JPH02235572A - Pipe welder - Google Patents

Abstract

PURPOSE: To weld a thin wall pipe without any hot spot by operating a pair of welding electrodes so as to rotate facing each other around the pipe as the center and weld only during moving from an upper position to a lower position and welding a semicircle each respectively. CONSTITUTION: Electrodes 18, 20 are rotated, the electrode 20 is placed in an uppermost position and the electrode 18 is placed in a lowermost position. A pipe 10 is set to a V shaped block 22 and a weld zone is fitted to the electrodes 18, 20. The electrode 20 is electrically energized, welding is executed through 180 degrees down to the lowermost position while rotating the electrode 20 clockwise, and energization is stopped. At this time, the electrode 18 is placed in the uppermost position. The electrode 18 is electrically energized, welding is executed down to the lowermost position while rotating the electrode 18 counterclockwise, residual welding through 180 degrees is executed to complete the whole circle welding of the pipe 10. Since the whole welding is executed with the electrode faced downward, the excellent welding without generating any hot spot is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pipe welding machine, and more particularly to a pipe welding machine adapted to perform high quality welds in thin-walled pipes. [Prior art and its problems] Thin-walled pipes are widely used in muffler devices for internal combustion engines. Such muffler devices are widely used in connection with automobiles. As a muffler device, there is a muffler that includes a pipe extending to its input side and a pipe extending from its output side. This pipe is made of thin-walled material (usually steel).

Also, this pipe is usually not straight, that is, it does not extend in a straight line from the input side to the output side of the muffler. This pipe is usually bent with a number of special curvatures and, when installed in connection with the chassis of a motor vehicle, is located in a special area so that it does not interfere with the working parts of the motor vehicle. This pipe usually extends through the empty space inside the chassis of a car.

A number of pipe joints must be formed by threading the pipes through the undercarriage. Each pipe joint must be sealed throughout.
Sealing with adhesives or rubber seals is a time consuming process.

When manufacturing a 7FRA device, it is important that all seals are 100% effective (no leaks) and do not deteriorate over time. A leaky muffler system can be hazardous to the health of vehicle occupants. Also, today it is against environmental standards to release car engine exhaust directly into the atmosphere without passing it through a pillow system equipped with a catalytic converter. The reason is that it causes air pollution.

A widely used technique for producing the most effective seals is to weld each joint in the muffler system. However, this welding must be done carefully due to the thin wall structure of the muffler pipe. conventionally,
This welding was normally done by hand. However, manual welding often results in poor welds and
Leakage may occur from this weld. It is also very easy to create "hot spots" in welding operations. These hot spots create holes in the muffler pipe, causing the product to be rejected. The rejection rate associated with manufacturing muffler pipe by using manual welding techniques is approximately 20 percent. This construction of muffler pipes is associated with automobile assembly lines.

It is known to use automatic welding machines to weld pipes. This type of equipment is commonly used on all types of pipes, but is generally used on pipe sidewalls or those thicker than the pipe sidewalls of macra devices. Due to the thin-walled structure of muffler pipes, automated welding is much more difficult than for most pipes. A common procedure associated with automatic welding equipment is to move the welding electrode 360 degrees around the weld joint to effect the desired weld. Here, it was found that welding can be performed successfully if the welding electrode is moved downward, that is, in the direction of gravity. However, when the welding electrode begins to move against gravity, the welding beat becomes a "puddle".
dle)r L/ tends to create "hot spots" and create holes in the pipe. It has therefore been found that common automatic welding operations are unsatisfactory when used in conjunction with muffler pipes.

OBJECTS AND CONSTRUCTION OF THE INVENTION The structure of the present invention is an automatic welding device for muffler pipes and other similar types of thin-walled pipes, which performs automatic welding only in a downward direction from a high point to a low point. related to automatic welding equipment. Here, two separate welding electrodes placed at least 90 degrees apart around the pipe are utilized. In some configurations, the welding electrodes are diametrically spaced apart. In this configuration, one of the welding electrodes starts at the uppermost point of the weld joint and moves clockwise through 180 degrees to complete the weld along the joint. During this movement, the other welding electrodes are deenergized and are moved toward this northernmost point and then energized. The first welding electrode is deenergized. The energized welding electrode is moved counterclockwise through 180 degrees to complete this portion of the weld joint. All welding is done in a downward direction. Therefore, there are no hot spots that could cause holes in the pipe, and therefore no rejects. The actual welding work is precisely controlled by using a computer, which is considered convenient in conjunction with an automatic welding machine. The welding head can be adjusted slightly back and forth relative to the pipe and can always maintain firm contact with the pipe.

