HK1096900A - Orbital friction welding method and device for carrying out said method - Google Patents

Abstract

The invention relates to an orbital friction welding method and a friction welding device, for welding workpieces (16, 18) by means of friction welding units, wherein the workpieces (16, 18) are pressed against each other in the contact plane (F) during the application of the oscillation energy. To this effect, n>1 friction welding heads [I, II, III, IV or I', II', III', IV' or I'', II'', III'', IV''] are mounted, in a stationary manner, at least on one side of the contact plane (F) in an orbital plane, in the area of the workpieces (16, 18), so that the n>1 friction welding heads, respectively facing one side, are oscillated with the same friction frequency, the same amplitude and the same preset phase position.

Description

Rail friction welding method and device for implementing said method

The present invention relates to an orbital friction welding method for welding workpieces such that the workpieces are continuously pressed against each other in an axial direction during application of oscillating energy to a joint face. The invention further relates to a device for carrying out the method, wherein a circular motion for welding a workpiece can be introduced into the connecting surface, the workpiece being under axial pressure and having a selectable cross section in the connecting surface (F).

Friction welding methods are known whereby, due to the relative movement and the simultaneous pressure, vibrations are generated to obtain the necessary melting energy at the surfaces to be welded.

DE 19938100 a discloses a multi-head friction welding method for the production of window frames and door coverings consisting of profile parts. In order to achieve synchronous welding, the profile parts of the frame are clamped tightly in and close to the side friction welding joints on both sides of the connecting plane, with the aid of which the parts are vibrated so that the connecting surfaces are pressed together simultaneously. The use of a friction welding head in this way enables a considerable reduction in the processing time, but in this way only relatively short shafts facing at an angle to each other can be welded, so that the friction axis is not located in the center of the surface (centroid).

It is therefore an object of the present invention to find a method for welding relatively large and long workpieces, so that a large amount of energy needs to be introduced into the joint surfaces in a simple manner in order to achieve a temperature at which a continuous welding can be carried out for a large amount of material.

According to the invention, this object is achieved in that the orbital friction welding method described above is used in a feed-in channel, since at least on one side of the connecting surface (F), a plurality (n > 1) of friction welding heads on at least one friction disc are arranged at the orbital plane of the workpiece region, the vibration heads of the friction welding heads are firmly fixed to the friction disc, and at least one (n > 1) of the friction welding heads adjacent to one side is vibrated with the same friction frequency, the same amplitude and the same predetermined phase.

For this method, it is also provided that the more than one (n > 1) friction welding heads are used for the incoming thrust of the energy supply, i.e. the axial connecting pressure is realized by more than one (n > 1) thrust shaft, so that an imaginary (hereinafter "virtual") composite thrust shaft formed by the superposition of the plurality of thrust shafts passes through the center of the connecting surface when the force is used to control the infeed.

To optimize the movement conditions, provision is made for: the n > 1 friction welding heads are arranged such that the plurality of friction shafts, which generally constitute a composite virtual friction shaft, pass through the composite center of mass (masscentroid) of all vibrating objects, which includes at least the eccentric shaft and friction plate of the friction welding heads, the friction discs, the workpiece holders and the workpieces.

To increase the available vibrational energy, the method further provides: the vibrating heads of the friction welding head with the n & gt 1 are respectively and fixedly arranged on two sides of the connecting surface (F), a plurality of rail surfaces and the friction disc, and the friction welding head with the n & gt 1 on one side of the connecting surface (F) vibrates in a preset phase relative to the friction welding head with the n & gt 1 on the other side of the connecting surface.

In order to generate the pressure which is introduced into the connecting surface during the supply of the vibration energy, the material supply device is guided axially under distance-time control to the connecting surface of the workpiece, so that, ideally, the virtual resultant axis passes through the center of the connecting surface of the workpiece. This gives rise to the advantage that connecting surfaces which are not nearly coplanar with one another are gradually ground flat, so that a completely symmetrical weld is achieved.

