Resin loose flange and manufacturing method therefor

Abstract

To provide a loose flange which is combined with a resin pipe to form a pipe joint, and which comprises a weld that is less susceptible to effects of stress generated during bolt fastening.SOLUTION: A resin loose flange 200 which is combined with a resin pipe 300 to form a pipe joint 100 has a thin, approximately annular shape in a longitudinal direction (axial direction) of the resin pipe 300. The resin pipe 300 is fitted into a central hole 202, and around the resin pipe, two or more (here, eight) bolt holes 240 are provided for passing fastening bolts. Welds are provided only in a region W of a flange surface (front and back surfaces) between the bolt holes 240 and an outer peripheral edge of the loose flange 200.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a resin loose flange that forms a pipe joint in combination with a resin pipe, and to a resin loose flange that forms a pipe joint used when flange-connecting a synthetic resin pipe (resin pipe) used for piping such as gas, water supply, and sewage (especially tap water piping), and a manufacturing method thereof.

Background Art

[0002] Conventionally, resin pipes such as polyethylene, polypropylene, and polybutene have been widely used as pipes for gas, water supply, sewage, etc. As a structure for connecting such resin pipes, a loose flange (rotatable flange) is engaged with a flange portion provided at the pipe end (a pipe or short pipe having such a flange portion provided at the pipe end may be called a flange adapter), and a flange connection structure is known. When a large stress is applied to the flange connection portion, stress may concentrate at the root of the flange portion and cause cracks or the like. Therefore, this portion is made thick or the connection radius is increased to prevent breakage.

[0003] Under such circumstances, as a pipe joint that can improve the strength of the flange portion with which the loose flange engages and withstand a large stress, a reinforcing member made of steel, engineering plastic, etc. is integrally formed on the flange portion of a synthetic resin short pipe with a flange (flange adapter) that engages with the loose flange. There was one in which a pipe joint was formed by attaching a loose flange to the outside of the short pipe with a flange and then joining the two by heat fusion.

[0004] However, even if such a pipe joint can improve the strength of the flange portion with which the loose flange engages and withstand large stresses, it is only due to integrally forming a reinforcing member made of steel, engineering plastic, etc., and there are problems such as leading to cost increase or weight increase. Also, from another perspective, when setting a loose flange on a pipe portion provided with a flange portion for regulating the position of the loose flange at one end side, there is a problem that its positioning is difficult and the workability is not preferable (especially when the weight increases as described above).

[0005] In order to solve such problems, the applicant of the present application developed a synthetic resin flange joint disclosed in Japanese Patent Application Laid-Open No. 2021-101117 (Patent Document 1) that has sufficient strength without using a separate member such as a reinforcing member. The synthetic resin flange joint disclosed in this Patent Document 1 is a flange pipe joint including a loose flange made of synthetic resin and a pipe portion made of synthetic resin provided with a flange portion for regulating the position of the loose flange at one end side of the pipe body. The loose flange has a substantially annular shape that is thin in the longitudinal direction of the pipe body, the pipe body is fitted into its central hole, and is provided with two or more bolt holes through which bolts for fastening pass around it. The flange portion has a circumferential concave groove on the end face of the other end side opposite to the one end side. The loose flange has, on the end face of the one end side, a convex portion that engages with the concave groove, a concave portion that engages from the outer peripheral surface of the flange portion to the start position of the concave groove, and a locking piece that locks the outer peripheral surface of the flange portion from the outer peripheral side, in this order in a direction away from the pipe center axis of the pipe portion. When looking at a longitudinal cross-section passing through the pipe center axis and having no bolt holes, the concave groove, the convex portion, the concave portion, and the locking piece are substantially rectangular shapes. Taking the longitudinal dimension of the pipe body as the length dimension and the radial dimension of the pipe body as the width dimension, with respect to the pipe portion, taking the depth of the concave groove as the length M(X), the groove width of the concave groove as the width M(Y), and the width H from the outer peripheral surface of the flange portion to the start position of the concave groove, and with respect to the loose flange, taking the length T(X) of the convex portion, the width T(Y) of the convex portion, the length K(X) of the locking piece, and the width K(Y) of the locking piece, the relationship of 2×T(X)<K(X) is established, which is characterized thereby.