In another configuration, the welding electrodes are placed 90 degrees apart from each other. These welding electrodes are energized simultaneously to weld a 90 degree arc of each welding electrode or circular welding beat. Each welding electrode is actuated twice to form a circular weld bead. In each configuration, a pilot welding electrode may be provided in close combination with each welding electrode.

It is a primary object of the present invention to provide an automatic welding device that is capable of producing high quality welds in thin-walled pipes and significantly reducing the number of rejects associated with the pipes.

[Example] Referring to the drawings, a part of a muffler piping system consisting of a thin-walled muffler pipe 10 and a thin-walled muffler pipe 12 is shown here. The muffler pipe 12 is an annular sleeve 1
It has an elongated end constituting 4. One end of the pipe 10 is adapted to fit within this annular sleeve l4. The sealing between the pipe IO and the sleeve 14 is to take place at the edge 16. Also note that the drawings do not show welding electrodes 18 and 20 in alignment. However, in reality, this or the edge l6
Please understand that this is the correct position. The pipe 10 is designed to rest on a ■-shaped block 22. The ■-shaped block 22 has a recessed seating area 24 in which the pipe 10 is positioned. A separate fixing bracket 26 is utilized to secure the pipe 10 in place, such as when located within the seating area 24. The anchoring bracket 26 is bifurcated to form legs 28,30. leg portion 28,
30 are interconnected by a top 32.

The inner surface of the leg 28 has a recess 34, and the inner surface of the leg 30 has a similar leg 36. The nape 32 has a screw hole 3.
8 is formed. This screw hole 38 has an ordinary bolt.
Fastener 40 is screwed together.

■ The figure-shaped block 22 has a side rail 42 in the longitudinal direction,
Includes 44. Recess 34 engages sight rail 42 and recess 36 engages side rail 44. Bracket 26 slides along rails 42, 44 to a predetermined longitudinal position. At this time, the bolt/fastener 40 is rotated within the threaded hole 38 to bring its inner end into contact with the pipe 10. Bolt fastener 40 is then rotated further to apply force to pipe 10 and hold it tightly within seating area 24 of square block 22. It should be understood that the separate bracket 22 can be removed to remove the pipe 10 from the welding apparatus 46 of the present invention. ■ The shape block 22 is the hole 50 of the housing body 52.
The hole 48 is aligned with the hole 48. Housing body 52 has a straight ridge 54 defining a hole 50. ■The figure-shaped block 22 rests on this protuberance 54, and the retaining pin 56 is inserted into the hole 48.
, 50 are concatenated. A pair of threaded bolts (not shown)
secures housing body 52 and V-shaped block 22 together. The housing body 52 includes a narrow sheet-like portion 58 in which a centrally located enlarged recess 60 is formed. The pipe IO is positioned within this recess 60. A gear body 62 is mounted in direct contact with the sheet-like portion 58. This gear body 62 has a sheet-like portion 58
It can be slid against. Gear body 62 has an enlarged recess 64 of the same dimensions and matching recess 60. The gear body 62 has an annular recess 66. A link gear 70 is fixed to the gear body 62 with bolts 68. Ring gear 70 is located within annular recess 66. A recess 66 is mounted on the inner surface of the gear body 62. An annular enlarged recess 72 is provided on the outer surface of the gear body 62.

Annular enlargement <A plate 74 is mounted within the recess 72. Plate 74 also has an enlarged recess 76 which is the same size and aligned with recesses 60, 64. The plate 74 is attached to the housing by bolts 78.
It is fixed to the body 52. However, gear body 64 can slide relative to plate 74.
A pair of spaced apart actuation buttons 80, 82 are provided mounted within recess 66 and secured to gear body 62. These buttons 80, 82 are slightly elevated above the surface of the recess 66. The functions of these buttons 80, 82 will be explained later.

A drive gear 84 is installed within the recess 66. This drive gear 84 meshes with the ring gear 70. The drive gear 84 is fixed to a motor shaft 86. Motor shaft 86
is supported by a bearing assembly 88. The bearing assembly 88 is attached to the chamber 90 of the motor mount spacer 92.
It is installed inside. The spacer 92 is secured to the housing body 52 by suitable fasteners.

