JP2004314450A - Welding machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a welding machine capable of heating and melting a joint receiving port to fit and weld the same to a pipe end part by making a heating jig movable to fix a joint clamp to firmly hold a joint. <P>SOLUTION: The welding machine is constituted so as to weld the receiving port of a pipe joint to a pipe and equipped with a pipe joint fixing and holding means for fixing and holding a support stand for supporting the pipe joint and the pipe joint receiving port part in a horizontal direction, a pipe holding means sliding so as to approach and separating from the pipe joint fixing and holding means on the same axis as the pipe joint fixing and holding means and the heater provided between the pipe joint fixing and holding means and the pipe holding means so as to be capable of going in and out on the same axis as both means in a slide-movable manner to melt the outer surface of the pipe end part and the inner surface of the pipe joint receiving port part. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a welding machine for melting and joining a synthetic resin pipe and a pipe joint to a sleeve, and particularly when a water supply pipe or a hot water supply pipe in a building is supplied with a header pipe at a water supply point or a hot water supply point, or at a semiconductor manufacturing plant. The present invention relates to a welding machine suitable for use in welding a branch pipe receiving port of a header to a pipe in a branch pipe of an ultrapure water pipe line inside the pipe.
[0002]
[Prior art]
Conventionally, in order to melt-weld a pipe and a pipe joint, the inner peripheral surface of the socket of the pipe joint and the outer peripheral surface of the end of the pipe are fitted into a heater block, heated and melted, and then removed from the heater block to remove the pipe joint. A method of inserting and fitting a pipe end into a socket is common.
As this sleeve welding machine, "a first and a second clamp member for gripping the end of the pipe or the pipe joint in an opposed state, a guide rod for slidably inserting the two clamp members, and between the two clamp members. In a welding machine comprising a heating jig arranged, a heater face for a joint and a stopper on a joint side are attached to one side of the heating jig, and a heater face for a tube and a tube side stopper are attached to the other side, A slide rack is provided in parallel with the guide bar, one end of the rack is connected to a first clamp member, and the other end of the rack has a second clamp member inserted therethrough. A rotating shaft having a pinion that meshes with the rack is fixed on the shaft. A handle is provided at one end of the rotating shaft. Welder characterized in that it made possible. "Is known (e.g., see Patent Document 1.).
[0003]
[Patent Document 1]
Japanese Utility Model Publication No. 7-34663 (Pages 1-4, Figures 1-5)
[0004]
[Problems to be solved by the invention]
However, in the welding machine described in Patent Document 1, the ends of the pipe and the pipe joint are gripped by the first and second clamp members, and both clamp members are moved together by the rotation of the handle to approach / separate from each other. Then, heat fusion with a heating jig and fusion bonding between the pipe and the joint are performed.
In this case, a pipe joint which is difficult to grasp, for example, an elbow or a cheese (for example, when the main pipe diameter is largely different from the main pipe diameter such as a main pipe diameter of 150φ and a branch pipe diameter of 20φ), a branch of the branch header The joint cannot be held in a well-balanced manner simply by holding the socket such as the pipe socket with the joint clamp (first clamp). Therefore, when the joint clamp is moved, the joint moves and the joint for the heating jig is used. The heater face cannot be fitted coaxially with the heater face, or even if it can be fitted, the joint is eccentric when pressed and the heater face cannot be pushed into the depth of the socket of the joint, and the inner surface of the socket of the joint is sufficient In some cases, it could not be melted and could not be welded to the tube.
Even if the joint port can be heated, the clamp for the joint moves when the clamp for the joint is retracted and the heater face is separated from the joint port. In some cases, it may not be possible to fit the pipe.
[0005]
As described above, when the joint clamp is moved, in the case of a joint that cannot be stably held, the held joint moves and cannot be held in the same axial center state as the heater face or the pipe, so that the fitting with the heater face or the pipe is performed. Therefore, there is a problem that welding cannot be performed in some cases.
When the interval between a plurality of branch pipe receiving ports (header branch pipe diameter 16 to 50φ) of the branch header is as short as 135 to 155 mm, the pipe is welded and joined using a welding machine of Patent Document 1. To do so, there were the following problems.
