JP2589652B2 - Electric welding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plug for a thermoplastic resin tube at a joint of a thermoplastic resin by supplying an electric current to a heating element provided on an inner peripheral surface of the joint. The present invention relates to an electric fusion bonding method for fusion bonding.

[0002]

2. Description of the Related Art Conventionally, a thermoplastic resin is heated at a stretch to a temperature higher than the melting temperature by a heating element by turning on a start button after inserting a pipe opening into a receiving port of a fitting and setting it by fusion. Was.

[0003]

When the fusing step is performed from the start of the fusing operation, if water is attached to the insertion port of the pipe or the receiving port of the joint, a short circuit occurs and the electric fusing apparatus and the heat generation are generated. In addition to the possibility of damaging the body, there is a problem in that bubbles are formed in the molten resin and the resin is melt-bonded in a state where "su" is contained therein, and the bonding strength is extremely weakened.

[0004]

According to the present invention, a thermoplastic resin pipe is provided at a receiving port of a joint made of a thermoplastic resin by supplying a current to a heating element provided on an inner peripheral surface of the receiving port. In the electric fusion bonding method for fusion-bonding the insertion port, before the melting step of heating the thermoplastic resin to the melting temperature or more by the heating element, the thermoplastic resin is removed by the heating element. A drying step of heating at a low temperature and a high temperature at a temperature lower than the melting temperature for a predetermined time is provided, and a fixing step of heating at a temperature lower than the melting temperature and a temperature higher than the drying temperature for a predetermined time is provided after the melting step. Even if water has adhered to the lip or the joint receiving port, the melting process is performed after evaporating the water and completely drying the fusion bonding part,
It prevents the breakage of the electric fusion bonding apparatus and the heating element and the decrease in the bonding strength as with conventional water, so that the proper fusion bonding can always be performed.
In addition, the latter half is heated at a high temperature for a certain period of time, respectively, and while efficient stepwise drying is performed to a predetermined value that becomes a melting start temperature while preventing a sharp rise in temperature, after melting, the molten resin is melted. This prevents rapid solidification and ensures stable cooling without adversely affecting the resin properties, thereby enabling appropriate and high-quality fusion welding between the joint and the pipe.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a heat pattern diagram, and FIG. 2 is an explanatory view of an electric fusion welding operation. In FIG. 2, reference numeral (1) denotes a controller for electric fusion wearing, and a start button (3) and a stop are provided on the upper surface of a main body case (2). A button (4) and a liquid crystal display (5) are provided, a plug (6) for connecting to a power supply is provided at a tip thereof, and a power cord (7) and a connector (8) connected to an end face of a thermoplastic resin opening. A control code (9) provided at the end extends from the main body case (2).

As shown in FIG. 3, the main body case (2)
Is formed in a square box-shaped closed structure by a square frame-shaped side plate (10), a top plate (11) closing the upper surface of the side plate (10), and a bottom plate (12) closing the lower surface of the side plate (10). In order to prevent water from entering the main body case (2) in which various electric and electronic parts and a wiring board on which the electric and electronic parts are mounted, the bottom plate (12) is made of aluminum having excellent heat dissipation. And a plurality of radiating blades (13) are integrally formed on the lower surface side of the bottom plate (12), and the bottom plate (12) is used as a radiating plate to suppress a rise in temperature inside the main body case (2). To protect various electric and electronic components from heat, and to attach a power control element (14) or the like, which becomes high in temperature during operation, to a bracket (15) which is in close contact with the bottom plate (12) to obtain a high temperature rise suppressing effect. Is configured as

In FIG. 2, reference numeral (16) denotes a joint made of a thermoplastic resin, and reference numeral (17) denotes the joint (16).
This is a tube made of a thermoplastic resin of the same material.

As shown in FIG. 4, the inner peripheral surface of each receiving port (18) of the joint (16) into which the insertion port of the pipe (17) is inserted is provided with a folded electric resistance wire (19) on a cylindrical surface. (20) Heating element formed into a sleeve shape by spirally winding along it
However, terminal pins (21) and (21) attached to both ends of the electric resistance wire (19) protrude from the end face of each of the receptacles (18) and are fixed by insert molding in advance.

The electric resistance wire (19) is obtained by forming an insulation coating on a resistance electric wire such as a nickel wire with a thermoplastic resin of the same material as the joint (16).

In addition, between the terminal pins (21) and (21) at the end face of each of the receptacles (18), a concave portion for discriminating the kind, which has a different depth depending on the kind, such as the material, shape and size of the joint (16). (22) is formed.

As shown in FIG. 5, fixed terminals (23) and (23) for inserting and connecting the terminal pins (21) and (21) are embedded in the connection end surface of the connector (8), and fixed terminals (23). ) And (23) through the recesses (2).
A movable terminal (25), which is a sensor arm whose tip is inserted into 2), protrudes slidably.