The shaft 86 is an electric 4L mounted in the motor housing 94.
! (not shown) and is operated by it. The operation of the electric motor is controlled using some type of computer (not shown). The electric motor within motor housing 94 is a reversible electric motor. A mounting plate 98 is secured onto the housing body 52 by fasteners 96. A limit switch housing 100 is mounted on this mounting plate 98.
is installed. The limit switch eighting 100 has an actuation arm 102. This actuating arm 1
It is in constant contact with 02 Palever 104. Leher 104
The inner end of the housing 100 is pivotally connected to the housing 100 at a connecting portion 106 . lever! The outer end of 04 is connected to a wheel 108. The wheel 108 is in constant contact with the surface of the recess 66 of the gear body 62. Similarly, the housing body 52 has fasteners 11
The mounting plate 112 is attached by 0. The plate 112 has a limit 5) and switch housing 1.
14 is attached, and this limit switch housing 114 is almost the same as the housing 100. A lever 116 extends from the bottom surface of the housing 114,
Its outer end is connected to roller II'8. even here,
The roller 118 is in constant contact with the wall surface of the recess 66. An electrode 18 is fixed in the probe 122 by a set screw 120. The block 122 is made of a conductive material such as copper. The electrode 18 is made of ceramic gas.
It is installed inside the cup 124. A sleeve 126 is disposed concentrically surrounding a portion of the electrode 18, and this sleeve is integral with the block 122. sleeve 126
is screwed to flag 12B. Blug 128 also has external threads and is threadedly engaged with the inner surface of gas cup 124. An annular space is provided between the sleeve 126 and the electrode l8, through which an inert gas is introduced after being supplied to a passage 130 formed in the block 122. Gas is supplied to passage 130 through conduit 132.
An inert gas, such as nitrogen, is supplied to conduit 132 from a source (not shown). gas cup 1
A plastic seal 134 is installed between block 122 and block 122.

Seal 134 prevents gas leakage between block 122 and gas cup 124 and electrically isolates gas cup 124 from block 122. A cooling block 136 is electrically connected to the block 122. The cooling block 136 has a recess 13B into which the block 122 fits tightly. Place set screw 140 or cooling block 136 in block 1.
It is fixed at 22.

A water inlet passage 142 and a water outlet passage 144 are provided within the cooling block 136 . Water inlet passage 142 connects to water supply conduit 146 and water outlet passage 144 connects to water discharge conduit 148. Water is continuously supplied through passages 142, 144 to dissipate excess heat generated during the welding process. Block 136 is also made of copper.

Block 136 is secured to mounting block 152 by bolt fasteners 150.

The mounting block 152 is secured to the gear body 62 by fasteners 154. Here, welding electrode 2
It will be appreciated that block 15B is mounted in a similar manner within a gas cup 156 mounted on block 158 similar to block 122.
The cooling block 160 is mounted to a block 162 similar to block 152. Block 162 is fixed to gear body 62. Further, as is clear from the drawing, the electrodes 18 and 20 are connected to the pipe 1.
They are located diametrically opposite each other with 0 as the center. Further, the electrodes l8 and 20 are spaced apart from the wall surface of the pipe 10 at equal intervals. Gas is supplied to gas cup 156 by conduit 164. In addition, water discharge conduit 166
are shown in relation to cooling block 160.

A pair of spaced apart recesses are formed in the sides of housing body 52, with only recess 168 shown in the figure. Each recess 168 has a coil spring 1
70 is installed. The free end of the coil spring 170 fits into a recess 172 (again only one shown) formed in the intermediate base 174. The base 174 is attached to the housing body 52 by bolts 176.
It is installed on. Here, the bolt 176 is attached to the intermediate base 1
74 is installed at a slight distance from the housing body 52 to form a gap 178. As a result, housing body 52 can move relative to intermediate base 174 over a distance less than the width of gaff 78. The normal rest position is when spring 170 is fully extended as shown. Intermediate base 174 is connected to main support base 18 by fasteners 180.
It is attached to 2. This main support base 182 is adapted to be fixed to a fixed structure (not shown). The operation of the welding device 46 of the present invention is as follows. base 182
is attached to a fixed structure such that the electrode 18.20 lies in a vertical plane.