That is, as shown in FIG. 3 of Patent Document 1, after the joint surface of the joint and the tube is heated and melted by the heater 1, the handle is rotated in the reverse direction to detach the end of the joint and the tube from the heater. Then, after the heater is flipped up (to the position shown by the one-dot chain line in FIG. 3), the two are fitted and welded. When a plurality of branch pipe receptacles as described above are present at short intervals. In addition, the adjacent branch pipe receptacle hits the heater during welding and cannot be welded and joined. Therefore, the interval between the branch pipe receptacles is limited (minimum spacing is 600 mm).
[0006]
[Means for Solving the Problems]
The present invention provides a welding machine capable of fixing a joint clamp by heating a heating jig so that a joint can be firmly held and a joint receiving port is heated and melted to be fitted and welded to a pipe end. Is provided.
[0007]
The welding machine according to claim 1, wherein the welding part is a welding machine for a pipe joint receiving portion and a pipe, wherein the support base for supporting the pipe joint and the joint receiving portion are fixedly held in a horizontal direction. Holding means, pipe holding means coaxial with the pipe joint fixing and holding means, sliding in close proximity to and detachable from the pipe joint fixing and holding means, and coaxially protruding and retracting between the pipe joint fixing and holding means and the pipe holding means And a heater for melting the outer surface of the pipe end slidable along the axis and the inner surface of the pipe joint receiving portion, the interval between the pipe holding means and the heater, and the heater and the pipe joint fixed holding means. A stopper that regulates an interval between the pipe holding means, a stopper that regulates a moving position of the heater toward the pipe holding means, and a stopper that regulates an interval between the pipe holding means and the pipe joint fixing and holding means. Features.
As described above, the pipe joint is held in a fixed state, and the pipe joint is supported by the support base, so that the joint receiving portion is fixed and held, so that it is more stable than when only the receiving portion is held. It can be held without moving, and heating and welding between the pipe joint and the pipe can be reliably performed.
[0008]
According to a second aspect of the present invention, there is provided a welding machine according to the first aspect, wherein the pipe holding means is slidable toward and away from the pipe joint fixed holding means along the guide, and is parallel to the guide. One end of the rack slidably mounted on the rack is fixed to the tube holding means, and the rack is slid by rotating a pinion rotatably provided at a predetermined position so as to mesh with the rack by rotating the handle, The pipe holding means approaches and separates from the pipe joint fixing and holding means.
In this manner, the pipe holding means can be moved toward and away from the pipe joint fixed holding means along the guide by sliding of the rack by rotation of the pinion, so that the pipe joint fixed holding means is fixed. Then, the pipe holding means is slid, the joint receiving portion and the pipe end are inserted into the heater to be heated and melted, the pinion is rotated in the reverse direction, and the pipe holding means is retracted, and the fitting receiving portion and the pipe end are rotated. By moving the heater away from the tube axis, the tube holding means is brought close to the pipe joint fixing and holding means again, and the pipe end can be fitted and welded to the joint receiving port. That is, a series of welding operations can be performed by forward and reverse rotation of the handle, and the operation is simplified.
[0009]
Further, in the welding machine according to the third aspect, the heater is mounted on the slidable guide rod supported by the slide bearing, and the heater is mounted so as to advance and retreat by the operation of the fluid cylinder. Switching can be done instantly only by turning on and off.
[0010]
Further, the welding machine according to claims 4, 5 and 6 is an invention in which the pipe joint fixing and holding means in claims 1, 2 and 3 is specified as a header fixing and holding means. The same effect as the invention relating to the present invention is exerted. In addition, the header is fixed and held, and the pipe holding means can be moved closer to and away from the header fixed holding means and slidable, and the heater is provided so as to be able to come and go, so that the space between the branch pipe receiving portions of adjacent headers can be increased. Can be welded even if it is narrow, making it a versatile welding machine.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described based on examples with reference to the drawings.
1 to 3 show an embodiment of the present invention, FIG. 1 is a front view of the welding machine of the present invention, FIG. 2 is an enlarged plan view of FIG. 1, and FIG. 3 is an enlarged side view taken along line AA of FIG. is there. This embodiment shows an example of a welding machine for welding a pipe P to a branch pipe receiving portion R of a header H provided with a branch pipe.
[0012]
In FIGS. 1 to 3, 1 is a header fixing and holding means, 2 is a tube holding means, and 3 is a heater. The header fixing and holding means 1 includes a support base 11 for supporting the main body S of the header H, a pressing tool 12 for pressing and holding the main body S supported by the support base 11, and a branch pipe receiving portion R of the header H in a horizontal direction. And a branch pipe receiving fixture 13 for holding the header H fixedly.
