JP6966841B2 - Resin pipe fittings - Google Patents

Description

The present invention has an internal flow path through which a fluid flows, and a curved portion in which the central axis of the internal flow path is curved, and a welded end portion of another resin piping member provided at each of both ends of the curved portion. It relates to a resin pipe joint provided with a welded end portion to be welded by butt, and in particular, proposes a technique capable of realizing good flow of a fluid in an internal flow path.

Piping such as chemical liquid transportation lines used in various industries uses a welding machine to form resin pipe joints made of thermoplastic resin, etc., and resin pipe members such as resin tube members or other resin pipe joints. It may be constructed by abutting and welding the respective ends of the plastic.

More specifically, for example, in each of the pairing clamp jigs of the welding machine, the end of the resin pipe joint and the end of the resin tube member face each other, and the resin pipe joint and the resin pipe joint and the end of the resin tube member are opposed to each other. Hold each of the resin tube members.
Next, both ends of the resin pipe joint and the resin tube member held by the clamp jig are heated by a heater or other heating device to melt those ends, and in that state, the resin pipe joint. And the resin tube members are brought close to each other and their ends are abutted and welded by the action of the required pressure.

Among this type of resin pipe joint, a so-called elbow in which the central axis of the internal flow path is curved or bent is, for example, as described in Patent Documents 1 and 2, the gold of an injection molding machine. It can be molded by injecting a resin material into the cavity with the core pin placed in the cavity of the mold.
Here, in any of the techniques described in Patent Documents 1 and 2, the ease of pulling out the core pin after the resin material supplied to the cavity in the mold is solidified to form the resin pipe joint is taken into consideration. It is decided to use a core pin composed of a plurality of divided segments which are divided at substantially the bending center position of the curved portion of the resin pipe joint and also divided into the outside and the inside in the bending direction.

Japanese Patent Publication No. 2006-506247 U.S. Pat. No. 6,399,006

By the way, when a resin pipe joint is formed by using a core pin composed of a plurality of divided segments, it can be formed between the divided segments at a position corresponding to a contact point between the divided segments of the core pin on the inner surface of the resin pipe joint. Due to the gap, a parting line of a convex portion protruding from the inner surface is formed.
In particular, in the methods described in Patent Documents 1 and 2, a parting line is formed on the inner surface of the curved portion of the resin pipe joint by using the divided segment divided at the position of the curved portion of the resin pipe joint. This has the problem of increasing the pressure loss of the fluid flowing through the internal flow path when the resin pipe joint is used, and hindering the smooth flow of the liquid in the internal flow path of the resin pipe joint.

Further, in the past, in order to make it easier to pull out the core pin, a taper may be provided in which the cross-sectional area of the internal flow path gradually increases from the curved portion toward each welding end portion. Changes in the cross-sectional area lead to an increase in pressure loss.

An object of the present invention is to solve such a problem of the prior art, and the object thereof is to be made of a resin capable of realizing good flow of a fluid in an internal flow path. To provide pipe fittings.

As a result of diligent studies, the inventor has determined the shape of the resin pipe joint in the vertical cross section including the central axis of the internal flow path, and the contour lines of the inner surface of the curved portion in the bending direction are both the inner and outer contour lines of the curved portion. By making the curved portion a gentle arc shape as an arc shape having a common center with the arc shape of the central axis in the above, it is not necessary to use the divided segment divided at the position of the curved portion as in the prior art. It was also found that a resin pipe joint can be formed without providing a taper in which the cross-sectional area of the internal flow path gradually increases from the curved portion toward each welding end portion.

Based on the above findings, the resin pipe joint of the present invention has an internal flow path through which fluid flows, and a curved portion in which the central axis of the internal flow path curves in an arc shape and a curved portion at both ends of the curved portion. It is provided so that the central axis of the internal flow path becomes linear and includes a welded end portion that is abutted against and welded to the welded end portion of another resin piping member, and the central axis of the internal flow path is provided. In the vertical cross section including, both the inner and outer contour lines of the inner surface of the curved portion in the bending direction form an arc shape having a common center with the arc shape of the central axis in the curved portion, and the internal flow path is formed. It has a constant cross-sectional area over the entire resin pipe joint, the cross-sectional shape of the internal flow path is circular, the internal flow path has the same diameter over the entire resin pipe joint, and the curved portion of the curved portion. It is formed on a smooth surface from the inner surface to the inner surface of one welded end portion, and a convex portion and / or a concave portion exists between the inner surface of the curved portion and the inner surface of the other welded end portion. ..
Here, the "smooth surface" means that the surface is smooth without any protrusions or recesses on the inner surface caused by the parting line or the like .

