JPH1044244A - Method for gas fusion of heat fusible member together and gas fusion apparatus used for it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve fusion strength at a low temp. and in a short time by heating a gas which emits far infrared rays in a region of wave lengths with relatively high absorbance at a temp. where a large quantity of far infrared rays are emitted and blowing it on both end parts of adjoining members. SOLUTION: A gas fusion apparatus 10 is provided with a heater 30 which can heat a gas to a temp. where a large quantity of far infrared rays with specified wave lengths can be emitted on a quartz glass surrounding body. Carbon dioxide emits a large quantity of far infrared rays when it is heated e.g., at 550 deg.C On the other hand, absorption spectra of PTFE being a material for pipe members P and P exhibit high absorbance in a region of far infrared rays. The quartz glass absorbs far infrared rays and passes them through it while they are wholly reflected inside and when there exists an end face 24a being approximately square to the wall face, they are emitted concentratedly therefrom. When the far infrared rays emitted from carbon dioxide are concentratedly emitted from the end face 24a, vicinity of fusion end face is heated with these far infrared rays to improve furthermore heating efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas welding method (including welding) for arranging weldable members adjacent to each other and welding them, and a gas welding apparatus used therefor. The present invention relates to a gas welding method for welding a resin tubular part and a resin sheet such as an engineering plastic, and a gas welding apparatus used for the method.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for higher quality resins in the fields of medicine, food, semiconductor industry, biotechnology, chemical industry, housing, gas, etc. due to their chemical resistance and cleanliness. Fluororesins such as polyvinylidene fluoride and high-grade engineering plastics such as polyphenylene sulfide and polyetheretherketone have been used as piping materials and sheet materials.

[0003] As a method of connecting these resin members,
Attention has been paid to a connection method by welding, and a welding method and apparatus using a heated gas have been developed. For example,
Japanese Unexamined Patent Publication (Kokai) No. 63-104824 discloses an apparatus 5 for fusing and joining first and second pipe part connection ends 51, 51 which are aligned and abutted with each other in the axial direction and the circumferential direction.
0 and methods are disclosed (see FIG. 8). This device 5
0 means a heating means 54 for heating the fusion zone adjacent to the butting edges of the first and second piping components 51, 52 at least to the softening point of the thermoplastic material in the fusion zone.
And vacuum means 55 for causing the outward movement of the molten material in the fusing region under the action of a vacuum, and fluid channels 56 for conducting thermal fluid used to transfer thermal energy to the fusing region.

[0004]

The above-mentioned conventional fusion welding method and welding apparatus transmit heat energy to a fusion region by heat transfer, and assume air, silicon or glycerin as a thermal fluid. Gazette, page 12, lower right column, eleventh
Line to line 14). That is, since the molten material is heated by transferring heat from the thermal fluid to the member to be fused, the fusion region is heated from the surface side toward the middle side in the fusion region.

[0005] Therefore, there is a disadvantage that the amount of heat required for fusion increases and the temperature is relatively high, so that energy consumption is large. The publication also discloses heating by radiation (claim 4), but this refers to heating by infrared rays from the context. In other words, the heater needs to be heated to a relatively high temperature for melting, and the portion close to the end face is heated and melted. When welding is performed in such a state, there is a fatal defect in which bubbles (voids) are generated in the welded portion and the welding strength is extremely reduced.

The present invention solves the above-mentioned drawbacks in the prior art, and enables heat-weldable members capable of extremely increasing welding strength in a short time with a small amount of energy despite a low temperature. It is an object of the present invention to provide a gas welding method and a gas welding apparatus used therefor.

Another object of the present invention is to provide a gas welding method for heat-weldable members capable of supplying far-infrared rays radiated from a gas to an end face of an adjacent member to be welded without waste. An object of the present invention is to provide a method and a gas welding apparatus used for the method.

[0008] The present invention further relates to PTFE, FEP, P
A gas welding method for welding a resin-made tubular part or sheet having a circular cross section made of a fluorine-based resin such as FA, ETFE, CTFE, PVDF or a high-grade engineering plastic such as PPS by far-infrared rays radiated from carbon dioxide gas and used therefor An object of the present invention is to provide a gas welding device.

