DE3225995A1 - Device for welding at a constant welding rate all-around weld seams whose length changes during welding - Google Patents

Abstract

In order to keep constant the welding rate of the welding rate change which occurs particularly in claddings and multi-layer all-around welds a height path-measuring measured value converter (34) is assigned to the torch height control device (33), whose output signal is passed to the travelling mechanism control (35) for the travelling speed correction. In the preferred use in orbital welders with a rotating travelling mechanism (13), a simple and inexpensive maintenance of a constant welding speed in all-around weld seams whose length changes during welding is made possible by the arrangement of a height path-measuring measured value converter (34). <IMAGE>

Description

MESSER GRIESHEIM GMBH _{MG 1396}

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Password: welding speed _EM -1044

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Inventor: Hahn File: n

Device for welding circumferential weld seams which change in length during welding at a constant welding speed.

The invention relates to a device for welding circumferential weld seams which change in length during welding with a constant welding speed, with a chassis supporting the welding torch, a chassis control and a torch height control to keep the arc length constant.

The welding speed of the welding head of orbital welding equipment depends on several parameters, for example on the thickness of the weld to be performed, the material to be welded and the welding filler material or the welding electrode, as well as the one used Voltage and amperage. The Schwoißgoijchwindigkcit of the welding head should, however, during the execution of the Weld seam are usually kept constant.

MG 1396 _ j. ·. :: ** * ·· ** · July 8, 1982

In the case of straight weld seams, this does not cause any problems because the welding speed is permanently set on the welding device.

Orbital welding devices are used, however, in particular for producing weld seams that are not straight but curved. These are welds that are used, for example, in the Weld cladding of circular surfaces in the form of a spiral or around such weld seams which the spiral course consists in the fact that the weld beads lie one above the other and with each full one Rotation of the ring formed by the weld bead has a larger diameter. In this case changed 5 the relative speed between the welding head and the workpiece to be welded is constant Undercarriage speed steady. One has to remedy this difficulty with such welds tried to adjust the welding speed of the welding head by hand from time to time.

However, this procedure inevitably results in very large and not readily recognizable Irregularities and fluctuations in the speed of the welding head in relation to the workpiece.

It is known in cladding to avoid these disadvantages, the welding speed by frictional connection to be picked up and converted mechanically into a speed by which speed-0 synchronous light pulses are generated. These are removed from the heat zone by means of a fiber optic light guide out and fed to a sensor and an amplifier arrangement for influencing the welding speed forwarded (DE-OS 30 21 659). However, a complex and, for example, smaller welding

MG 1396:. ·. ::, **. * .-] ' , ^: July, 1982

joint widths and small workpiece dimensions are not Usable construction via friction wheel with perforated screen and light source necessary. This construction will further enlarged by the light source not to be placed directly in the area of the welding heat. The weight then caused by this construction has the same effect as the frictional force of the friction wheel in the case of orbital undercarriages, this has a detrimental effect on the driving characteristics and thus on the weld seam. Even -Q is subject to this in the welding zone or on the weld seam Friction wheel running under contact pressure is subject to continuous wear, which leads to measurement errors.

The invention is based on the object of a device to create a constant welding speed with a simple structure and low manufacturing costs in the case of circumferential weld seams that change in length, and in particular does not affect the driving characteristics.

This object is achieved according to the invention in that the burner height control is assigned a height distance measuring transducer, the output signal of which is the Chassis control for driving speed correction can be supplied.

The burner height control is an advantageous further development as an arc-dependent height control and the measuring transducer for measuring the height travel as a potentiometer educated. The chassis control advantageously has a drive motor with an associated control amplifier on, which is connected with an integrator with a height-sensing transducer. The advantages achieved by the invention are in particular that on the one hand by the at a height

MG 1396 Γ. ' . ::. ·. . ··. * July 3, 1982

control arranged height distance measuring transducer no scanning means exposed to the welding zone are upstream or downstream, and on the other hand the low weight of, for example, a pulse encoder, absolute encoder, inductive encoder or potentiometer Trained measuring transducers that pick up the height distance do not affect the driving characteristics. Due to the simple circuit design, the height distance measuring transducer is more cost-effective Way and avoiding complex mechanical aids in the circuit for height control of the burner can be integrated.

An embodiment of the invention is shown in FIG tion and is described in more detail below with reference to further advantageous features.

It illustrates:

2Q Fig. 1 a device for keeping constant

the welding speed in the case of circumferential weld seams that change with length,

FIG. 2 shows a device according to FIG. 1 under

Connection of a computer.

1 shows a device for keeping the welding speed constant when the length changes Circumferential weld seams of a schematically

provided arc welding torch 11 in its entirety designated by 12. The burner 11 is preferred designed as a TIG torch and only schematically on it Chassis 13 shown attached, which is held in a guide 15 placed around a tube 14 and thus in

this can be guided orbitally around the tube 14.

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On the chassis 13 are not shown in more detail burner adjustment and pendulum devices and in a known manner attached to a wire supply roll. The burner 11 is in this case, via a hose package (not shown in more detail) with a welding power source (also not shown) tied together. The drive of the chassis 13 has a traction motor 16, the rotor with a not Gear shown in more detail is connected, which meshes with a drive gear 17 which is connected to the chassis wheel 18 communicates.

