JP6126862B2 - Manufacturing method of pipe joint and pipe joint - Google Patents

Description

  The present invention relates to a pipe joint, and more particularly to a method for manufacturing a pipe joint provided with a water-swellable nonwoven fabric as a water-stopping material, and the pipe joint.

  Conventionally, resin pipes such as polyethylene pipes have been employed as protective pipes for water and sewage pipes and electric cables. This resin pipe is formed with spiral ridges, and is connected by a pipe joint in which spiral grooves corresponding to the spiral ridges are formed for each appropriate length. In this case, in order to prevent unknown water or the like from entering from the connection portion between the pipe joint and the resin pipe, a water stop material is disposed on the inner peripheral surface of the pipe joint.

  As shown in Patent Document 1, a pipe joint in which such a water-stopping material is provided on the inner peripheral surface is formed by supplying a parison between an inner mold having a water-stopping material and an outer mold, The outer mold is clamped with respect to the mold, and the parison and the waterstop material are formed into shapes corresponding to the outer peripheral surface shape of the inner mold and the inner peripheral surface shape of the outer mold.

Japanese Patent No. 3955913

  By the way, in the manufacturing method disclosed in Patent Document 1, the pipe joint is clamped to the inner mold with respect to the inner mold as described above, and the parison and the waterstop material are formed into the outer peripheral surface shape of the inner mold and It will be molded by so-called compression molding, which is shaped to the shape corresponding to the inner peripheral surface shape of the outer mold, but if it is such compression molding, means to pull the inner mold from the pipe joint is required However, Patent Document 1 has no disclosure about this point. Therefore, it is actually impossible to form a pipe joint by the conventional manufacturing method.

  Even if it can be molded, there are problems as described below.

  In the pipe joint described above, when a non-woven fabric having water swellability is used as the water-stopping material, the parison 104 is attached to the non-woven fabric 105 that is placed in the inner mold 102 by clamping the outer mold 101 as shown in FIG. When the outer mold 101 is clamped, the parison 104 having a diameter larger than that of the nonwoven fabric 105 flows in the radial direction as well as the axial direction (see FIG. 14). The nonwoven fabric 105 also moves in the radial direction while being integrated with the parison 104 flowing in the radial direction, so that the nonwoven fabric 105 is separated from the outer peripheral surface of the inner mold 102 between the pair of outer molds 101 to be clamped. It expands outward in the radial direction (see FIG. 15). Therefore, when the pair of opposing outer molds 101 are clamped, the nonwoven fabric 105 is integrated with the parison 104 and is pushed out from the abutment surface of the outer mold 101 and is expanded and folded, and further folded. A folded portion 110 is formed in which the non-woven fabric 105 is sandwiched by the parison 104 (see FIG. 16).

  As a result, the pipe joint 200 having the folded portion 110 extending in the longitudinal direction along the position corresponding to the butting surface of the outer mold 101 is formed.

  When such a pipe joint 200 is used, when unknown water or the like enters and the nonwoven fabric 105 swells, a tensile force is generated in the radial direction in the pipe joint 200, and the tensile force follows the outer peripheral surface of the pipe joint 200. Thus, tensile stress and compressive stress act along the inner peripheral surface. Here, in the pipe joint 200, since the folded portion 110 in which the nonwoven fabric 105 is folded is present along the longitudinal direction as a cutout portion, tensile stress acts on the folded portion 110 and the folded portion 110 is acted on. And the synthetic resin 104A integrated on the outside is broken along the folding part 110 (see FIG. 17).