[0009]

According to the present invention, there is provided a gas welding method for heat-sealable members in order to achieve the above-mentioned object. A step of selecting a gas capable of emitting far-infrared rays, a step of arranging heat-sealable members adjacent to each other, and a step of heating the gas to a temperature at which a large amount of far-infrared rays in a predetermined wavelength region can be emitted. And a step of blowing heated gas to both ends of the members arranged adjacent to each other to make the vicinity of the both ends softened and welded.

According to a second aspect of the present invention, in the gas welding method of the first aspect, the gas heating step is performed in a quartz glass enclosure having a gas outlet, and the gas outlet is connected to the gas outlet. The surface is cut so as to have an end surface substantially perpendicular to the wall surface of the enclosure, and far infrared rays of a predetermined wavelength emitted from gas and absorbed by the enclosure are radiated from the end surface in a concentrated manner. It is characterized by.

[0011] The invention described in claim 3 is the invention according to claim 1 or 2.
In the gas welding method described in the above, the welding step is to soften the replenishing material made of the same material as the material that can be welded, and to perform welding or It is characterized by welding.

According to a fourth aspect of the present invention, in the gas welding method according to any one of the first to third aspects, the member to be welded is made of PTFE, FEP, PFA, ETFE, or CTF.
It is made of fluorine resin such as E or PVDF or high-grade engineering plastic such as PPS, and the gas is carbon dioxide.

According to a fifth aspect of the present invention, in the gas welding method according to any one of the first to fourth aspects, the member to be welded is a pipe of a factory of a chemical, food, semiconductor industry, biotechnology or the like. It is characterized by being formed of a resin-made tubular part having a circular cross section used as.

According to a sixth aspect of the present invention, in the gas welding method according to any one of the first to fourth aspects, the member to be welded is a thin sheet used as a waterproof sheet for a garbage disposal site, a tunnel or the like. It is characterized by being made of a resin sheet.

The gas welding apparatus used for welding members capable of being thermally welded according to the second aspect of the present invention is capable of detecting far infrared rays in a wavelength region having a relatively high absorptivity in an absorption spectrum of a member to be welded. A gas supply for supplying a gas that can be emitted, an enclosure having a gas inlet for receiving gas from the gas supply and a gas outlet for discharging heated gas, and a predetermined wavelength disposed inside or outside the enclosure. Heating means for heating the gas to a temperature at which a large amount of far-infrared rays in the region can be radiated.

According to an eighth aspect of the present invention, in the gas welding apparatus according to the seventh aspect, the enclosure is made of quartz glass and the gas outlet is substantially perpendicular to the wall surface of the enclosure. It is characterized in that far-infrared rays of a predetermined wavelength emitted from gas and absorbed by the enclosure are radiated from the end face in a concentrated manner.

According to the ninth aspect of the present invention, there is provided the seventh or eighth aspect.
In the gas welding apparatus described in the above, the member to be welded is P
TFE, FEP, PFA, ETFE, CTFE, PVD
It is made of fluorine resin such as F or high-grade engineering plastic such as PPS, and the gas is carbon dioxide.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A gas welding method for heat-sealable members and a gas welding apparatus used therefor according to the present invention will be described below in detail with reference to FIGS.

FIG. 1 is a sectional view of a main part of an embodiment of a gas welding apparatus according to the present invention.

The illustrated gas welding apparatus 10 welds a pair of fluorine resin pipe members P, P (including a joint, a valve, etc., having a tubular inlet / outlet), and generally stores carbon dioxide gas. A quartz glass envelope 20 having an inlet 22 through which carbon dioxide gas supplied from the cylinder flows, and a gas outlet 24 through which carbon dioxide gas heated to a predetermined temperature is discharged, A heater 30 is provided in the enclosure 20 and heats the gas to a temperature at which a large amount of far infrared rays in a predetermined wavelength region can be emitted.

In the illustrated preferred embodiment, the heater 30 is located inside the enclosure 20 but the enclosure 2
0, and the carbon dioxide gas may be heated to a high temperature before being sent into the enclosure 20. It is known that carbon dioxide emits a large amount of far infrared rays when heated to, for example, 550 ° C. Similarly, steam and hydrocarbons (HCl) also emit a large amount of far-infrared rays when heated, and can be used in place of carbon dioxide as needed.