For an orbital friction welding apparatus capable of carrying out the method, in which circular motion energy is required to be transmitted to a joint face to weld a workpiece, which is subjected to an axial compressive force and has an arbitrary cross section at the joint face (F), according to the invention: the oscillating head of the n > 1 friction welding head is fixedly mounted on at least one friction disc around the workpiece to be welded at least one orbital plane in such a way that a virtual resultant orbital friction axis formed by the superposition of the n > 1 friction axes of the respective friction welding heads passes through the region of the center of mass (22) of the object, and the n > 1 friction welding heads oscillate with the same friction frequency and the same amplitude and with a predetermined phase.

The arrangement of a plurality of friction welding heads at the rail plane around the workpieces to be welded results in the advantage that by increasing the number of friction welding heads, an arbitrarily high energy can be applied, so that workpieces, for example long thick-walled pipes, extended structural bar components or excessively wide workpieces, can be welded in only a very short time.

In order to ensure that the same amount of energy is supplied to all areas of the connection surface, the invention provides that, when force control is used, all thrust axes are at equal distances from the center of the connection surface on the connection surface and are distributed angularly symmetrically in order to form surface symmetry with respect to the center of the connection surface. Furthermore, at the resultant orbital axis for all of the friction welding heads, the mathematical product of the distance of each thrust axis to the center of the joining surface multiplied by the respective axial pressure (P) is constant.

In the case of an asymmetrical configuration of the cross-section of the workpiece, or which has to be so designed, it is provided according to the invention that the distances of all the thrust shafts from the center of the connecting surface are unequal, that the pressure (P) exerted by each thrust shaft is inversely proportional to its distance from the center of the connecting surface, taking into account the angular position of the thrust shafts relative to each other, and that the mathematical product of the distance of each thrust shaft from the center of the connecting surface multiplied by the respective axial pressure (P) at the resultant orbital friction axis is constant for all the thrust shafts.

Further with respect to all of these friction welding processes, there is provided: on both sides of the connecting surface (F), a plurality of friction welding heads, including the oscillating heads thereof, are fixedly mounted on a friction disc which is fixed at a rail plane surrounding the workpieces to be welded, and all the friction welding heads on the same friction disc oscillate with the same frequency, the same amplitude and the same phase.

One embodiment of the invention provides that one workpiece selected from two workpieces to be welded end to end is stationary, i.e. fixed, and that only the n > 1 friction welding head is arranged at the orbital plane surrounding the other workpiece, so that the second workpiece is subjected to frictional oscillation.

This embodiment of the invention has the advantage of being suitable for workpieces of relatively small amounts of material, or workpieces made of relatively easily weldable material, such as thin-walled plastic pipes.

Considering the case of friction welding heads arranged at the orbital planes on both sides of the joint plane, the circular distribution of n > 1 friction welding heads on both sides of the joint plane (F) of the workpiece, which are to be welded together end to end, generates a linear thrust vector, so that the n > 1 friction welding heads on both sides of the joint plane vibrate with the same running phase or with continuous rotation in anti-phase with continuously varying phase differences, and are opposite to each other and have a predetermined starting phase. (Linear relative motion)

If the n > 1 friction welding heads arranged on one side of the joint face oscillate with respect to those n > 1 friction welding heads arranged on the other side of the joint face in opposite operating phases or in the same direction of rotation and with a predetermined phase difference, a circumferential thrust vector in the joint face results. (circular relative motion)

The amount of energy introduced into the connection surface can be adjusted by adjusting the phase difference between the friction welding head on one track plane and the friction welding head on the other track plane of the connection surface, wherein a phase difference of 180 ° results in the greatest relative movement at the connection surface, i.e. in the greatest frictional oscillation.

The invention also makes it possible to weld structural bars, for example in a T-shape, on transverse beams, with the oscillating head of a n > 1 friction welding head firmly fixed to said transverse beams, at an axial plane vertically aligned with the longitudinal axis of said structural bars, and with the oscillation head of a n > 1 friction welding head fixed at a orbital plane surrounding said structural bars.

In this arrangement, it is to be noted that a virtual composite orbital friction axis passes through the center of mass region, this virtual composite orbital friction axis is formed by superposition of vibrations of a plurality (n) of vibration axes of the respective friction welding heads, and the friction welding heads on both sides of the joint face vibrate at the same friction frequency, wherein a preset phase difference between the friction welding head on one side of the joint face and the friction welding head on the other side of the joint face is maintained.