  In addition, the nonwoven fabric 105 is provided in a sheet shape, and is rounded into a tubular shape, and the end edges are overlapped and joined to each other and placed on the inner mold 102. Therefore, the joining edge 105x is compared with other parts. Thus, the thickness is increased (see FIG. 18). In this state, when the outer mold 101 is clamped and the parison 104 is pressure-bonded to the non-woven fabric 105 (see FIG. 19), the parison 104 corresponding to the joining edge portion 105x of the non-woven fabric 105 is attached to another site. Compared to the thin portion 104x, which is relatively thin (see FIG. 20). For this reason, a thin-walled portion with a thin synthetic resin 104A, that is, a relatively low strength portion is generated along the longitudinal direction in the molded pipe joint 110. As a result, when water enters during use and the nonwoven fabric 105 swells, the pressure may cause the pipe joint 110 to break from a low-strength portion extending in the longitudinal direction.

  Such pipe joints are connected to resin pipes as protective pipes such as water and sewage pipes and electric cables, and are buried in the ground together with resin pipes. Is done. That is, the water-stopping performance is lost due to the breakage of the pipe joint, and when unknown water enters the resin pipe through the pipe end of the resin pipe, damage to the sewer pipe, corrosion of the electric cable, etc. occur. Along with this, there is a risk of water outages, power outages, road collapses, flooding of houses, etc., and at that time, a great deal of cost is required for restoration work. Therefore, the above-described pipe joint that may cause variations in quality in production lacks reliability as a product and cannot be adopted.

  The present invention has been made in view of such problems, and it is possible to form a highly reliable and highly reliable pipe joint by reliably preventing the occurrence of a folded portion in which the parison sandwiches the nonwoven fabric. A method for manufacturing a joint and a pipe joint are provided.

  The present invention relates to a method for manufacturing a pipe joint in which a spiral groove is formed on an inner peripheral surface and a non-woven fabric having water swellability is attached to the inner peripheral surface, the spiral unevenness corresponding to the spiral groove Is formed on the outer peripheral surface, and a nonwoven fabric disposing step for disposing a cylindrical nonwoven fabric on the holding body on which air jets opening at a plurality of locations on the outer peripheral surface are formed, and unevenness corresponding to the unevenness of the holding body A mold that is formed on a peripheral surface and is divided into three or more divided molds around the axis of the holding body outside the holding body, and at least one split mold of the divided molds is used. After removing and closing, the remaining divided mold is closed and clamped, and a nonwoven fabric shaping step for shaping irregularities in the nonwoven fabric, and after the irregularities are shaped into the nonwoven fabric, the mold is opened, and the mold and nonwoven fabric A parison arrangement step of arranging a cylindrical parison between the mold and the mold , Except for at least one split mold among the split molds, and then closing the remaining split mold and clamping, forming irregularities corresponding to the mold irregularities on the parison, and both ends of the pipe joint The non-woven fabric and the parison are integrated only in the portion corresponding to the above, while in the portion other than the integrated portion, the clearance set to the sum of the thickness of the non-woven fabric and the thickness of the parison is set. The both ends integrated step of securing the added interval between the outer peripheral surface of the holding body and the inner peripheral surface of the mold, and the nonwoven fabric is expanded by blowing compressed air from the air outlet of the holding body. A blow process for attaching at least a part of the surface to the inner circumferential surface of the parison, and after the parison is solidified, the holding body is rotated and detached with respect to the parison and the nonwoven fabric in which both ends in the longitudinal direction are integrated, And the retrieval step of retrieving a pipe joint and the mold is opened the mold, is characterized in that comprises a.

  According to this invention, after arrange | positioning a cylindrical nonwoven fabric to a holding body, a metal mold | die is clamped and an unevenness | corrugation is shaped to a nonwoven fabric. At this time, after closing at least one of the three or more divided molds constituting the mold, the remaining divided molds are closed and clamped. Next, after opening the mold and placing a cylindrical parison between the mold and the nonwoven fabric with irregularities, the mold is clamped to hold the irregularities corresponding to the irregularities of the nonwoven fabric on the parison Through the shape. At this time, after closing at least one of the three or more divided molds constituting the mold, the remaining divided molds are closed and clamped. At this time, the nonwoven fabric and the parison are integrated only at the portions corresponding to both ends of the pipe joint, and the thickness of the nonwoven fabric before the mold clamping and the thickness of the parison are integrated at portions other than the integrated portion. An interval obtained by adding a clearance set to the sum is secured between the outer peripheral surface of the holding body and the inner peripheral surface of the mold. Thereafter, compressed air is ejected from the air outlet of the holding body to inflate the nonwoven fabric, and at least a part of the outer circumferential surface of the nonwoven fabric is adhered to the inner circumferential surface of the parison. Next, when the parison is solidified, the holding body is rotated with respect to the formed pipe joint to be detached from the pipe joint, and then the mold is opened to take out the pipe joint.

