JPH0767743B2 - Molding method for receiving and fitting pipe fittings - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a secondary molding method for a receiving and fitting pipe joint, and more specifically, for ensuring a reliable receiving and fitting pipe connection, a socket side is provided. The present invention relates to a method of secondarily forming a barbed portion to a predetermined rising angle. In the following description, the case of the barb formed at the receiving / joining part of the corrugated pipe will be described as a typical example, but the barb of the present invention can be applied to pipes of other shapes. It is not specified in.

[Prior Art] A corrugated tube 1 as shown in FIG. 2 as a cable protection tube.
Is commonly used. One end of the corrugated tube 1 forms a receiving portion 11, and the other end has an insertion portion 12. Further, as shown in FIG. 3 (cross-sectional view), a peripheral groove 15 for inserting the ring-shaped packing 14 is formed in the receptacle 11 and
A barb 11a that fits into the fitting peripheral groove 12a of the insertion opening 12 is formed on the inner side thereof in the circumferential direction intermittently. And in inserting and connecting the insertion portion 12 in the receiving portion 11 in the illustrated example, while fitting the packing 14 in the circumferential groove 15,
Forcibly fit the insertion opening 12 into the receiving opening 11, and insert the fitting peripheral groove 12a.
Insert the hook portion 11a into the inside, and by this fitting, the insertion opening 1
2 is configured to be restricted from coming out of the receiving portion 11.
This also confirms that the insertion tube for receiving and joining has been inserted to the required depth.

[Problems to be Solved by the Invention] The corrugated pipe 1 is generally formed by extrusion blow molding, and while the thermoplastic resin pipe extruded into a straight pipe is kept in a softened state, The corrugated pipe 1 shown in FIG. 2 is manufactured by holding the divided moving outer mold and introducing (blowing) compressed air into the pipe. Fourth
The figure is a cross-sectional explanatory view showing a state in which the circumferential groove 15 and the engaging portion 11a of the corrugated tube 1 are blow-molded, and 2 in FIG.
Is a block-divided outer mold, and it is desired that the barb 11a rise sharply at about 90 degrees, as can be understood from the above description of the operation. However, in the blow molding method, it is difficult to form the rising angle of the inner surface of the hook portion 11a to about 90 degrees because the outer mold is restricted. That is, by increasing the pressure of the compressed air, the outer surface of the pipe can be made to fit the moving outer mold sufficiently, but the uniformity of the wall thickness is lost due to the effect of high air pressure. Is far from 90 degrees. Further, sometimes the resin is concentrated in this portion to form a resin pool, and the inner surface may have a completely different shape even if the outer surface can be molded cleanly. Therefore, the engaging portion 11a cannot be formed to have the rising angle as designed. FIG. 5 is an enlarged sectional view of the barb 11a formed by the blow molding, and the rising angle θ of the barb 11a is limited to about 60 degrees. Therefore, even if the one molded in this state is fitted with the fitting peripheral groove 12a of the insertion opening 12, there is a problem that the engaging force of the engaging portion is insufficient and the insertion opening 12 easily comes out. there were.

As a means for solving this problem, the circumferential length of the barb 11a may be formed to be long, and it may be possible to form it over the entire circumference at any time. It has been found that if it is too large, the insertion force for inserting the insertion opening 12 beyond the barbed portion must be increased, the pipe connection workability becomes poor, and it is not practical.

Therefore, the present inventors have completed the present invention by conducting research for the purpose of providing a product in which the rising angle of the barbed portion 11a is formed to have a predetermined value.

[Means for Solving the Problems] The present invention that has achieved the above object is to form a barb formed on the receiving side of a receiving and fitting pipe joint and projecting inward at a predetermined rising angle. In the secondary molding method, the outer die having a convex portion corresponding to the projecting concave portion of the barb portion while regulating the inner surface of the barb portion by an expandable and contractible inner die that forms a predetermined rising angle after heating and softening the barb portion. Is a method for forming a receiving fitting pipe joint in which the protruding portion of the receiving portion is pressed against the pipe axis of the receiving fitting pipe joint in an oblique direction to form a predetermined rising angle. It is a thing.

