JP5555531B2 - Welded joint and welding method thereof - Google Patents

Description

  The present invention relates to a welded joint and a welding method therefor, and more specifically, the end of a synthetic resin tube has a pipe end into which the end is fitted and inserted, and the heating means enclosing the pipe end is heated by the heating means. The present invention relates to a synthetic resin welded joint configured to be able to weld a pipe end portion and the end portion fitted and inserted therein, and a welding method thereof.

  As this type of welded joint, the one disclosed in Patent Document 1 is known, and when welding a synthetic resin welded joint and a synthetic resin tube, the welded joint can be fixed so as not to be displaced. The present invention relates to a welding apparatus for welded joints. According to this, both ends of the welded joint are surrounded by the annular heater (welding head) of the half structure and heated at the joint where the tube end and the tube end are fitted to each other. The joints and the tube are integrally connected with each other by welding.

  In the above prior art, the annular heater is surrounded so that it just fits outside, and it is possible to heat the joint efficiently, but it has also been found that there is a chronic problem. It was. That is, in the means for fusing and integrating the resin by heating, the welded part expands, so that the welded part extends over the inside of the diameter or protrudes inside the diameter to form a weld bead. It is a problem that the passage is narrowed and the street is likely to get worse.

  Therefore, as disclosed in Japanese Patent Application Laid-Open No. H10-228561, a device for forming each end surface on a plurality of cut surfaces so that a gap is formed between both of the welded joint and the tube in the butted state as disclosed in Patent Document 2. Therefore, a technique has been developed that enables heat welding without forming a bead or a bulging portion inside the joint.

  However, although it takes a lot of cost to form the pipe ends of the welded joint and the tube in a complicated shape, it does not necessarily function as expected, and may still bead and bulge. A dent may occur, and there is room for further improvement in the smoothing of the internal flow path at the joint.

JP 2008-069880 A JP 2007-239973 A

  The object of the present invention is to suppress or eliminate as much as possible the inward bulging and bead formation caused by thermal welding in the joint portion formed by fitting and inserting the tube end portion and the tube end portion. Thus, it is an object to provide an improved welded joint and a method for welding the same, which can be welded and integrated well without causing fluid passage resistance.

The invention according to claim 1 has a tube end portion 2T into which an end portion 1T of a synthetic resin tube 1 is fitted and inserted, and the tube end portion is heated by heating means 4 surrounding the tube end portion 2T. In a weld joint made of synthetic resin that is configured to be welded to 2T and the end portion 1T fitted and inserted therein,
A synthetic resin holder 3 that is externally fitted to the tube end 2T is provided, and a flange 12 is formed in the holder 3 for securing a radial expansion gap S between the holder 3 and the heating means 4. It is characterized by that.

  The invention according to claim 2 is the welded joint according to claim 1, wherein the flange 12 is arranged at the inner end of the joint in the direction of the axis P of the holder 3. .

  The invention according to claim 3 is the welded joint according to claim 1 or 2, wherein the radial thickness of the flange 12 is 1.4 to 15 times the radial thickness of a portion of the holder 3 other than the flange. It is characterized by being set.

  According to a fourth aspect of the present invention, in the welded joint according to any one of the first to third aspects, the axial center P direction length of the holder 3 is 2 to 2 of the axial center P direction length of the flange 12. It is characterized by being set to 10 times.

  The invention according to claim 5 is the weld joint according to any one of claims 1 to 4, wherein the synthetic resin forming the holder 3 is higher than the melting temperature of the synthetic resin forming the pipe end 2T. It is characterized by being set to have a high melting temperature.

In the invention according to claim 6, the pipe end 2T of the synthetic resin welded joint 2 and the end 1T of the synthetic resin tube 1 fitted and inserted into the pipe end 2T are connected to the pipe end 2T. In the welding method of the welding joint to be welded by heating with the annular heater 4 arranged in the surrounding state,
A synthetic resin holder 3 is externally fitted to the tube end 2T, and the annular heater 4 is disposed with a predetermined radial gap S between the holder outer peripheral surface 13 and the holder .
The holder 3 is formed with a flange 12 projecting a predetermined amount outward in the diameter, and is heated with the annular heater 4 circumscribed on the flange 12 .

  According to the first aspect of the present invention, as will be described in detail in the section of the embodiment, due to the presence of the expansion gap on the outer diameter side of the holder, expansion deformation of the joining portion and the holder to the outer diameter side by heating of the heating means. The tube end portion and the tube end portion are well welded and integrated while maintaining a uniform diameter state of the internal flow passage and the joint flow passage of the tube, that is, maintaining a good flow passage state. As a result, by further structural improvements, the bulging inward and bead formation due to thermal welding are suppressed or eliminated as much as possible in the joint formed by fitting and inserting the tube end and the tube end. Therefore, it is possible to provide an improved welded joint so that it can be welded and integrated well without causing fluid passage resistance. Further, since the expansion gap for this purpose is formed between the heating means and the radial direction by the flange formed in the holder, there is an advantage that uniform welding can be surely performed at low cost.

  According to the invention of claim 2, since the flange is disposed at the inner end of the joint in the axial direction of the holder, the flange extends in the axial direction from the joint where the tube end and the tube end are fitted. Thus, there is an advantage that it is possible to contribute to further uniform welding of the joint portion while being able to surround the shaft center together without biasing the heating means.

  According to invention of Claim 3, the radial direction thickness of a flange is set to 1.4 to 15 times the radial direction thickness of parts other than the flange in a holder. If it is less than 1.4 times, it becomes difficult to secure an expansion gap for allowing expansion deformation to the outside of the diameter of the joint and holder accompanying welding, and if it exceeds 15 times, satisfactory welding cannot be performed. Since the heat conduction efficiency to the joint portion is deteriorated, it is possible to perform good welding when the range is 1.4 to 15 times.

  According to the invention of claim 4, the axial length of the holder is set to 2 to 10 times the axial length of the flange. If it is less than 2 times, the joint tends to be exposed too much to the heating means, making it difficult to maintain a perfect circle after welding, and if it exceeds 10, the axial length of the joint is inadequate. It becomes necessary and long and it is not compact. Therefore, it becomes possible to perform favorable welding in the range of 2 to 10 times.

  According to the invention of claim 5, since the holder is set to have a melting point higher than that of the tube end portion, even if the tube end portion melts during welding, the holder does not melt, and the cylindrical shape is maintained and welded. There is an advantage that the perfect circle of the subsequent joint can be maintained.

According to the invention of claim 6, since this is a method of the invention of claim 1, an effect equivalent to the effect of the invention of claim 1 can be obtained .

Sectional drawing of the principal part which shows the welding joint and the junction part of this and a tube (Example 1) A holder is shown, (a) is a sectional view, (b) is a front view. It is sectional drawing which shows another structure of a flange, (a) is a separate body type, (b) is an inner peripheral part abbreviation form, (c) is an axial center position change. It is a front view which shows the circumferential direction intermittent structure of a flange, (a) is a 6 division type, (b) is a 4 division type Examples of different shapes of flange cross sections are shown, (a) is a grooved shape, (b) is a chamfered shape, (c) is a triangle, (d) is an outer spherical surface

  Embodiments of a welded joint and a welding method thereof according to the present invention will be described below with reference to the drawings.

[Example 1]
As shown in FIG. 1, the weld joint A is a PFA (thermoplastic material) having a joint body 2 including a pipe end portion 2T into which an end portion 1T of a PFA tube 1 which is an example of a thermoplastic synthetic resin is fitted and inserted. The tube end 2T is welded to the tube end 1T fitted and inserted by the heating of the annular heater 4 as a heating means surrounding the tube end 2T. It is configured to be possible. A holder 3 made of PTFE (an example of a thermoplastic synthetic resin) that is externally fitted to the tube end 2T is externally fitted, and the holder 3 is used for expansion in the radial direction between the annular heater 4 and the holder 3. A flange 12 for securing the gap S is formed.

  The outer diameter of the tube end portion 2T is slightly narrower than that of the tube portion 2K including the flange portion 5, whereby a step-side peripheral surface 6 is formed. The step side circumferential surface 6 is configured to function as positioning when the holder 3 is externally inserted into the tube end 2T. That is, the axial center P direction length of the tube end 2T determined by the step side peripheral surface 6 and the axial center P direction length of the holder 3 are set to the same value. The holder 3 is preferably press-fitted into the outer peripheral surface 7 of the pipe end 2T, but may be fitted so as not to come out.

  The pipe end portion 2T is formed on the large-diameter inner peripheral surface 8 for insertion in which about half of the length in the axial center P direction from the opening portion is larger than the diameter of the joint flow path 2W. The end portion 1T of the tube 1 is press-fitted and inserted into the inner peripheral surface 8, and the insertion amount of the end portion 1T is set by contact with the inner stepped surface 9. Further, the inner corner portion of the inner step surface 9 is formed on an inclined surface 10 that is cut obliquely.

  As shown in FIGS. 1 and 2, the holder 3 has a cylindrical shape with a flange having an inner peripheral surface 11 and an outer peripheral surface 13 having a uniform diameter that are externally fitted to the outer peripheral surface 7 of the pipe end 2T. A flange for securing a radial expansion gap S between the inner peripheral surface 4a of the annular heater 4 at the end which is the innermost side (arrow B direction side) as the weld joint A in the center P direction. An outer peripheral flange) 12 is integrally formed. The radial thickness R of the flange 12 is set to 1.4 to 15 times the radial thickness r of the portion other than the flange 12 in the holder 3, and the axial length P direction length N of the holder 3 is set to the flange It is set to 2 to 10 times the length n of 12 axial centers P direction.

  PTFE which is a synthetic resin forming the holder 3 has a melting temperature higher than that of PFA which is a synthetic resin forming the pipe end 2T, that is, the joint body 2. The synthetic resin forming the holder 3 is desirably a material having a higher melt viscosity than the synthetic resin forming the tube 1 and the joint body 2.

  The diameter of the internal flow path 1W of the tube 1 is set to be equal to the diameter of the joint flow path 2W, and the end 1T is inserted into a large-diameter inner peripheral surface for insertion by being strongly inserted (or relatively easily inserted). 8 can be internally fitted. The tube 1 is inserted into the joint body 2 by inserting until the tube end surface 1t comes into contact with the inner step surface 9.

  Next, a connection method (welding method) between the welded joint A and the tube 1 will be described. First, the holder 3 is inserted and maintained in the tube end 2T with the flange 12 leading, or the holder 3 is press-fitted with the flange 12 in the tube end 2T in advance. Alternatively, whether to prepare the welded joint A that is tightly fitted is selected and executed. When the holder 3 is inserted into the pipe end 2T, the insertion operation is performed until the holder 3 comes into contact with the step-side peripheral surface 6.

  Next, the end 1T of the tube 1 is inserted into the tube end 2T until the tube end surface 1t comes into contact with the inner stepped surface 9, and then the annular heater 4 is inserted into the outer periphery of the flange 12 of the holder 3 by the inner peripheral surface 4a. It is enclosed and fitted so as to be in contact (contact) with the surface 12a (state shown in FIG. 1). Then, the annular heater is energized to generate heat, and the fitting insertion portion between the tube end portion 2T and the tube end portion 1T, that is, the joint portion C is heated and welded from the outer peripheral side.

  That is, the pipe end 2T of the synthetic resin welded joint 2 and the end 1T of the synthetic resin tube 1 fitted and inserted into the pipe end 2T are arranged so as to surround the pipe end 2T. In the welding method of the welding joint 2 to be welded by heating with the annular heater 4, a synthetic resin holder 3 is externally fitted to the pipe end 2 T, and a predetermined radial gap is provided between the holder 3 and the outer peripheral surface 13. This is a welding method in which the annular heater 4 is arranged and heated in a state where S is opened. Then, a flange 12 that protrudes by a predetermined amount outside the diameter is formed on the holder 3, and heating is performed with the annular heater 4 circumscribing the flange 12, so that the axis between the holder 3 and the annular heater 4 can be easily provided. They can be matched and thereby a uniform heating state can be obtained.

  Most of the heat generated by the annular heater 4 is transmitted to the joint C as radiant heat through the expansion gap (annular space) S, but partly directly through the flange 12. In this case, the holder 3 has an important function of protecting the tube end 2T and uniformizing the heat generated by the annular heater 4 to the tube end 2T.

  The joint C expands by heating, and unless otherwise restricted, expands outward (in other words, expands outward in the radial direction). In this case, in the product of the present invention, although the illustration is omitted, the expanded portion is absorbed by the expansion gap S existing outside the diameter together with the holder 3, and there is no or almost no expansion toward the inside (diameter inside). Will come. Even if there is a slight inward expansion, the slight expansion can be absorbed by the annular space formed by the inclined surface 10 and the tube end surface 1t.

  In other words, the PFA welding is configured so that the pipe end 2T can be welded to the end 1T of the PFA tube 1 fitted and inserted by heating the annular heater 4 surrounding the pipe end 2T. In the joint, a PTFE holder 3 that is externally fitted to the pipe end 2T is provided, and a flange 12 for securing a radial expansion gap S between the holder 3 and the annular heater 4 is formed. It is characterized by being. As a result, expansion deformation to the outside of the diameter by heating is permitted, and the inner channel 1W and the joint channel 2W having the same diameter are maintained in a uniform state, that is, while maintaining a good channel state, the end portion The present inventors have succeeded in providing a welded joint which can be improved so that 2T and 1T are well welded and integrated, and a welding method therefor.

  Since the portion other than the flange 12 (main body portion 3H) of the holder 3 is thin and easily bent, the welded portion expands to the gap with the annular heater 4, that is, the expansion gap S during welding, and the inner surface of the weld (joint portion C). The bead bulging to the inner surface) is suppressed or eliminated. Since the flange 12 holds the pipe end 2T, it is possible to suppress uneven unevenness of the welded portion (joint portion C) during welding. Further, since the flange 12 comes into contact with or strongly contacts the inner peripheral surface 4a of the annular heater 4 due to thermal expansion, the heat conduction efficiency to the main body portion 3H that is not in contact with the annular heater 4 is improved, and uniform welding is performed. It can contribute to the realization of the state.