On the other hand, PTF which is the material of the pipe members P, P
In the absorption spectrum of a fluorine-based resin such as E, FEP, PFA, ETFE, CTFE, and PVDF, and a high-grade engineering plastic resin such as PPS, the absorptivity in the far infrared region is high. Therefore, when a gas that can emit far-infrared rays in a wavelength region having a relatively high absorptivity in the absorption spectrum of each pipe member is used, heating near the welding end face can be performed with a small amount of energy and a short time despite the low temperature. This has the advantage that the welding strength can be extremely increased in time. This is presumed to be due to a synergistic effect between heat transfer by the heat of the far infrared rays and radiant heating by the far infrared rays.

In the preferred embodiment shown, the enclosure 20 is made of quartz glass and the gas outlet 24 is chamfered so as to be substantially perpendicular to the wall of the enclosure. The quartz glass absorbs far-infrared rays, passes through the inside while totally reflecting the inside, and radiates concentratedly from the end face 24a that is substantially perpendicular to the wall surface. When far infrared rays radiated from the carbon dioxide gas are concentrated and emitted from the end face 24a, the vicinity of the welding end face is also heated by the far infrared rays, and the heating efficiency is further improved.

As the heater 30, various known heating elements can be used. For example, an Fe-Cr-based alloy heating element, a platinum-rhodium-based alloy heating element, a tungsten-based heating element, or the like can be used. In the device 10 of the present invention, since a gas capable of emitting a large amount of far infrared rays by heating is used, it is not necessary to select a material capable of emitting far infrared rays to the heating body itself. When a member to be welded is heated by far infrared rays, the temperature also rises from the inside of the member as compared with heating by heat transfer. Therefore, when welding the pipe members P, P,
There is an advantage that heating can be performed uniformly from the outer peripheral side to the inner peripheral side. Thereby, the pair of pipe members P, P
Welding is performed over the entire area of the end face, and as a result, the welding strength is dramatically improved.

FIG. 4 is an absorption spectrum diagram of PVDF. As can be seen from FIG.
At m, the absorptivity of far infrared rays is 0.5 or more. In the case of PVDF, the wavelength region where the absorptance is 0.5 or more is 6 to 10 μm, so by selecting a gas having a high emissivity in this wavelength region, for example, by selecting carbon dioxide gas,
The pipe made of PVDF can be heated efficiently and in a short time.

FIG. 5 is an absorption spectrum diagram of PFA. As can be seen from FIG. 5, as in the case of PVDF, the absorptivity of far infrared rays is 0.5 or more in the wavelength range of 6 to 10 μm. . Therefore, by selecting a gas having a high emissivity in this wavelength region, the pipe made of PFA can be heated efficiently and in a short time.

FIG. 6 is an absorption spectrum diagram of PPS. As can be seen from FIG. 6, in the case of PPS, the absorption coefficient is intermittently 0 in the wavelength region of 2.5 to 3.5 μm and 6 to 13 μm. .5 or more. Therefore, by selecting a gas with a high emissivity in this wavelength range,
The pipe made of PPS can be heated efficiently and in a short time.

As is clear from the above description, efficient heating can be achieved by focusing on a value having a higher absorptance of a member to be heated and selecting a gas having a high emissivity in such a region. It is. For example, in the case of PFA and PVDF, the wavelength range where the emissivity is 0.6 or more is 6.8 to 9.2.
μm and 7.2 to 8.8 μm, it is possible to heat them efficiently and in a short time by selecting a gas having a particularly high emissivity in such a wavelength region.

Next, a comparison will be made of the heating characteristics between the gas welding apparatus according to the present invention and the gas welding apparatus using air instead of carbon dioxide gas.

FIG. 2 is a graph showing the temperature displacement of the PFA surface when air and carbon dioxide are used in the gas welding apparatus shown in FIG.

FIG. 2A shows the positional relationship of each member used in the measurement test. A K-type thermocouple 40 (0.32 mm in diameter) was arranged on the surface of a plate made of PFA. The gas welding apparatus 10 of FIG.
, The set temperature of the heater 30 is 550 ° C., the flow rate of the heating fluid is 4000 cc, and the pressure of the heating fluid is 3 kg /
cm3, the temperature change for 2 minutes from the start of heating was measured. FIGS. 2B and 2C show K-type thermocouples 40 when air and carbon dioxide gas are used as the heating fluid, respectively.
3 shows a change in the temperature of PFA assumed as follows.

As shown in FIG. 2 (b), when air is used as the heating fluid, the temperature rises almost linearly up to 20 seconds, and after 30 seconds, the rate of temperature rise is slow. And finally settles at about 340 ° C. On the other hand, in the case of the present invention in which carbon dioxide gas is used as the heating fluid, the temperature becomes 380 ° C. in about 20 seconds, and thereafter, the temperature stably hardly changes. Before 20 seconds, the temperature of the thermocouple once
It is considered that the temperature rises to 00 ° C. because the thermocouple is directly heated by far-infrared rays (the actual temperature of the PFA is presumed to show the temperature rise characteristics as shown by the dotted line).
Is not 400 ° C. In any case, it is certain that the temperature has reached 380 ° C. before the elapse of 20 seconds after the start of heating, and the PFA can be heated to a high temperature in a short time as compared with the case using air.

In the same test, a thermocouple was arranged at a depth of 1 mm from the surface of the PFA, and the temperature change at that position was measured. As shown in FIG. 3A, when air is used as the heating fluid, the temperature rises almost linearly for up to 10 seconds. On the other hand, in the case of the present invention in which carbon dioxide gas is used as the heating fluid, the temperature becomes 210 ° C. in about 8 seconds, after which the temperature stably changes little. Even at a depth of 1 mm from the surface of the PFA, in the case of the present invention using carbon dioxide gas as a heating fluid, PFA can be heated to a high temperature in a short time as compared with the case using air.

In this measurement, PFA having excellent heat resistance was used, but it is presumed that other fluororesins have the same tendency. In the case of the present test apparatus, the distance between the tip of the gas outlet 24 of the enclosure 20 and the PFA was larger than 2 mm, that is, about 5 mm, the heating rate was higher and the temperature was higher.

Next, another embodiment of the gas welding apparatus according to the present invention will be described.

FIG. 7 shows that the members to be welded are a garbage disposal plant,
This figure shows a case where the sheet is a thin resin sheet used as a waterproof sheet for a tunnel or the like.

In recent years, prices of fluorine resins and high-grade engineering plastic resins have been rapidly decreasing. Therefore, sheet materials for various uses conventionally produced from vinyl chloride or polyethylene are replacing these resins. The illustrated gas welding apparatus 100 is for welding a waterproof sheet at a garbage disposal site. Generally, a first gas welded body 110 that heats and welds the vicinity of an edge of a sheet S to be welded, , A second gas welded body 120 that heats the band-shaped supply material 114 to be in a softened state, and a pair of sheets S on which the softened band-shaped supply material 114 is already welded. Pressing roller 1 that presses upwardly near the welding edge of the roller to weld them together
And 12. First and second gas welds 11
Reference numerals 0 and 120 have the same configuration as the gas welding apparatus 10 described above. In the illustrated preferred embodiment, the gas outlet 124 of the second gas weld 120 is configured to have an elongated rectangular cross-section so that it can be uniformly heated over the entire width of the band-shaped refill material 114.

In this embodiment, the first gas welded body 11
According to 0, after the edge of the waterproof sheet S is welded, the belt-shaped replenishing material 114 is further placed thereon, welded, and copied by the pressing roller 112. Since the waterproof sheet S is made of a material having excellent strength and chemical resistance, and the seam thereof is double welded, there is an advantage that accidents such as water leakage can be drastically reduced.

Further, a so-called welded structure in which the edge of the waterproof sheet S is beveled obliquely, a V-shaped groove is formed between the two, and the band-shaped replenishing material 114 is melt-filled and connected therein. . In the case of welding, the end faces of the waterproof sheet S may have a slight gap.

The present invention is not limited to the above-mentioned fluorine resin and high-grade engineering plastic, but can be applied to general thermoplastic resins such as polypropylene and polyethylene polybutylene. Confirmed to be valid.

[0041]

According to the gas welding method for heat-weldable members of the present invention, a step of selecting a gas capable of emitting far infrared rays in a wavelength region having a relatively high absorptivity in the absorption spectrum of the member to be welded, A step of arranging adjacent members that can be welded, a step of heating a gas to a temperature at which a large amount of far-infrared rays in a predetermined wavelength region can be radiated, and heating both ends of the adjacently arranged members And the step of spraying the melted gas to make the vicinity of both ends softened and welded, so that the member to be welded can be heated not only by heat transfer of the gas but also by radiant heating by far infrared rays. With low energy despite low temperature,
This has the effect that the welding strength can be extremely increased in a short time.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of an embodiment of a gas welding apparatus according to the present invention.