The resin pipe joint of the present invention, the ratio of the axial length of the welding end portion to the diameter of the internal passage, it is preferable that 0.1 to 1.0.
In the case of this, the roundness of the cross section of the internal passage at least the welding end portion is preferably not less 0.3 mm.

In the resin pipe joint of the present invention, the length of the welded end portion in the axial direction is preferably 1.0 mm to 2.0 mm.
Further, in the resin pipe joint of the present invention, it is preferable that the peripheral wall portion constituting the welded end portion has a uniform axial length in the circumferential direction.

In the resin pipe joint of the present invention, in the vertical cross section including the central axis of the internal flow path, both the inner and outer contour lines of the inner surface of the curved portion in the bending direction have an arc shape of the central axis in the curved portion. By forming an arc shape with a common center, it is possible to pull out the core pin after injection molding even if a core pin that is not divided at the position of the curved portion is used when molding the resin pipe joint. become. As a result, a smooth surface is formed from the inner surface of the curved portion to the inner surface of at least one welded end portion, and an increase in pressure loss can be effectively suppressed when the fluid flows through the internal flow path.

Further, here, since the above-mentioned shape eliminates the need for the above-mentioned taper for easy pulling out of the core pin, the internal flow path has a constant cross-sectional area over the entire resin pipe joint. The increase in pressure loss during fluid flow can be further suppressed.
Therefore, according to the resin pipe joint of the present invention, good flow of the fluid in the internal flow path can be realized.

It is a vertical cross-sectional view including the central axis of an internal flow path which shows the resin pipe joint of one Embodiment of this invention. It is a top view of the resin pipe joint shown in FIG. It is sectional drawing of the mold at the same position as FIG. 1 which shows an example of the method of manufacturing the resin pipe joint of FIG. It is a similar sectional view showing the process following FIG. It is a similar vertical sectional view showing an enlarged view of one welded end portion of the resin pipe joint of FIG. 1. It is a similar vertical sectional view showing the other welded end portion of the resin pipe joint of FIG. 1 in an enlarged manner. It is a schematic diagram which shows the test apparatus used in an Example.

Hereinafter, embodiments of the present invention will be described in detail with reference to those shown in the drawings.
The resin pipe joint 1 of the embodiment illustrated in the vertical sectional view and the plan view shown in FIGS. 1 and 2, respectively, has an internal flow path P for flowing a fluid inside thereof, and is the central axis of the internal flow path P. The CL is at least partially curved and can be referred to as an elbow for changing the direction of fluid delivery in a pipe (not shown) configured using it. The resin pipe joint 1 is curved so as to change the direction in which the fluid is sent by approximately 90 °, but may be curved in the range of, for example, 20 ° to 140 °. Considering the removal from the mold after molding at the time of manufacturing the resin pipe joint described later, it can be curved within this range.

More specifically, the resin pipe joint 1 shown in the figure is provided at each of the curved portion 2 in which the central axis CL of the internal flow path P is curved in an arc shape and both ends of the curved portion 2, and the internal flow path P is provided. It is provided with welded end portions 3a and 3b having a linear central axis CL.

Here, the welded end portions 3a and 3b of the resin pipe joint 1 are made of a resin tube such as a straight pipe or a curved tube by using a welding machine or the like (not shown) when forming a pipe including the resin pipe joint 1. It is welded by abutting against the welded end of a resin pipe member such as a member or another resin pipe joint. In this welding, for example, the welding ends 3a and 3b of the resin pipe joint 1 and the ends of the resin piping members face each other on each of the pairing clamp jigs of the welding machine, and the resins thereof are subjected to the welding. Each of the resin pipe joint 1 and the resin pipe member is held, and then the ends of the resin pipe joint 1 and the resin pipe member are heated by a heater or other heating device to melt the resin. This can be done by bringing the pipe making joint 1 and the resin piping member close to each other and abutting their ends by the action of a required pressure.