Prior Art Documents

Patent Document

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] The synthetic resin flange joint disclosed in this Patent Document 1 has sufficient strength without using separate members such as reinforcing members, so it does not lead to cost increase or weight increase, and furthermore, it is favorably evaluated in terms of easy positioning and good workability.

[0008] By the way, when manufacturing the loose flange made of synthetic resin that constitutes this synthetic resin flange joint by injection molding, a streak-like weld line (sometimes simply referred to as a weld) is generated at the location where the molten resin converges. The presence of this weld line at the location where a large stress is generated when tightening the bolt through the bolt hole on the flange surface is not preferable in terms of strength. Although it is designed with a large safety factor and there is no problem in practice with the loose flange of Patent Document 1, the applicant of the present application has confirmed that when tightening the bolt until the loose flange breaks, it breaks at this weld line, and has focused on devising the weld location.

[0009] In addition, by using such a loose flange of Patent Document 1, when analyzing the stress generated when tightening the bolt through the bolt hole on the flange surface, the stress concentration location is further reinforced, and attention has been paid to reducing waste of the resin material to achieve weight reduction and cost reduction.

[0010] The present invention has been developed in view of the above-mentioned focus, and its object is to provide a resin loose flange that forms a pipe joint in combination with a resin pipe, which has (A) a weld that is less susceptible to the influence of stress generated during bolt tightening, (B) further reinforces stress concentration points, and can reduce weight and cost by saving waste of resin material, and a manufacturing method thereof.

Means for Solving the Problems

[0011] In order to achieve the above object, the resin loose flange and its manufacturing method according to the present invention take the following technical means.

[0012] That is, a resin loose flange according to an aspect of the present invention is a resin loose flange that forms a pipe joint in combination with a resin pipe, the loose flange has a thin substantially annular shape in the longitudinal direction of the resin pipe, the resin pipe is fitted into its central hole, and has two or more bolt holes through which bolts for fastening pass through the peripheral flange surface, and is characterized in that it has a weld only on the flange surface between the bolt hole and the outer peripheral edge of the loose flange.

[0013] Preferably, around the bolt hole, a rib having a width of 40% or more of the diameter of the bolt hole from the inner peripheral edge of the bolt hole and covering the periphery of the bolt hole is configured to be provided without exceeding the outer peripheral edge of the loose flange.

[0014] More preferably, the loose flange is provided with a rib covering the periphery of the bolt hole on the entire circumference of the inner peripheral side of the substantially annular shape at the end surface on the other end side, the rib has a cutout portion between the bolt holes, and the ratio of the finished rib width (radial dimension and non-cut length) C4 of the portion without the bolt hole to the flange width (radial dimension) C5 obtained by multiplying by 1 / 2 the value obtained by subtracting the finished inner diameter A2 of the central hole from the outer diameter C1 of the loose flange is 25% or more and 45% or less.

[0015] More preferably, the resin tube has a flange portion on one end side for restricting the position of the loose flange, and the flange portion has a circumferential concave groove on the end face of the other end side opposite to the one end side. The loose flange has a rib covering the periphery of the bolt hole on the entire circumference of the inner peripheral side of the substantially annular shape on the end face of the other end side. The rib has a cutout portion between the bolt holes. When looking at a cross section passing through the center axis of the loose flange and without the bolt holes, the end face of the one end side is provided with a convex portion engaging with the concave groove, a concave portion engaging from the outer peripheral surface of the flange portion to the start position of the concave groove, and a locking piece for locking the outer peripheral surface of the flange portion from the outer peripheral side, in this order in a direction away from the center axis of the loose flange. As the total thickness (axial dimension) D1 of the loose flange from the end face of the one end side to the end face of the other end side of the loose flange, the length (axial dimension) D2 of the locking piece, and the length (axial dimension) D4 from the end face of the other end side of the loose flange to the end face of the cutout portion of the loose flange, the ratio of (D1 - D 2 - D4) to D1 can be configured to be 35% or more and 45% or less.

[0016] Also, a method for manufacturing a resin loose flange according to another aspect of the present invention is a manufacturing method for manufacturing a resin loose flange that forms a pipe joint in combination with a resin tube by injection molding. The loose flange has a thin substantially annular shape in the longitudinal direction of the resin tube. The resin tube is fitted into its central hole and has two or more bolt holes through which bolts for fastening pass through the surrounding flange surface. The method is characterized in that a disk gate is adopted for the gate in the injection molding.