This means that block 162 will be in a higher position than block 152. Referring to Figure 2, the structure shown here must be rotated 90 degrees counterclockwise. Block 152 may be placed higher if desired. Next, pipe 10 is set to V as mentioned above.
Place it on the glyph block 22 and connect the edge l6 to the electrodes l8 and 20.
located on a vertical plane extending between At the beginning of a welding operation, welding electrode 20 is energized and welding electrode 18 is deenergized. Welding electrode 20 is moved clockwise, which is accomplished by rotation of gear 84 causing ring gear 70 to rotate. This rotation of ring gear 70 is done by button 80.
continues until it engages roller 10B, and roller 108 linearly moves switch member 102 which de-energizes the motor rotating gear 84. At this time, the current being supplied to electrode 20 is deenergized, electrode 20 is now in a vertically downward position, and electrode 18 is now in a vertically upward position. At this time, the motor drive gear 84 is again energized in the opposite direction, and the electrode 18 is energized. As a result, electrode l8 is moved counterclockwise through 180 degrees, and the remaining 180 degrees
Perform degree welding. Electrode 18 is then energized.
A satisfactory weld beat has now occurred and the pipe 10 is firmly welded to the pipe 12. The bracket 26 is then removed and the welded pipe is removed from the welding fitting W46. The electrodes 18, 20 can also be mounted at 90 degrees apart instead of 180 degrees as shown. In this case, the welding operation will be different. Electrode 20 remains in the same position as electrode 18 is rotated clockwise through 90 degrees in FIG. Electrodes 18, 20 are energized simultaneously and clockwise 90°
The pipe is rotated once, and the right side of the pipe IO, that is, the half arc part, is to be welded. Next, electrodes 1B, 2
0 is deenergized and rotated counterclockwise through 180 degrees so that the electrode 20 is in its highest position in the vertical plane. Electrodes 18, 20 are then re-energized and rotated 90 degrees counterclockwise to complete the weld over a 360 degree arc of pipe IO. When using a welding electrode 18 as shown in FIG. 4, a surge of electrical energy is required to generate a welding arc. This surge of electrical energy is combined with high voltage within the welding circuit. Generally, the welding circuit includes a generator consisting of a hot spark gap generator that provides a high voltage output at radio frequency. This high frequency generator generates a series of closely spaced bursts of high voltage energy.
This high voltage ionizes the gas between the electrode 18 and the pipe 10.14. This ionized gas will guide the welding current. A disadvantage of starting this type of welding arc is that the radiation from the high frequency generator can interfere with radio wave transmissions. Therefore, the use of this type of equipment is governed by Federal Communications Commission regulations. If the arc occurs without the use of such high-frequency generators, there is no such governmental interference and no external approval is required to operate such equipment. One method that does not use a high frequency generator is to use a pilot arc arrangement, as shown in Figure 11. This pilot arc arrangement utilizes a pilot arc 184 that is continuously activated in a manner similar to the pilot light on a conventional gas stove. This pilot arc 184 is defined between welding electrode 186 and pilot electrode 18B. Pilot electrode 188 has a series of threads 19 on its outer surface.
0, and these threads are adapted to threadably engage the mounting sleeve 193. This mounting sleeve 19
2 is installed inside a metal gas cup 194. This gas cup 194 also acts as an anode ring.

Electrode 186 is fixed to block 19B by set screw 196. Block 198 is made of a conductive material such as copper. Electrode 186 is centrally mounted within gas cup 194. The electrode 186 passes through a passage 200 formed in the block 198. gas cup 194
A plug 202 is screwed into the . Gas is in passage 200
Or it is supplied to the connection passage 204. Gas is in the passage 204
, 200 and is discharged near the tip of the welding electrode 186. A plastic seal 206 is installed between gas cup 194 and block 19B. Seal 206 prevents gas leakage between block 198 and gas cup 194 and acts to electrically isolate gas cup 194 from block 198. A cooling block 208 is electrically connected to the block 198 . The cooling block 20B is provided with a pair of water cooling passages.
Only one passageway 210 is shown.

A work piece to be welded in the form of a pipe 212 and a welding electrode 186
A welding power supply device 214 is provided between the two. Electrode 18
A pilot arc feeder 216 is electrically connected between the gas cup 194 and the gas cup 194 . gas cup 194
Attached to the top is a snap connector 218 having a pair of retaining nuts attached thereto, between which a connector 222 of a conductor 224 is tightly coupled. The threaded connector 218 is for gas
Closely cup 194. It is fixed to a tightened metal ring 219. Conductor 224 connects to pilot arc feeder 216. The connection from pilot arc feeder 216 to welding electrode 186 is via conductor 22
According to 6. A conductor 228 or a welding power supply is connected to the work piece 212. A conductor 230 connects welding power supply 214 to welding electrode 186. While welding power supply 214 is energized and de-energized, pilot arc power supply 216 is energized and arc 184 is continuously generated. Adjustment of the pilot electrode 188 is achieved by manually rotating the electrode 188 at the knurled area 232 to move the electrode 188 into the welding electrode 186.
This is done by moving it back and forth. As long as arc 184 is maintained, welding supply! It is only necessary to generate a conventional level of voltage from device 214 to effect the weld between electrode 186 and workpiece 122.

