JP2860809B2 - Core for manufacturing electric fusion joints - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a core for manufacturing an electro-fusion joint for piping of a pipe made of a thermoplastic polymer material and a method for manufacturing an electro-fusion joint.

[Conventional technology]

Polymer materials such as various synthetic resins and synthetic rubbers are easy to mold, have excellent properties such as water resistance and chemical resistance, and are lightweight, and are used instead of metals or ceramics. The field is expanding rapidly. For example, pipes such as iron pipes, lead pipes, copper pipes, stainless steel pipes, earthen pipes, pottery pipes, joints for connecting these pipes, and valve plugs, etc., have already used quite a lot of polymer materials. Have been.

Now, pipes, joints or valve plugs made of such a polymer material, particularly a thermoplastic resin or rubber, are connected so as not to cause leakage, etc., to enable smooth pipe construction. Requires that each connection be tightly sealed. However, for example, adhesives suitable for each of limited polymer materials such as ABS resin, polyvinyl chloride, and polystyrene have been developed, and if they are appropriately applied to the connection parts and cured, Although it can easily achieve its purpose, a suitable adhesive has not yet been obtained for many materials such as polyolefin, polyamide, polyacetal, and fluorine-containing resin. Therefore, for a polymer material without such an adhesive, a method of softening or melting the connecting portion by an external heating method (a flame or a tubular furnace, etc.) and joining at once without cooling, and cooling and solidifying is used. Has been adopted. However, it is extremely difficult with such an external heating method to uniformly heat and adjust and maintain an appropriate softening or melting state, and good results cannot be obtained.

In view of this, the present inventor has disclosed in Japanese Patent Application No. 1-10689 a linear heating element which is folded in two and spirally wound in parallel without contact with each other. A joint sleeve encapsulated within a layer of thermoplastic polymer material molded into a body, and methods of making and using such a sleeve, are disclosed. But,
When manufacturing this joint sleeve, a linear heating element coated with a thermoplastic polymer material is spirally wound on the surface of the roller while being in parallel with and in close contact with each other, and furthermore, a spiral coated linear shape that has been wound It has been found that there is an undesirable disadvantage, especially in the case of mass production, such as complicated operations and long time required for energizing the heating element and fusing the adjacent coatings to each other and then cooling and solidifying the coatings. Came.

In order to eliminate such a drawback, the present inventor has proposed a linear heating element (Nichrome wire 13) as illustrated in FIGS. 6 and 7.
The adjacent spiral spirals composed of the thermoplastic polymer material coated wires 14 containing the inside are fused at at least one position in the circumferential direction, and are fixed so as not to be separated by the coated fused portions 15. Japanese Patent Application No. 1-173617 discloses a technique relating to a sleeve C, a method for manufacturing the joint sleeve C, and a method for connecting pipes using the joint sleeve C. This joint sleeve C is easy to manufacture, can easily cope with mass production, and is light in weight, so it can be highly evaluated. However, the feature of its simple structure and light weight is behind the scenes. And easily deforms even with a slight external force, resulting in a time-consuming installation on the pipe end, which is far from satisfactory.

[Problems to be solved by the invention]

As described above, in the conventional technology, it is possible to connect the pipes made of a polymer material with high accuracy by stable work even in a particularly unstable environment such as a construction site, and further mass production. However, there has been a problem that a technology capable of coping with the speeding up of construction has not yet been developed, and solving this problem has been an issue.

[Means for solving the problem]

In order to solve the above problems, the present invention provides a core including a base and a trunk, wherein the outer diameter of the trunk is equivalent to the inner diameter of the desired joint, and the outer diameter of the base is at least larger than the outer diameter of the trunk.
1 mm thick, a hole is provided at the step on the boundary between the base and the trunk to insert and temporarily fasten the end of the coated linear heating element, and the end face of the trunk is perpendicular to the rotation axis. An axially slidable engagement means which is in contact with the end face of another core which is face-to-face and joined, so that both cores can form a shaft which rotates in conjunction with each other, or , Comprising a base portion and a body portion similar to the above, and providing at least one cut in the peripheral portion of the end surface, or making the end surface a concave curved surface, and the curved surface of the core described above alone or when the body is joined Means for forming a core for producing an electro-fusion joint that can be in close contact with the outer surface, and spirally wrapping a coated linear heating element around these cores for producing an electro-fusion joint, and tightly connecting them facing each other. Or other cores from the side Fitted into a T-shaped, cross-shaped or other branched state and set in a corresponding split mold, injecting molten resin into the formed mold cavity, and integrated with the coated linear heating element Then, after cooling and solidifying, a mold and a core are appropriately removed to manufacture an electrofusion joint.