The reason why the direction of the branch pipe receiving portion R of the header H is set to the horizontal direction is to facilitate the fixing and holding of the header H and the pipe P, and may be slightly inclined.
[0013]
The pipe holding means 2 has a pipe holder 21 for holding the pipe end of the pipe P welded to the branch pipe receiving portion R of the header H. The axis of the pipe holder 21 is the branch pipe holder. The branch pipe receiving portion of the header H, which is provided coaxially with the axis of the mouth fixing device 13, that is, the axis of the pipe P held by the tube holding device 21 is held by the branch tube receiving portion fixing device 13. It is configured to be held coaxially with the axis of R. The pipe holding means 2 is provided so as to be slidable toward and away from the header fixed holding means 1 so as to be able to approach and separate therefrom.
In order to slide and move the tube holding means 2 close to and away from the header fixed holding means 1, two guide rods 22 are provided in the sliding movement direction of the tube holding means 2. Is fitted to the guide rod 22 and slides. One end of a rack 23 is fixed to the pipe holding means 2 in parallel with the guide rod 22. The rack 23 is rotated forward and backward at a predetermined position. When the handle 25 attached to the rotation shaft of the pinion 24 is rotated forward and backward, the rack 23 moves along the guide rod 22 and one end of the rack 23 is fixed. The means 2 slides along the guide rod 22.
[0014]
The heater 3 is provided with a heater face 32 for melting the inner surface of the branch pipe receiving portion R of the header H and a heater face 33 for melting the outer surface of the pipe end of the pipe P in the heater main body 31. It is provided in the middle of the means 2 and is coaxial with the branch pipe receiving portion R to be welded and the pipe P. When the end of the pipe P is to be inserted and fitted into the branch pipe receiving portion R, The holding means 2 is provided so as to be able to protrude and retract so as to move to a position which does not hinder the sliding movement. In order to allow the heater 3 to move in and out, the heater main body 31 is fixed to the tips of guide rods 35, 35 supported and slid by the slide bearings 34, 34, and the heater main body 31 is moved by the air cylinder 36. Has become. The direction in which the heater 3 moves in and out may be up, down, front and back as long as it does not hit the guide bar 22 for movement of the tube holding means 2. It is preferable to be able to move it downward so that it can be stored.
[0015]
The heater 3 is slidable in a direction parallel to the guide rod 22. To this end, the heater 3 attached to the tip of the guide rods 35 and 35 and assembled so as to be retractable by the air cylinder 36 is fixed below the guide rods 22 and 22 in parallel with the guide rods 22. 37, 37 are movably attached. As shown in FIGS. 1 and 3, a sliding plate 38 is slidably mounted on the guide rods 37, 37 by slide bearings 39, 39, and the guide rods 35, 35 are supported on the sliding plate 38 so as to be able to protrude and retract. The slide bearings 34 and 34 and the air cylinder 36 are mounted.
[0016]
In the welding machine of the present invention, the header fixing and holding means 1, the pipe holding means 2, and the heater 3 are respectively attached to the gantry 4, and a heating temperature and a heating time can be set to the heater face 32 and the heater face 33 of the heater 3. An electric heater is provided so as to be electrically heated, and compressed air is supplied to the air cylinder 36.
[0017]
Further, the heater body 31 holds the space between the tube holding means 2 and the heater 3, that is, the tube holding when the end of the tube P held by the tube holding means 2 is inserted into the heater face 33 for a predetermined length. A stopper 51 for regulating an interval between the means 2 and the heater 3 to a predetermined interval, and an interval between the heater 3 and the header fixing and holding means 1, that is, the branch pipe receiving fixture 13 of the header fixing and holding means 1 A stopper 52 is provided for regulating the interval between the heater 3 and the header fixing and holding means 1 at a predetermined interval when the heater face 32 is inserted into the branch pipe receiving portion R fixed at a predetermined length. A predetermined length of the outer surface of the end portion and the inner surface of the branch pipe receiving portion R of the header H can be heated and melted.