[Brief explanation of drawings]

FIG. 1 is a top view of the welding apparatus of the present invention, showing a pillow pipe attached thereto. FIG. 2 is a partially sectional front view taken along line 2-2 in FIG. 1. Figure 3 is a cross-sectional view taken along line 3-3 in Figure 2. Figure 4 shows one of the welding electrodes used in the welding device of the present invention.
FIG. 3 is a cross-sectional view taken along line 4--4 of FIG. 2 through the FIG. FIG. 5 is a cross-sectional view taken along line 5--5 of FIG. 3 through the weld head housing of the weld head apparatus of the present invention. FIG. 6 is a cross-sectional view taken along line 6--6 in FIG. 5 through the motor mounting structure incorporated in the welding device of the present invention. FIG. 7 is a rear view taken along line 7--7 of FIG. FIG. 8 shows the passage of one of the microswitches of FIG.
FIG. 8 is a cross-sectional view taken along line -8. FIG. 9 is a cross-sectional view taken along line 9--9 of FIG. 3, showing in detail the configuration of actuation buttons for the microswitch. FIG. 10 is a front view of a separate clamp utilized to securely hold the pipe to be welded in a fixed position during welding operations. FIG. 11 is a diagram similar to FIG. 4, showing a modification of the welding electrode-gas cup including the pilot arc. In the drawings, 10, 12...thin muffler pipe,
14... Annular sleeve, 18, 20... Welding electrode,
22... V-shaped block, 26... Fixed bracket, 34.36... Recess, 4゛2, 44... Sight rail, 52... Housing body, 60...
Center enlarged recess, 62... Gear body, 70...
Ring gear, 74...Plate, 80, 82...
Operation button, 84... Drive gear, 98... Mounting plate, 112... Mounting plate, 116...
・Lever 118...roller, 122...block,
124... Gas cup, 126... Sleeve, 1
28...Plug, 134...Seal, 1 3 6-
...Cooling block, 156...Gas cup, 158
, 162--Block, 170-Coil spring, 174-Intermediate base, 182-Main support base

Claims (5)

[Claims] (1) includes a mounting base adapted to be attached to a fixed structure and a welding head housing mounted to the mounting base, the welding head housing having a central enlarged recess; Access to the enlarged recess is from above the welding head housing, and a pipe support means is mounted within the central enlarged recess for supporting the pipe to be welded thereon. A pair of welding electrodes are mounted on the welding head housing, and these welding electrodes are diametrically opposed to each other with the pipe to be welded at the center, and the welding electrode is mounted on and adapted to move together on a ring gear, the ring gear being movable relative to the welding head housing to move each of the welding electrodes from an upper position to a lower position; the upper position is spaced 180 degrees relative to the diameter of the pipe from the lower position, and the upper and lower positions together extend through the center of the pipe to be welded; A pipe welding device characterized in that it is located on one vertical plane. (2) In the pipe welding apparatus according to claim 1, a spring means is attached between the mounting base and the welding head housing, and the welding head housing is responsive to the biasing force of the spring means against the welding head housing. A pipe welding device characterized by being able to move by a limited amount against resistance. (3) The pipe welding apparatus of claim 2, wherein the pipe support means includes a V-shaped block, the V-shaped block being attached to the lower end of the central enlarged recess, and a separate securing bracket being attached to the V-shaped block. The separate fixing bracket is provided in conjunction with the V-shaped block and is set in place so as to fix the position of the pipe to be welded when it rests on the V-shaped block. A pipe welding device characterized by: (4) The pipe welding apparatus of claim 3, wherein each of said welding electrodes is provided with a pilot arc electrode immediately adjacent to said welding electrode, one separate pilot arc electrode for each welding electrode; A pipe welding device characterized in that a pilot arc is generated between each welding electrode and its corresponding pilot arc electrode, and each pilot arc is generated while the respective welding electrode is not activated. . (5) In the pipe welding device according to claim 4, each pilot arc electrode is adjustably attached to the corresponding welding electrode so that the distance therebetween can be changed. Pipe welding equipment featuring: