JP2012102800A - Welding joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a welding joint formed to be straight in outline and improved further so as to exhibit effects to prevent early damage in a gate part or a parting line by effectively utilizing an increase of the thickness in a joint body and so as to exhibit an effect to also work as a welding position deciding means, and possible to be miniaturized in the pipe end, while maintaining required functions.SOLUTION: The welding joint made of a synthetic resin has: a pipe end T wherein an end 13a of a synthetic resin tube 13 is fitted by means of insertion; and a straight cylindrical joint body 3 continued to the pipe end part T. This welding joint is configured so that welding is possible between the pipe end T and the tube end 13a fitted by means of insertion into the tube end T, by means of the heating of a heating means which surrounds the outside of the pipe end T. The joint body 3 is formed with a difference in thickness between the pipe end T so that the thickness b of the joint body 3 is larger than the thickness t of the pipe end T, and an annular end surface 3a is formed by the difference in thickness in a boundary of the joint body 3 between the pipe end T, and the pipe end part T is integrally provided with projection parts 10 so as to form a recessed groove m between the end surface 3a, using the outer peripheral surface of the tube end T as the bottom surface of the recessed groove m.

Description

  The present invention relates to a welded joint, and more specifically, includes a pipe end portion into which an end portion of a synthetic resin tube is fitted and inserted, and a joint body portion having a straight cylindrical outer shape following the pipe end portion. In particular, the present invention relates to a synthetic resin welded joint that is configured to be capable of welding a tube end portion and a tube end portion that is fitted and inserted into the tube end portion by heating from a heating means that surrounds the tube.

  In this type of welded joint, there are many other than linear shapes such as elbow (L-shaped), T-shaped, Y-shaped and the like. For example, in FIG. 25 of the welded joint disclosed in Patent Document 1, an elbow shape is shown, and in FIG. 26, a T shape is shown. With welded joints that take a shape other than this linear shape, that is, the shape outside the straight line, it is possible to withstand stricter acceleration testing machines in tests at the commercialization stage in order to ensure sufficient durability even in various usage forms. Has been required.

  Synthetic resin welded joints are generally made by molding, and in the case of a T-shaped welded joint, a body part that is the base of three pipe end parts is connected, and in the case of an elbow-type welded joint, a pair of pipe end parts are connected. A molten resin supply port, a so-called gate, is provided in the curved main body. It has been found that when such a welded joint is put on the acceleration test machine, cracks and cracks are likely to occur at an early stage along the gate portion and parting line.

JP-A-7-144367

  Therefore, in order to improve the above-mentioned early damage, it is considered that means for increasing the thickness of the gate and the vicinity thereof is effective instead of making the welded joint constant thickness. In this case, from the viewpoint of avoiding stress concentration as much as possible, it is preferable to adopt a gradual thickness change structure in which the thickness is gradually increased. However, there is an advantage obtained by deliberately changing the thickness. That is, for example, as shown in the comparative example of FIG. 4, in the case of a T-shaped welded joint A, the step 3 a due to the thickness difference between the joint body 3 and the pipe end T is utilized as a positioning means in the welding apparatus B. This is an advantage. Thereby, it is the rational structure which can also exhibit the effect that the prevention means (the thickness increase of the joint main-body part 3) of early damage can also be used as the positioning means at the time of welding.

  That is, as a means for gripping the tube end portion T in the welding apparatus B, as shown in FIG. 4, a means for clamping by sandwiching between the second side walls 30 having an inner peripheral surface 30a having a certain width in the axial center p direction. It is reasonable that the second side wall 30 is brought into contact with the step 3a for positioning. In addition, since a space portion 31 is provided as a minimum buffer region for alleviating the thermal effect between the heat generating means (heater) 14 for welding and the axial center p direction of the second side wall 30, the tube The length in the axial center p direction excluding the portion corresponding to the heat generating means 14 at the end T is equal to or longer than the protruding length F (= d + e) obtained by adding the width e of the second side wall 30 and the width d of the space 31. There is a need.

  Thus, an improved weld joint (FIG. 4) that adopts a rational configuration that simultaneously obtains (a) the effect of preventing early damage at the gate and parting line, and (b) the combined use effect of the welding positioning means. Although the welded joint A) shown in Fig. 2 is recalled, it seems that the pipe end T is long. Therefore, it seems that there is still room for further improvement in that the pipe end T can be made compact by making another effort.

  Accordingly, an object of the present invention is to provide the above-mentioned effects (a) and (b) in a welded joint that adopts a shape outside the straight line so as to effectively utilize the structure in which the thickness of the joint body portion is increased. Therefore, the tube end portion can be made compact while maintaining the above, and further improved so that it can be provided as a more rational one.

The invention according to claim 1 has a pipe end T into which the end 13a of the synthetic resin tube 13 is fitted and inserted, and a joint body 3 having a straight cylindrical outer shape following the pipe end T, A synthetic resin welded joint configured to be able to weld the tube end T and the tube end 13a fitted and inserted into the tube end T by heating from the heat generating means 14 surrounding the tube end T. In
A thickness difference is provided to make the thickness b of the joint body 3 thicker than the thickness t of the pipe end T, and an annular shape due to the thickness difference is formed at the boundary with the pipe end T in the joint body 3. Is formed integrally with the tube end T. The protrusion 10 forms a concave groove m between the outer end surface 3a and the end surface 3a. It is characterized by this.

  The invention according to claim 2 is the welded joint according to claim 1, wherein the protrusion 10 is an annular ridge with respect to the axis P of the pipe end T, and the end face 3 a of the joint body 3. A circumferential concave groove m is formed on the surface.

  According to a third aspect of the present invention, in the welded joint according to the first or second aspect, the second pipe end having the same structure as the pipe end T and the coaxial center P is formed in the joint main body 3. The portion T and the tube end portion T have the same structure as each other, and are T-shaped to which a third tube end portion T having an axis P intersecting the axis P is connected. To do.

  According to a fourth aspect of the present invention, in the welded joint according to the first or second aspect, the joint main body portion 3 has the same structure as the pipe end portion T and an axis P intersecting with the axis P. The second pipe end portion T having the shape is an L-shape to be connected.

  The invention according to claim 5 is the welded joint according to any one of claims 1 to 4, which is made of a fluororesin.

  According to the first aspect of the present invention, although described in detail in the section of the embodiment, the groove formed by the end face due to the thickening of the joint body part for avoiding early damage and the protrusion provided at the pipe end part Therefore, it is possible to prevent the tube end portion from shifting in the axial direction by using a structure that fits into the concave groove as a means for supporting the tube end portion in the welding apparatus. Therefore, compared with the case of adopting a structure that has a certain area and grips the pipe end, the required length (protrusion length) of the pipe end can be shortened, and thereby the pipe end in the welding apparatus. The support structure portion of the can also be made compact. As a result, in the welded joint that takes the shape outside the straight line, the above-described effects (a) and (b) can be exhibited so as to effectively utilize the structure that increases the thickness of the joint body part, while maintaining the necessary functions. The tube end portion and the welding apparatus can be made compact, and further improved and a more rational welding joint can be provided.

  According to the invention of claim 2, since it is formed in the circumferential groove as the groove, it is not necessary to fit in the location where the groove is present when setting it in the welding device. The advantage that simplification of the operation at the time of welding is also achieved can be added.

  It is suitable for a T-shaped or L-shaped welded joint frequently used as a joint having a linear outer shape as in the inventions of claim 3 and claim 4, and if it is made of a fluororesin as in claim 5, it is heat resistant. Therefore, it is possible to provide a welded joint that is excellent in generality and chemical resistance, can be used regardless of the type and temperature of the fluid, and is versatile.

The front view of the notch which shows the welding joint by Example 1 The figure which shows the welding operation state by the welding apparatus of the welding joint and tube of FIG. Sectional drawing of the principal part which shows the junction part of a welding joint and a tube The figure which shows the welding work state using the welding joint by a comparative example The welding joint by Example 2 is shown, (a) is a left side view of a partially cutout, (b) is a right side view of a partially cutout.

  Embodiments of a welded joint according to the present invention will be described below with reference to the drawings. The weld joint A and the tube 13 are made of PFA which is a thermoplastic synthetic resin, and the holder H is made of PTFE which is a thermoplastic synthetic resin.

