JP2969074B2 - Tube manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a tubular body and a core used for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a tube is generally manufactured by molding or extrusion using a core. However, in molding using a core, since the core must be extracted after molding, there is a drawback that it is difficult to manufacture the core in a shape that is difficult to extract, for example, a curved tube. Extrusion molding is also suitable for producing straight pipes, but it has been difficult to produce curved pipes and the like due to its structure.

[0003] In order to solve this problem, various methods have been proposed. Hereinafter, the method will be briefly described. In Japanese Patent Application Laid-Open No. Hei 7-266401, in extrusion molding, the amount of extrusion when extruded from a molding opening is made different in the circumferential direction by the action of the throttle portion. As a result, since the speed of the extruded material extruded from the forming opening differs in the circumferential direction, the extruded material bends toward the side where the extruding speed is lower, and as a result, a desired curved tube is formed. Japanese Patent Application Laid-Open No. Sho 62-238728 extrudes by a usual method, and then passes through a guide portion having a curved shape. That is, the thermosetting rate of the thermosetting resin tube immediately after being extruded by a usual method is 80 to 90%.
After that, the heat is passed through the curved guide portion while applying heat, so that the curved guide portion is reformed into a curved tubular shape. As an example of using a core for molding, there is known an example in which a core is formed in a tapered shape or divided into a plurality of pieces to prevent the core from being difficult to remove after forming a curved tube. As disclosed in Japanese Examined Patent Publication No. Hei 5-1101, there is a type in which a core used for molding is thermally melted by a molding material. In this case, it is not necessary to remove the core, so that even a curved tube can be easily formed.

[0004]

However, in the manufacturing method described above or above, the extrusion amount differs in the circumferential direction or the straight pipe is molded and then forced to bend (the molding material expands outside the curved portion, It is difficult to make the thickness of the peripheral wall forming the curved pipe uniform. Further, in the manufacturing method described above, if the core is tapered, the opening width is different at both ends of the curved tube, and if the core is divided into a plurality of parts, the manufacturing becomes complicated. In this respect, the above-described manufacturing method can solve the above-mentioned disadvantage, but in order to heat and melt the core, at least the molding material must have a higher melting point. However, when a thermosetting urethane resin or the like is used as the molding material, its melting point is 12%.
Since the temperature is as low as about 0 ° C., there is no suitable material for the core, so that this method cannot be practically adopted. The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a method for manufacturing a tube in which the core can be easily removed regardless of the shape of the tube, and a core used for the manufacturing method. is there.

[0005]

According to a first aspect of the present invention, an engaging groove is formed on one side edge along a length direction, and the engaging groove is formed on the other side edge. An engaging ridge that can be inserted into the mating groove so that the insertion depth can be changed is formed into a tube-shaped core that can be bent by spirally winding a strip formed along the length direction while closely contacting the strip. A core is placed in a molding die, a molding material is injected into a space between the molding die and the core and cured, and then, one end of a strip forming the core is pulled, The present invention is characterized in that the core is removed from the inside of the molding die by continuously disengaging the engagement groove and the engagement ridge from the end of the child.

[0006]

[0007]

According to the first aspect of the present invention, in order to manufacture a tubular body, first, a strip is spirally wound to form a tubular core, and the core is formed into a tubular body. Set in the mold. Then, a molding material is injected into a space between the molding die and the core and cured. Next, the molded article in which the core is disposed inside is taken out of the molding die, and thereafter or prior to this, one end of the strip forming the core is pulled out of the molded article. Then, the core is removed from the inside of the molded article so as to be unwound in order. Thus, the production of the tube is completed. In the case of manufacturing a curved tube, a desired curved tube can be obtained by appropriately changing the overlap allowance between the inner peripheral side and the outer peripheral side when the strip is spirally wound. Thereafter, if the molding is performed in the same manner as above, a desired curved tube is taken out.