A potentiometer type sensor (26) is provided inside the connector (8).
The movable terminal (25) inside the connector (8) is formed with a rack gear (28) that is always engaged with the pinion gear (27) of the type sensor (26), and is connected to each terminal pin (21) (21) of the receptacle (18). When the respective fixed terminals (23) and (23) of (8) are connected, the receptacle (1)
The movable terminal (2) of the connector (8) is inserted into the concave portion (22) of the connector (8).
5) is connected, and the reciprocating movement amount of the movable terminal (25) is detected by the type sensor (26), whereby the joint (1) is connected.
It is configured to determine the type of 5).

The movable terminal (25) is connected to a spring (29) for elastically pressing the movable terminal (25) in a projecting direction and a mounting bracket (30) of the product type sensor (26) to regulate the projecting amount of the movable terminal (25). The movable terminal (25) is positioned at the reference position of the type sensor (26) by the stopper (31).

The movable terminal (25) is formed in a cylindrical shaft shape, and a sensor case (32) having a cylindrical shaft shape is detachably inserted into the movable terminal (25). A temperature sensor (33), which is a thermistor, is attached to the tip of the movable terminal (32), and the tip of the temperature sensor (33) is exposed to the tip of the movable terminal (25).
When 5) is connected to the recess (22), the recess (2)
2) The tip surface of the temperature sensor (33) is brought into contact with the bottom surface to detect the temperature (outside air temperature) of the joint (16) at the time of starting the electric fusion welding operation.

The control code (9) having the connector (8) attached at the tip thereof includes a power supply cord connected to the fixed terminals (23) and (23) and a kind signal transmission code connected to the kind sensor (26). And a temperature signal transmission cord connected to the temperature sensor (33) is connected to a CPU (34) provided in the controller (1).

As shown in FIG. 6, the controller (1)
A CPU (34) constituted by a microcomputer, and the CPU (34) is provided with the start button (3).
And a stop button (4) and the type sensor (26)
And a temperature sensor (33), the heating element (20), the display (5), and a memory (35) for storing a heat pattern, and a current is supplied to the heating element (20) based on the heat pattern. Is supplied, and the insertion opening of the pipe (17) is electro-fused to the receiving opening (18) of the joint (16).

The memory (35) stores a heat pattern for each type of the joint (16). As is clear from the heat pattern diagram of FIG. ) Electric resistance wire (1
9) shows the relationship between the current value (A) to flow in (9) and time (S). The current starts to flow from the start of the electrofusion operation, and the current value (A) is first raised to a first set current value (A1). The first set current value (A1) is maintained for a first time (S1).
Next, the current value (A) is increased to a second set current value (A2), and the second set current value (A2) is increased for a second time (S2).
2) Keep. Next, the current value (A) is increased to a fifth set current value (A5) which is the maximum current value, and the fifth set current value (A5) is maintained for a third time (S3). Next, the current value (A) is decreased to a third current value (A3),
Current value (A3) for a fourth time (S4),
After the elapse of the time (S4), the current supply is cut off.

The fourth current value (S4) is a current value for heating the thermoplastic resin, which is a molding material of the joint (16), the pipe (17) and the insulating coating of the electric resistance wire (19), to this melting temperature. And the first to third set current values (A
1) (A2) (A3) is the fourth set current value (A4)
While setting it lower, the fifth set current value (A5) is set higher than the fourth set current value (A4), and A1 <A
2 <A3 <A4 <A5, and the drying process is performed from the start of the electrofusion operation until the second set time (S2) elapses. The heating element (2
0) evaporating the water adhered to the inner peripheral surface of the receiving port (18) of the joint (16) and the outer peripheral surface of the insertion port of the pipe (17) by the amount of heat generated from the heating step, thereby drying the surface of the resin to be melted; A period until the third set time (S3) elapses from the end is defined as a melting step, and the amount of heat generated from the heating element (20) in this melting step is used as the inner peripheral surface of the receiving port (18) of the joint (16) and the pipe ( 17) Melting the insulating film on the outer peripheral surface of the insertion opening and the electric resistance wire (19), and the fixing process is performed until the fourth set time (S4) elapses after the completion of the melting process. , The molten resin is gradually solidified in a stable state by the amount of heat generated from the heating element (20).

Thus, as shown in FIG. 2, the controller (1) is brought into the piping site, and the plug (6) at the end of the power cord (7) is connected to a power source such as a generator provided at the piping site. At the same time, the terminal pin (2) on the end face of the receptacle (18) of the joint (16) into which the insertion port of the pipe (17) is inserted.
1) After connecting the fixed terminals (23) (23) and the movable terminal (25) of the connector (8) at the tip of the control code (9) of the controller (1) to the (21) and the concave portion (22), By turning on the start button (3) of (1), the receptacle (1) of the joint (16) is turned on.
8) Automatic control for automatically fusing the opening of the pipe (17) is started. As shown in the heat pattern diagram of FIG. 1 and the flowchart of FIG. 7, the start button (3) is When turned on, first, the output values of the type sensor (26) and the temperature sensor (33) are read, and the type of the joint (16) is determined based on the output value of the type sensor (26). Heat pattern selection setting control (initial setting) for reading the corresponding heat pattern from the memory (35) is performed. Thereafter, the drying control, the melting control, and the fixing control for controlling the current flowing to the heating element (20) are performed based on the selected and set heat pattern, and the electric fusion is completed.