[Operation and Example] FIGS. 1A and 1B are process explanatory views showing a typical example of the present invention. In both figures, the outer mold 3 has a catch 11
It has a convex portion 3c corresponding to the protruding concave portion of a, and first, the vicinity of the hooked portion 11a is heated and softened to such an extent that it can be secondarily molded. Next, as shown in FIG. 1 (A), the expandable / contractible inner mold 4 is expanded in the radial direction (arrow C direction), and the outer mold 3 is slanted with respect to the pipe axis of the receiving and fitting pipe joint, that is, the arrow. Pressing and moving in the A direction, the hooked portion as shown in FIG. 1 (B)
11a is clamped between the inner mold 4 and the outer mold 3 so as to be tightened from the outside, and the rising angle θ of the engaging portion 11a is formed to be about 90 degrees.
After cooling, the inner mold 4 is moved in the direction opposite to the arrow C direction, and the outer mold 3 is moved in the direction opposite to the arrow A direction to remove the mold. It is preferable that the outer mold 3 is moved closer to the hook portion 11a from an oblique direction with respect to the pipe axis as shown by an arrow A, rather than being moved in a direction B ₁ which is completely orthogonal to the pipe axis. Because, when it is moved from a direction completely orthogonal to the pipe axis, a part of the root side of the hook portion 11a is sandwiched between the inner mold 4 and shearing, and the hook portion
This is because there is a risk of tearing off 11a. It is also conceivable to bring the outer mold 3 close to the position slightly apart from the catch 11a in the direction orthogonal to the pipe axis and then move the outer mold 3 in the pipe axis direction.
The molding material may concentrate on the root-side protruding portion of 11a, and this portion may be thickened to make the rising angle dull. The expandable / contractible inner mold 4 may be configured to be radially expanded so as to be expanded and moved in the arrow C ₃ direction (pipe axis direction), or may be obliquely moved in the C ₄ direction. .

Also, as shown in the example of the expandable / contractible structure of the inner die 4, one using a tapered expanding / contracting member 41 (for example, one shown in Japanese Patent Laid-Open No. 51-28172), or combination division divided in the circumferential direction. A structure in which the piece is expanded / contracted by an eccentric cam member, an expansion / contraction member, or the like (for example, as shown in JP-A-50-117851) may be used.

Further, the restricting surface 3a of the outer die 3 for forming the barb 11a is not at right angles to the tube axis but at an angle α (for example, α
= 10 to 20 degrees) is preferably formed in the form of an overhang, so that after the mold is removed, the hanging portion 11a is formed.
The rising angle can be maintained at a predetermined angle even if the formation angle of the is slightly deformed in the direction of blunting.

EFFECTS OF THE INVENTION Since the present invention is configured as described above, the barbed portion on the coil gate tube receiving side can be formed by abruptly rising to a predetermined angle, and the receiving section and the insertion section can be formed. The mating connection with has been made more reliable, and it has become possible to prevent the mating connection part from slipping out.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 (A) and 1 (B) are cross-sectional explanatory views showing the process sequence of the method of the present invention, FIG. 2 is a side view showing a corrugated pipe, and FIG. 3 is shown in FIG. FIG. 4 is a partial sectional view showing a receiving / inserting connection state of the corrugated tube, FIG. 4 is a sectional explanatory view showing a manufacturing example of the corrugated tube receiving portion, and FIG. 5 is a partially enlarged sectional view of FIG. 1 ... Corrugated pipe, 2 ... Outer mold 3 ... Outer mold, 4 ... Inner mold 11 ... Receiving part, 11a ... Barring part 12 ... Inserting part, 12a ... Fitting peripheral groove 13 ... … Corrugated part, 14 …… Ring packing 15 …… Circumferential groove

Claims (1)

[Claims] 1. A secondary molding method for forming an inwardly projecting barb formed on the receiving side of a receiving and fitting pipe joint at a predetermined rising angle, wherein the barb is heated and softened. , An outer mold having a convex portion corresponding to a protruding concave portion of the catch portion while restricting the inner surface of the catch portion by an expandable / contractible inner mold forming the predetermined rising angle. With respect to the above, the method for forming a receiving and fitting pipe joint is characterized in that the protruding portion of the engaging portion is abutted and pressed from an oblique direction to form the engaging portion at a predetermined rising angle.