JPS6194741A - Butt welder for resin pipe - Google Patents

Abstract

PURPOSE:To obtain the welder capable of compensating for primary tensile load and also primary pushing load effectively by providing a specified pressurizing mechanism applying specified pushing force to a movable cramp to weld both welding and joining surfaces of resin pipes mutually with a specified pushing force. CONSTITUTION:A slider 51 and springs 75, 83, 83' are provided at the pressurizing mechanism 50 for applying a specified pushing force to a movable cramp 3 at the heating, pressurizing and melting of the pipes by a heater and at the press welding of the pipes mutually, while pushing a movable cramp 3 to a stationary cramp 2. The slider 51 is caused to be slidable by a guidance rod 10, and a screw 61 is connected to the output shaft of a mator M, and further a screw 75 is arranged at the periphery of a screw part 61A. Springs 83, 83' are arranged between the large diameter part 77A of a slide pin 77 connecting the slider 51 to the movable cramp 3 and a draw out stopping plate 81. The sum of the spring constants of the springs 83, 83' is preferably caused to be equal to the spring constant of a spring 75.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a welding machine for butting and welding resin pipes (eg, polyethylene pipes or plastic pipes) together.

BACKGROUND OF THE INVENTION In recent years, resin pipes such as polyethylene pipes have been increasingly used as gas pipes in place of conventional metal pipes. The resin pipes are connected to each other by heating and fusing the opposing end surfaces of the resin pipes. That is, when the tubes are butt-fused together, a method is used in which the joint surfaces of both tubes are heated and melted with a heater, and the heated and melted surfaces are crimped together under a predetermined pressure. The pair of tubes crimped in this manner are completely integrated and connected after being allowed to cool for a certain period of time.

□ By the way, when butt-bonding plastic pipes together, for example, in the case of gas pipes or water pipes, the work is often done at a buried site. On the other hand, recently, transportation and maintenance.

For ease of management, pipes are wound in a spiral shape. Of course, pipes wound in a spiral like this are used by being straightened out on site.
It is impossible to stretch the pipe completely straight, so if the pipe is laid in a U-shaped trench (under the ground) buried at the burial site, the pipe will meander to some extent. That is, the pipe comes into contact with or is pressed against the side wall of the U-shaped groove at some point when viewed in the longitudinal direction. When the pipe is pulled in the longitudinal direction in this state, resistance is applied to the pipe due to friction between the pipe and the side wall of the U-shaped groove. That is, a tensile resistance force acts in the opposite direction to the crimping direction. It is necessary to apply an initial load in advance to the pipe, and thus to the movable clamp that clamps the pipe, by an amount corresponding to this resistance force. Otherwise, when the pipes are pressed against each other with a predetermined pressing force, the actual pressing force will be smaller than the predetermined pressing force by an amount corresponding to the above-mentioned initial load.

Therefore, the applicant of the present invention first developed and proposed a butt fusion machine that can effectively absorb and cancel out the initial tensile load for resin pipes subjected to such an initial tensile load and always perform fusion with a constant pressure force. (Utility Model Publication No. 59-61914). This makes it possible to substantially always maintain the crimp pressure at a predetermined value regardless of the magnitude of the undefined initial tensile load.

Problems to be Solved by the Invention However, the initial load that subsequently acts on the resin pipe is not limited to the above-mentioned tensile load that is opposite to the direction of the crimping pressure.
It has been found that the initial suppressing load in the same direction as the crimping pressure action direction, that is, in the opposite direction to the initial tensile load, must also be taken into consideration. In other words, the above-mentioned initial tensile load acts in a direction that separates the resin pipe from the crimping direction, and therefore, in order to obtain a predetermined crimping pressure, it is necessary to add an amount corresponding to this initial tensile load in advance. However, in the case of the initial pressing load, it acts in the direction of pressing the resin tubes together, so in order to obtain a predetermined crimping pressure, it is necessary to reduce the amount corresponding to the initial pressing load in advance. As with the initial tensile load, the initial pressing load may be caused by the above-mentioned "meandering", or the resin pipe may be tilted with respect to the horizontal, or the installation position of the butt fusion machine itself may cause the initial pressure load to occur. It is also caused by the component force in the direction of inclination of the weight of the resin pipe or the fuser body when the pipe is inclined.

However, although the structure disclosed in the above-mentioned Japanese Utility Model Application Publication No. 59-61914 can effectively absorb and offset the initial tensile load, there is no way to deal with the initial pressing load.