2 (a) to 2 (c) are schematic diagrams showing a positional relationship of each member in a temperature measurement test, and temperature displacement of a PFA surface when air is used in a gas welding apparatus shown in FIG. And PFA using carbon dioxide gas
It is the graph which showed the temperature displacement of the surface.

FIGS. 3 (a) and 3 (b) are graphs each showing a temperature displacement at a position 1 mm inward from the PFA surface under the same conditions as in FIG.

FIG. 4 is an absorption spectrum diagram of PVDF. It is a figure which shows the correlation of.

FIG. 5 is an absorption spectrum diagram of PFA.

FIG. 6 is an absorption spectrum diagram of PPS.

FIG. 7 is a schematic perspective view of another embodiment of the gas welding apparatus according to the present invention.

FIG. 8 is a longitudinal sectional view of a conventional gas welding device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Gas welding apparatus 20 Enclosure 22 Gas inlet 24 Gas outlet 24a End face 30 Heater 40 K type thermocouple P Tube member S Sheet

Claims (9)

[Claims] 1. A gas welding method for heat-weldable members, the method comprising selecting a gas capable of emitting far-infrared rays in a wavelength region having a relatively high absorptivity in an absorption spectrum of a member to be welded; A step of arranging the heat-sealable members adjacent to each other; a step of heating the gas to a temperature at which a large amount of far-infrared rays in a predetermined wavelength region can be emitted; and both ends of the members arranged adjacent to each other And fusing the heated gas to soften the vicinity of the both ends so as to be welded. 2. The gas welding method according to claim 1, wherein the heating of the gas is performed in a quartz glass enclosure having a gas outlet, and the gas outlet is attached to a wall surface of the enclosure. And cut it so that it is almost a right angle,
A gas welding method characterized in that far-infrared rays of a predetermined wavelength emitted from gas and absorbed by the enclosure are radiated from the end face in a concentrated manner. 3. The gas welding method according to claim 1, wherein in the welding step, a replenishing material made of the same material as the material capable of being welded is placed in a softened state, and is disposed adjacently or with a slight gap therebetween. Welding or welding while replenishing the both ends of the formed member. 4. The gas welding method according to claim 1, wherein the member to be welded is made of PTFE, FEP, PFA, ET.
A gas welding method comprising a fluorine resin such as FE, CTFE and PVDF or a high-grade engineering plastic such as PPS, wherein the gas is carbon dioxide. 5. The gas welding method according to claim 1, wherein the member to be welded has a circular cross section used as a pipe of a factory of a chemical, food, semiconductor industry, biotechnology, or the like. A gas welding method comprising a resin tubular part. 6. The gas welding method according to claim 1, wherein the member to be welded is a thin resin sheet used as a waterproof sheet for a garbage disposal site, a tunnel, or the like. A gas welding method characterized by the following. 7. A gas welding apparatus used for welding members capable of being thermally welded, wherein a gas capable of emitting far-infrared rays in a wavelength region having a relatively high absorptivity in an absorption spectrum of a member to be welded is provided. A gas supply source, an enclosure having a gas inlet for receiving gas from the gas supply, and a gas outlet for discharging heated gas, and a gas supply source disposed inside or outside the enclosure and having a predetermined wavelength range. Heating means for heating the gas to a temperature at which a large amount of infrared rays can be emitted. 8. The gas welding apparatus according to claim 7, wherein the surrounding body is made of quartz glass, and the gas outlet is formed so as to have an end surface substantially perpendicular to a wall surface of the surrounding body. A gas welding apparatus characterized in that far-infrared rays of a predetermined wavelength emitted from a gas and absorbed by the enclosure are concentrated and emitted from the end face. 9. The gas welding apparatus according to claim 7, wherein the members to be welded are PTFE, FEP, PFA, E
Fluorinated resin such as TFE, CTFE, PVDF or PPS
A gas welding apparatus made of high-grade engineering plastics such as the above, wherein the gas is carbon dioxide gas.