[Example 1]
As shown in FIG. 1, the welded joint A according to the first embodiment has the same structure as the main pipe end 1 (T) having the axis p (P) and the main pipe end 1 (T), and is coaxial with each other. A main pipe end (an example of a second pipe end) 1 (T) having a center p (P) and opposite to each other in the direction of the axis p (P), and orthogonal to the axis p One example) A single branch pipe end portion (an example of the third pipe end portion) 2 (T) having an axial center q (P) and the base end sides of these three pipe end portions 1, 1 and 2, respectively. It is made of PFA (an example of a synthetic resin) having a joint body portion 3 that is a portion, and has a T-shape. The pipe end portions 1, 1 and 2, which are portions outside the step-side peripheral surface 3a of the joint body portion 3, are the same constituent portions. The thickness (thickness) of the joint body 3 is thicker than the thicknesses (thicknesses) of the pipe end portions 1, 1 and 2, and the sprue (molten resin supply port at the time of molding) part 4 or parting Premature damage along the line (not shown) is prevented.

  The structure of each of the pipe end portions 1, 2 will be described with respect to the main pipe end portion 1. The end body cylinder 9 following the step-side peripheral surface 3 a, and the outer peripheral flange (protrusion section) in a state standing from the end body cylinder 9 And an example of an annular ridge) 10, an outer peripheral surface 6 for a holder exterior having an outer diameter slightly smaller than the end main body tube 9, a large inner peripheral surface 5 for insertion, and a large inner peripheral surface for insertion 5 is a cylindrical portion that includes an inner step surface 7 that defines the depth in the direction of the axis p of 5, an inclined inner peripheral surface 8 that follows the inner step surface 7, and a joint flow path W. The outer peripheral surface 6 is slightly smaller in diameter than the outer peripheral surface 11 of the end body tube 9, thereby forming a small side peripheral surface 12 that serves as a surface that defines the insertion position of the holder H described later.

  The joint body 3 is a continuous T-shaped portion (an example of a straight outer shape) having a wall thickness b larger than the wall thickness t at the base ends of the tube end portions 1, 1, 2, A step-side circumferential surface 3a, which is an annular step, is formed at the boundary between the tube end portions 1, 2 and 1. That is, a thickness difference is provided so that the wall thickness b of the joint body 3 is larger than the wall thickness t of the pipe end T, and the annular end surface 3a due to the wall thickness difference at the boundary with the pipe end T in the joint body 3 is provided. The joint flow paths W, W of the main pipe end portions 1, 1 and the joint flow path W of the branch pipe end portion 2 also form a T-shaped flow path as a whole. A gate portion 4 is formed on a wall portion opposite to the axial center q direction of the branch pipe end portion 2 in the joint main body portion 3. In this case, a parting line (not shown) is likely to occur near the boundary between the joint main body 3 and the branch pipe end 2.

  Here, the wall thickness t may be 1.5 times or more of the tube thickness, and the thick wall thickness b is set to be 2 or more times the tube thickness. In the welded portion between the tube 13 and the joint main body 3, there is a possibility that insufficient welding will occur at the joint between the inner stepped surface 7 and the inclined inner peripheral surface 8 located away from the annular heater 14. When the wall thickness t is less than 1.5 times the tube thickness, there is a possibility that the weld strength between the tube 13 after welding and the joint body 3 is less than 1/2 of the tensile strength of the tube. When the pulsation of the equipment is added, there is practically a problem in the safety of the welded part. Therefore, in consideration of the safety of the welded portion, the wall thickness t needs to be at least 1.5 times the tube thickness. Preferably, if the wall thickness t is set to 2 times or more the tube thickness, The tensile strength can be ensured equal to or higher than the tensile strength of the tube.

  An outer peripheral flange 10 that is set to be equal to or less than the thick wall thickness b exists at a position slightly away from the end surface 3a in the axial center p direction, and the inner peripheral surface 10a of the outer peripheral flange 10 is defined as one side surface. A circumferential groove (an example of a concave groove and a circumferential concave groove) m is formed with the outer peripheral surface 11 (the outer peripheral surface of the tube end portion T) 11 of the end body cylinder 9 as the bottom surface and the end surface 3a as the other side surface. . That is, a circumferential groove m formed by the outer peripheral flange 10 and the end surface 3a provided on the proximal end side in each pipe end T is formed.

  As shown in FIGS. 2 and 3, the welding joint A welds and integrates the tube 13 fitted into the large-diameter inner circumferential surface 5 for insertion. In the welding apparatus B, the welding joint A is externally attached to the outer circumferential surface 6. An annular heater (an example of a heating means) 14 surrounding the holder H to be fitted and loaded is provided. More specifically, a holder H is externally fitted to the outer peripheral surface 6, and a tube end 13 T is fitted and inserted into the large-diameter inner peripheral surface 5 for insertion, and heat is generated by the annular heater 14 surrounding the holder H. The distal end of the tube end 1 and the tube end 13T are welded by heating. On the proximal end side of the holder H, a flange 15 is formed for securing a radial expansion gap S between the holder H and the annular heater 14.