Against this background, an object of the present invention is to provide a butt fusion machine that can effectively compensate not only for the initial tensile load but also for the initial pressing load.

Another object of the present invention is to provide a butt fusion machine capable of compensating for the initial load in any direction as described above, which maintains the crimp force of the tube at a substantially constant value regardless of the magnitude of the initial load. The objective is to be able to automatically maintain the

- In order to achieve the above first purpose of Ruta, a fixed clamp on the machine base that holds one of the resin tubes to be fused, and the other resin tube that can be subjected to a predetermined initial tension or pressure load action. A movable clamp that holds the pipe is connected by a guide rod extending between the two clamps in a direction parallel to the pipe axis, so that the movable clamp can approach and leave the fixed clamp along the guide rod, and melts the resin pipe. In a butt fusion machine for resin pipes, which is equipped with a pressure mechanism that applies a predetermined pressure to a movable clamp in order to press the joining surfaces together with a predetermined pressure, according to the present invention, the pressure mechanism is parallel to the guide rod. a presser element connected to the movable clamp so as to be relatively movable in the tube axis direction via a slide pin; a first elastic means for absorbing and offsetting an initial tensile load transmitted to the clamp and acting on the movable clamp in a direction opposite to the welding direction; and an initial pressing force provided on the slide pin in a direction opposite to the initial tensile load. and second elastic means for absorbing and offsetting the load.

Furthermore, in order to achieve the second object of the present invention, according to the present invention, in addition to the above configuration, the pressurizing mechanism includes an actuator that moves the presser in the tube axis direction, and an actuator that drives the actuator. A driving means, a detecting means for detecting that the initial tensile or pressing load has been absorbed and canceled, and a control means for controlling the driving means in accordance with a signal from the detecting means are provided.

EXAMPLES Hereinafter, a butt fusion machine according to the present invention will be described in detail with reference to the accompanying drawings.

Figures 1 and 2 show polyethylene pipe P as a city gas conduit.
1. The outline of the entire butt fusion machine for butt fusion joining (butt fusion joining) of P2 at its end faces is shown.
Reference numeral 2.3 denotes a clamp that clamps one pipe P1 to be joined; 3 a clamp (vise) that clamps the other pipe P2; each clamp 2.3 has a split ring 4a, 4b. One of the two split rings 4b is formed integrally with the vise body, and the other ring 4a is pivotally connected thereto by a pivot pin 40 so as to be expandable. The pipe P1. P2
The tube is clamped by tightening the female thread 7 with a handle that is screwed into the male thread 6 provided on one side 4b of the split ring. For this purpose, the ring 4a is provided with a shoulder 14 against which the internally threaded member 7 is pressed. The clamp ring 4a can be opened counterclockwise in FIG. 3 by loosening the screw 7 and tilting it clockwise.

One of the clamps 2.3 is fixed to the base (bed) 1, and the lower part 4b of the other clamp 3 is attached to be slidable along a pair of parallel guide rods io, io. That is, the clamp 3 constitutes a carriage that approaches and moves away from the clamp 2. Both ends of the guide rod 10.10 are fixed to brackets 11 provided on the base 1.

The heater 20 (shown in phantom lines only in FIG. 1.2) is rotatably and slidably attached to one of the parallel guide rods 10, 10, and is brought to a retracted position away from both clamps 2.3 when not needed. 1. Both lamps are brought between the lamps 2 and 3 only when necessary.

The heater 20 is provided with, for example, a disc-shaped heater face (both sides) 28 (which may have any shape), and a pipe Pt is provided on the heater face 28.

The fused surface S1.82 of P2 is pressed and heated.

For pressing the movable clamp 3 toward the fixed clamp 2, a pressurizing mechanism 50 is provided to apply a predetermined pressing force to the movable clamp 3 when the pipe is heated and pressurized to the heater to melt it and when the pipes are crimped together.

The pressing mechanism 50 has a slider (presser) 51 that straddles the guide rods 10, 10 and is slidable along them. The slider 51 has an integral nut member 53 in its central portion. The output shaft 57 of the motor M in the motor housing 55 fixed to the base 1 is located in the central female threaded hole of the nut member 53.
A threaded portion 61A of the feed screw shaft 61, one end of which is connected to the feed screw shaft 61, is screwed into the feed screw shaft 61. The other end of the feed screw shaft 61 is rotatably supported by the fixed clamp 2 via a bearing 63 fixed by a presser plate 69. The feed screw shaft 61 passes through a cylindrical body 71 fixed to the movable clamp 3, and further passes through a through hole 73 of the movable clamp 3 coaxial with the cylindrical body 71. A first spring 75 constituting a first elastic means is provided around the threaded portion 61A of the feed screw shaft 61 between the cylindrical body 71 of the movable clamp 3 and the nut member 53 of the slider 51.