  Next, various other shapes of the holder 3 will be described. First, the holder 3 shown in FIG. 3A is composed of two parts, and is configured by fitting and integrating an annular large-diameter flange 14 with a cylindrical holder body 3A. The overall shape is the same as that of the integrated holder 3 shown in FIG. 2, and the large-diameter flange 14 corresponds to the flange 12. Note that as the integration means, press-fitting, fitting and adhesion, and the like can be considered.

  The holder 3 shown in FIG. 3B is shaped like the holder 3 shown in FIG. 2 without the inner peripheral end on the flange 12 side. That is, it is the holder 3 having a structure in which an end portion on the inner back side of the thin-walled main body portion 3H is provided with an annular gap portion k in which about half of the width of the flange 12 in the axis P direction is omitted from the end. In this case, the flange 12 is formed integrally with the main body portion 3H.

  The holder 3 shown in FIG. 3C has a structure in which the position of the flange 12 is set in the middle of the main body part 3H in the direction of the axis P, and is set at a position slightly on the inner side.

  FIG. 4A shows a holder 3 having a flange 12 having a structure intermittently present in the circumferential direction. This is because a small gap 15 is formed between adjacent 6-divided flange portions 12s (between the circumferential directions), and each 6-divided flange portion 12s should be inscribed in the inner periphery of the annular heater 4. An arc outer peripheral surface 16 centering on the axis P is formed.

  FIG. 4B shows the second part of the holder 3 having the flange 12 having a structure intermittently present in the circumferential direction. This is a large gap 17 formed between adjacent four divided flange portions 12f (between the circumferential directions), and each four divided flange portion 12f should be inscribed in the inner periphery of the annular heater 4. An arc outer peripheral surface 18 centering on the axis P is formed.

  The holder 3 shown in FIG. 5 (a) has a structure in which an outer peripheral groove 19 is formed in the flange 12 of the holder 3 shown in FIG. The illustrated outer peripheral groove 19 is an annular groove continuous in the circumferential direction, but may be intermittently configured in the circumferential direction.

  The holder 3 shown in FIG. 5B has a structure in which the inclined cut surfaces 20 and 20 are provided by chamfering at both corners in the axis P direction of the flange 12 in the holder 3 shown in FIG.

  The holder 3 shown in FIG. 5 (c) has the outer surface of the flange 12 in the holder 3 shown in FIG. It is configured to exhibit 12 cross-sectional triangles.

  The holder 3 shown in FIG. 5D has a structure in which both corners in the direction of the axis P of the flange 12 in the holder 3 shown in FIG.

[Another Example]
The position of the flange 12 may be at the tube side (outer front side) end of the holder 3, or a structure in which a pair is provided at each end in the axial center P direction of the holder 3 may be used. Further, any synthetic resin that melts by heating may be used, and synthetic resins other than PFA and PTFE may be used.

DESCRIPTION OF SYMBOLS 1 Tube 1T end part 2 Joint body 2T Pipe end part 3 Holder 4 Heating means 12 Flange 13 Holder outer peripheral surface P Axis center S Expansion gap, radial direction gap

Claims (6)

An end portion of the synthetic resin tube has a tube end portion that is fitted and inserted, and the tube end portion and the end portion that is fitted and inserted into the tube end portion by heating of a heating means that surrounds the tube end portion; A weld joint made of synthetic resin that can be welded
A welded joint in which a synthetic resin holder that is externally fitted to the pipe end portion is provided, and a flange for securing a radial expansion gap is formed between the holder and the heating means.   The welded joint according to claim 1, wherein the flange is disposed at the inner end of the joint in the axial direction of the holder.   The welded joint according to claim 1 or 2, wherein a radial thickness of the flange is set to 1.4 to 15 times a radial thickness of a portion other than the flange in the holder.   The welded joint according to any one of claims 1 to 3, wherein an axial length of the holder is set to 2 to 10 times an axial length of the flange.   The welded joint according to any one of claims 1 to 4, wherein the synthetic resin forming the holder is set to have a melting temperature higher than that of the synthetic resin forming the pipe end. The pipe end of the synthetic resin welded joint and the end of the synthetic resin tube fitted and inserted into the pipe end are welded by heating with an annular heater arranged so as to surround the pipe end. A welding method for welding joints,
A synthetic resin holder is externally fitted to the pipe end, and the annular heater is arranged with a predetermined radial gap between the holder outer peripheral surface ,
A method of welding a welded joint , wherein a flange projecting a predetermined amount on the outside of the diameter is formed on the holder, and heating is performed with the annular heater circumscribed on the flange .

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