[Action]

The core for manufacturing an electro-fused joint according to the present invention is set in a mold for forming a joint with the coated linear heating element spirally wound around the body, and the spiral of the coated linear heating element is integrated with the inner surface. Since it is possible to form a joint in one step, waste of the process can be eliminated.

〔Example〕

 The details of the present invention will be described below with reference to the drawings.

First, the core A ₁ in this invention is a mold for forming a hollow portion of the casting which also commonly referred to as a cage (core). The cross-sectional shapes of the base 1 and the body 2 are generally circular, but a polygonal shape does not hinder the present invention.

The reason for providing a step at the boundary between the base 1 and the body 2 is that when the coated linear heating element 9 described later is spirally wound around the outer surface of the body 2, a pore for temporarily fixing the tip thereof is formed. 3
Not only is it convenient to provide the joint, but also very effective in chamfering the rising portion of the joint end face by connecting to the inner surface of the split mold B described later. The reason why the step is set to at least 0.5 mm is because it is desirable that the step is approximately the same as the thickness (or thickness) of the coated linear heating element 9 determined according to the size of the joint. The pores 3 provided at one place in the stepped portion or at an arbitrary interval correspond to the cross-sectional shape and size of the covered linear heating element 9 to be inserted, and include a bare wire and a covered wire. Alternatively, a circle, an ellipse, a daruma type, or the like may be appropriately selected depending on whether the wire is a single wire, a double wire, or the like. Is not preferred. If the orientation of the pores 3 is a degree of parallel or slightly downward to the axis of the core A _1, after fitting the molding,
Preferably, the core A is easily removed, and the depth is particularly limited as long as the length of the tip of the coated linear heating element 9 to be inserted can be secured to a length necessary for connecting to a power supply or the like, for example, about 10 to 20 mm. is not.

Next, the linear heating element incorporated in the coated linear heating element 9 of the present invention is a linear heating element made of a material having a property of generating heat when energized, such as a nichrome wire or carbon fiber, and It is desirable that the covering material containing such a linear heating element is a thermoplastic polymer material having the same or higher affinity as the material of the tubing to be connected. The number of built-in linear heating elements is not particularly limited, but one or two is practical. Then, if a single wire with a built-in heating element is spirally wound alone, its terminals will be located at both ends of the spiral. It is not easy to take out the ends without crossing the outside on the same side. However, even in the case of winding a covered wire containing one linear heating element, the wire is connected to the end of a spiral wound similarly on another core to be joined and joined, or one wire is wound. The insulated wire is folded in two and wound into a double wire, or two separate insulated wires are connected in parallel and closely together (although it is necessary to connect the ends of the linear heating elements of both insulated wires). If it is wound, it becomes possible to take out the two terminals without overlapping them. On the other hand, in the case of a covered wire in which two linear heating elements are incorporated in advance, only the two linear heating elements exposed at one end of the covered wire are appropriately connected (one linear heating element is connected). This operation is unnecessary if the body is folded in two and two are arranged in parallel.) This is convenient because both terminals can be taken out to the same place by a simpler operation. In any case, the thickness of the coating material layer, the diameter of the spiral, etc. may be appropriately selected along with the dimensions of the linear heating element, etc., depending on the dimensions, shape, and the like of the pipes to be subjected to piping construction. It is not limited.

Furthermore, the most general and practical case is that the end face 4 of the body 2 is perpendicular to the rotation axis as shown in FIG. Then, the another core A ₂ and slidable engagement means axially mutually butted as shown in FIG. 2, for example, the contact surface or the peripheral surface of both cores A ₁ and A ₂ This is a means for providing projections and depressions and fitting each other, and is not particularly limited. By employing such an engagement means, not only can the two cores A ₁ and A _{2 be} coaxially rotated when the coated linear heating element 9 is spirally wound around the outer surface of the body 2,
Good results can also be expected to improve the stability when setting in combination in the split mold B (see FIG. 5).