[0017] Preferably, it can be configured to use a disk gate with a gate diameter A1 that is 95% or more and 99% or less of the finished inner diameter A2 of the central hole.

[0018] More preferably, in the injection molding, a mold that closes the central hole and does not close the bolt holes is used, and after the injection molding, it can be configured to open the central hole.

[0019] More preferably, the injection molding can be configured such that welding occurs only on the flange surface between the bolt hole and the outer peripheral edge of the loose flange.

Advantages of the Invention

[0020] According to the present invention, there are provided a resin loose flange and a method for manufacturing the same, which form a pipe joint in combination with a resin pipe, have a weld that is less susceptible to the influence of stress generated during bolt tightening, further reinforce stress concentration points, and can reduce weight and cost by eliminating waste of resin material.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0022] <Resin loose flange> Hereinafter, a resin loose flange (hereinafter sometimes simply referred to as a loose flange) 200 that forms a synthetic resin flange pipe joint (hereinafter sometimes simply referred to as a flange pipe joint or a pipe joint) 100 in combination with a pipe part (which may be described as a resin pipe, a short pipe part, or a flange adapter) 300 according to an embodiment of the present invention will be described in detail with reference to FIG. 1 showing an overall side view (half-sectional view) along the longitudinal direction of the pipe body 350 of the synthetic resin flange pipe joint 100 including the synthetic resin flange pipe joint 100, FIG. 2(A) showing a front view of the resin loose flange 200 that constitutes the synthetic resin flange pipe joint 100 (a view of the loose flange 200 seen from one end side having a flange portion 310 in the pipe part 300), FIG. 2(B) showing a 2BU cross-sectional view (upper half) and a 2BD cross-sectional view (lower half) shown in FIG. 2(A), FIG. 2(C) showing a rear view (a view of the loose flange 200 seen from the other end side opposite to the one end side in the pipe part 300), and FIG. 3 showing a detailed cross-sectional view of the synthetic resin flange pipe joint 100 shown in FIG. 1. Here, FIGS. 2(A) to (C) show molded products, and FIG. 2(D) shows a product after the molded product is finished. Although it will be described in detail later, in the molded product in FIG. 2(B), the central hole 202 is not opened (there is a closed portion 201 formed of resin), and the central hole 202 is opened as shown in FIG. 2(D) by a finishing process (machining). In FIGS. 2(B) and 2(D), except for the points that A1 shown in FIG. 2(B) is processed (drilled and widened to the finished dimension A2 by machining) to A2 shown in FIG. 2(D) and the rib width C2 before processing shown in FIG. 2(B) is machined to the rib width C4 after processing shown in FIG. 2(D) by the finishing process, they are the same. Therefore, the reference numerals attached to the loose flange are not changed between FIGS. 2(A) to (C) and FIG. 2(D) (both are the loose flange 200). In the molded product in FIG. 2(B), the central hole 202 is not opened (there is a closed portion 201 formed of resin), and the central hole 202 is opened as shown in FIG. 2(D) by a finishing process (machining). In FIGS. 2(B) and 2(D), except for the points that A1 shown in FIG. 2(B) is processed (drilled and widened to the finished dimension A2 by machining) to A2 shown in FIG. 2(D) and the rib width C2 before processing shown in FIG. 2(B) is machined to the rib width C4 after processing shown in FIG. 2(D) by the finishing process, they are the same. Therefore, the reference numerals attached to the loose flange are not changed between FIGS. 2(A) to (C) and FIG. 2(D) (both are the loose flange 200).

[0023] This synthetic resin flange pipe joint 100 includes a loose flange 200 made of synthetic resin (a preferred material will be described later), and a synthetic resin pipe part (sometimes called a resin pipe, a short pipe part, or a flange adapter) 300 provided with a flange part 310 for restricting the position of the loose flange 200 at one end side of the pipe body 350. The loose flange 200 has a thin substantially annular shape in the longitudinal direction of the pipe body 350, and the pipe body 350 is fitted into its central hole 202 and is provided with two or more (here, 8) bolt holes 240 through which bolts for fastening pass around it.