As shown in the flowchart of FIG. 8, in the melting control, the output value (t
When a) is within the set range (for example, 10 ° C. to 30 ° C.), the heating element (2) is set based on the initially set heat pattern.
0) is controlled, but when the outside air temperature at the work site is high, the resin temperature rises quickly, and when it is low, the rise of the resin temperature becomes slow.
When the output value (ta) of 3) is higher than the set range, the third set time (S3) of the heat pattern corresponding to the difference.
Is shortened, and conversely, if it is low, the heat pattern is corrected so as to increase the third set time (S3) of the heat pattern in accordance with the difference, and thereafter, the heating element based on the corrected heat pattern The current flowing to (20) is controlled.

Further, a socket (18) of the joint (16)
If the opening of the pipe (17) is not properly inserted into the tube, the amount of heat transferred from the heating element (20) to the resin is small, and the temperature of the heating element (20) rises quickly, and the temperature rises. Then, while the electric resistance increases, on the other hand, when inserted properly, the amount of heat transmitted to the resin is large, and the temperature rise of the heating element (20) is delayed. Using the fact that the rise time of the current flowing through the heating element (20) changes due to this characteristic, the insertion failure of the pipe (17) is detected, and the flow to the heating element (20) starts from the start of the melting control. When the time when the current value (Ax) rises to the set current value (A0) set lower than the fourth set current value (A4) of the heat pattern is within the set time (S0), the pipe (17) is properly inserted. When the rise time exceeds the set time (S0) while the supply of current to the heating element (20) is continued to perform the electric fusion welding operation,
7) is determined not to be inserted properly, and the heating element (2)
In addition to relaying the supply of electric current to 0), the display (5) causes the display of the insertion failure of the pipe (17) to be displayed, and is interrupted before the resin for the electric fusion welding operation is melted. )
Is prevented from being fused to the joint (16) in the state of poor insertion.

[0022]

As is apparent from the above embodiments, the present invention is directed to a socket (18) of a joint (16) made of a thermoplastic resin.
Electric fusion is performed by supplying an electric current to a heating element (20) provided on the inner peripheral surface to melt-bond a leading end of a thermoplastic resin pipe (17) to a receiving opening (18) of the joint (16).
In the method , before the melting step of heating the thermoplastic resin above the melting temperature by the heating element (20), the thermoplastic resin is heated by the heating element (20) to two stages of a low temperature and a high temperature below the melting temperature. Since a drying step for heating for a predetermined time is provided, and a fixing step for heating for a predetermined time at a temperature equal to or lower than the melting temperature and higher than the drying temperature is provided after the melting step, an insertion port or a joint of the pipe (17) is provided. Even if water adheres to the receiving port (18) of (16), the water is evaporated to completely dry the fused portion, and then the melting step is performed. It prevents damage to the heating element and lowers the bonding strength, so that proper fusion bonding can always be performed. Particularly, the first half of the drying process is heated at a low temperature, and the second half is heated at a high temperature for a certain period of time. While efficient stepwise drying is performed up to a predetermined value at which the melting start temperature is prevented while preventing the rise, after the melt-adhesion, rapid solidification of the molten resin is prevented and the property of the resin is adversely affected. There is a remarkable effect such as that no stable cooling is performed and that the joint (16) and the pipe (17) can be properly welded while maintaining high quality.

[Brief description of the drawings]

FIG. 1 is a heat pattern diagram.

FIG. 2 is an explanatory view of an electric fusion bonding operation.

FIG. 3 is a sectional view of a controller.

FIG. 4 is a cross-sectional view of a joint receiving port.

FIG. 5 is a sectional view of the connector.

FIG. 6 is an electric fusion control circuit diagram.

FIG. 7 is a flowchart of the entire control.

FIG. 8 is a flowchart of a melting control.

[Explanation of symbols]

 (1) Controller (16) Joint (17) Pipe (18) Receptacle (20) Heating element

Claims (1)

(57) [Claims] 1. An electro-melting method in which current is supplied to a heating element provided on an inner peripheral surface of a receiving portion of a joint made of a thermoplastic resin so that a leading end of a pipe made of a thermoplastic resin is fused to a receiving portion of the fitting. in wearing method, prior to the melting step of heating the thermoplastic resin by the heating element to above the melting temperature, respectively for heating a predetermined time a thermoplastic resin in two steps of low and high temperature below the melting temperature by the heating element An electric fusion bonding method , comprising a drying step and a fixing step of heating at a temperature equal to or lower than the melting temperature and higher than the drying temperature for a predetermined time after the melting step.