Further, a notch 6 can be provided in a peripheral portion of the end face 4. When the cut 6 is set in the split mold B with the end faces 4 of the two cores A ₁ and A ₂ in contact with each other to form a joint, the molten resin injected into the mold cavity 10 infiltrates, This is for forming a projection at the center of the inner surface of the joint which is a molded product. The projections formed in this way are:
Usually, it is a stopper for preventing the pipes from being inserted deeper than necessary into the joint, and about 1-4 stoppers can be provided as necessary. However, it is often necessary to connect pipes that cannot move in the length direction so that the union is widely used during pipe construction.In such a case, the projections are inserted with a slightly stronger force than in the normal state. It would be very advantageous if the ends of the cut tubing could be cut relatively easily so that the tubing could freely penetrate the inner surface of the joint. Therefore, if the notch 6 provided in the end face 4 is formed such that the root of the inner surface of the joint is narrowly narrowed to some extent like a mushroom, and a projection that is relatively easily cut can be formed,
A joint having the same function as the union is obtained.

Further, the core for manufacturing an electro-fusion joint according to the present invention described above.
The following can be disclosed as modifications of A ₁ and A ₂ . That is, although the main configuration of the base 1 and the trunk 2 serving as the backbone is the same or similar to the above,
The end surface 4 of the body 2 is different from the surface perpendicular to the rotation axis.

One of them is a case where an end face forms a plane inclined with respect to the rotation axis, though not shown. When two cores having such end faces are butt-joined and joined, if the inclination angles of the respective end faces with respect to the rotation axis are complementary to each other, the two cores are engaged and rotated on the same axis. Therefore, it can be used as a core for manufacturing an electro-fusion joint as in the present invention. However, as compared with a plane perpendicular to the rotation axis, machining is not easy, and an effect superior to that is hardly expected.

The other one is a curved surface whose end face 7 is concave as exemplified in FIG. 3, and the curved surface is used when the above-mentioned cores A ₁ and A ₂ for producing an electro-fusion joint of the present invention are connected alone or connected. It adheres to the outer surface of the part 2. Then, the rotation axis of the core A ₃ having an end surface 7 of such a curved surface, not necessarily perpendicular to alone or connected to core A _1, the A ₂ the rotating shaft core are in close contact, obliquely at any angle It may intersect. One or more of the cores A ₃ having such a curved surface are adhered to the outer surface of the trunk portion 2 of the single or connected cores A ₁ and A ₂ from one side, both sides or any direction, By setting it in the corresponding split mold B and injecting the molten resin, it is possible to easily form a three-way (T-shaped) type, a four-way (cross) type, and other branch joints branched in any direction. it can. Needless to say, by appropriately selecting the outer diameter of the body 2 of each of the cores A ₁ , A _2, and A ₃ to be brought into close contact with each other, joints of pipes having different diameters can be easily obtained.

However, since it is not easy to form the end face 7 having a curved surface as shown in FIG. ₃ , a core A ₄ as shown in FIG. it can. That is, the core A ₄ is basically the same as the above-described core A ₁ or A ₂ in the configuration of the base 1 and the body 2, except that the entire surface of the end face 4 of another core is provided on the side surface of the body 2. Alternatively, it is different only in that it has a notch 8 in which a part is fitted and adhered. It is desirable that the body 2 of the core to be fitted is inscribed around the notch 8 so that the molten resin does not flow into the inscribed portion during the molding of the joint, so that an unnecessarily large gap is not generated. Moreover, such a notch 8 may be a plurality, if also the circular inner diameter of the body portion 2 of the cross also notch 8 of the core to be fitted, for example, independently of the body portion 2 of the A ₁ or in Matage the core a ₁ and core a ₂ in a state of being bonded butt, it is advantageous can easily be drilled using a drill or lathe.

Or core A ₄ as described alone, or two articulated to insert fitting another core barrel 2 of which corresponds to the core A ₁ or A ₂ in the notch 8 made lever, to have the It can be used to form a similar three-way, four-way, or other branch joint that branches off in any direction.

Further, FIG. 5 schematically illustrates a state in which the two cores A ₁ and A ₂ are set in the split mold B by abutting each other.
The split mold B used in the method of manufacturing the electro-fusion joint according to the present invention is characterized by the required properties of the joint to be manufactured, such as the dimensions of the pipes to be connected, the number and direction of branches, pressure and other regulations. The number of cracks in the mold and the shape of the mold cavity 10 are of course determined by the thickness and the like satisfying the constraints, but the molten resin injection port 11 and the air discharge port 12 or the coated linear heating element If the leading end outlet 9 is provided in a split of the split mold B, it is easy and convenient to remove the molded product from the mold.

〔effect〕

As is evident from the above description, the coated linear heating element is spirally wound around the core for manufacturing various electrofusion joints of the present invention, and the core is set as it is in a mold as appropriate. Inject the molten resin into the cavity,
If the mold and the core are disassembled and removed after cooling and solidification, a pipe joint in which the column of the linear heating element is integrated and embedded on the inner surface can be obtained at a stroke. Therefore, the molding of the spiral coated linear heating element and the forming of the pipe joint are performed consistently, and various problems during transportation of each molded article (for example, the spiral coated linear heating element is crushed and Deformation, and it takes time to fit it into the end of the pipes during construction), which is extremely effective for mass production and speeding up construction.

[Brief description of the drawings]

FIGS. 1, 2, 3 and 4 are perspective views illustrating the structure of a core for manufacturing an electro-fusion joint of the present invention, and FIG. 5 is a method for manufacturing an electro-fusion joint of the present invention. FIG. 6 is a perspective view showing a state in which the core of the present invention is set in a split mold for illustrating a conventional joint sleeve, FIG. 6 is a front view illustrating a conventional joint sleeve, and FIG. 7 is a side view of FIG. is there. A ₁ , A ₂ , A ₃ , A ₄ ... core, B ... split mold, C ... joint sleeve, 1 ... base, 2 ... trunk, 3 ... pores, 4 ... End face, 5 ... locking projection, 6 ... cut,
7 ... end face, 8 ... notch, 9 ... coated linear heating element, 10
... mold cavity, 11 ... molten resin inlet, 12 ... air outlet, 13 ... nichrome wire, 14 ... covered wire, 15 ... covered fusion spliced part.

──────────────────────────────────────────────────の Continued on front page (51) Int.Cl. ⁶ Identification code FI B29L 31:24

Claims (5)

(57) [Claims] In a core comprising a base and a trunk, an outer diameter of the trunk corresponds to an inner diameter of a desired joint, an outer diameter of the base is at least 1 mm larger than an outer diameter of the trunk, and a boundary between the base and the trunk. A hole for inserting and temporarily fixing the tip of the coated linear heating element is provided in the stepped portion, and the end surface of the body is a surface perpendicular to the rotation axis and is abutted and joined. A core for producing an electro-fusion joint, characterized in that a shaft in which both cores rotate in conjunction with each other can be constituted by engagement means slidable in the axial direction in contact with an end surface of another core. 2. A core for producing an electro-fusion joint according to claim 1, wherein at least one notch is provided in a peripheral portion of an end face of the core for producing an electro-fusion joint. 3. A core comprising a base and a trunk, wherein the outer diameter of the trunk corresponds to the inner diameter of the desired joint, the outer diameter of the base is at least 1 mm larger than the outer diameter of the trunk, and the boundary between the base and the trunk. A hole for inserting and temporarily fixing the tip of the coated linear heating element in the stepped portion is provided, and the end surface of the body portion is manufactured by the electrofusion joint according to claim (1) or (2). A core for producing an electric fusion joint, wherein the core has a concave curved surface which is in close contact with an outer surface of a body portion when the core is connected alone or connected. 4. A side surface of a body portion of a core for manufacturing an electro-fusion joint according to claim 1, 1 or 2,
Electrocutting wherein at least one cutout portion is provided in which the whole or a part of the end face of the core for manufacturing another electrofused joint according to claim (1) or (2) is fitted and adhered. Core for manufacturing joints. 5. A core for producing an electro-fusion joint according to claim 1, 1, 2, 3 or 4, wherein each of the cores is used alone or connected to a pore. A coated linear heating element with the tip inserted and temporarily fastened is spirally wound around the outer peripheral surface of the body, and it is coaxially opposed and closely connected, or another core is brought into close contact with it from the side. Into a T-shaped, cross-shaped, or other branched state and set it in the corresponding split mold, inject molten resin into the formed mold cavity, and join the joint that is integrated with the coated linear heating element. A method for manufacturing an electro-fusion joint, which comprises forming, cooling and solidifying, and then appropriately removing a mold and a core.