Both ends or at least one end of the spring 75 is not fixed and is free.

The slider 51 is connected to the movable clamp 3 by a pair of slide pins 77 (FIG. 4) extending parallel to the guide rod 10. The slide pin 77 has one end fixed to the slider 51 and the other end slidably inserted into a corresponding slide hole 79 formed in the movable clamp 3 in a piston-like manner.

The tip of the slide pin 77 is a large diameter portion 77A,
A second spring 83, which constitutes a second elastic means, is arranged between the large diameter portion 77A and a plate 81 that prevents the slide pin 77 from being removed, which is fixed to the movable clamp 3, so as to surround the slide pin 77. will be established. The sum of the spring constants of the two second springs 83 is preferably equal to that of the first spring 75.

A racked shaft 89 extending parallel to the guide rod 10 is fixed to the movable clamp 3 . The racked shaft 89 extends slidably within a corresponding through hole 91 formed in the slider 51. Further, the shaft with rack 89 can be moved in and out of a guide tube 96 that extends slidably through a corresponding through hole 95 of a mounting plate 93 fixed to the motor housing 5. The guide tube 96 is fixed to the slider 51 and can move therewith. The mounting plate 93 rotatably supports the feed screw shaft 61 by a bearing 97.

The pinion 99 screwed onto the shaft with rack 89 is the slider 51
It is rotatably supported by a support shaft 101 inside. As will be described later, the pinion 99 functions as an encoder for maintaining the amount of compression of the first spring 75, that is, the compression pressure between the pipes P1 and P2 at a predetermined value. An electromagnetic pickup 103 is provided close to the pinion 99 and detects the amount of rotation angle of the pinion 99 by counting the number of teeth of the nine pinions. The output signal S1 of the electromagnetic pickup 103 is sent to the control device 100.

The limit switches 105 and 106 are placed in front of the movable clamp 3 at a predetermined distance L1. They are fixedly installed on the base 1 with a distance L2 between them. Distance L1. L2 is activated by the limit switch 105 when the movable clamp 3 moves forward by a predetermined meter, that is, when the fused end surfaces S1 and S2 of the pipes P1 and P2 contact the heater surface, and when the fused end surfaces S1 and 82 directly contact each other. .106 corresponds to the ON position. Detection signals 82 and 83 of limit switches 105 and 106 are also sent to control device 100.

The butt welding operation of a pair of pipes is performed as follows.

Pipe P1. Attach P2 to vibe clamp 2.3 (
The installation work is not directly related to the present invention, so explanation is omitted.)
Before welding these two vibrators P1 and P2 together, it is necessary to heat the welding surfaces of both the pipes P1 and P2, and the heating action will be described later. P2 joint surface S1. It is assumed that the heating for the predetermined time in S2 is completed and the heater 20 is moved to the retracted position and removed.

After removing the heater 20, move the movable clamp 3 to the guide rod 10.
The fused surfaces 81 and 82 of the pipes Pz and P2 are brought into contact with each other.

At this time, first, consider the case where an initial tensile load in the direction of arrow A (FIG. 1) is applied to the pipe P2.

When the motor M is started by the start switch 121 (FIG. 5) in order to bring the pipe P2 into contact with the pipe P1, the feed screw shaft 61 rotates, and as a result, the slider 51 begins to move forward toward the movable clamp 3 by the nut member 53. . However, at this time, the initial tensile load T1 in the direction opposite to the forward movement of the slider 51 (in the six directions of arrows) is acting on the pipe P2, and therefore on the movable clamp 3.
Although the forward movement of the slider 51 is transmitted through the spring 75, the movable clamp 3 remains stationary without moving because of the initial tensile load acting thereon. As a result, the first spring 75 is compressed little by little. As soon as the amount of compression of the first spring 75 becomes larger than the initial tensile load, the movable clamp 3 starts moving toward the fixed clamp 2 together with the slider 51.