The non-melting tungsten electrode is used to adjust the height of the burner 11

19 and the pipe 14 are connected to the input 22 of a comparator 23 via lines 20 and 21. The other Input 24 of comparator 23 is connected to a setpoint generator 26 via the line. The exit of the comparator 23 is connected via a line 28 to a burner height adjustment device 29, which has a Has motor 30 with associated rack 31 and pinion 32 for burner adjustment.

According to the invention, the burner height control 3 3 is assigned a measuring transducer 34 that scans the height Output signal of the chassis control 3 5 can be fed to the speed correction.

about the travel speed correction of the undercarriage driving traction motor 16 is used in multi-layer welds with changing length (development of the weld seam length) the circumferential weld seam 10 and thus the changing relative speed between the tip 19a of an electrode 19 and the pipe 14 a constant dor SchwoifWo-chwindLc / - achieved. The traction motor 16 is a landing gear :; Lf-iu-rung 35 assigned, who ciufwaist a Roqelvcrstürkcr 36, its one input 37 with the integrator 40 and its

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other input 38 is connected to a setpoint generator 39. The setpoint generator 3 9 is used as a setpoint potentiometer formed on which the vehicle speed V setpoint setting he follows. The analog voltage set on the setpoint generator 39 and proportional to the driving speed is fed to the control amplifier 3 6, so that the traction motor 16 moves at a speed corresponding to the setpoint value will. .

To correct the driving speed / regulating the speed of the traction motor 16, the arc-dependent one is on the pinion 32 Burner height adjustment 29 of the height distance measuring transducers 3 4 are arranged. This is located in its zero position (middle position) when the electrode tip 19a is on a reference circumference 50 and in a provided henen is positioned at a constant distance 41 to be kept from the pipe 14.

The measuring transducer 3 4, which takes off the height, is in the circuit arrangement 1 provided as a potentiometer on the pinion 32. Of course it is also possible that Train the potentiometer as a sliding potentiometer and arrange it on the rack 31. The result of an angry first welding layer decreasing distance 41 causes a height adjustment and a corresponding movement of the Measuring transducer 34. The span falling over the measuring transducer 34, which takes off the height, when the height is adjusted is proportional to the change in driving speed and is fed to the control amplifier 3 6 and in this with the on the Sc value transmitter 39 compared generated nominal voltage. This link ensures a constant welding speed 0 reaches a changing driving speed. For example, if the length of the circumferential weld seam is increased, the driving speed is reduced, and if the length of the circumferential weld seam is increased Reduction of the circumferential weld seam (for inner pipe welds) increased.

5 Between the control amplifier 3 6 and the measured value measuring the height path

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converter 34, an integrator 40 is interposed via the lines 4 2 and 47, which integrates only the Measured value converter 34 supplies the voltage dropping to the control amplifier 3 6 as a correction measure. The others Signals from the transducer that arise during height control during welding are suppressed. As a result of this suppression of the voltage dropping at the measuring transducer 34, which taps off the height path, when the voltage is low Burner height adjustment is thus the driving speed of the motor 16 so controlled that it is only at one Torch height adjustment, such as when welding or cladding a second weld seam layer 10 takes place on a first weld seam layer, becomes effective. Irregularities in height when welding the

T5 first or a further weld seam layer 10 thus lead to no speed correction.

In Fig. 2 a device according to Figure 1 is connected of a computer. There is between control amplifier 36 and integrator 40, a computer 43 is connected, the input 44 of which with a setpoint input for driving speed 45 and pipe diameter 4 6 is connected and the computer 43 of the chassis control 3 5 a setpoint value after the correction adds formula "f,

V ₁ = V. RD

RD + 2 K

where V = nominal value of the speed, RD = * pipe diameter and K = change in radius.

0 By calculating according to the correction formula in the analog and / or digital computer, the nominal value becomes the F <theircre. ^r jspeed _; the pipe diameter and the correction value supplied by the measured value formor 34, which is taken from the height wave, the actual value for the driving speed leading to a constant welding speed crniiLLolt "and inside K <: 'ic.l vcn; I:.' irker 'Ib zuqi'fuhri

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Claims (4)

MG 1396 Ί \ .:. y y. '. : -: *.: July 8, 1982 Claims 1. Device for welding circumferential weld seams which change in length during welding at a constant welding speed with a chassis carrying the welding torch, one Chassis control and a torch height control to keep the arc length constant, characterized in that the burner height control (33) is a height path tapping Measuring transducer (34) is assigned, the output signal of which is the chassis control (35) for driving speed correction is feedable. 2. Device according to claim 1, characterized in that the torch height control (33) is designed as an arc-dependent height control. 3. Device according to claim 1, characterized in that the height path pick-up transducer (3 4) as a potentiometer is trained. 4. Device according to one of claims 1 to 3, characterized in that the chassis control (35) has a drive motor (16) with an associated control amplifier (36) which with the connection of an integrator (40) and the height-sensing transducer (34) is connected. mg 1396 ": '." * .:: · "* · \ * * · ^{D> Jun} Device according to one of Claims 1 to 4, characterized in that between the control amplifier (36) and the integrator (48) Computer (43) is connected, whose input (44) with a setpoint input for driving speed (45) and pipe diameter (46) is connected, and the calculator (43) supplies a target value to the chassis control (35) according to the correction formula RD + 2K where V = nominal value of the speed, RD = pipe diameter and K = change in radius.