JP2005238659A - Butt fusion joining method and heating implement - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a butt fusion joining method which stabilizes joining strength even when the outside temperature of the site is low and a heating implement for a pipe end part. <P>SOLUTION: When thermoplastic resin pipes are butt-joined, one or two expandable/contractable pipe end part insertion ports are formed in a heating implement main body of an insulating container, a heat source is placed in the heating implement main body, pipe end parts are inserted from the respective insertion ports, and the insertion ports are contracted. The pipe end parts are housed, by the heating implement for heating the pipe end parts by the heat source, the pipe end parts to be joined are pre-heated, and pipe end surfaces are contacted with a surface-like heater and heated/melted. After the pipe end surfaces are melted, the heater is removed, and the pipe end surfaces are butted and fusion-joined together. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  In the present invention, thermoplastic polyolefin pipes used in water pipes for transporting clean water, agricultural water, industrial water, etc., chamfer the surfaces to be joined, and heat and melt the chamfered pipe end faces with a planar heater, After removing the planar heater from the tube end surface, the molten tube end surfaces are butted together and fusion bonded, and a heating bag for heating the bonded tube end in advance before melting the bonded end surfaces with the planar heater About.

    Thermoplastic resin pipes such as polyethylene pipes and polypropylene pipes are lightweight and excellent in corrosion resistance, flexibility and earthquake resistance, and are being widely used for gas pipes and water pipes. As a method of joining these resin pipes in the field, the joint surfaces of the pipes to be joined are chamfered, the chamfered pipe end faces are heated and melted by a planar heater, etc., and the planar heater is removed and melted. There is a butt fusion bonding method in which the bonded surfaces are fusion bonded together.

  A general butt fusion bonding method conventionally performed is performed as follows using a fusion bonding apparatus as shown in FIG. That is, first, the ends C1 and C2 of the thermoplastic resin pipe are fixed to the fixed clamp A and the movable clamp B, respectively, and then the movable clamp B is advanced by a driving device D such as an air cylinder to pipe the end C2. The end face is pressed against the chamfering machine F attached to the movable platform E, further advanced and pushed in, the chamfering machine F is sandwiched between the pipe end faces of the ends C1 and C2, and the chamfering machine F is driven to drive the ends C1 and C2. Chamfer each tube end face. After the chamfering, the chamfering machine F is removed from the movable dual-purpose stand E, and a planar heater G is attached instead. Similarly, the planar heater G is sandwiched and pressed between the pipe end surfaces of the ends C1 and C2. After the tube end faces of the parts C1 and C2 are heated and melted, they are heated and held for a certain time. Next, the movable clamp B is moved backward by the driving device D to free the planar heater G sandwiched between the ends C1 and C2, and the planar heater G is removed from the movable combined platform F. Thereafter, the movable clamp B is again advanced by the driving device D, and the melted end C2 is fixed to the fixed clamp A and butted against the melted end C1 with a required pressing pressure (for example, fusion joining) (for example, , See Patent Document 1).

  However, in the butt fusion bonding method, predetermined time, temperature, and pressure in each process such as a pressure melting process, a heating and holding process, a planar heater removing process, a pressure bonding process, and a cooling process are strictly observed. Otherwise, there is a problem that the temperature of the end face of the pipe to be fused is lowered and the molten state is changed, resulting in uneven or insufficient bonding strength.

  Therefore, in the above conventional butt fusion bonding method, the air temperature at the construction site and the surface temperature of the tube end are measured, and the time of pressure melting and heating and holding is changed according to the measured temperature. It has been performed to adjust the tube end heating conditions such as changing the heat generation temperature of the upper heater.

Polyolefins such as polyethylene and polypropylene have poor thermal conductivity, and when the outside air temperature is low, such as in a cold region or in winter, the joints are not easily melted in a short time and the joint strength tends to decrease. For this reason, when these pipes are butt-welded and joined at these times and regions, the joints are partially covered with a windshield tent or the like so that the wind does not directly hit the fusion part and the temperature The fusing work is performed in such a way that the change in temperature is reduced, but this work is very troublesome, and therefore the temperature at the end of the pipe changes greatly for each worker, and the setting of the heating conditions often varies, In some cases, the joining strength varies from joint to joint, and stable joining may not be possible.
JP 2001-191415 A paragraph number [0002]

  An object of the present invention is to solve the above-described problems in the conventional butt-fusion bonding method, and to provide a butt-fusion bonding method and a tube end heating tool in which the bonding strength is stable even when the outside air temperature at the site is low. It was made.

  In order to solve the above problems, the butt-fusion bonding method (Invention 1) according to claim 1 of the present invention is such that when the thermoplastic resin pipes are butt-joined, the tube ends to be joined are heated in advance. A planar heater is brought into contact with the end face and melted by heating. When the end face of the pipe is melted, the planar heater is removed and the pipe end faces are brought into contact with each other for fusion bonding.

  The heating tool according to claim 2 (invention 2) is a tube end heating tool that heats the tube end portion in advance before melting the tube end surface in the butt fusion bonding method of the thermoplastic resin tube, The heating tool body consisting of a heat insulating container is provided with one or two tube end insertion ports that can be expanded and contracted, a heat source is stored inside the heating tool body, and the tube ends are inserted through the respective insertion ports. The mouth is squeezed, the tube end is enclosed, and the tube end is heated by a heat source.

  The pipe | tube joined by the invention 1 is a pipe | tube which consists of thermoplastic resins, such as polyethylene, a polypropylene, a polyvinyl chloride, polyamide, for example.

  The surface temperature of the tube end to be heated in advance is suitably about 30 ° C to 60 ° C. If it is less than 30 ° C., the heating is insufficient and the surface temperature is lowered before the contact with the subsequent surface heater, so that the joining performance is likely to vary. Further, if the temperature exceeds 60 ° C., the tube may be softened and flattened, and when a hand or the like comes into contact with the end surface of the tube, it is hot and workability is deteriorated, and there is a risk of burns.

  In addition, the butt fusion bonding apparatus used is a fixed clamp and a movable clamp, which fixes the pipe ends to be joined, chamfers the pipe end faces to be joined, and presses the pipe end faces after chamfering to a planar heater. It is not particularly limited as long as it has a mechanism that heats and melts and then removes the planar heater and then abuts the end surfaces of the pipes again and fuses them, and the same as the conventional one (see, for example, FIG. 4) is applied. May be.

  Invention 2 is a heating tool used in the butt fusion bonding method. This heating tool is provided with one or two tube insertion openings in the heating tool main body through which the tube end to be heated is inserted, and the insertion opening can be expanded and contracted. A heat source is housed in the main body of the heating tool, which is an insulated container, and the tube ends are inserted from the respective insertion ports, the insertion ports are squeezed, the tube ends are enclosed, and the heat source is heated to heat the tube ends. It is for heating.

  This heating tool is attached to the end of the tube before the surface heater is brought into contact with the end surface of the tube that has been chamfered. When the tube insertion port provided in the heating tool main body is one place, the tubes are arranged side by side, and the tube ends are collectively inserted into the heating tool from the tube insertion port.

  When there are two tube insertion openings, the tube ends can be inserted so that the tube ends face each other. For example, the ends of the tubes are fixed by a fixed clamp and a movable clamp after chamfering. Can be inserted into the tube insertion port while being covered with a heating tool while facing each other, and can also be removed in a short time, so that the work after the heat at the end of the tube can be performed in a short time. .

  The heating device body is not particularly limited as long as it has excellent heat resistance and heat insulation properties, and is excellent in water resistance, wear resistance, oil resistance, weather resistance, etc., considering the suitability for use at the joining site. The thing which is is preferable. For example, as an example, foam of thermoplastic resin such as polyethylene, polypropylene, vinyl chloride resin, acrylic resin; foam of thermosetting resin such as hard or soft urethane resin, phenol resin; natural material containing bubbles such as wood and charcoal Kinds: Insulating cloths such as cotton, silk, wool, glass wool, carbon fibers, thermoplastic resin fibers, thermosetting resin fibers, or mixed fibers thereof, such as woven fabrics, non-woven fabrics or woven fabrics; And a laminated cloth-like material such as aluminum; and a multilayer cloth-like material in which a heat insulating material made of cotton, glass wool, urethane foam or the like is sandwiched between these cloth-like materials or laminated cloth-like materials.