Here, in the present invention, in the vertical cross section shown in FIG. 1 by a plane including the central axis CL of the internal flow path P of the resin pipe joint 1, the inner surface of the curved portion 2 is inside in the bending direction (diagonally lower left in FIG. 1). ) And the contour line Lo on the outside of the bending direction (in the diagonally upper right side in FIG. 1) both form an arc shape having a common center with the arc-shaped center Ca of the central axis CL in the bending portion 2. .. As a result, the internal flow path P is gently curved at the curved portion 2, so that the core pin can be easily and surely pulled out when the resin pipe joint 1 is manufactured by injection molding as described later. Become.

Further, here, it is assumed that the internal flow path P has a constant cross-sectional area over the entire resin pipe joint 1, that is, the curved portion 2 and both welded end portions 3a and 3b. That is, the internal flow path P has a uniform cross-sectional area without changing in any portion of the resin pipe joint 1.
As a result, at the location of the resin pipe joint 1 of the liquid flowing through the pipe, as compared with the conventional technique having a tapered internal flow path in which the cross-sectional area gradually increases from the curved portion to the welded end portion. Since the increase in pressure loss of the liquid is prevented, it can contribute to the smooth flow of the liquid. Such a constant cross-sectional area of the internal flow path P is realized by allowing the core pin to be pulled out during injection molding due to the shape of the curved portion 2 being gently curved as described above. can do.

The internal flow path P has a cross section orthogonal to the central axis CL and can have various shapes such as a rectangle or other polygons, but in this type of resin pipe joint 1, it is generally circular. Often. In the case of the internal flow path P having a circular cross-sectional shape, the resin pipe joint 1 has the same diameter D throughout.

The resin pipe joint as described above can be manufactured by injection molding through the steps illustrated in FIGS. 3 to 4.
That is, first, as shown in FIG. 3A, the inner surface shape of the resin pipe joint 1 is formed in the cavity 12 having the inner surface shape corresponding to the outer surface shape of the resin pipe joint 1 of the mold 11 of the injection molding machine. A core pin 13 having an outer surface shape corresponding to the above is arranged. Here, the core pin 13 extends to a relatively long split segment 13a extending from the inner surface of one welded end 3a to a region corresponding to the inner surface of the curved portion 2 and a region corresponding to the inner surface of the other welded end 3b. Those having a relatively short split segment 13b are used, for example, a protruding portion provided on the tip surface of one of the split segments 13a is provided in a recessed portion provided on the tip surface of the other split segment 13b. By inserting them, the divided segments 13a and 13b can be connected to each other.

Next, as shown in FIG. 3B, a predetermined resin material is supplied to the cavity 12 of the mold 11 in a molten state. As a result, the portion of the cavity 12 excluding the core pin 13 is filled with the molten resin material. Then, this is solidified by cooling to form a resin pipe joint 1 in the cavity 12.

After that, the relatively short split segment 13b of the core pin 13 is pulled out from the inside of the other welded end 3b of the resin pipe joint 1 as shown by an arrow in FIG. 4 (a), and the relatively long split segment 13b is pulled out. As shown by an arrow in FIG. 4 (b), 13a is rotationally displaced around the center Ca of the central axis CL in the curved portion 2 of the internal flow path P of the resin pipe joint 1, and the resin pipe joint is formed. It is pulled out from the curved portion 2 of 1 and the welded end portion 3a on one side.

Here, as described above, since the internal flow path P is formed to be gently curved at the curved portion 2, the relatively long split segment 13a can be easily formed without significantly deforming the resin pipe joint 1. It can be pulled out reliably. Therefore, it is not necessary to provide a tapered shape in which the cross-sectional area of the internal flow path gradually increases from the curved portion to the welded end portion for the ease of pulling out the core pin as in the prior art.