For welding, for example, pipe fittings, such as pipes which can carry gas, oil or water and which can be made of plastic, metal or composite materials, it is advantageous if a plurality (n) of friction welding heads arranged in a rail-like manner can each be firmly fixed around the pipe fitting and can be moved by a transport means. Obviously, in this case, it is also possible to have an arrangement: wherein the pipes to be welded can be moved to the respective welding position by means of a fixed friction welding head arranged in the form of a rail and fixed in this position during welding.

In the case of this arrangement, in order to move the tube pieces into the position of pressure action for the distance/time-controlled welding at the joint faces, it is advantageous to provide a thrust unit with hydraulic or pneumatic drive, or with mechanical and/or electromechanical power drive, which is either connected to the workpiece or to a friction disc which is fastened to the workpiece.

The features and advantages of the invention will be examined in more detail with the aid of the following description of an embodiment, taken in conjunction with the accompanying drawings and the claims. The attached drawings show:

FIG. 1 is a schematic illustration of an orbital friction welding apparatus for welding two tubulars along a joint plane;

fig. 2 is a schematic illustration on a rail plane, showing a friction welding head in an axial view of a connecting surface from one side, wherein, on the one hand, a left side view of the rail plane shows the oscillating friction welding head in a zero-state position, and, on the other hand, a middle view of the friction welding head is used to explain the same phase of operation or the opposite direction of rotation of operation, respectively, while a right side view of the friction welding head explains the opposite phase of operation or the same direction of rotation of operation, respectively;

FIG. 3A and FIG. 3B are top views of two friction weld joints vibrating in opposite directions on the joint surface and rotating in the same direction of rotational travel with a phase difference of 0 or 360, respectively;

FIG. 3C shows a graph from which it can be inferred that a phase difference of 0/360 does not result in relative motion of the vibrating head;

FIGS. 4A-4C are top views of the vibrating head facing each other with a phase difference of 45/315 and the same direction of operational rotation;

FIGS. 4D and 4E are uniform circular relative motion plots of 45 ° phase difference consistent with FIG. 4B and 315 ° phase difference consistent with FIG. 4C;

FIGS. 5A to 5C are top views of the vibrating head, facing each other, with a phase difference of 90 or 270, respectively, and the same direction of operational rotation;

FIGS. 5D and 5E are a composite uniform circular relative motion map of 90 ° phase difference consistent with FIG. 5B and a composite uniform circular relative motion map of 270 ° phase difference corresponding to FIG. 5C;

6A-6C are top views of the vibrating head facing each other with a phase difference of 135 and 225 and the same direction of operational rotation;

FIGS. 6D and 6E uniform circular relative motion map of 135 ° phase difference consistent with FIG. 6B, and uniform circular relative motion map of 225 ° phase difference consistent with FIG. 6C;

FIGS. 7A and 7B are top views of the vibrating head facing each other with a phase difference of 180 and the same direction of operational rotation;

FIG. 7C is a composite uniform circular relative motion map of 180 ° phase difference consistent with FIG. 7B;

FIGS. 8A and 8B are top views of the vibrating head, facing each other, with a phase difference of 0 or 360, respectively, and opposite directions of operational rotation;

FIG. 8C is a graph of the resulting linear relative motion with a 360 phase difference consistent with FIG. 8B;

FIGS. 9A-9C are top views of the vibrating head facing each other with a starting phase difference of 45 or 315 and opposite direction of travel rotation, respectively;

9D and 9E are graphs of linear relative motion with a phase difference of 45 consistent with FIG. 9B and a graph of linear relative motion with a phase difference of 315 consistent with FIG. 9C;

10A-10C are top views of vibrational heads facing each other, each with a 90 or 270 phase start-out difference and opposite operational rotational directions;

10D and 10E are graphs of linear relative motion with a phase difference of 90 deg. consistent with FIG. 10B, and a graph of linear relative motion with a phase difference of 270 deg. consistent with FIG. 10C;

11A-11C are top views of the vibrating head facing each other with a starting phase difference of 135 or 225, respectively, and opposite directions of operational rotation;

11D and 11E are graphs of linear relative motion with a phase difference of 135 deg. consistent with FIG. 11B, and a schematic of linear relative motion with a phase difference of 225 deg. consistent with FIG. 11C;

12A and 12B are top views of the vibrating head facing each other with a starting phase difference of 180 and opposite running rotational directions;

FIG. 12C is a linear relative motion plot of 180 phase difference consistent with FIG. 12B;

FIG. 13 is a schematic illustration of the distribution of three friction weld heads/thrust shafts at the orbital plane relative to the surface center of the structural bar joint face; and

FIG. 14 is a schematic view of the distribution of the friction weld head on a disk that surrounds the pipe to be welded and is secured to the pipe to be welded by a set screw.

An orbital friction welding apparatus 10 for welding two elongated tubular members 12 and 14 which are pressed together by an axial force P to meet end-to-end at a joint plane F is schematically illustrated in fig. 1. The rail discs 16 and 18 are stably fixed to the two members 12 and 14. In this arrangement, it is advantageous if the virtual resultant thrust axis and the virtual resultant friction axis are aligned with each other, and the center position of the connection surface coincides with the center position of mass. It is clear that in applications where the two centers are offset from each other, that is to say the thrust axis does not need to be absolutely aligned with the friction axis.

The rail disks 16 and 18 are used for the mounting of the friction weld joints I, II, III, IV or I ', II', III ', IV' or I ', II', III ', IV', respectively. These welding heads with the respective vibration heads are fixed on the rail disc. Thus, they are fixed by a connecting member (not shown).

The friction weld joint of DE 4436857a is applicable and suitable for carrying out the invention. The use of these friction welding heads has the advantage that a plurality of friction welding heads can be easily synchronized, in particular that it allows error-free initial synchronization, so that the friction welding process starts at the desired phase and the phase between the oppositely arranged friction welding heads can be maintained quite reliably. The friction welding joint is assembled with the control eccentric wheel and the parallel guide device, so that the rotation energy of the driving side can be converted into the energy of the circumferential parallel guide motion. To start the synchronization, all eccentrics of the respective friction welding heads are set to the full starting amplitude, and then the friction welding heads located in opposite positions are adjusted to the desired starting phase. The phase shift adjustment between the friction welding heads mounted on the opposite rail discs is then the rail discs 16 and 18, which are clamped to the pipe elements 12 and 14, and the welding operation of the pipe elements on the joint faces is subsequently carried out.

Fig. 2 shows orbital discs 16 and 18 to help illustrate the relative motion of the oscillating heads of the oppositely disposed friction weld heads, wherein the view of orbital disc 16.1 illustrates the same phase of operation or opposite direction of rotation, respectively, and the view of orbital disc 16.2 illustrates the opposite phase of operation or same direction of rotation, respectively. For the purpose of illustration, the kinematic conditions on the connection surfaces are shown in an axial view from one side.

For purposes of illustration, only the friction welding tips I and I' or I ", respectively, are discussed in the following description. With regard to the desired function, it is clear that the other friction welding heads II, III, IV and II ', III ', IV ' and II ", III", IV "concerned also operate correspondingly with the same frequency, amplitude and phase, respectively, so that the desired relative movement of the rail disc located in the opposite position and the pipe piece on the joint face F therewith is established.

As the welding process continues, an axial pressure is applied to the pipe pieces to be welded with the aid of the thrust unit. The pressure is transmitted through the tube itself and through a rail disc firmly fixed to the tube. These thrust means may comprise hydraulic or pneumatic drive means and mechanical or electromechanical drive means, respectively.

Since the center of the surface of the connecting surface is located in the center of the tubes of the two pipe elements, the friction welding heads are arranged in an angularly symmetrical manner with respect to the center of the surface and are equally spaced apart from the center of the surface, so that the same movement energy is transmitted to the rail disk and to each point of the connecting surface, i.e. to the weld seam, by all the friction welding heads. Depending on the material used for the pipe and the thickness of the pipe wall and depending on the amount of material, the welding process requires more or less energy. To meet the needs of a particular application, rather than four friction welding heads as described above mounted on a single orbital disk, more or fewer friction welding heads, such as three, may be used to obtain welding energy commensurate with the welding task being performed.

