the segment group of the mold, and then exposed to the outside of the mold by expanding the diameter of the segment group. It remains stable and fixed.

Therefore, by covering the mold and ring maintained in this state with a softened thermoplastic resin material and reducing the diameter of the segment group after the material has hardened, the ring is no longer fixed by the mold.

Next, the configuration of the present invention will be described in more detail.

The ring implanting mold of the present invention is composed of a movable member and a non-movable member, and the term "movable movement" here refers to the relative positional relationship inside the mold.

Therefore, "non-movable member" means a member that can maintain a given fixed position inside the mold, and "movable member" means
If moved by an external force, << means a member that can be deformed, or movement of the member. If << means a member that can be moved or deformed in response to deformation.

Therefore, the absolute positional relationship between the movable member and the non-movable member does not matter; for example, when implanting a ring in a pipe, a configuration in which the mold itself is fixed at a predetermined position and the pipe is moved is not applicable. A configuration in which the tube is fixed and the mold itself is inserted into the tube or moved to be removed from the tube, or a configuration in which the tube and the mold are moved together is at the discretion of the person implementing the present invention. It is up to the

The movable member in the present invention includes a tapered core.

The taper core is a ring with a hollow core that is arranged approximately in the center of the mold and has a tapered outer peripheral surface, but it goes without saying that a solid mandrel type can be adopted.

The taper is normally provided so as to be inclined toward the tip of the mold, but in some cases it may be provided so as to be inclined toward the base of the mold.

It should be noted that the taper does not need to be provided over the entire axial width of the outer circumference of the Tahar core, and it is desirable to maintain the inclination angle of the taper at a constant value over the entire circumference. It is also possible to make the inclination angles different in the above), and if necessary, it is also possible to make the inclination angles of the small angle portions zero.

Furthermore, although the axial forward and backward movement of the tapered core is normally provided by piston movement outside the mold, any other appropriate motion transmission mechanism may be employed.

The piston is usually connected to the back surface of the tapered core at the base of the mold, but only one piston is required.

The tapered core of the present invention is usually constructed as described above, and if it is solid, it can be molded in one piece, but if it is hollow, it can be formed into one piece.
It is also possible to divide it into two or more constituent parts and move all or part of them back and forth in the axial direction, or to make them move back and forth at the same time in an appropriate order at the time of experience. .

Next, another movable member of the present invention is a segment group.

The segment group is formed so as to be in contact with the tapered surface of the tapered core and to be able to slide on the tapered surface, and is usually divided into several to several tens of pieces, and each segment is in contact with each other adjacently. when the outer diameter is the smallest《
It has become.

Therefore, when the tapered core moves back and forth, the segments slide on the tapered surface, so when sliding up the tapered surface, each segment is separated while maintaining its adjacency, and the outer circumference curve and inner circumference of each segment are The outer and inner diameters of the circle formed by connecting the curved lines are enlarged, and when sliding down the tapered surface, the segments gradually approach each other until the respective boundary surfaces come into contact, and the outer and inner diameters of the circle become larger. It is reduced to the minimum value.

Since each segment of the present invention is constructed as described above, the outer surface is a curved surface with a constant curvature and is always at a constant distance from the center axis of the mold, while the inner surface has a constant curvature and a tapered surface. is provided.

In addition, each segment may all have the same shape, and may be configured into a fan shape that is slightly reduced in the center direction in the cross section perpendicular to the center axis of the mold, or it may be roughly divided into two groups with different shapes, It is also possible to configure one of them to have the fan shape and the other to have a rectangular shape that is not reduced in the center direction or an inverted trapezoid shape, and to arrange these alternately.

Furthermore, when the segments are roughly divided into two groups, they can be configured as follows, for example.

In other words, when sliding up the taper core to the highest position, the segments are not separated from each other and adjacent individual segments are in contact with each other, and the taper angle of the taper core is adjusted so that every other segment has a different size. It is set up so that it changes depending on the situation.