  In addition, if the heater body is made of a hard material such as hard urethane foam and is made into a tube insertion port that can be expanded or contracted at both ends, the heat insulation performance is excellent and the tube insertion port is tightened. Although convenient, it is preferable that the bag is made of a soft material because it is easy to handle and has good workability in a narrow space.

  The volume of the main body of the heating tool, which is an insulating container, is sized to enclose the inserted tube end. Further, since the tube insertion opening can be expanded and contracted, the structure can be changed in shape. Therefore, the tube insertion opening is usually made of a soft material. The method for expanding / contracting the tube insertion port is appropriately selected depending on the situation, for example, a method of making the tube insertion port elastic by making it elastic, a method of providing a string to the tube insertion port and squeezing and tying it. It may be used.

  The heat source is not particularly limited as long as it can heat the temperature inside the heating tool body and raise the surface temperature of the tube end of the pipe inserted into the heating tool to about 60 ° C. Examples thereof include electric heating elements such as wires and infrared heaters; water, other heat storage materials; high-temperature fluids such as high-temperature steam and high-temperature air; iron powder mixtures in which the oxidation rate is adjusted.

  If the heat source is, for example, an electric heating element such as a nichrome wire or an infrared heater, high-temperature steam, high-temperature air, etc., the temperature inside the heater body is detected by a thermocouple, etc. It is easy to control to a desired temperature, which is preferable.

  When the heat source is a heat storage material, it is preferable to use a medium having a large heat capacity such as preheated hot water.

  If the heat source is a heat source that is used in disposable warmers, for example, iron powder, water, activated carbon, diatomaceous earth, vermiculite, salts, etc. to adjust the oxidation rate, the maximum temperature reached should be adjusted appropriately. Is preferred.

  In the invention 1, since the tube end surfaces to be joined are preheated, the temperature of the tube end surface when the planar heater is brought into contact with the tube end surface is constant, and the pressure melting when the planar heater is brought into contact and heated and melted In addition, the heating and holding time can be made constant, and a butt fusion method with stable bonding strength is achieved.

  In the invention 2, the heating tool is a heating tool composed of a heat insulating material layer with a built-in heat source, and heats the tube end to a predetermined temperature. Therefore, when the tube end surface is melted with a planar heater, pressure melting is performed. In addition, the heating and holding time can be made constant, and butt fusion with stable bonding strength can be achieved.

  Next, the butt-fusion bonding method and heating tool of the present invention will be described with reference to the drawings. FIG. 1 is a side view showing an example of the use of a heating tool having a single tube insertion opening. FIG. 2 is a side view showing an example of the use of a heating tool having two tube insertion openings. FIG. 3 is a cross-sectional view of an example of a heat insulating container.

  The heating tool 1 is provided with one or two insertion openings for the pipe end C of the pipe to be fused to the heating tool main body 2 which is a heat insulating container, and the insertion opening is provided with a bellows, a rubber string, a sheet rubber, or a fastening. It can be expanded and contracted with a string or the like, and a heat source is housed inside the main body.

  FIG. 3 shows an example of the structure of the main body 2 of the heating tool 1 used in the illustrated example. The heating tool body 2 is a heat-insulating container, and is a flexible bag-like material in which a nichrome wire heater 23 is built in a laminated fabric of glass wool 21 and cotton 22 and is prevented from slipping by a binding thread 24 made of carbon fiber or the like. A bag-shaped heating tool 1 which detects a temperature with a thermocouple (not shown) built in at the same time as the nichrome wire 23 and turns on / off the energization to the nichrome wire to obtain a predetermined temperature. It is.

  The tube end C of the tube to be heated is inserted from the tube insertion port 31, the tube insertion port 31 is tightened, a desired temperature is set by a temperature controller (not shown), and the nichrome wire heater 23 is energized from the power cord 4 To do. In this case, it is preferable that the tube ends C of the tubes to be heated are simultaneously inserted into the main body 2 of the heating tool 1 and heated.