Although it is economically advantageous to use the same type of friction welding head, each of which can accordingly provide the same welding energy, it is also possible to mount different types of welding heads on a rail disc, wherein only the following considerations need to be taken into account: on the one hand, the angular symmetry with respect to the center of the surface remains constant, and on the other hand, the mathematical product of the distance of the axis of friction to the center of the joint face multiplied by the respective incoming vibration energy at a continuously constant axial pressure exerted on the pipe to be welded remains constant. The resultant relative motion, i.e., the resultant thrust vector between the two orbital discs 16 and 18 for different directions of travel, the same or opposite, and the effective phase difference between the two orbital discs is explained below. However, since all the friction welding heads on one orbital disk impose the same relationship due to having the same phase difference, the vibration behavior of the vibrating heads of the two friction welding heads I and (I), respectively, is explained mainly next.

The relationship of the oscillating heads of the friction welding heads I and (I) is shown in fig. 3A and 3B, where the arrows for the zero-phase motion vectors at all points in time, i.e. 1, 2, 3, 4, 5, 6, 7, 8, are solid (bold), and the motion vectors for the same operating phase, i.e. opposite operating rotational direction, for all points in time, i.e. (1), (2), (3), (4), (5), (6), (7), (8), accordingly have open arrows. The same applies to the following explanation of the phase shift.

In fig. 3A and 3B, a phase difference of 0 ° or a phase difference of 360 ° is shown for the same operational rotational direction. By superimposing the motion vectors of the same magnitude and direction, respectively, at different points in time 1 to 8 or (1) to (8), no relative motion is produced by the oscillating heads of the friction welding heads, which are located opposite one another on the track disks 16 and 18. It can also be seen in the display provided in fig. 3C, where the motion vectors for all displayed time points are superimposed on each other, which illustrates that no relative motion is caused.

Referring now to fig. 4A and 4B, uniform circular relative motion due to a phase difference of 45 ° is shown by plotting vectors for respective observation time points in accordance with fig. 4D. From this representation it can be concluded that a relative movement between the oscillating heads of the friction welding heads I and (I) has occurred, which is characterized in fig. 4D by the bold connecting line between the two motion vector arrows.

The same applies to a phase difference of 315 °, which can be derived from the representation in fig. 4E by comparing the motion vectors in fig. 4A and 4C. In both cases, a circular relative movement of the uniform circumference or a thrust vector of the uniform circumference is generated.

From fig. 5A and 5B and fig. 5A and 5C, the 90 ° and 270 ° phase difference in the same direction of operation rotation can be observed, respectively. Fig. 5D shows the superposition of the corresponding motion vectors with a phase difference of 90 deg., while fig. 5E shows the superposition of the corresponding motion vectors with a phase difference of 270 deg.. From these illustrations it can be concluded that the relative motion caused by the 90 ° and 270 ° phase difference is greater than the relative motion caused by the 45 ° and 315 ° phase difference.

Correspondingly, the same applies for a phase difference of 135 ° or 225 ° respectively in the same direction of rotation of operation, which is caused by the superposition of the motion vectors according to fig. 6A and 6B and fig. 6A and 6C. The relative motion resulting from the superposition of motion vectors as shown in fig. 6D and 6E is also a uniform circular relative motion, but with a larger magnitude than in the previous case.

Observing the 180 phase difference, the superposition of motion vectors at each given point in time results in a uniform circular relative motion of maximum magnitude for the same operating rotational direction, as shown in fig. 7C.

For all the cases of different phase differences described above, it is understood that the relative movements resulting from the superposition of the movement vectors of the friction welding heads arranged relative to the orbital disk are all uniform circular relative movements, the amplitude of which and the circular movement of which are only changed with reference to the observation time points 1 to 8 or (1) to (8), respectively.

It follows that it is possible that the phase-dependent linear direction, i.e. the direction of friction, and the phase-dependent energy transfer can be changed simultaneously by adjusting the phase.

In the following observation, the superposition of the motion vectors of the different time points 1 to 8 and (1) and (8) in the opposite direction of the running rotation can be seen.

The situation of the opposite operating rotational direction with a phase difference of 0 ° and 360 ° is shown in fig. 8A and 8B. The relative motion of the phase difference of 0 ° and 360 ° as shown in fig. 8C produces such a result by superimposing the motion vectors of the time points represented by the same arabic numerals, and it is apparent that the linear relative motion is produced except that the relative motion at the time points 3 and 7 is zero.