  Here, when forming irregularities corresponding to the irregularities of the mold on the parison, the diameter of the parison is closed by closing the remaining divided molds after closing at least one divided mold among the divided molds. The flow in the direction can be suppressed as much as possible, and the nonwoven fabric can be integrated with the parison and prevented from expanding away from the outer peripheral surface of the holding body. Even if the parison swells in the radial direction, it is possible to reliably prevent the folded portion from being generated in the parison by crushing the bulge in the radial direction of the parison by closing the remaining split mold.

  As a result, the folded part of the parison sandwiching the nonwoven fabric along the longitudinal direction is not formed, and a pipe joint having excellent strength can be reliably formed.

  In the present invention, a sheet-like nonwoven fabric is formed into a tubular shape by joining both edge portions, and the nonwoven fabric is disposed on the holding body so that the joined edge portion of the nonwoven fabric faces a specific split mold. It is preferable to set the moving stroke small corresponding to the thickness of the nonwoven fabric. As a result, a laminated body in which the thickness of the parison laminated on the joining edge of the nonwoven fabric is reduced, that is, a pipe joint in which the thickness of the synthetic resin is partially small is not formed, and the strength is almost uniform over the entire circumference. It is possible to reliably form the pipe joint.

  The pipe joint according to the present invention is a pipe joint in which a spiral groove is formed on the inner peripheral surface of an outer layer material made of synthetic resin, and a nonwoven fabric having water swellability is attached to the inner peripheral surface as the inner layer material. The outer layer material and the non-woven fabric are integrated only at both ends of the pipe joint, and at least a part of the outer peripheral surface of the non-woven fabric is attached to the inner peripheral surface of the outer layer material.

  ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of the folding part which the parison pinched | interposed the nonwoven fabric was prevented reliably, and the reliable highly reliable pipe joint can be provided.