  Due to the small peripheral surface 12 that functions as positioning when the holder H is externally inserted into the outer peripheral surface 6, the axial center p direction length of the outer peripheral surface 6 and the axial center p direction length of the holder H are the same value. Is set. The holder H is preferably press-fitted into the outer peripheral surface 6, but may be fitted so as not to come out. The axial center p-direction length of the large-diameter inner peripheral surface 5 for insertion, which is larger than the diameter of the joint flow path W, is set to approximately half the length of the outer peripheral surface 6 in the axial center p direction. The amount of insertion of the tube end portion 13T is set by contact with the surface 7. Further, the inner corner portion of the inner step surface 7 is formed on an inclined inner peripheral surface 8 that is cut obliquely.

  2 and 3, the holder H has a flanged cylindrical shape having an inner peripheral surface 16 and an outer peripheral surface 17 having a uniform diameter that are externally fitted to the outer peripheral surface 6. The flange 15 described above is located at the end closest to the joint body 3. The thickness of the flange 15 is set to 1.4 to 15 times the thickness of the other portion of the holder H, and the length in the axis p direction of the holder H is set to 2 to 10 times the length of the flange 15. Yes. The PTFE forming the holder H has a melting temperature higher than the melting temperature of the main pipe end 1, that is, the PFA forming the welded joint A. The synthetic resin forming the holder H is desirably a material having a higher melt viscosity than the synthetic resin forming the tube 13 or the welded joint A.

  As shown in FIG. 2, the welding device B includes an annular heater 14 that surrounds the holder H, a first side wall 19 that can be fitted to the concave and convex portions in a positioning state, and a locking clamp 18 that holds the tube 13. It is configured to have a second side wall 20 and the like that can be fitted to the circumferential groove m and can be positioned and mounted. The first side wall 19 and the second side wall 20 are made of glass cloth base material in which the glass cloth base material is fixed with resin. It is comprised with the heat insulating material which consists of a system resin board. The annular heater 14 has a lateral width equivalent to that of the holder H, and the annular heater 14 and the side walls 19 and 20 are separated from each other by providing a space 21 having a length d in order to buffer the thermal effect. Yes. The width (thickness) of the second side wall 20 that is fitted into the circumferential groove m and is positioned relative to the weld joint A in the direction of the axis p is sufficiently thinner than the width (thickness) of the first side wall 19. Is done.

  That is, in order to weld the welded joint A and the tube 13 by the welding device B, the tube end 13a is inserted into the large-diameter inner peripheral surface 5 for insertion of the main pipe end 1 on which the holder H is sheathed. The tube 13 is supported on the first side wall 19 via the locking clamp 18, and the welded joint A is supported on the second side wall 20 using the circumferential groove m. Then, the annular heater 14 is energized to generate heat, whereby the joint R between the main pipe end 1 and the tube end 13a is heated and melted and integrated. The length from the annular heater 14 to the outer surface of the second side wall 20 in this welding apparatus B, that is, the protruding length D of the main pipe end 1 is a length obtained by adding the groove width c of the circumferential groove m to the width d of the space 21. (D = d + c). The width c is also the width of the second side wall 20.

  On the other hand, in the case of the comparative example shown in FIG. 4, the width d of the space 31 from the annular heater 14 is the same as that shown in FIG. 2, but the width (thickness) e of the second side wall 30 is clear. 2 is larger than the width c of the second side wall 20 shown in FIG. 2 (e> c). Therefore, the protrusion length F (= d + e) in the comparative example is clearly larger than the protrusion length D of Example 1 shown in FIG. 2 (D <F). In the case of the comparative example shown in FIG. 4, the main pipe end 1 is sandwiched between the second side walls 30 by friction and supported so as not to move in the axial center p direction. Some width is required. However, in the structure of the first embodiment in which the second side wall 20 is fitted into the circumferential groove m so as not to physically move in the axial center p direction, the width of the second side wall 20 is the same as that of the comparative example shown in FIG. Compared to the two side walls 30, it can be significantly narrowed.