In this way, when the taper core is moved back and forth in the axial direction, the segment corresponding to the large taper part will slide in the axial direction, and then the segment corresponding to the small taper part will slide in the axial direction. do.

Therefore, the design of the inner surface of the segment may need to be changed in various ways depending on the shape of the tapered surface of the tapered core.
The structure does not necessarily have to be formed as described above, but it may be preferable to partially arrange members that cannot be deformed or to arrange members of different sizes.

In addition, when a segment slides up the tapered surface of the taper core, the outer diameter and inner diameter are forcibly expanded, but when sliding down the tapered surface, it may be difficult to reduce the outer diameter and inner diameter, so the segment can be expanded and contracted. It may be preferable to install a built-in rubber or spring with resilience.

These springs may be installed so that the opposite segments are brought into tight contact through the center of the circle formed by the segments, but it is preferable to use rubber bands or ring-shaped springs, so that when the diameter expands, An example is a configuration in which the segment is forcibly restored and contracted by using the restoring force against elongation.

Alternatively, the contact surfaces of the segments and the tapered ring may be engaged with each other by a T-shaped guide groove and a T-shaped protrusion, and an external force may be applied from the back surface of the segment to forcibly move it in the axial direction.

1 of other movable members provided as desired in the present invention
One is a locking member that has a vertical locking surface and can move back and forth in the axial direction.

The locking member comes into contact with the end face of the ring to be implanted by using the mold of the present invention, and is particularly useful when it is necessary to suppress swinging or sliding of the ring during coating with the thermoplastic resin material. Although useful, the locking member does not necessarily have to be configured as a movable member, and even if it is fixed in advance as a non-movable member at a position adjacent to the ring locking position, the object of the present invention will not be fully achieved. obtain.

One of the other movable members optionally provided in the present invention is a movable mold for shaping the outer peripheral wall surface of a thermoplastic resin tube (hereinafter simply referred to as a shaping mold).

When a ring is implanted on the inner wall of a thermoplastic resin pipe using the mold of the present invention, the extruded pipe is usually partially inserted (usually at the end of a long pipe). This is done by heating and softening the pipe and inserting the mold of the present invention into the pipe.

Therefore, the softened pipe slides on the mold and the ring to be implanted, and the pipe tip that goes over the ring is re-reduced in diameter so as to embrace the ring. .

However, due to the weight of the resin material itself, the diameter cannot necessarily be reduced to the desired shape at the bottom of the mold.

In the case of small-diameter pipes, there is a natural tendency to reduce the diameter as the pipe material cools, and there is no particular disadvantage, but in the case of large-diameter pipes, it is advantageous to use an external force to help reduce the diameter.

In addition, the pipe material that has exceeded the ring naturally exhibits a tendency to cool and contract in diameter at the ring portion, and the enveloping state of the ring (i.e., the state in which it is planted in the pipe) is increased, but a better planting state can be obtained. In order to achieve this, it may be preferable to compress the root of the ridge by applying an external force to both ends in the axial direction of the small ridge created by climbing over the ring.

Furthermore, when the mold of the present invention is used as a secondary forming means for pipes that have been extruded, even if the mold is a small ridge, the wall must be made slightly thinner than the non-protruded part. If an external force is applied in the direction of the small protuberance with the center at Since it is not necessarily uniform throughout the circumference, it is also possible to apply an external force to the vicinity of the small raised portion to adjust the shape of the portion.

The molding die of the present invention is added when it is deemed particularly useful for the reasons described herein or when there are other special circumstances, but it is not necessarily necessary.

As is clear from the above-mentioned reasons, various types of mechanisms can be used as the shaping mold.

Typical mechanisms include a mechanism that is movable in the direction of the central axis from outside the mold of the present invention, and a mechanism that is movable in the direction parallel to the central axis along the outer circumferential wall of the covered pipe material outside the mold of the present invention. Examples include a mechanism such as this, or a structure that appropriately combines these mechanisms.

It goes without saying that such movement or deformation of the movable member can be linked to movement or deformation of other movable members.