In the resin pipe joint 1 of the embodiment manufactured in this manner, a relatively long split segment 13a extending from the inner surface of one of the welded end portions 3a to the region corresponding to the inner surface of the curved portion 2 is formed. As a result, as shown in the enlarged view of FIG. 5, there is no parting line on the inner surface of the curved portion 2 and the one welded end portion 3a due to the unevenness of the divided portion of the core pin 13, and the total length and the entire circumference thereof are not present. Over, it is formed on a smooth surface with no recesses or bumps.

Therefore, in this embodiment, it is possible to effectively prevent an increase in pressure loss due to the formation of a concave portion or a convex portion of the parting line in the curved portion. As a result, the liquid flows smoothly in the internal flow path P of the resin pipe joint 1. As a result, the pressure loss performance is almost the same as that when the resin tube member such as a straight tubular member is bent after the fact. Manufacturing can be performed efficiently.

On the other hand, on the inner surface of the other welded end portion 3b, a portion corresponding to the mutual connection portion of the relatively long divided segment 13a and the relatively short divided segment 13b, that is, the central axis CL is curved in an arc shape. An annular convex portion and / or a concave portion, generally a convex portion 4, is formed at a position serving as a boundary with the portion 2. However, all of the welded end portions 3a and 3b are subjected to welding with the welded end portions of other resin piping members as described above, and are welded to the welded end portions of other resin piping members. After that, since such a minute convex portion 4 almost disappears, the convex portion 4 on which the welded end portion 3b is applied does not have a great influence on the flow of the liquid.

Although not shown, the gently curved resin pipe joint as described above uses an undivided core pin extending from the inner surface of one welded end portion through the inner surface of the curved portion to the other welded end portion. It can also be manufactured, in this case a resin fitting with a smooth surface over the entire inner surface of the resin fitting from the inner surface of one welded end through the curved part to the other welded end. Is obtained.

In the case of the resin pipe joint 1 of the internal flow path P having a circular cross-sectional shape, the ratio (Le / D) of the length Le of the welded ends 3a and 3b in the axial direction to the diameter D of the internal flow path P is It is preferably 0.1 to 1.0.
That is, if the length Le of the welded end portions 3a and 3b in the axial direction is too long with respect to the diameter D of the internal flow path P, the core pin 13 is formed from the resin pipe joint 1 formed in the mold 11 at the time of manufacturing. When pulling out, it may be difficult to pass the curved portion of the core pin 13 through the linear welded end portions 3a to 3b, and the welded end portions 3a and 3b with respect to the diameter D of the internal flow path P. If the length Le in the axial direction is too short, there is a concern that welding problems such as melting and crushing margins cannot be obtained.

More specifically, when the diameter D of the internal flow path P is 2.02 mm to 2.32 mm, the above ratio Le / D is more preferably 0.46 to 0.92, and the internal flow path is more preferable. When the diameter D of P is 4.2 mm to 4.5 mm, the above ratio Le / D is more preferably 0.23 to 0.46, and the diameter D of the internal flow path P is 7.38 mm. When it is ~ 7.68 mm, the above ratio Le / D is more preferably 0.13 to 0.27.
Specifically, the length Le of the welded end portions 3a and 3b in the axial direction is preferably 1.0 mm to 2.0 mm. The axial length Le of the welded end portions 3a and 3b was measured from the boundary position with the curved portion 2 along the central axis CL to the outermost edge of the welded end portions 3a and 3b in the axial direction. Means distance.

Further, in the case of the resin pipe joint 1 of the internal flow path P having a circular cross-sectional shape, the roundness of the cross-sectional surface of the internal flow path P at least at the welded end portions 3a and 3b is preferably 0.3 mm or less. Is. The smaller the value of roundness, the more preferable it is, so there is no particular suitable lower limit. Generally, it may be 0.5 mm or more. In particular, it is preferable that the roundness of the cross section of the internal flow path P is within the above range not only in the welded portions 3a and 3b but also in the entire resin pipe joint 1.
When the core pin 13 is pulled out after injection molding, the curved portion of the core pin 13 passes through the linear welded end portions 3a to 3b, and the passage of the core pin 13 causes deformation of the welded end portions 3a and 3b. This is because it is desirable in terms of quality that the welded end portions 3a and 3b maintain a predetermined high roundness even with such deformation.
This roundness is measured by a three-dimensional measuring machine.