It is a perspective view of the pipe joint manufactured with the manufacturing method of the present invention. It is a fragmentary sectional view of the pipe joint of FIG. FIG. 2 is a front view schematically showing the pipe joint forming apparatus of FIG. 1 with a part thereof omitted. It is a top view which shows typically the metal mold | die of the shaping | molding apparatus of FIG. 3 with a holding body. It is a longitudinal cross-sectional view which shows the state which clamped the metal mold | die of the shaping | molding apparatus of FIG. 3 with respect to the holding body. It is a longitudinal cross-sectional view explaining the process of shape | molding a pipe joint using the shaping | molding apparatus of FIG. FIG. 7 is a longitudinal sectional view for explaining a pipe joint forming step following FIG. 6. FIG. 8 is a longitudinal sectional view for explaining a pipe joint forming step following FIG. 7. FIG. 9 is a longitudinal sectional view for explaining a pipe joint forming step following FIG. 8. FIG. 10 is a partial cross-sectional view illustrating a portion corresponding to a joining edge portion of a nonwoven fabric in the forming step of FIG. 9. FIG. 10 is a longitudinal sectional view for explaining a pipe joint forming step following FIG. 9. FIG. 12 is a longitudinal sectional view for explaining a pipe joint forming step following FIG. 11. It is a cross-sectional view explaining the formation process of the pipe joint by the manufacturing method of patent document 1. FIG. 14 is a transverse cross-sectional view for explaining a pipe joint forming step according to the manufacturing method of Patent Document 1 following FIG. 13. FIG. 15 is a cross-sectional view for explaining a forming process of a pipe joint by the manufacturing method of Patent Document 1 and an enlarged view of an X part following FIG. 14. FIG. 16 is a cross-sectional view for explaining a forming process of a pipe joint by the manufacturing method of Patent Document 1 following FIG. 15 and an enlarged view of a Y portion. It is a perspective view which shows the state which the pipe joint shape | molded by the manufacturing method of patent document 1 fractured | ruptured. It is a partial cross-sectional view explaining the formation process of the joining edge part of the nonwoven fabric in the pipe joint by the manufacturing method of patent document 1. FIG. FIG. 19 is a partial cross-sectional view for explaining a forming process of a joining edge portion of a nonwoven fabric in a pipe joint by the manufacturing method of Patent Document 1 following FIG. 18. FIG. 20 is a partial cross-sectional view illustrating a process for forming a joining edge portion of a nonwoven fabric in a pipe joint according to the manufacturing method of Patent Document 1 following FIG. 19.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1 and 2 show a pipe joint 10 formed by the manufacturing method of the present invention. This pipe joint 10 is formed by a parison 11P (see FIG. 3) supplied by a parison supply device 4 described later, and a synthetic resin 11 as an outer layer material and a non-woven fabric having water swellability as an inner layer material (hereinafter, It is a laminated body with 12 and is formed in a tubular shape. And in the pipe joint 10, while forming the helical recessed part 10a in an outer peripheral surface, the helical convex part 10b which protrudes toward inner direction corresponding to the said recessed part 10a is formed in the inner peripheral surface, Thereby, a spiral groove 10 c (female screw) is formed on the inner peripheral surface of the pipe joint 10. Although not shown in detail, the spiral groove 10c of the pipe joint 10 corresponds to a spiral protrusion (male thread) formed on the outer peripheral surface of the resin pipe, and the pipe joint 10 is relatively positioned with respect to the resin pipe. By screwing, the tube end of one resin tube and the tube end of the other resin tube can be connected.

  However, while the synthetic resin 11 and the nonwoven fabric 12 are compressed and integrated at both ends in the longitudinal direction of the pipe joint 10, the synthetic resin 11 and the nonwoven fabric 12 are substantially the same in thickness except for both ends. And a part of the surface layer of the nonwoven fabric 12 is impregnated and adhered to the synthetic resin 11. In other words, the spiral groove 10c of the pipe joint 10 has a spiral groove 10c1 at both ends and a spiral having a smaller valley diameter at which the nonwoven fabric 12 is not compressed than a valley diameter of the spiral groove 10c1 at both ends except for the both ends. And a groove 10c2. Similarly, the spiral convex portion 10b of the pipe joint 10 is also a convex portion having a smaller inner diameter because the nonwoven fabric 12 is not compressed than the inner diameter of the convex portions 10b1 at both ends and the convex portions 10b1 at both ends except for both ends. Part 10b2. For this reason, when connecting the resin pipe which has the spiral protrusion corresponding to the spiral groove 10c1 in the longitudinal direction both ends of the pipe joint 10 by screwing into the pipe joint 10, about the site | part except both ends, it is the spiral protrusion of the resin pipe. Will enter while crushing the nonwoven fabric 12.

  In addition, it is preferable that the length of each end portion in the longitudinal direction where the synthetic resin 11 and the nonwoven fabric 12 in the pipe joint 10 are integrated is approximately equal to or longer than the length corresponding to one pitch of the spiral. As a result, when the nonwoven fabric 12 is screwed into the pipe joint 10 while crushing the nonwoven fabric 12 and the resin tube is connected, when the nonwoven fabric 12 swells with water, both ends are integrated with the synthetic resin 11. Can be reliably held without protruding from the pipe joint 10, and the water stop performance can be exhibited by pressing the inner peripheral surface of the synthetic resin 11 and the outer peripheral surface of the resin pipe of the pipe joint 10.