[0018]
Further, a stopper 53 for regulating the moving position of the heater 3 toward the tube holding means 2 is attached to the guide rod 37 slidably moving the heater 3 so as to adjust the fixed position, and is inserted into the heater face 33. The end of the tube P that has been heated and melted can be separated from the heater face 33.
Further, a stopper 54 for regulating the distance between the pipe holding means 2 and the header fixing and holding means 1 is provided on the pipe holding means 2, and the end of the pipe P heated and melted by the heater 3 is connected to the branch pipe of the header H. The length of insertion at the time of insertion into the socket R can be adjusted.
Note that these stoppers 51, 52, 54 may be provided on the colliding partner member.
[0019]
Next, an operation of welding the pipe P to the branch pipe receiving portion R of the header H using the above welding machine will be described.
First, the heater face 32 and the heater face 33 are mounted on the heater body 31, the header H is fixed to the header fixing and holding means 1, and the pipe P is held by the pipe holding means 2. To fix the header H, the header main body S is placed at a predetermined position on the support base 11, pressed and fixed by the pressing tool 12, and the branch pipe receiving section R is fixed by the branch pipe receiving section fixing tool 13. Further, the end of the pipe P is projected from the end face of the pipe holder 21 of the pipe holding means 2 by a predetermined length and held by the pipe holder 21. At this time, the adjustment is performed so that the axes of the branch pipe receiving portion R, the heater face 32, the heater face 33, and the pipe P coincide.
[0020]
In addition, the branch pipe receiving part fixing tool 13 and the pipe holding tool 21 hold the branch pipe receiving part R and the pipe P, are divided into upper and lower parts, and the rear side can be opened and closed with a hinge, and the front side can be opened and closed. A handle is provided on the front side of the upper half, and the upper half can be opened and closed with the handle.
In addition, these branch pipe receiving portion fixing tool 13 and pipe holding tool 21 are designed such that the liner is exchanged and mounted in accordance with the outer diameters of the branch pipe receiving portion R and the pipe P. Even a pipe P having a diameter can be held so as to have the same axis. At this time, the support 11 of the header fixing and holding means 1 is also replaced according to the diameter of the main body S of the header H.
Further, the heating temperature and the heating time of the electric heater provided on the heater face 32 and the heater face 33 of the heater 3 are set.
[0021]
When the preparation is completed, the handle 25 is rotated to move the rack 23 forward, so that the tube holding means 2 fixed to the leading end of the rack 23 slides along the guide rod 22 and moves forward to move the tube holding means. The end of the tube P held by the second fitting 2 fits into the recess of the heater face 33. When the handle 25 is further rotated, the heater 3 moves forward together with the tube holding means 2, and the heater face 32 fits into the branch tube receiving portion R of the header H. The reason why the heater 3 moves forward is that the heater 3 is slidably mounted along the guide rods 37.
When the handle 25 is further rotated in this state, the stoppers 51 and 52 provided on the side surfaces of the heater 3 abut against the tube holding means 2 and the header fixing and holding means 1, and the degree of fitting of the tube P to the heater face 33. In addition, the degree of fitting of the heater face 32 to the branch pipe receiving portion R becomes appropriate, and the outer surface of the end of the pipe P and the inner surface of the branch pipe receiving portion R can be heated and melted in a state suitable for welding.
[0022]
While maintaining this state, energization of the electric heaters of the heater faces 33 and 32 is started to heat the heater faces 33 and 32, and the outer surface of the end of the pipe P and the inner surface of the branch pipe receiving portion R are heated and melted. After the set heating time has elapsed, when the handle 25 is rotated in the reverse direction, first, the heater 3 and the tube holding means 2 are retracted in an integrated state, and the heater face 32 is separated from the branch pipe receiving portion R. When the handle 25 is further rotated in the reverse direction, the heater 3 hits the stopper 53 and is prevented from retreating, and the pipe P separates from the heater face 33.
[0023]
Here, first, the heater 3 and the tube holding means 2 are retracted in an integrated state, and the heater face 32 is separated from the branch pipe receiving portion R because the branch pipe receiving portion R and the heater face 32 are separated from each other. While the pipe P and the heater face 33 are fitted with each other in a tapered manner, the fitting between the pipe P and the heater face 33 does not have a taper, and the cylindrical pipe P is fitted to the heater face 32 having a flat inner peripheral surface. , It will be tightly fitted. Therefore, even after heating and melting, the fitting state between the pipe P and the heater face 33 is tighter than the fitting state between the branch pipe receiving portion R and the heater face 32. First, the heater face 32 is separated from the branch pipe receiving portion R.