[0024] The flange part 310 provided at one end side of the pipe body 350 in the pipe part 300 is provided with a circumferential concave groove 312 on the end face of the other end side opposite to the one end side. On the contrary, the loose flange 200 is provided, on the end face of the one end side, with a convex part 210 that engages with the concave groove 312, a concave part 220 that engages from the outer peripheral surface 314 of the flange part 310 to the start position 316 of the concave groove, and a locking piece 230 that locks the outer peripheral surface 314 of the flange part 310 from the outer peripheral side, in order in the direction away from the pipe center axis of the pipe part. As shown in the 2BU cross-section of FIG. 2(B), looking at the longitudinal cross-section passing through the pipe center axis and without bolt holes 240, the concave groove 312, the convex part 210, the concave part 220, and the locking piece 230 are substantially rectangular in shape.

[0025] Here, although not limited, the material of the pipe part 300 constituting this synthetic resin flange pipe joint 100 is polyethylene resin, and the material of the loose flange 200 is a polyolefin resin (such as polypropylene resin, polyethylene resin, etc.) or nylon resin reinforced with glass fiber or carbon fiber.

[0026] Also, although not limited, the nominal diameter of the pipe connected by this synthetic resin flange pipe joint 100 is about 50, 75, 100, 150, and although not limited, the number of bolt holes 240 is 4 for a nominal diameter of 50 and 8 for the others. Also, the central diagrams in FIGS. 1 and 3 show a state where the concave groove 312 and the convex portion 210 are engaged and the position of the loose flange 200 is regulated. Here, in FIG. 3, other than the central diagram, one is a diagram for explaining the flange portion 310 in the pipe portion 300, and the other is a diagram for explaining the 2BU cross-section in the loose flange 200.

[0027] Also, referring to the 2BD cross-sectional view of FIG. 2(B) and FIG. 2(C), the loose flange 200 is provided with ribs 250 on the entire circumference of the inner peripheral side of the substantially annular shape at the end face on the other end side shown in FIG. 2(C), and the periphery 242 of the bolt hole 240 is provided with a cutout portion 254 outside the rib 250 side (between the bolt hole and the other bolt hole), and is provided with a connecting portion 252 connected to the rib 250 on the rib 250 side.

[0028] Then, in order to explain the characteristic structure (shape) of the loose flange 200, after defining the axial direction and the radial direction shown in FIGS. 1 and 2, the dimensions are defined as follows, like the reference signs (one digit + one letter of the alphabet) shown in FIG. 2. Note that FIGS. 2(A) to (C), which are referred to in this definition of dimensions, show the dimensions of the molded product, and the point that FIG. 2(D) shows the dimensions of the product after processing is as described above.

[0029] In the loose flange 200, let the diameter of the bolt hole 240 through which the fastening bolt provided on the flange surface passes be B1, the outer circumference B2 of the rib 250 covering the periphery 242 of the bolt hole 240 (= the outer circumference radius R of the rib 250 × 2), and the rib width B4 of the rib 250 covering the periphery 242 of the bolt hole 240 ((B2 - B1) / 2) (in some cases, (B2 - B1) is described as B3).

[0030] In the loose flange 200, the outer diameter C1, the finished inner diameter A2 of the central hole 202, the flange width (radial dimension) C5 (= (C1 - A2) / 2), and the finished rib width (radial dimension, the length not cut out by the cutout portion 254) C4 of the portion of the flange surface without the bolt hole 240. ) Let it be C4.

[0031] In the loose flange 200, in the cross-section where the bolt hole 240 does not exist, the total thickness (axial dimension) D1 of the loose flange 200 from one end face to the other end face of the loose flange 200, the length (axial dimension) D2 of the locking piece 230, and the length (axial dimension) D4 from the other end face of the loose flange 200 to the end face of the cutout portion 254.

[0032] This loose flange 200 is an injection-molded product as described later, and the welds associated with injection molding are only on the flange surface between the bolt hole 240 and the outer peripheral edge of the loose flange. More specifically, the welds of this loose flange 200 exist only in the region W shown in FIGS. 2(A) and 2(C). Here, since this loose flange 200 has 8 bolt holes 240, the region W exists at 8 locations on the front and back of the flange surface.

[0033] In this way, when it exists only on the flange surface between the bolt hole 240 and the outer peripheral edge of the loose flange 200, this portion (region W) is less likely to be affected by the stress generated during bolt tightening (because it is not a portion where a large stress concentrates), and it is possible to realize a loose flange having a weld that is less likely to be affected by the stress generated during bolt tightening.

[0034] For example, when a pin gate is adopted for a gate in injection molding, if four pin gates are provided at four locations with a 90-degree interval between bolt holes for four-hole bolt holes, there will be welds between the outer peripheral edge of the bolt hole 240 and the loose flange 200 and between the outer peripheral edge of the bolt hole 240 and the inner peripheral edge of the central hole 202 (the welds exist so as to straddle the bolt hole 240 along the line connecting the central axis of the loose flange 200 and the center of the bolt hole 240). If four pin gates are provided at four locations with a 90-degree interval between bolt holes for eight-hole bolt holes, there will be continuous welds between the outer peripheral edge of the loose flange 200 and the inner peripheral edge of the central hole 202 on the flange surface between the bolt hole 240 and the adjacent bolt hole 240.

[0035] That is, when a pin gate is adopted, there will be welds on the central hole 202 side (on the front and back flange surfaces) around the bolt hole 240, or on the central hole 202 side (on the front and back flange surfaces) of the flange surface where the bolt hole 240 does not exist. However, these parts are more susceptible to the influence of stress generated during bolt tightening (large stress concentration) compared to the flange surface between the bolt hole 240 and the outer peripheral edge of the loose flange 200 (shown by the region W where welds exist when adopting a disk gate described later). For the loose flange injection molded using a pin gate, the loose flange 200 according to the present embodiment (adopts a disk gate described later instead of a pin gate) does not have welds in the parts where large stress concentration occurs as described above (because there are no welds on the central hole 202 side of the loose flange 200), so the performance can be improved. Considering the disadvantages (such as an increase in waste resin material and an increase in cost due to an increase in the manufacturing process) that the closed portion 201 formed of resin in resin molding exists and the central hole 202 must be opened after finishing (machining) the resin molding, the advantage of performance improvement is quite large.

[0036] In this loose flange 200, around the bolt hole 240, there is a rib 250 with a width of 40% or more of the diameter of the bolt hole 240 measured from the inner peripheral edge of the bolt hole 240, which covers the periphery 242 of the bolt hole, and is provided without exceeding the outer peripheral edge of the loose flange 200. As shown in FIGS. 2 and 4(B), with respect to the diameter B1 of the bolt hole 240 through which the fastening bolt provided on the flange surface passes, the ratio (reinforcement ratio) of the rib width B4 of the rib 250 covering the periphery 242 of the bolt hole 240 is 40% or more.

[0037] The rib width B4 of the rib 250, which is the reinforcement part (thickened part) of the periphery 242 of the bolt hole 240, is provided such that it is 40% or more (lower limit) with respect to the diameter B1 of the bolt hole 240 and does not exceed the outer peripheral edge of the loose flange 200 (upper limit). As described above, the side on the central hole 202 side in the periphery 242 of the bolt hole 240 is susceptible to the influence of the stress generated during bolt tightening (a large amount of stress is concentrated). However, this part can be suitably reinforced, further reinforcing the stress concentration location, and saving waste of the resin material, enabling weight reduction and cost reduction, and improving the performance of the loose flange 200.

[0038] In this loose flange 200, with respect to the flange width (radial dimension) C5 (= (C1 - A2) / 2) obtained by multiplying by 1 / 2 the value obtained by subtracting the finished inner diameter A2 of the central hole 2 02 from the outer diameter C1 of the loose flange 200, the ratio of the finished rib width (radial dimension, not thinned (reinforced) by the cutout part 254) C4 of the part without the bolt hole 240 is 25% or more and 45% or less. As shown in FIGS. 2 and 4(C), with respect to the flange width C5 of the loose flange 200, the ratio (reinforcement ratio) of the finished rib width C4 of the part without the bolt hole 240 (the length not thinned but reinforced by the cutout part 254) is 25% or more and 45% or less.

[0039] With respect to the flange width C5, by leaving the portion not cut out by the cutout portion 254 as a reinforcing portion (the portion without the bolt hole 240) and having the ratio of the finished rib width C4 (radial dimension ratio) in the range of 25% or more and 45% or less, this portion can be suitably reinforced, waste of the resin material can be saved, weight reduction and cost reduction can be achieved, and the loose flange 200 can be improved in performance.