  Alternatively, if two tube insertion ports 31 and 32 are provided at positions where the tubes of the bag-shaped heating tool body 2 face each other, for example, as shown in FIG. The pipe ends C1 and C2 of the opposed pipes can be inserted into the bag-shaped heating tool main body 1 from the respective pipe insertion ports 31 and 32, and the insertion ports 31 and 32 can be tightened and heated simultaneously. In this case, the tube ends C1 and C2 are simultaneously at a desired temperature. After removing the heating tool 1, the tube end surfaces C1 and C2 can be heated and melted immediately by applying the surface heater G, so that the working time is shortened and the temperature at the tube end C is reduced, and the tube ends C of each other are reduced. Since the temperatures of these are almost the same, the variation in fusion is reduced.

  The preheating of the tube ends C1 and C2 may be performed after the tube end C is chamfered before chamfering, but in order to reduce the temperature change, it is preferably performed after the chamfering.

  The tube ends C1 and C2 are preferably heated equally. Therefore, it is preferable that the heat sources 23 are arranged substantially evenly on the inner peripheral surface of the bag-like main body 2 rather than being arranged in a dot shape or a line shape. Therefore, the heat source 23 is an electric heating element such as a nichrome wire or an infrared heater; water, other heat storage materials; high-temperature fluid such as high-temperature steam or high-temperature air; The method of fixing the heat source 23 to the inner surface of the heating tool body 2 is not particularly limited as long as the heat source 23 is fixed to the inner surface of the heating tool main body 2 as appropriate.

(Examples 1 to 10)
Using the heating tool shown in FIG. 2, as shown in Table 1, under the preheating conditions and the butt fusion conditions with the heating tool, a polyethylene pipe for water distribution (nominal diameter 100, manufactured by Sekisui Chemical Co., Ltd., outer diameter 114 mmφ, Wall thickness 10.4 mm). The heater removal time was the time from the start of moving the movable clamp until the fused pipe end surfaces contacted each other.

  A prismatic sample having a width of 8 mm, a thickness of 8 mm and a length of 100 mm and having a fusion interface horizontal to the central position in the length direction was cut out from the obtained fusion bonded tube. A 1.4 mm deep cut was made with a razor into the fusion bonded surface of this sample. Thereafter, the cut sample was subjected to a stress of 4.9 MPa on the fusion bonded surface in hot water at 80 ° C., and the presence or absence of fracture was observed. The results are shown in Table 1.

(Comparative Examples 1-3)
For comparison, a test was performed in the same manner as in Example except that no heating tool was used. The results are also shown in Table 1. There is also variation by the operator, the temperature at the end of the tube is lowered at the start of melting, and there is also variation by the operator. Also, the time until the breakage varied from 1,000 hours to 400 hours.

  The present invention can also be used for high-pressure fusion bonding in cold regions.

It is a side view which shows an example of use of the heating tool which has a single tube insertion port. It is a side view which shows an example of use of the heating tool with two pipe insertion openings. It is sectional drawing of an example of a heat insulation container. It is a side view of an example of a fusion bonding apparatus.

Explanation of symbols

1 Heating tool 2 Insulated container (heating tool body)
21 Glass wool 22 Cotton 23 Heat source (Nichrome wire)
24 Binding thread 31, 32 Tube insertion port 4 Power cord A Fixed clamp B Movable clamp C Tube end C1, C2 Tube end fixed to fixed clamp A or working clamp B D Drive unit E Movable combined stand F Chamfering machine G Surface heater

Claims (2)

  When the thermoplastic resin pipes are butt-joined, the pipe end faces to be joined are preheated, and then a sheet heater is brought into contact with the pipe end faces to heat and melt. When the pipe end faces are melted, the sheet heater is removed and the pipe end faces are removed. A butt-fusion joining method characterized in that they are brought into contact with each other and fusion-bonded. In a butt-fusion bonding method for thermoplastic resin pipes, a pipe end heating tool that heats the pipe end in advance before melting the pipe end face, and the pipe that can be expanded and contracted to the heating tool main body made of a heat insulating container One or two end insertion ports are provided, a heat source is housed inside the heating tool body, the tube ends are inserted from the respective insertion ports, the insertion ports are squeezed, the tube ends are enclosed, and the heat source is used. A heating tool characterized by heating a tube end.

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