  That is, in the welded joint A according to the first embodiment, the wall thickness of the joint body 3 is set to the pipe end portions 1, 1, 1 so that early damage such as cracks and cracks does not occur in the spout portion 4 and the parting line in the vicinity thereof. The circumferential groove m is formed by the step-side circumferential surface 3a that is an end surface by using a structure that is thicker than 2 and the outer peripheral flange 10 that is newly provided at the main pipe end portion 1. To do. Thereby, the projection length D of each pipe end part 1,1,2 can be shortened, and the possibility of the early damage in the sprue part 4 or a parting line can be avoided, aiming at compactization of the welding joint A and the welding apparatus B. , Has succeeded in obtaining a multiple effect.

  Further, the outer peripheral flange 10 is in contact with a heat insulating material made of a glass cloth base inorganic resin plate, and the other faces the space (atmosphere) 21. In consideration of the thermal conductivity of the heat insulating material, the atmosphere, and the PFA, since “the thermal conductivity of the heat insulating material <the thermal conductivity of the air <the thermal conductivity of the PFA”, infrared rays (heat rays) emitted from the annular heater 14 Is absorbed by the PFA (welded joint A, tube 13), it is difficult to dissipate heat outside the PFA, that is, outside the joint body 3. Therefore, when the thickness of the outer peripheral flange 10 is larger than the thick wall thickness b, the heat of the annular heater 14 is easily absorbed, and the absorbed heat moves to the main pipe end 1 (T) of the joint, and the main pipe end 1 There is a possibility of causing abnormal deformation of (T). Therefore, the thickness of the outer peripheral flange 10 is preferably thin (low) so that the second side wall 20 of the annular heater 14 can be positioned, and is considered to be at most as thick as the thick wall thickness b considering the certainty of positioning. Is preferred.

[Example 2]
As shown in FIGS. 5 (a) and 5 (b), the welded joint A according to the second embodiment has the same structure as the main pipe end 1 (T) and the shaft center p (P). The second pipe end 22 (T) having an axis q (P) orthogonal to (an example of crossing) is connected to an L shape. This L-shaped welded joint A, also referred to as an elbow pipe, has the same pipe end 1 (T) as the main pipe end 1 (T) of the T-shaped welded joint A according to Example 1, and the T-shaped welded joint A according to Example 1. It has the same 2nd pipe end part 22 (T) as the branch pipe end part 2 (T), and the same code | symbol is attached | subjected to the same location and the description was made | formed.

[Another Example]
The concave groove m into which the second side wall 2 is fitted may be, for example, an intermittent circumferential groove (arc concave groove) in which arc-shaped protrusions 10 such as four or six are intermittently arranged in the circumferential direction. The part 10 can also take a shape other than a circle such as a regular octagon. As the second side wall 20 of the welding apparatus A, a structure in which the width of the concave groove m shown in FIG. For example, the tube end portion T in the direction of the axial center p can be further shortened.

3 Joint body 3a End face 10 Projection (annular ridge)
13 Tube 13a End 14 Heating means P Axle T Tube end b Thickness of joint body m Groove (circumferential groove)
t Thickness of pipe end

Claims (5)

It has a tube end portion into which the end portion of the synthetic resin tube is fitted and inserted, and a joint body portion having a straight cylindrical outer shape following the tube end portion, and is heated by a heating means surrounding the tube end portion. A weld joint made of a synthetic resin configured to be weldable between the tube end portion and the tube end portion fitted and inserted therein,
A wall thickness difference is provided so that the wall thickness of the joint main body portion is greater than the wall thickness of the pipe end portion, and an annular end face is formed at the boundary between the pipe main body portion and the pipe end portion. In addition, a welded joint in which a protrusion that forms a concave groove between the outer peripheral surface of the tube end portion and the end surface is provided integrally with the tube end portion.   The weld joint according to claim 1, wherein the protrusion is an annular ridge with respect to the axis of the pipe end, and a circumferential groove is formed between the protrusion and the end surface of the joint body.   The joint main body includes a second pipe end having the same structure as the pipe end and having the same coaxial center, and an axis having the same structure as the pipe end and intersecting the axis. The welded joint according to claim 1, wherein the welded joint has a T-shape connected to a third pipe end portion having a tip.   The said joint main-body part is an L-shaped thing to which the 2nd pipe end part which has the same structure as the said pipe end part and has an axial center which cross | intersects the said axial center is connected. Welded joints.   The welded joint according to any one of claims 1 to 4, wherein the welded joint is made of a fluororesin.

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