[0040] In this loose flange 200, in the cross-section where the bolt hole 240 does not exist, the total thickness (axial dimension) D1 of the loose flange 200 from one end face to the other end face of the loose flange 200, the length (axial dimension) D2 of the locking piece 230, and the length (axial dimension) D4 from the other end face of the loose flange 200 to the end face of the cutout portion 254, the ratio of the central portion (D1 - D2 - D4) (not cut out) to the total thickness D1 is 35% or more and 45% or less. As shown in FIGS. 2 and 4(D), with respect to the total thickness D1 of the loose flange 200, the ratio (central portion ratio) of the thickness D3 (= D1 - D2 - D4) of the central portion (not cut out) is 35% or more and 45% or less.

[0041] By having the ratio of the central portion (D1 - D2 - D4) for forming the outer peripheral edge of the loose flange 200 without being cut out by the cutout portion 254 in the range of 35% or more and 45% or less with respect to the total thickness D1 of the loose flange 200, waste of the resin material can be saved, weight reduction and cost reduction can be achieved, and the loose flange 200 can be configured.

[0042] <Manufacturing Method of Resin Loose Flange> Hereinafter, the manufacturing method of the loose flange 200 having the above-described structural features will be described with reference to FIG. 5 in addition to FIG. 2.

[0043] The above-described loose flange 200 is a resin product that forms the pipe joint 100 in combination with the resin pipe 300. This loose flange 200 is manufactured by injection molding, and the manufacturing method of the loose flange 200 according to the present embodiment has the following features.

[0044] As described above, as a structural feature of the article, this loose flange 200 has a thin substantially annular shape in the longitudinal direction of the resin tube 300. The resin tube 300 is fitted into its central hole 202 and is provided with two or more bolt holes 240 through which bolts for fastening pass through the peripheral flange surface. The loose flange 200 having such a structure is characterized by being manufactured by adopting a disk gate as the gate in injection molding. Fig. 5 shows the loose flange after injection molding (before processing) when a disk gate is adopted as the gate in injection molding. There is a closed portion 201 formed of resin and the central hole 202 is not opened. By adopting the disk gate, the molten resin is supplied from above (in this Fig. 5), spreads radially, and welds exist only in the region W shown in Fig. 5, Fig. 2(A) and Fig. 2(C). As described above, since the loose flange 200 has 8 bolt holes 240, the region W exists at 8 locations on the front and back of the flange surface respectively.

[0045] By manufacturing the loose flange 200 by adopting a disk gate as the gate in injection molding in this way (by adopting a disk gate instead of a pin gate), since there is no weld in the portion where large stress concentrates when tightening the bolts (since there is no weld on the central hole 202 side of the loose flange 200), it is possible to manufacture the loose flange 200 with easily improved performance.

[0046] Also, in the manufacturing method of the loose flange 200 according to this embodiment, as shown in Fig. 4(A), it is preferable to use a disk gate with a gate diameter A1 that is 95% or more and 99% or less of the finished inner diameter A2 of the central hole 202. Thereby, the central hole 202 can be easily formed in the post-processing (machining) after injection molding.

[0047] Also, in the manufacturing method of the loose flange 200 according to the present embodiment, in injection molding, it is preferable to use a mold that closes the central hole (forms the closing portion 201) and does not close the bolt hole 240. In this case, after injection molding, the closing portion 201 is opened by cutting (as a post-processing) to form the central hole 202 and complete the product.

[0048] If a mold that closes the bolt hole 240 is adopted and disk gate is adopted for injection molding, the weld generated in the region W in the loose flange 200 according to the present embodiment can be completely eliminated. However, the bolt hole 240 must be opened by cutting the closing portion (made of resin) at the bolt location (as a post-processing), which may result in waste of resin material and cost increase. Moreover, since the region W is a location where excessive stress does not concentrate during bolt tightening, it may lead to over-specification. Therefore, it is not preferable to adopt a mold that closes the bolt hole 240.

[0049] As described above, according to this resin-made loose flange, in the resin-made loose flange that forms a pipe joint in combination with a resin pipe, (A) it has a weld that is less susceptible to the influence of stress generated during bolt tightening, (B) further reinforces the stress concentration location, and can save waste of resin material to achieve weight reduction and cost reduction. It is possible to provide a resin-made loose flange and its manufacturing method.