The movable clamp 3 is attached to the fused surface S2 of the pipe P2 to the pipe P1.
When the limit switch 106 is turned on, the detection signal S3 is sent to the control device 10.
0 counter 113 is reset. As shown in FIG. 5, the control device 100 converts the output waveform from the electromagnetic pickup 103 into a pulse output waveform via a waveform shaping circuit 111, and counts the number of pulses using a counter 113.

Since the pinion 99 is rotated by the racked shaft 89 as long as there is relative movement between the movable clamp 3 and the slider 51, the counter 113 also counts.
Since the pinion 9 is used to maintain the compression pressure between the pipes P1 and P2 at a predetermined value, the rotation of the pinion 99 until the pipes P1 and P2 come into contact is idling. That is, pipe P1
The counter 113 is always reset by the limit switch 106 immediately after P2 and P2 come into contact with each other. When the pipes P1 and P2 come into contact, the movable clamp 3 cannot move any further, but when the slider 51 is further advanced by the feed screw shaft 61, the first spring 75 is gradually compressed by the slider 51. This amount of compression determines the crimp pressure of pipes P1 and P2.

To determine this amount of compression of the first spring 75, the binion 9
Nine rotation angle amounts are utilized. In other words, if the slider 51 is advanced until the rotation angle amount of the pinion 99, that is, the number of pulses N by the counter 113 reaches a predetermined value X in the register 115, the first spring 75 will be compressed by a predetermined amount. Become. A comparison between N and X is performed by comparator 119. As soon as N≧X, relay 123 turns OFF
Then, the power supply to the drive circuit 125 of the motor M is stopped.

As described above, after the first spring 75 absorbs and offsets the initial tensile load T1, the motor M is driven until the first spring 75 is compressed by an amount corresponding to a predetermined crimp pressure, and the first spring 75 As soon as the motor M is compressed by a predetermined amount, the power to the motor M is cut off and the movement of the slider 51 is stopped. As a result, the movable clamp 3 and therefore the pipe P2 have a first spring 7
A pressing force determined only by the compression amount of 5 acts, so that the pipe P2 can be pressed against the pipe Pi with a predetermined constant crimping pressure.

As an actuator for operating the slider 51, it is also possible to use a fluid pressure cylinder, a cam, or other feeding means instead of the feed screw shaft. Further, instead of the toothed pinion 99, it is also possible to use a disc having holes at predetermined intervals around its periphery, and an optical encoder that optically reads the number of holes. Furthermore, if a pulse motor or a step motor is used as the motor M, an encoder is not necessary, and the pulse motor or step motor can be directly driven to rotate for a predetermined period at the same time as the limit switch 105 is turned on.

Next, the initial pressing load T2 (
A case in which FIG. 1) works will be explained.

In this case, before starting the motor M, the movable clamp 3 is already slightly moved toward the fixed clamp 2 with respect to the slider 51 by an amount balanced by the pair of second springs 83 due to the initial pressing load T2.

That is, the second spring 83 is compressed by a predetermined amount, while the first spring 75 in a free state has at least one end free and is away from the nut member 53 or the bottom of the cylinder body 71. Turn on the start switch 121 in this state.
When the motor M is started, the movable clamp 3 is moved by the second spring 83 due to the cooperation between the feed screw shaft 61 and the nut member 53.
It starts moving forward together with the slider 51 via the slider 51. After that, the movable clamp 3 turns on the limit switch 105, and then the slider 51 starts moving forward. One end of the first spring 75 is attached to the nut member 53 or cylinder body 71 that was separated.
Only the slider 51 moves until it touches the bottom of the first spring 75, and both ends of the first spring 75 come to the initial position (corresponding to the position shown in FIG. 4) where they touch the bottom of the nut member 53 and the cylinder 71. It should be noted here that when the first spring 75 reaches the above-mentioned initial position, the compressed second spring 83 has also returned to its initial free position. That is, at this time, the initial pressing load T2 has already been absorbed and canceled out.

The control mode for driving the motor M until a predetermined crimp pressure is applied to the pipe P2 is exactly the same as in the case of the initial tensile load T1.

Pipe P1. The work of heating and melting the end faces St 82 of P2 is exactly the same as the work of fusing the end faces 81° $2 of pipes Pi 2 and P2 described above. That is, when pressing the end surfaces S1 and 82 against the heater surface of the heater 20, it is necessary to stop the movable clamp 3 at a position corresponding to the thickness of the heater 20 (on the right side in FIG. 4), so the limit switch 10
The distance L2-Lt between 5 and 106 is the thickness t of the heater 20.
(The size should be the same as that shown in Fig. 1.) In this case, if a changeover switch 108 is provided between the limit switches 105 and 106, as shown in Fig. 5, only the necessary limit switches are needed. can be activated.