The conditions of the opposite running rotation direction and the starting phase difference of 45 ° and 315 ° are shown in fig. 9A to 9C with continuously varying phase difference. By superimposing the motion vectors of fig. 9A and 9B, a 45 ° start phase difference results in a linear relative motion, the magnitude of which is smaller at time points 2, 3, 6 and 7 than at time points 1, 4, 5 and 8. Thus, at a phase difference of 45 °, the amplitudes at 67.5 ° and 247.5 ° are zero amplitude values, and the amplitudes at 157.5 ° and 337.5 ° are maximum amplitude values.

Correspondingly, this also applies to the superposition of the motion vectors shown in fig. 9A and 9C, which results in a shift of the linear relative motion only with respect to the time points shown, which shift is phase-dependent. In this case, zero amplitude values occur at 112.5 ° and 292.5 °, and maximum amplitudes occur at 22.5 ° and 202.5 °.

Also in the case shown with respect to fig. 10A to 10C, the opposite running rotational direction yields corresponding results for the starting phase differences of 90 ° and 270 °, respectively. For a 90 ° starting phase difference corresponding to fig. 10A and 10B, linear relative motion is caused, as shown in fig. 10D, and likewise, the magnitude of the relative motion at each time point changes, and there is no relative motion at time points 2 and 6.

In the superposition of the motion vectors corresponding to fig. 10A and 10C and the 270 ° starting phase difference, the same relative motion with varying amplitude is caused, so that at points in time 4 and 8 there is no relative motion.

For the case of opposite running rotation directions and starting phase differences of 135 ° or 225 °, respectively, the result shown in fig. 11D results, which is the case of the superposition carried out at the starting phase difference of 135 ° and corresponding to fig. 11A and 11B. Likewise, it is recognized that the magnitude of the linear relative motion becomes larger or smaller according to each observation time point. The same applies to the superposition of the motion vectors corresponding to fig. 11A and 11C, which at a starting phase difference of 225 ° results in a linear relative motion with varying amplitude according to fig. 11E. In this case, for a phase difference of 135 °, it results in zero amplitude values at 22.5 ° and 202.5 ° and maximum amplitude values at 112.5 ° and 292.5 °. The same applies to a phase difference of 225 ° for the start of the vibration, which has zero amplitude values at 157.5 ° and 337.5 ° and maximum amplitude values at 67.5 ° and 247.5 °.

Finally, the situation is shown for the opposite running direction of rotation and at a starting phase difference of 180 °, wherein the motion vectors corresponding to fig. 12A and 12B are superimposed on each other. The superposition of the 180 phase difference results in the linear relative motion of fig. 12C, where there is no relative motion at time points 1 and 5.

Fig. 13 is a schematic illustration of a rail disc 21 fixed to a structural bar, on which three friction welding heads I, II and III are arranged. Also shown in the given figure is a surface center 22, which is connected to the friction welding head by a virtual connecting line. In order to ensure that each point of the weld receives the same amount of energy, the friction welding head is placed at a position on the orbital disc, wherein the mathematical product of the distance multiplied by the axial pressure acting on each friction welding head is constant at equal energy inputs. Such equal energy is imparted to the joint face, thereby ensuring a uniform and continuous weld.

It is also possible that the friction welding head must be positioned to one side of the center of mass of the rail disk, for reasons of spatial position. If this is the case, then the use of a balancing method for weight compensation must be carefully considered. The virtual resultant friction axis must be made to pass through the centers of mass of all the movable parts.

In order to ensure a stable fixing of the workpieces to be welded, a number of different methods are provided. In the case of the operative welding of pipe elements, a simple solution is shown in fig. 14, in which a divided rail disc is shown, which is divided into two halves 24 and 25, and which, for the welding of tubular workpieces, surrounds the periphery of the pipe and is clamped tightly thereto.

Such segmented rail discs have the ability to be reassembled and have friction welding heads I, II and III which can be mounted on a vehicle, moved along a pipe to effect welding of long pipes, such as pipes for gas, oil or water, which are arranged one after the other, and which grip the pipe elements to weld them to each other at each welding location by clamping the pipe elements between the rail discs and transmitting the axial pressure required for welding to the joint faces.