Note that the inner surface of the shaping mold and the outer circumferential shape of the resin tube are not necessarily required to match, and for example, only both sides of the ring implantation portion may be compressed and shaped.

The movable member of the present invention usually includes those described above, but it is beyond the technical scope of the present invention to provide other movable members that do not adversely affect the present invention or for the purpose of various improvements. It's not something you do.

Such movable members include, for example, parts that are not involved in the fixing operation of the ring, such as those in which the enlarged diameter part of the lower tube end of a long tube is movable, and in short, the movable member's movement or All structures in which the ring is fixed by deformation, are moved or deformed again after the ring is installed on the inner circumferential wall of the tube, and can allow separation of the mold and the tube belong to the technical scope of the present invention.

By using the mold of the present invention, the material of the ring implanted on the inner circumferential wall of the pipe is not particularly limited. Examples include metals such as steel, alloys, and thermosetting resin. can.

Further, although only one ring may be provided at the end of the tube, it is also possible to provide two or more rings if desired.

In addition, since the ring is installed at the end of the pipe and then used by engaging packing such as a rubber seal ring when joining the pipes, the size of the ring and Any shape may be used as long as it does not adversely affect the engagement of packings, the insertion and joining of pipes, and the reinforcement of pipes.

For example, the cross-sectional shape of the ring may be rectangular, circular, semicircular, oval, etc., and hollow rings may also be used.

Therefore, the mold of the present invention may employ a partial structure that corresponds to the outer shape of the rings so that these rings can be latched and fixed.

The mold of the present invention is constructed as described above, and its construction and operation will be explained below based on the drawings which are examples.

FIG. 1 is a partial cross-sectional view showing a state in which a rubber ring is engaged with a ring-embedded pipe molded using the mold of the present invention. This shows the case of an inserted pipe.

In the figure, 1 is a pipe main body, 2 is a first stage enlarged part, 3 is a second stage enlarged part, 4 is a small raised part, 5 is a ring, and 6 is a rubber ring.

Figures 2 to 6 are partial sectional views or cross-sectional views showing schematic diagrams of each process when a ring is implanted into extruded pipes using the mold of the present invention. , FIGS. 7 and 8 are cross-sectional views.

Figure 2 shows the mold body 7, ring 5, and undeformed pipe 1.
FIG. 2 is a schematic partial cross-sectional view of the prepared state.

In the figure, 8 is a segment before deformation.

9 is a tapered core, 10 is an annular spring, 11 and 12 are shaping molds, and 13 is a stepped portion of a segment.

Incidentally, a sectional view taken along line A-A in this state is as shown in FIG.

FIG. 3 is a schematic cross-sectional view of a state in which the ring 5 is releasably hooked to the stepped portion 13 of the segment and is opposed to the pipe 1.

It will be appreciated that the upper end of the ring 5 is latched within the step 13 of the segment, and the lower end is free.

FIG. 4 shows that the taper core 9 is slid to the right in the drawing, the segments 8 slide and expand on the contact surface, and the entire circumference of the ring 5 from the upper end to the lower end is pressed and fixed by the segment stepped portion 13, and the pipe 1, the ring 5 is stably fixed in place in the mold by the step 13 of the segment; FIG.

In this case, even if the ring 5 is slightly distorted, for example, into an elliptical shape, the diameter of the segment 80 is uniformly expanded in the circumferential direction as shown in FIG. Roundness is properly corrected.

Further, the tapered core 9 can be slid by a mechanism such as a piston (not shown).

The annular spring 10 is formed of a circular spring, for example, and is expandable and contractible, and does not adversely affect the expansion and deformation of the segment 8.

Incidentally, a sectional view taken along line B-B in this state is as shown in FIG.

FIG. 5 shows the heated and softened pipe sliding on the mold thus deformed. 4, and a ring 5 is brought into contact with the inner circumferential surface corresponding to the small raised portion 4 to raise the tube wall.