  As shown in FIGS. 3 to 5, the molding apparatus 1 for the pipe joint 10 includes a mold 2 that can be clamped and opened, and a mold 2 that is disposed in the mold 2 and a nonwoven fabric 12 that is disposed on the outer peripheral surface. The main part is comprised from the body 3 and the parison supply apparatus 4 which supplies the parison 11P used as the synthetic resin 11 between the nonwoven fabric 12 arrange | positioned at the holding body 3, and the metal mold | die 2. FIG.

  The mold 2 is arranged to be opposed to four divided dies 21, 22, 23, and 24, respectively, which can be moved by hydraulic cylinders (not shown), specifically, two pairs in two directions orthogonal to each other when viewed from above. The molds 21, 22, 23, and 24 are opened, and the mold is opened and clamped based on the holding body 3 and the parison supply device 4.

  The four divided dies 21 to 24 of the mold 2 have inner peripheries so that, when the mold is clamped, a cylindrical opening corresponding to the outer peripheral surface shape of the pipe joint 10 is formed at the center. On the surface, a spiral convex portion 2a that protrudes inward corresponding to the spiral concave portion 11a of the pipe joint 10 is formed.

  The holding body 3 is formed in a cylindrical shape that is slightly smaller than the opening, and a helical recess 3a is formed on the outer peripheral surface of the holder 3 in which the protrusion 2a is disposed when the mold 2 is clamped. Has been. The holding body 3 is rotatably supported via a rotating device 5 such as a motor, and is operated in synchronism with a moving device (not shown) to rotate in the axial direction while rotating with respect to the mold 2. It can be advanced and retracted along.

  In this case, the holding body 3 is integrated at each end in the longitudinal direction of the pipe joint 10 with the inner peripheral surface of each end in the longitudinal direction of the clamped mold 2 at both ends in the longitudinal direction. It is formed in the recess 3 a 1 having an interval corresponding to the sum of the thickness of the resin 11 and the thickness of the nonwoven fabric 12. On the other hand, in a portion excluding both ends in the longitudinal direction, an interval obtained by adding a clearance set to the sum of the thickness of the parison 11P before molding and the thickness of the nonwoven fabric 12 between the inner peripheral surface of the clamped mold 2 Is formed in the recess 3a2. That is, the holding body 3 is formed in a spiral shape at each end in the longitudinal direction of the pipe joint 10 on the outer peripheral surface of the cylindrical body having an outer diameter corresponding to the diameter of the valley of the spiral groove 10c1 at each end in the longitudinal direction of the pipe joint 10. After processing the spiral concave portion 3a1 having a trough diameter corresponding to the inner diameter of the convex portion 10b1, the portions excluding those both end portions are formed between the inner peripheral surface of the mold 2 and the thickness of the parison 11P before molding. The spiral recess 3a2 having a valley diameter smaller than the recess 3a1 at both ends is processed so as to have an interval corresponding to the sum of the thickness of the nonwoven fabric 12 and the set clearance, and the outer diameter portion 3b1 at both ends. The outer diameter portion 3b2 having a smaller diameter is processed.

  Here, it is preferable that the length of each end portion whose outer diameter and valley diameter are slightly larger than other portions is equal to or longer than the length corresponding to one pitch of the spiral.

  Therefore, when the mold 2 is clamped around the holding body 3, the gap between the mold 2 and the holding body 3 is slightly larger than the cavity corresponding to the pipe joint 10 as shown in FIG. 5. A cavity C is formed.

  A plurality of air jets 3x are formed in the holding body 3 in a range corresponding to the cavity C facing the portions corresponding to the outer diameter portions 3b1 and 3b2, and inside the holding body 3. Are formed with communication passages 3y communicating with these air ejection ports 3x, and an air blowing pipe 42 extending from an air outlet of the parison supply device 4 is detachably connected to the communication passage 3y.