By the way, if the entire resin pipe joint is formed in an arc shape and the linear end portion does not exist, the arc-shaped welded end portion is formed due to the difference in the diameter of the arc in the vertical cross-sectional view. Since the axial length of the peripheral wall portion to be formed increases from the inside to the outside in the bending direction, the axial length of the peripheral wall portion of the welded end portion is different between the inside and the outside in the bending direction and becomes non-uniform. In this case, there is a problem that it is difficult to uniformly melt the welded end portion with a heater or the like having a flat heating surface at the time of welding with another resin piping member.

On the other hand, in this embodiment, linear welded end portions 3a and 3b are provided at both ends of the curved portion 2, and the peripheral wall portions 5 of the welded end portions 3a and 3b are uniformly axially oriented in the circumferential direction. Since it has a length, it is possible to uniformly melt the welded end portions 3a and 3b with a heater or the like having a flat heating surface. Here, when determining whether or not the axial length of the peripheral wall portion 5 is uniform in the circumferential direction, the axial length of the peripheral wall portion 5 is set to the diameter of the peripheral wall portion 5 at each portion in the circumferential direction. It shall be confirmed at the same position in the direction. For example, when confirming at the inner surface position of the welded end portions 3a and 3b which are the innermost in the radial direction of the peripheral wall portion 5, the axial length Lwi of the peripheral wall portion 5 inside the bending direction and the outside in the bending direction at the inner surface position. Compare with the axial length Lwo of the peripheral wall portion 5 of the above.

When the welded ends 3a and 3b of the resin pipe joint 1 are abutted against each other and welded, the welded ends are in a molten state and are subjected to the action of a predetermined pressure. Due to the crushing of the molten resin due to being pressed, the resin is cured in a state of being raised from the inner surface to the inner peripheral side at the welded part between the resin pipe joint 1 and other resin piping members, and the resin is hardened on the inner surface thereof. It is known that a ridge, which can be called an inner bead, is formed.
In order to prevent the occurrence of such an inner bead, in the illustrated embodiment, the end faces of the welded end portions 3a and 3b are inclined with respect to the plane orthogonal to the central axis CL and are directed toward the inner peripheral side in the axial direction. The inclined surface 6 that enters the inside is used. This makes it possible to effectively suppress the crushing of the resin to the inner peripheral side during welding. Since the portion provided with the inclined surface 6 is welded to the welded end portion of another resin piping member, the internal flow path P is not formed during piping.

Examples of the material constituting the resin pipe joint 1 include perfluoroalkoxy alkane (PFA), perfluoroethylene propene copolymer (FEP), polyetheretherketone (PEEK), and the like. It is also possible to use materials other than materials.

Next, the resin pipe joint of the present invention was prototyped and its performance was confirmed, which will be described below. However, the description here is for the purpose of mere illustration, and is not intended to be limited thereto.

The joints of Comparative Example 1, Comparative Example 2 and Example 1 shown in Table 1 were prepared. The joint of Comparative Example 1 is a so-called mechanical joint that is mechanically connected to the end of the tube member, and the joints of Comparative Example 2 and Example 1 are welded joints that are welded by abutting against the end of the tube member. Is. Both joints are made of PFA.

The joint of Comparative Example 1 had a smaller inner diameter at the central portion than at the end portion because the inner surface was provided with a taper for die cutting. Since the joint of Comparative Example 2 was also provided with a die-cutting taper, the inner diameter was smaller at the central portion than at the end portion.
On the other hand, the joint of Example 1 had no taper and had a constant inner diameter over the entire joint.

When the inner surface of the joint of Comparative Example 1 was confirmed, a step of misalignment and a minute pocket were generated when the tube end portion (A) and the tubular seal portion (B) were fitted. Since the joint of Comparative Example 2 is connected to the end of the tube by welding, there is no step or pocket at the end as in the joint of Comparative Example 1. Further, in the joints of Comparative Examples 1 and 2, a convex parting line was formed at the center position of the inner surface corresponding to the contact points of the two split segments having substantially the same shape at the time of molding.
On the other hand, in the joint of the first embodiment, since the joint is formed by using the long and short divided segments as shown in FIGS. It was inside.