[0024]
When the heater 3 is separated from the pipe P and the branch receiving portion R, the air cylinder 36 is operated to retract the spindle and move the heater 3 downward.
Then, the handle 25 is rotated to advance the tube P held by the tube holding means 2, and the heated and melted end of the tube P is fitted to the fixedly held heated and melted branch pipe receiving portion. With the stopper 54 provided on the tube holding means 2 kept in contact with the header fixing and holding means 1 and the fitting portion is cooled, they are welded.
[0025]
When the weld is cooled, the pipe holding means 2 and the header fixing and holding means 1 are opened, and the process proceeds to the next welding operation. When welding the pipe P to another branch pipe port R of the same header H, the mounting position of the header H on the support base 11 is shifted, and the other branch pipe port R is connected to the branch pipe port R. The other tube P is held in the tube holding means 2 fixed and held by the part fixing device 13 and retracted by the reverse rotation of the handle 25, and the air cylinder 36 is operated to make the heater 3 coaxial with the tube P. What is necessary is just to advance upward to a certain position.
[0026]
When the tube P is welded to another header H, the same operation may be performed after removing the welded header H and the tube P and returning the welding machine to the initial state.
However, when the diameter of the main body S of the header H, the diameter of the branch pipe receiving portion R, and the diameter of the pipe P are changed, the support 11 of the header fixing and holding means 1 is moved to the axial center of the branch pipe receiving portion R. The support base is replaced so that the diameters of the pipes become the same, and the liner is replaced with a liner having an appropriate size corresponding to the change in the diameter of the branch pipe receiving portion R and the pipe P, and the heater faces 32 and 33 of the heater 3 are replaced with the receiving portion and the pipe. It will be necessary to replace it with one that matches the caliber of.
[0027]
Although the above description has shown an example in which the pipe P is welded to the branch pipe receiving portion R of the header H, in the present invention, a socket such as an elbow or a cheese may be used instead of the header H to stabilize the socket. It is possible to stably weld even a pipe joint that cannot be held.
In this case, replace with a support base that matches the shape and diameter of the pipe joint to be welded, so that the pipe joint can be stably supported, and the socket for welding the pipe is oriented horizontally and coaxial with the pipe. What is necessary is just to make it.
[0028]
In the above-described embodiment, the rack 23 and the pinion 24 are used to move the tube holding means 2, and the pinion 24 is rotated forward and backward by the handle 25. Also, a fluid device such as an air cylinder may be used.
Further, in order to provide the heater 3 so as to be able to protrude and retract, the heater main body 31 is fixed to the tips of guide rods 35, 35 supported and slid by the slide bearings 34, 34, and the heater main body 31 is moved by the air cylinder 36. However, a crank mechanism or a cam mechanism may be used as long as the heater 3 can be supported and fixed and the guide rod can be moved forward and backward.
[0029]
【The invention's effect】
Since the welding machine according to the first aspect of the present invention includes the support base for supporting the pipe joint and the pipe joint fixing and holding means for fixing and holding the joint receiving portion in the horizontal direction, the receiving portion is gripped. The pipe joint can be fixed more stably than the clamp means.
In addition, the pipe holding means is slidable toward and away from the pipe joint fixing and holding means, and a heater is provided between the pipe joint fixing and holding means and the pipe holding means so as to be able to protrude and fall along the axis. Slidable, the pipe joint fixing and holding means can be fixed without moving, so that the pipe joint can be fixed stably, as a result, It is a welding machine that can reliably perform welding work such as heating and melting work to insert a heater into the socket and the pipe of the pipe joint, and joining work to fit the heated and melted pipe and the mouth with each other. .
[0030]
Further, in the welding machine according to the second aspect, the pipe holding means can be slid close to and away from the pipe joint fixing and holding means along the guide by sliding of the rack by rotation of the pinion. With the joint fixing and holding means fixed, the pipe holding means is slid, the joint receiving portion and the pipe end are inserted into the heater to heat and melt, and the pinion is reversely rotated to retract the tube holding means. To separate the joint receiving port and the pipe end from the heater, move the heater from above the pipe axis, again bring the pipe holding means close to the pipe fitting fixing and holding means, and place the pipe end in the fitting receiving section. Fitting and welding can be performed. That is, a series of welding operations can be easily performed by forward and reverse rotation of the handle.
[0031]
In the fusing machine according to the third aspect of the present invention, the heater is mounted on the slidable guide rod supported by the slide bearing, and the heater is mounted so as to advance and retreat by the operation of the fluid cylinder. Switching can be done instantly only by turning on and off.
[0032]
Further, in the welding machine according to claims 4, 5 and 6, the pipe joint fixing and holding means in claims 1, 2 and 3 is specified as a header fixing and holding means. The same effect as the invention relating to the present invention is exerted. In addition, the header is fixedly held, the pipe holding means can be moved closer to and away from the header fixed holding means, and the heater can be protruded and retracted, so that the distance between the branch pipe receiving portions of adjacent headers can be increased. Can be welded even if it is narrow, making it a versatile welding machine.
[Brief description of the drawings]
FIG. 1 is a front view showing one embodiment of a welding machine of the present invention.
FIG. 2 is an enlarged plan view of the embodiment shown in FIG.
FIG. 3 is an enlarged side view taken along line AA of FIG. 1;
[Explanation of symbols]
H Header S Header main body R Header branch pipe receiving part P Pipe 1 Header fixing and holding means 11 Supporting stand 13 Branch pipe receiving part fixing tool 2 Pipe holding means 21 Pipe holding tool 22 Guide rod 23 Rack 24 Pinion 25 Handle 3 Heater 34 Slide bearing 35 Guide rod 36 Air cylinder 4 Frames 51, 52, 53, 54 Stopper

Claims (6)

A welding machine for a pipe joint receiving portion and a pipe, comprising: a support base for supporting the pipe joint; and a pipe joint fixing and holding means for fixing and holding the joint receiving portion in a horizontal direction. A pipe holding means that slides in a manner close to and releasable from the pipe joint fixed holding means coaxially with the pipe joint, and is coaxially protrudable and retractable along the axis between the pipe joint fixed holding means and the pipe holding means. A stopper for melting the outer surface of the pipe end and the inner surface of the pipe joint receiving portion, the stopper regulating the distance between the pipe holding means and the heater and the distance between the heater and the pipe joint fixing and holding means, and the heater A stopper for regulating a moving position of the tube holding means to the pipe holding means side and a stopper for regulating an interval between the pipe holding means and the pipe joint fixing and holding means. The pipe holding means is slidable toward and away from the pipe joint fixed holding means along the guide, and one end of a rack mounted slidably in parallel with the guide is fixed to the pipe holding means, and A pinion rotatably provided at a predetermined position so as to mesh with the handle is rotated by rotating the handle to slide the rack so that the pipe holding means approaches and separates from the pipe joint fixed holding means. Item 1. A welding machine according to Item 1. 3. The welding machine according to claim 1, wherein the heater is mounted on a slidable guide rod supported by a slide bearing, and the heater is mounted so as to advance and retreat by operation of the fluid cylinder. A welding machine for a branch pipe receiving portion and a pipe provided in a header main body, a support base for supporting the header main body and a header fixing and holding means for fixing and holding the branch pipe receiving portion in a horizontal direction, and A tube holding means coaxial with the header fixing and holding means and slidably close to and releasable from the header fixing and holding means, and between the header fixing and holding means and the pipe holding means, capable of protruding and retracting coaxially and sliding along the axis. A stopper that includes a heater that melts an outer surface of a movable pipe end and an inner surface of a branch pipe receiving portion, and that regulates an interval between the pipe holding unit and the heater and an interval between the heater and the header fixed holding unit. A stopper for restricting a position of the heater moving toward the tube holding means and a stopper for restricting an interval between the tube holding means and the header fixing and holding means are provided. Welding machine. The tube holding means is slidable toward and away from the header fixed holding means along the guide, and one end of a rack mounted slidably in parallel with the guide is fixed to the tube holding means and meshes with the rack. The pinion rotatably provided at a predetermined position is rotated by the rotation of the handle to slide the rack so that the tube holding means approaches and separates from the header fixing holding means. The welding machine described. 6. The welding machine according to claim 4, wherein the heater is mounted on a slidable guide rod supported by a slide bearing, and the heater is mounted so as to advance and retreat by operation of a fluid cylinder.

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