Also, pipe P1. End face St of P2.

If the crimping pressure between S2 and the crimping pressure on the heater surface are not the same, the setting value X of the register 115 described above may be set to a value corresponding thereto.

Also, depending on the length of the pipes Pi and P2 protruding from their respective clamps, the movable clamp 3 may be attached to the limit switch 10.
The position where 5,106 is added is the end face S1. of the pipe P1°P2.
The position where S2 contacts the heater surface or the end surface S1.8
It is possible that the two do not correspond to the positions where they abut each other.

In such a case, even after the movable clamp 3 turns on the limit switch 105 or 106, the movable clamp 3 will move further by a predetermined distance, but the pinion 99 will not move relative to the movable clamp 3 and the slider 51. There is no problem because it will not operate unless it occurs.

Instead of providing the first spring 75 around the feed screw shaft 61,
The movable clamp 3 and the slider 51 may be provided symmetrically around the guide rod 10, as shown by the imaginary line 75' in FIG. In this way, the force is stably transmitted from the slider 51 to the movable clamp 3 via the first spring, and there is no possibility that the force will be biased.

As described above, according to the present invention, the initial load acting on the pipe can be easily and reliably nullified regardless of its direction and magnitude.

Furthermore, according to the present invention, it is possible to automatically apply a predetermined constant pressure to the pipe to be welded at substantially all times.

[Brief explanation of the drawing]

FIG. 1 is a front view showing the overall configuration of a butt fusion machine according to the present invention, FIG. 2 is a plan view of FIG. 1, FIG. 3 is a left side view of FIG. 1, and FIG. 4 is a side view of FIG. 1. FIG. 5 is a block diagram showing an example of the control device shown in FIG. 4; DESCRIPTION OF SYMBOLS 1... Bed, 2... Fixed clamp, 3... Movable clamp, 10... Guide rod, 50... Pressure mechanism, 5
1...Slider (presser), 61...Feed screw shaft,
75...first spring, 77...slide pin, 83...
...Second spring, 105...Limit switch, 10o
...Control device, 1...Motor, Pr, P2...
pipe.

Claims (1)

[Claims] 1. A fixed clamp on the machine base that holds one resin pipe to be fused, and a movable clamp that holds the other resin pipe that can receive a predetermined initial tension or pressure load action. The two clamps are connected by a guide rod extending in a direction parallel to the tube axis, so that the movable clamp can approach and leave the fixed clamp along the guide rod, and the molten joint surfaces of the resin tubes are crimped together with a predetermined pressing force. A butt fusion machine for resin pipes is equipped with a pressure mechanism that applies a predetermined pressing force to the movable clamp, and the pressure mechanism applies pressure to the movable clamp in the tube axis direction via a slide pin parallel to the guide rod. a presser element that is relatively movably connected; a welding direction that is interposed between the presser element and the movable clamp, elastically transmits the movement of the presser element to the movable clamp, and acts on the movable clamp; has a first elastic means for absorbing and canceling an initial tensile load in the opposite direction, and a second elastic means provided on the slide pin for absorbing and canceling an initial pressing load in a direction opposite to the initial tensile load. A butt fusion machine for resin pipes, which is characterized by: 2. A fixed clamp on the machine that holds one resin pipe to be fused and a movable clamp that holds the other resin pipe that can receive a predetermined initial tension or pressure load are placed between the two clamps so that the pipe axis line The movable clamp is connected by a guide rod extending in a direction parallel to the guide rod, so that the movable clamp can approach and leave the fixed clamp along the guide rod. In the butt fusing machine for resin pipes, the pressurizing mechanism is movably connected to the movable clamp via a slide pin parallel to the guide rod in the direction of the tube axis. a presser element interposed between the presser element and the movable clamp, which elastically transmits the movement of the presser element to the movable clamp, and an initial tension acting on the movable clamp in the opposite direction to the welding direction. a first elastic means for absorbing and offsetting a load; and a second elastic means provided on the slide pin for absorbing and offsetting an initial pressing load acting in a direction opposite to the tensile load.
an actuator for moving the presser in the tube axis direction; a driving means for driving the actuator; a detecting means for detecting that the initial tension or pressing load has been absorbed and offset; 1. A butt fusion machine for resin pipes, comprising a control means for controlling a drive means in accordance with a signal.