Friction welding of such pipes can be carried out with the invention at very short intervals, so that it can be assumed that for the actual welding process each energy introduction takes less than a few minutes. For comparison purposes, the results demonstrate the great economic advantage of the present invention if the pipe welding is carried out using a conventional welding method, since the conventional method requires a time period exceeding 10 to 100 times the above period for producing a high quality weld for a pipe placed under high load.

Instead of the movable orbital friction welding device according to the invention, a welding device of the stationary type is possible, for which a plurality of pipes to be welded are slidably moved one after the other through the welding device, so that the welding operation is carried out.

No further description is given of the welding operation for T-shaped workpieces that are perpendicular to each other, such as structural support bars on transverse beams or T-shaped pipe branches.

For this purpose, the oscillating head of the plurality of friction welding heads is firmly fixed along an axial plane to a transverse beam perpendicular to the longitudinal axis of the support bar, and a further plurality (n) of friction welding heads is fixed on the other side of the joint plane, i.e. in the plane of the rail around the support bar. Then, the vibrating heads of the friction welding heads on both sides of the joint face vibrate at the same friction frequency, so that a preset phase difference between the friction welding head disposed on one side of the joint face and the friction welding head disposed on the other side of the joint face can be maintained. For this purpose, linear vibrations caused by opposite running rotational directions, or circumferential vibrations caused by the same running rotational direction, may be used.

Claims (22)

1. An orbital friction welding method for welding workpieces (12; 14; 20; 26) in which the workpieces are pressed together at a joint face during the introduction of vibrational energy,

it is characterized in that

At least on one side of the connecting surface (F), more than one (n > 1) friction welding head (I, II, III, IV; I ', II', III ', IV'; I ', II', III ', IV') is mounted on at least one friction disk in the rail plane of the workpiece region, such that the vibration head of the friction welding head is firmly fixed to the friction disk, and

the more than one (n > 1) friction welding heads adjacent to one side are vibrated with the same friction frequency and the same amplitude and the same preset phase respectively.

2. The orbital friction welding method according to claim 1,

it is characterized in that

The thrust or joining pressure of the more than one (n > 1) friction welding heads required for the energy input is generated by more than one (n > 1) thrust shafts in each case, so that the virtual resultant shaft formed by the superposition passes through the region of the joint face center (22).

3. The orbital friction welding method according to claim 1,

it is characterized in that

The more than one (n > 1) friction welding heads are arranged such that the friction axes as a whole and their imaginary resultant friction axes pass through the mass center area of all vibrating objects.

4. The rail friction welding method according to any one of claims 1 to 3,

it is characterized in that

The vibration heads of the more than one (n > 1) friction welding heads (I, II, III, IV; I ', II', III ', IV'; I ', II', III ', IV') are each fixedly arranged on both sides of the connecting surface (F) at a plurality of track planes, and

the more than one (n > 1) friction welding heads on one side of the connection surface (F) oscillate with a predetermined phase with respect to the more than one (n > 1) friction welding heads on the other side of the connection surface.

5. The rail friction welding method according to any one of claims 1 to 4,

it is characterized in that

The pressure pushing the workpieces together on the connecting surface is generated by a pushing mechanism which pushes the workpieces together in an axial direction under time/distance control, whereby the virtual resulting axis does not need to pass through the surface center of the workpieces.

6. An orbital friction welding apparatus for carrying out the method according to any one of claims 1 to 5, whereby circular motion energy is introduced into the joint face for welding of the workpieces (12; 14; 20; 26) having an arbitrary cross section at the joint face (F), which are subjected to axial pressure,

it is characterized in that

The vibration heads of the more than one (n > 1) friction welding heads (I, II, III, IV; I ', II', III ', IV'; I ', II', III ', IV') are fixedly arranged on at least one track plane and at least one friction disk of the workpieces to be welded, such that a virtual composite track axis formed by the superposition of the more than one (n > 1) friction axes of the friction welding heads passes through the region of the center of mass (22), and

the more than one (n > 1) friction welding heads vibrate with the same friction frequency and the same amplitude and the same preset phase.