[0050] It should be considered that all the embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims are included.

Industrial Applicability

[0051] The present invention is preferably applicable to a resin loose flange that forms a pipe joint in combination with a resin pipe and a method for manufacturing the same, and has a weld that is less susceptible to the influence of stress generated during bolt tightening, and further reinforces stress concentration points, saves waste of resin material, and enables weight reduction and cost reduction. It is particularly preferable in that it can provide a resin loose flange and a method for manufacturing the same.

Explanation of Signs

[0052] 100 Synthetic resin flange pipe joint (flange pipe joint, pipe joint) 200 Loose flange (resin loose flange) 240 Bolt hole 250 Rib 254 Cutout 300 Pipe portion (resin pipe, short pipe portion, flange adapter) 310 Collar portion 350 Pipe body 352 Pipe wall

Claims

1. A resin loose flange that is combined with a resin pipe to form a pipe joint, the loose flange has a generally thin annular shape in the longitudinal direction of the plastic pipe, the plastic pipe is fitted into a central hole of the loose flange, and the loose flange has two or more bolt holes through which fastening bolts are passed on the surrounding flange surfaces; A resin loose flange, characterized in that a weld is formed only on the flange surface between the bolt hole and the outer peripheral edge of the loose flange.

2. 2. A resin loose flange as described in claim 1, characterized in that a rib is provided around the bolt hole, the rib having a width of 40% or more of the diameter of the bolt hole from the inner edge of the bolt hole, and covering the periphery of the bolt hole without extending beyond the outer edge of the loose flange.

3. the loose flange has a rib covering the periphery of the bolt hole on the entire inner periphery side of the substantially annular shape at an end face on the other end side, and the rib has a lightening portion between the bolt holes, 2. The resin loose flange according to claim 1, characterized in that a ratio of a finished rib width (radial dimension, length without hollowing out) C4 of a portion without bolt holes to a flange width (radial dimension) C5 obtained by subtracting the finished inner diameter A2 of the central hole from the outer diameter C1 of the loose flange and multiplying the result by 1 / 2 is 25% or more and 45% or less.

4. the resin pipe has a flange portion at one end side for regulating the position of the loose flange, and the flange portion has a circumferential groove at an end surface at the other end side opposite to the one end side, the loose flange has a rib covering the periphery of the bolt hole on the entire inner periphery side of the substantially annular shape at an end face on the other end side, and the rib has a lightening portion between the bolt holes, Looking at a cross section passing through the center axis of the loose flange and not including the bolt hole, a protrusion that engages with the groove, a recess that engages from the outer circumferential surface of the flange to a start position of the groove, and a locking piece that locks the outer circumferential surface of the flange from the outer circumferential side, the protrusion being provided on the end face of the one end in this order in a direction away from the central axis of the loose flange, The resin loose flange as described in claim 1, characterized in that a total thickness (axial dimension) D1 of the loose flange from the one end face to the other end face of the loose flange, a length (axial dimension) D2 of the locking piece, and a length (axial dimension) D4 from the other end face of the loose flange to the end face of the hollowed-out portion, the ratio of (D1-D2-D4) to D1 being 35% or more and 45% or less.

5. A manufacturing method for manufacturing a resin loose flange by injection molding to form a pipe joint in combination with a resin pipe, comprising the steps of: the loose flange has a generally thin annular shape in the longitudinal direction of the plastic pipe, the plastic pipe is fitted into a central hole of the loose flange, and the loose flange has two or more bolt holes through which fastening bolts are passed on the surrounding flange surfaces; A manufacturing method characterized in that a disk gate is used as a gate in the injection molding.

6. 6. The manufacturing method according to claim 5, wherein a disk gate having a gate diameter A1 of 95% to 99% of a finished inner diameter A2 of the central hole is used.

7. In the injection molding, a mold is used that closes the central hole but does not close the bolt holes, 6. The method according to claim 5, characterized in that the central hole is opened after the injection molding. method.

8. The manufacturing method according to claim 5, wherein the injection molding generates welds only on the flange surface between the bolt holes and the outer peripheral edge of the loose flange.

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