The joints of Comparative Examples 1 and 2 had a shape that was bent at a right angle, but the joint of Example 1 had a shape that was smoothly curved.
The following tests were performed using these joints.

The liquid was flowed at a flow rate of 2 L / min with the joints of Comparative Example 1 set in each of the 10 bends of the test apparatus shown in FIG. When the value of the pressure P1 of the pressure gauge at that time was read, the pressure P1 was 0.08 MPa. Next, all the joints of Comparative Example 1 in the bent portion were replaced with the joints of Comparative Example 2, the liquid was flowed so as to have the above pressure P1, and the flow rate at that time was confirmed. After that, all the joints of Comparative Example 2 in the bent portion were replaced with the joints of Example 1, and similarly, the liquid was flowed so as to have the above pressure P1 and the flow rate was confirmed.
The results are also shown in Table 1. The test results in Table 1 show the flow rate obtained by preparing three joints of Comparative Example 1, a joint of Comparative Example 2, and three joints of Example 1 and conducting the above test for each of the three joints. It is an average value.

From what is shown in Table 1, it is clear that the joint of Example 1 has a higher flow rate than the joints of Comparative Examples 1 and 2 under the action of the same internal pressure. This is because the joint of Example 1 does not have a taper for die cutting on the inner surface as in Comparative Examples 1 and 2, and has steps and pockets as in Comparative Example 1 and a parting line as in Comparative Example 2. It is probable that this was due to the fact that the surface was smooth and the shape was curved smoothly.
From the above, it was found that the joint of Example 1 has a reduced pressure loss as compared with the joints of Comparative Examples 1 and 2, and the liquid can flow more smoothly.

1 Resin pipe joint 2 Curved part 3a, 3b Welding end part 4 Convex part 5 Peripheral wall part 6 Inclined surface 11 Mold 12 Cavity 13 Core pin 13a, 13b Divided segment P Internal flow path CL Central axis of internal flow path Lo Curved part inner surface Outer contour line in the bending direction Li Inner contour line in the bending direction of the inner surface of the bending part Ca Arc center of the central axis in the bending part D Diameter Le Axial length of the welding end Lwi Peripheral wall of the inner welding end in the bending direction Axial length of the part Lwo Axial length of the peripheral wall of the welded end on the outside in the bending direction

Claims (5)

It has an internal flow path that allows fluid to flow, and is provided at each of a curved portion in which the central axis of the internal flow path is curved in an arc shape and both ends of the curved portion, so that the central axis of the internal flow path becomes linear. , A resin pipe joint provided with a welded end portion to be welded by abutting against a welded end portion of another resin piping member.
In the vertical cross section including the central axis of the internal flow path, both the inner and outer contour lines of the inner surface of the curved portion in the bending direction form an arc shape having a common center with the arc shape of the central axis in the curved portion. At the same time, the internal flow path has a constant cross-sectional area over the entire resin pipe fitting .
The cross-sectional shape of the internal flow path is circular, and the internal flow path has equal diameters throughout the resin fitting.
A smooth surface is formed from the inner surface of the curved portion to the inner surface of one welded end portion, and a convex portion and / or a concave portion exists between the inner surface of the curved portion and the inner surface of the other welded end portion. comprising resin pipe fitting. The ratio of the length of the axial direction of the welding end portion to the diameter of the internal passage, the resin pipe joint according to claim 1 is 0.1 to 1.0. The resin pipe joint according to claim 1 or 2 , wherein the roundness of the cross section of the internal flow path at least at the welded end is 0.3 mm or less. The resin pipe joint according to any one of claims 1 to 3 , wherein the length of the welded end portion in the axial direction is 1.0 mm to 2.0 mm. The resin pipe joint according to any one of claims 1 to 4 , wherein the peripheral wall portion constituting the welded end portion has a uniform axial length in the circumferential direction.

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