After this, or at the same time, as shown in FIG.
1 and 12 (preferably divided into two or four parts) are moved in the direction of the small protuberance 4, press the pipe 1 and adjust the external shape, and at the same time complete the installation of the ring 5. The gap between the pipe 1 and the pipe 1 is reduced, and the tendency of the small raised portion 4 to decrease in thickness is suppressed.

In addition, the movement order of the shaping molds 11 and 12 was changed,
For example, first move the shaping mold 12 to the left to press the small protuberance 4, then move the shaping mold 11 to the right, move the shaping mold 12 to the right, and finally shape the The method is to return the shaping mold 11 to the left, or move the shaping mold 11 to the right in advance and slide the pipe 1, and at the same time move the shaping mold 12 to the left so that it is parallel to the pipe 1. It is also possible to adopt a method of moving the shaping mold 11 to the left and the shaping mold 12 to the right.

After the ring 5 has been completely installed, the pipe 1 is sufficiently cooled and the shaping molds 11 and 12 are returned to their original positions.

Next, when the taper core 9 is moved to the left, the segment 8 is reduced and restored by the restoring force of the elastic annular spring 10, so that the mold 7 can be easily removed from the pipe 1.

Further, the timing for extracting the pipe 1 may be the same as the reduction and restoration of the segment 8, and is not particularly limited.

The above example shows a mold used for molding the socket part of a single-receiver and single-insertion pipe, but the mold used for molding a collar joint also requires some design changes. provided.

Further, the above-mentioned embodiments are merely illustrative of typical embodiments, and it goes without saying that various other modified and improved embodiments may be adopted.

Since the present invention is constructed as described above, it is possible to prevent the separation of packings even by frictional force during insertion and joining, water pressure during use, etc., and to provide pipes with increased strength and rigidity at the pipe end. This makes it possible to form pipes with highly circular rings planted on the inner circumferential wall very easily and reliably, and the mold according to the present invention has extremely high industrial utility value. .

[Brief explanation of the drawing]

The drawings show an embodiment of the mold of the present invention, and the first
The figure is a partial cross-sectional view of a pipe formed by using the mold in its used state, Figures 2 to 8 are schematic partial cross-sections or sectional views showing the process of using the mold, and Nos. 7 and 8 are respectively l -A line,
It is a sectional view taken along the line BB. 1...Pipe, 4...Small raised part, 5.
...Ring, 6...Rubber ring, 7...
...Mold, 8...Segment, 9...
... Taper core, 10 ... Annular spring, 11,1
2...Mold for shaping.

Claims (1)

[Claims] 1. A method of implanting a ring for packing engagement on the inner circumferential wall of the end of a thermoplastic resin pipe in a plasticized state, the method comprising a plurality of segment groups whose diameter expands in a direction along the tapered surface of a tapered core. The ring is housed and held in an annular groove formed by a stepped portion formed by cutting out a portion of the top surface and an end surface of the ring, and a locking surface that abuts the end surface of the ring, and the outer circumferential surface of the ring is placed in the annular groove. After covering the thermoplastic resin pipe in a more protruding state and implanting and fixing the ring on the inner peripheral surface of the pipe,
A method for implanting a ring on an inner circumferential wall of a thermoplastic resin pipe, the method comprising reducing the diameter of the segment group and removing the mold. 2 A ring planting mold that is inserted into the end of a thermoplastic resin pipe in a plasticized state and plants a packing engagement ring on the inner circumferential wall of the end of the pipe, the mold having a tape core and , consisting of a plurality of segment groups whose diameter expands and contracts in the direction along the tapered surface of the tapered core, and an engaging surface that abuts one end surface of the ring, and each of the segment groups has a portion of its top surface and end surface cut out. The step portion and the engaging surface form a storage portion for the ring when the segment group is expanded in diameter, and the maximum outer diameter of the member constituting the storage portion is the maximum outer diameter of the ring. A mold for planting a ring on the inner circumferential wall of a thermoplastic resin pipe, characterized in that it is configured to be smaller.