  Further, a chuck device (not shown) is provided near the lower end portion of the holding body 3 to grip the lower end portion of the parison 11P when the entire outer peripheral surface of the holding body 3 is covered by the parison 11P.

  Furthermore, when the nonwoven fabric 12 formed into a tubular shape by joining the edge portions of the sheet-like nonwoven fabric is disposed on the holding body 3, the joining edge portion is a split mold 23 of the mold 2 (FIG. 4). It is arranged so as to oppose (see). The moving stroke of the selected one split mold 23 is set slightly smaller than the moving stroke of the split mold 24 facing the one split mold 23 in consideration of the thickness of the joining edge of the nonwoven fabric 12. ing. That is, the bonding edge portion of the nonwoven fabric 12 is formed so that the synthetic resin 11 having a thickness substantially equal to the thickness of the synthetic resin 11 in the portion excluding the bonding edge portion is also formed on the bonding edge portion of the nonwoven fabric 12. The movement stroke is set to be small corresponding to the difference between the thickness and the thickness of the nonwoven fabric 12 at other portions.

  The parison supply device 4 supplies the parison 11P heated and softened by an extruder (not shown) from the parison supply unit 41 to the outer peripheral surface side of the holding body 3, and the device itself is well known in the art. The parison 11P is a tubeless bottomless parison whose bottom is open.

  In addition, an air introduction path (not shown) is formed at the air inlet of the parison supply device 4, and an air source 6 such as a blower provided outside is connected to the air introduction path via a hose 61. ing. Therefore, by operating the air source 6, the compressed air can be ejected from the air ejection port 3x via the air blowing pipe 42 of the parison supply device 4, that is, blow molding can be performed. Can be inflated to adhere.

  Next, the process of forming the pipe joint 10 by the forming apparatus 1 configured as described above will be described.

  First, the tubular nonwoven fabric 12 is covered on the holding body 3 in a state where the mold 2 is opened, and is arranged on the holding body 3 (see FIG. 6).

  At this time, the non-woven fabric 12 is positioned so that the joining edge portion of the non-woven fabric 12 faces one split mold 23 of the mold 2.

  Thereafter, the mold 2 is clamped. Specifically, in FIG. 4, the split molds 21 and 22 that face the left and right of the four split molds 21 to 24 are advanced toward the holding body 3, and the setting range of each of the left and right semicircular portions of the nonwoven fabric 12 is set. Concavities and convexities corresponding to the inner peripheral surface shape of the split molds 21 and 22 and the outer peripheral surface shape of the holding body 3 are formed. Next, in FIG. 4, the split molds 23, 24 that face each other in the vertical direction are advanced toward the holding body 3, and the inner peripheral surfaces of the split molds 23, 24 that face up and down over the set range of the upper and lower half circumference portions of the nonwoven fabric 12. The unevenness corresponding to the shape and the outer peripheral surface shape of the holding body 3 is shaped. Thereby, the spiral unevenness | corrugation corresponding to the inner peripheral surface shape of the metal mold | die 2 clamped and the outer peripheral surface shape of the holding body 3 is shaped over the perimeter of the nonwoven fabric 12 (refer FIG. 7).

  Under the present circumstances, since the nonwoven fabric 12 has small elasticity, it can hold | maintain the shaped unevenness | corrugation.

  If the nonwoven fabric 12 is formed with spiral irregularities, the pair of split molds 23 and 24 facing vertically and the pair of split molds 21 and 22 facing left and right are retreated from the holding body 3 in this order, and the mold 2 is moved. Open the mold. Next, the parison supply device 4 supplies the parison 11P between the mold 2 in which the mold is opened from above and the holding body 3 holding the nonwoven fabric 12 and covers the outer periphery of the nonwoven fabric 12 (see FIG. 8).

  Subsequently, after the lower end portion of the parison 11P is held by a chuck device (not shown), the mold 2 is clamped again. That is, in FIG. 4, among the four split molds 21 to 24, the split molds 21 and 22 facing left and right are advanced toward the holding body 3, and the setting range of each of the left and right half circumference portions of the parison 11 </ b> P is set to the nonwoven fabric 12. Concavities and convexities corresponding to the spiral concavities and convexities are formed. Next, in FIG. 4, the remaining upper and lower split molds 23 and 24 are advanced toward the holding body 3, and the set ranges of the upper and lower half-periphery portions of the parison 11 </ b> P are formed into spiral irregularities formed on the nonwoven fabric 12. Shape the corresponding irregularities. Thereby, the spiral unevenness | corrugation corresponding to the internal peripheral surface shape of the metal mold | die 2 clamped to the parison 11P over the perimeter and the outer peripheral surface shape of the nonwoven fabric 12 hold | maintained at the holding body 3 is carried out between the holding bodies 3. It can be shaped (see FIG. 9).

  Here, at each end in the longitudinal direction of the mold 2 and the holding body 3, the distance between the inner peripheral surface of each of the divided molds 21 to 24 of the clamped mold 2 and the outer peripheral surface of the holding body 3 is a pipe joint. The nonwoven fabric 12 is compressed and integrated with the parison 11P because it is set to a thickness corresponding to the thickness of each end in the longitudinal direction. On the other hand, in the portion excluding the respective ends in the longitudinal direction of the mold 2 and the holding body 3, the distance between the inner peripheral surface of each of the divided molds 21 to 24 and the outer peripheral surface of the holding body 3 of the mold 2 is Since it is set slightly larger than the sum of the thickness of the parison 11P before molding and the thickness of the nonwoven fabric 12, the nonwoven fabric 12 is not compressed so as to reduce its thickness, and is integrated with the parison 11P. Not.

  By the way, the mold 2 is moved forward by moving the pair of split molds 21 and 22 facing left and right, and then moved forward and closed by the pair of split molds 23 and 24 facing vertically. When the split molds 21 and 22 are advanced, it is possible to suppress the parison 11P from flowing in the radial direction as much as possible, and the nonwoven fabric 12 is integrated with the parison 11P and separated from the outer peripheral surface of the holding body 3. Can be prevented from inflating. Even if the parison 11P swells in the radial direction, the bulge in the radial direction of the parison 11P can be crushed by advancing the pair of split dies 23, 24 facing each other up and down. It can be surely prevented from occurring.

  As a result, the folded portion of the parison 11P sandwiching the nonwoven fabric 12 along the longitudinal direction is not formed, and the pipe joint 10 that is a laminate of the parison 11P and the nonwoven fabric 12 having excellent strength is reliably formed. Can do.

  Further, the moving stroke of the one split mold 23 facing the joining edge portion 12x of the nonwoven fabric 12 is set slightly smaller than the moving stroke of the facing split mold 24, and the joining edge portion 12x of the nonwoven fabric 12 is set. The thickness of the parison 11P laminated on the bonding edge portion 12x can be ensured to be equal to the thickness of the parison 11P laminated on the portion excluding the bonding edge portion 12x. The thickness does not decrease and the strength is not reduced (see FIG. 10).

  In this state, the air source 6 is operated, and the compressed air is blown out from the air outlet 3x (see FIG. 11). That is, the site | part except the longitudinal direction both ends of the nonwoven fabric 12 is expanded by compressed air so that it may contact with the parison 11P. Thereby, a part of surface layer of the nonwoven fabric 12 is impregnated in the parison 11P, and the nonwoven fabric 12 adheres to the parison 11P. In this case, the nonwoven fabric 12 with small stretchability does not necessarily contact and adhere to the parison 11P over the entire surface, but as described above, because the parison 11P and the nonwoven fabric 12 are integrated at both ends, The nonwoven fabric 12 never leaves the parison 11P.

  When the blow process is completed and the parison 11P is solidified, the rotating device 5 and a moving device (not shown) are operated in synchronism so that the holder 3 is rotated with respect to the mold 2 and lowered along the axial direction. And extracted from the spiral groove 10c of the molded pipe joint 10. Subsequently, the pipe joint 10 which is a molded product can be taken out by opening the mold 2.

  In the above-described embodiment, the case where the outer peripheral surface excluding both ends of the holding body 3 is formed with a small diameter corresponding to the clearance is exemplified. However, the inner peripheral surface excluding both ends of the mold 2 is formed with a large diameter corresponding to the clearance. The outer peripheral surface excluding both ends of the holding body 3 may be formed with a small diameter, and the inner peripheral surface excluding both ends of the mold 2 may be formed with a large diameter, You may make it ensure the clearance set between the outer peripheral surfaces of the holding body 3. FIG.

DESCRIPTION OF SYMBOLS 1 Molding device 2 Mold 21-24 Split type 3 Holding body 3x Air ejection port 4 Parison supply device 10 Pipe joint 10a Spiral recessed part 10b Spiral convex part 10c Spiral groove 11 Synthetic resin 11P Parison 12 Nonwoven fabric 12x Joining edge Part

Claims (3)

A method for manufacturing a pipe joint in which a spiral groove is formed on the inner peripheral surface, and a nonwoven fabric having water swellability is attached to the inner peripheral surface,
A non-woven fabric arrangement step of arranging a cylindrical non-woven fabric on the holding body in which spiral concavo-convex portions corresponding to the spiral grooves are formed on the outer peripheral surface and air jets opening at a plurality of locations on the outer peripheral surface are formed;
An unevenness corresponding to the unevenness of the holding body is formed on the inner peripheral surface, and a mold composed of a split mold divided into three or more around the axis of the holding body outside the holding body A non-woven fabric shaping step of closing the remaining divided molds after closing except at least one of the divided molds, and clamping the non-woven fabric,
A parison placement step of opening the mold after forming irregularities on the nonwoven fabric and placing a cylindrical parison between the mold and the nonwoven fabric;
The mold is closed except for at least one of the divided molds, and then the remaining divided molds are closed and clamped to form irregularities corresponding to the irregularities of the mold on the parison, and the tube While the non-woven fabric and the parison are integrated only at the portions corresponding to both ends of the joint, the non-integrated portion is set to the sum of the thickness of the non-woven fabric and the thickness of the parison at a portion other than the integrated portion. A both-ends integration step for ensuring a gap with added clearance between the outer peripheral surface of the holding body and the inner peripheral surface of the mold;
A blow step of inflating the nonwoven fabric by blowing compressed air from the air outlet of the holding body, and attaching at least a part of the outer circumferential surface of the nonwoven fabric to the inner circumferential surface of the parison;
After the parison is solidified, the holding body is rotated and detached with respect to the parison and the nonwoven fabric in which both ends in the longitudinal direction are integrated.
The manufacturing method of the pipe coupling characterized by including.   The method for manufacturing a pipe joint according to claim 1, wherein the sheet-like nonwoven fabric is formed into a tubular shape by joining both edge portions, and the joining edge portion of the nonwoven fabric faces the specific split mold. A method for manufacturing a pipe joint, characterized in that the pipe is arranged and the moving stroke of the specific divided type is set to be small corresponding to the thickness of the nonwoven fabric. A pipe joint in which a spiral groove is formed on the inner peripheral surface of an outer layer material made of synthetic resin, and a non-woven fabric having water swellability is attached to the inner peripheral surface as an inner layer material,
The pipe joint, wherein the outer layer material and the nonwoven fabric are integrated only at both ends of the pipe joint, and at least a part of the outer peripheral surface of the nonwoven fabric is attached to the inner peripheral surface of the outer layer material.

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