[0008]

As described above, according to the first aspect of the present invention, the core is formed by spirally winding the strip and can be easily removed by pulling out one end of the core. Even if it is a thing, there is an effect that it can be easily molded.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a method for manufacturing a curved tube will be described below with reference to FIGS.
First, a mold that is a forming die for forming a curved tube will be described. This mold 1 is, as shown in FIGS. 1 and 2,
The whole is formed in an arc shape having a central angle of about 300 °. The mold 1 has a structure in which a pair of side walls 3 and 3 are erected in parallel at a predetermined interval on a base 2, and both ends thereof are supported by support plates 4 and 4, and a plurality of portions in the middle thereof are formed. After each of the molds 1 is surrounded by the gate-shaped support frame 11, the molds 1 are fixed by being bolted to the base 2. The upper and lower portions of the inner wall surface of the side wall 3 are symmetrically formed with the convex portions 13 along the length direction, so that the inside of the mold 1 has an octagonal cross section as shown in FIG. The molding surface 6 is formed, and the mold 1 is opened upward as shown in FIG. 7 (b), from which the molding resin stock solution (in this embodiment, the uncured thermosetting polyurethane resin stock solution, Hereinafter, it is simply called a urethane resin stock solution).
The connecting portion between each side wall 3 and the base 2 is filled with a sealing material 7 along the length direction, and sealed so that the poured urethane resin stock solution does not leak.

A core 8 to be described later is loaded into the mold 1 prior to molding. At this time, the core 8 is substantially aligned with the mold 1 by a resin-made positioning piece 9 described below. It is coaxial and is supported at a position raised from the base 2. That is, three or four sets of positioning pieces 9 are arranged in the mold 1 at appropriate intervals. A set of three positioning pieces 9 is disposed on the left and right side walls 3 and the base 2 and specifically fixed by bolts 10, and the cores 8 are held at approximately 90 ° intervals by these positioning pieces 9. Like that. Further, a set of four positioning pieces 9 is provided with the support frame 11 described above.
Are arranged in the place where the left and right side walls 3
And one on the base 2 by means of the bolt 10 in the same manner as described above, and the rest on the support frame 11. That is, a mounting piece 11a is horizontally formed on the upper opening edge of the support frame 11 so as to bridge the left and right side walls 3, and the positioning piece 9 is fixed to a central portion thereof by a bolt 10. I have. Then, the core 8 is held at intervals of about 90 ° from the entire circumferential direction by the set of four positioning pieces 9.

Each positioning piece 9 is formed of a synthetic resin material in a short columnar shape, one end of which is in close contact with the base, both side walls and the mounting piece 11a, and the other end of which is abutted against the outer peripheral surface of the core 8. ing. Further, a screw 9a is cut on the outer peripheral surface of each positioning piece 9 for the purpose of enhancing the adhesive strength with the molded product (curved pipe 5), thereby preventing the positioning piece 9 from falling off after molding. As a result, the sealing property in the curved tube 5 is ensured.

Next, the core 8 will be described. The core 8 has a tubular shape as a whole as shown in FIG. 6, but in practice, as shown in FIG. 4, a single long ribbon piece (band piece) 12 is tightly and spirally wound. It is formed by going. That is, as shown in FIG. 5, a slit (engaging groove) 1 is formed on one side edge of the ribbon piece 12.
2a is formed in a recess along the length direction, and the other side edge is provided with a protruding edge (engaging protrusion) 12b which can be closely inserted into the slit 12a along the length direction and protrudes in the width direction. I have. Therefore, by inserting the protruding edge 12b into the slit 12a while keeping the ribbon piece 12 in close contact and in a spiral shape, there is no gap in the side surface, that is, a tubular shape in which the sealing property for urethane resin as a molding material is secured. The child 8 is obtained. And the rim 12
Since the insertion depth of b into the slit 12a can be changed, the curvature of the core 8 can be freely changed within a range in which the protruding edge 12b does not separate from the slit 12a.

Next, a procedure for manufacturing the curved tube 5 will be described. First, the core 8 is formed by inserting the protruding edge 12b into the slit 12a while keeping the ribbon piece 12 in close contact and spiral. Next, a release agent is applied to the inner wall surface of the mold 1 and the outer peripheral surface of the core 8 in advance, so that the subsequent release operation is performed smoothly. The core 8 is concentrically set in the mold 1 while being curved along the mold 1 in an arc shape. To set, the positioning piece 9 is fixed to the left and right side surfaces and the bottom surface of the mold 1 with bolts 10 in advance, and the core 8 is placed on the positioning piece 9. Is fixed at a predetermined position on the base 2. When the core 8 is set in the mold 1, both ends of the core 8 are slightly projected from the support plate 4. If a seal tape is wrapped around the outer peripheral surface of the core 8 as necessary, the sealing performance of the core 8 itself is further ensured.

After the core 8 is set at the center of the mold 1 while using the positioning piece 9, the urethane resin stock solution is poured into the mold 1 (FIGS. 7A and 7B).
reference). When the urethane resin stock solution is poured, the buoyancy may cause the core 8 to deviate from the proper set position. For this purpose, in the present embodiment, the hollow portion of the core 8 is filled with a material having substantially the same specific gravity as the urethane resin stock solution (for example, plastic particles). In addition, in the process of injecting the urethane resin undiluted solution, the casting is usually performed after mixing the urethane curing material with the urethane main material. Before the mixing, a defoaming process (vacuum evacuation) is performed, and bubbles are mixed in the molded product. The situation is avoided beforehand.

After the casting, the urethane resin stock solution is allowed to stand for a predetermined period of time to cure the urethane resin stock solution.
Then, the mold 1 is opened by removing each support frame 11, and subsequently, the core 8 is extracted. In this case, when the tip of the core 8 (the free end of the ribbon piece 12) is pinched and pulled out, the engagement between the protruding edge 12b and the slit 12a is forcibly released, and the tight spiral of the ribbon piece 12 is released. The ribbon pieces 12 can be continuously pulled out as if peeling the apple (see FIGS. 8A and 8B).
If the ribbon piece 12 is pulled out to the end as it is, the removal of the core 8 is completed. Thereafter, if the molded product is taken out from the mold 1, an arc-shaped curved tube 5 having an angle of about 300 ° is obtained.
(See FIGS. 9A and 9B).

The curved tube 5 manufactured according to the above-described procedure.
May be used by connecting a plurality of them.
In this case, although not shown, a metal connection plate is inserted around the opening edge of the end surface of each curved tube 5 at the time of molding. As a result, the connection plates are embedded in both open ends of the curved tube 5 after the molding, and the connection plates 4 protrude from the end surfaces of the curved tube 5.
If an insertion hole is formed in the corner, the end faces of the curved pipes 5 can be aligned with each other, and then a bolt can be inserted into this section and fixed to the other side, so that the curved pipes 5 can be easily connected to each other. Can be spliced. Also, connect the connecting plate to the curved pipe 5
If the opening end is slightly protruded from the connection plate so that the opening end protrudes slightly from the connection plate, the protruding portion acts as a sealing surface at the time of joining, and the curved pipes 5 are made watertight. Can be spliced.

As described above, according to the present embodiment, since the core 8 set in the mold 1 is formed by spirally winding the ribbon piece 12, the core 8 can be easily removed by pulling out one end of the core. The extraction operation is extremely easy even for a curved tube having a shape in which the core 8 is difficult to be extracted, such as an arc-shaped, long, or small-sized radius of curvature. Further, the following effects are obtained from this.

Since the curved tube 5 can be manufactured by molding, it is not necessary to vary the amount of extrusion in the circumferential direction as in the case of extrusion molding when molding the curved tube 5. The thickness can be made uniform in the circumferential direction. Although it is a method of manufacturing the curved tube 5 by molding, it is not necessary to make the core 8 tapered, so that the thickness of the peripheral wall portion can be made uniform also in the length direction. It is a method of manufacturing the curved tube 5 by molding, while
Does not need to be divided into a plurality of parts, and its production is extremely easy. Even when the molding surface 6 is partially overlaid or recessed, the core 8 can be easily removed and the curved pipe 5 having a partially different thickness depending on the application can be easily manufactured. . Since there is no need to heat and melt the core 8, a molding material having a low melting point can be used, and the core 8 can be reused.

When the curved pipes 5 manufactured by the above-described manufacturing method are connected to each other and used as a vibration transfer path of a vibrating barrel polishing apparatus, the thickness of the curved pipes 5 can be made uniform or partially overlaid. The following effects are further obtained from the above-described specific effect that the above-described operation can be performed. That is, in the vibrating barrel polishing apparatus, since the abrasive fluid composed of abrasive grains, metal powder, granular material, slurry, and the like is vibrated and conveyed in the vibrating conveyance path, the inner wall surface of the curved pipe is worn by long-term use. However, if the curved tube 5 manufactured according to the present embodiment is used, the inner wall surface is uniformly worn because the thickness of the curved tube 5 is uniform, thereby prolonging the life of the vibration conveying path. be able to. On the other hand, when there is a portion where wear is remarkable, it is possible to increase the thickness of only that portion, so that it is possible to wear the entire portion in a well-balanced manner. I can do it. Furthermore, the pipe of the present invention refers to a structure having a pipe of an arbitrary shape inside, and the outer shape of the pipe itself does not matter.

Further, the present invention can be variously modified,
The following modifications are also included in the technical scope of the present invention. (1) In the above embodiment, the upper surface of the mold 1 is opened,
Although the configuration is such that the urethane resin is poured from there, the upper surface of the mold may be closed except for the filling port, and the molding material may be poured from the filling port.

(2) In the above-described embodiment, the arc-shaped curved pipe 5 is manufactured.
S-shaped pipe (for example, drain pipe 21 of sink shown in FIG. 10)
For example, the pipe body can be manufactured in various shapes such as a pipe body, and the effect is sufficiently exhibited particularly in a case where the core cannot be removed by the conventional method. Also, as shown in FIG. 11, the present invention can be applied to a case where a pipe 22 in which a flow passage is partially squeezed by making the inner diameter of the through hole 22a different is manufactured. Used.

(3) In the above embodiment, the arc-shaped curved pipe 5 is manufactured. However, when the through-hole formed in the molded product is curved regardless of the shape of the molded product, the curved tube 5 may be manufactured. It can also be applied to a method for manufacturing a molded article.

(4) In the above embodiment, a thermosetting polyurethane resin stock solution was used as the molding resin stock solution. However, a thermosetting resin stock solution of acrylic resin, polyester, silicone resin or the like or a thermoplastic resin stock solution was used. Well,
Furthermore, a concrete material may be used. In short, any molding material that does not deform or alter the ribbon pieces forming the core may be used.

(5) In the above-described embodiment, the method for manufacturing a curved pipe used in the vibration barrel polishing apparatus has been described. However, an underground pipe such as a water pipe or a sewage pipe for flowing a liquid or a gas, or a house pipe may be used. The present invention can be applied to a method for manufacturing pipes in various fields such as internal and external pipes.

(6) The core 8 is not necessarily a ribbon piece 12
It is not limited to the configuration in which the protruding edge 12b or the slit 12a is provided on the side edge of the ribbon piece and these are continuously inserted, and the side edge of the ribbon piece 12 is simply formed flat without providing these, It can also be constructed by spirally overlapping and winding.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view showing the present embodiment.

FIG. 2 is a plan view showing a state where a core is set in a mold.

FIG. 3 is a sectional view showing a state in which a core is set in a mold.

FIG. 4 is a front view of a core.

FIG. 5 is an enlarged sectional view showing a connection state of the ribbon pieces.

FIG. 6 is a perspective view of a core.

FIG. 7A is a plan sectional view showing a state in which a urethane resin is injected into a mold, and FIG. 7B is a front sectional view of the same.

FIG. 8 (a) is a plan sectional view showing a core extracting operation,
(B) is a front sectional view similarly.

FIG. 9A is a plan sectional view showing a part of a divided pipe body in a state where molding is completed, and FIG. 9B is a front sectional view of the same.

FIG. 10 is a side view showing another embodiment (drain pipe).

FIG. 11 is a cross-sectional view showing another embodiment (tubes having different inner diameters).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Die (molding die) 5 ... Curved tube 8 ... Core 12 ... Ribbon piece (band piece) 12a ... Slit (engaging groove) 12b ... Protrusion (engaging ridge)

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B29C 39/22-39/36 B29C 33/76 B29C 53/58-53/78

Claims (1)

(57) [Claims] An engagement groove is formed on one side edge along a length direction.
Is formed, and the other side edge has a depth of insertion with respect to the engagement groove.
The engagement ridge that can be inserted to change the length is along the length
By spirally winding the strip formed in close contact
Use a bendable tube-shaped core, and insert the core in the mold
And a molding material is provided in a space between the molding die and the core.
And then cured, then the strip forming the core
And pull the one end of the core from the end of the core with the engagement groove.
By continuously releasing the engagement with the engagement ridge,
A tubular body characterized in that the core is removed from the inside of a molding die.
Manufacturing method.