7. Orbital friction welding apparatus according to claim 6,

it is characterized in that

Using force control, all thrust axes are at the same distance from the center of the connecting surface at the connecting surface and are simultaneously distributed in an angular symmetry in order to achieve surface symmetry about the center (22) of the connecting surface, and

at the resultant orbital axis for all friction welding heads, the mathematical product of the distance of each thrust axis from the center of the joint face and the respective axial pressure (P) is constant.

8. Orbital friction welding apparatus according to claim 6,

it is characterized in that

The distances from all the thrust shafts to the center (22) of the connecting surface are different,

the thrust force (P) of each thrust shaft is inversely proportional to its distance to the centre of the connecting surface, taking into account the angular position of the thrust shafts with respect to each other, and

the mathematical product of the distance of the respective thrust axis to the center (22) of the joint plane and the respective axial pressure (P) is constant for all composite orbital axes of the friction welding head.

9. Orbital friction welding apparatus according to any one of claims 6 to 8,

it is characterized in that

On both sides of the connection face (F), a plurality of friction welding heads are each firmly fixed to a friction disk (16, 18) which is located at the rail plane around the workpieces (12, 14) to be welded, and

all friction welding heads on the same friction disc vibrate at the same frequency, the same amplitude and the same phase.

10. Orbital friction welding apparatus according to any one of claims 6 to 9,

it is characterized in that

One of the workpieces to be welded end-to-end is firmly fixed, and

the more than one (n > 1) friction welding heads fixed around the second workpiece are vibrated.

11. Orbital friction welding apparatus according to any one of claims 6 to 10,

it is characterized in that

The more than one (n > 1) friction welding heads are fixed in a ring-like manner on both sides of a connecting surface (F) of the workpieces (12, 14), which are welded to the end surface, so that the more than one (n > 1) friction welding heads on both sides of the connecting surface are opposite to each other, which are respectively rotated with the same operating phase or with opposite operating phases with continuously varying phase differences and are oscillated with a predetermined starting phase.

12. Orbital friction welding apparatus according to any one of claims 6 to 10,

it is characterized in that

The more than one friction welding head (I, II, III, IV) fixed on one side of the connecting surface vibrates in relation to the more than one friction welding head (I ', II', III ', IV'; I ', II', III ', IV') arranged on the other side of the connecting surface in opposite operating phases or in the same operating direction of rotation and with a predetermined phase difference, respectively.

13. Orbital friction welding apparatus according to claim 11 or 12,

it is characterized in that

The more than one friction welding head (I, II, III, IV) fixed on one side of the connecting surface is vibrated by a phase difference of 0 DEG to 360 DEG relative to the more than one friction welding head (I ', II', III ', IV'; I ', II', III ', IV') arranged on the other side of the connecting surface.

14. Orbital friction welding apparatus according to any one of claims 8 to 11,

it is characterized in that

A plurality of friction horn units on a friction disc are secured around the periphery of the workpiece or the workpiece to increase the vibrational energy imparted to the connecting face (F), such discs being arranged radially and/or sequentially with respect to one another.

15. Orbital friction welding apparatus according to any one of claims 6 to 14,

it is characterized in that

The more than one (n > 1) friction welding heads are each fixedly mounted around the pipe or part (24, 25) so that they can be positioned by means of a transport means, or

The tubes or structural parts can be moved to the respective welding position and fixed in this position by means of a plurality (n) of fixed friction welding heads distributed along the rail.

16. Orbital friction welding apparatus according to any one of claims 6 to 15,

it is characterized in that

In order to generate the pressure to be applied during the transmission of the vibration energy into the connection faces, the friction discs provided with the more than one (n > 1) friction welding heads and fixed to the workpiece may be moved relative to each other under distance/time control by means of a thrust unit, whereby a virtual resultant shaft passes through the center of the surface of the workpiece.

17. Orbital friction welding apparatus according to claim 16,

it is characterized in that

The thrust unit is coupled to the friction disk, and is disposed on both sides of the connecting surface fixed to the workpiece.

18. Orbital friction welding apparatus according to claim 16 or 17,

it is characterized in that

The thrust units comprise hydraulic or pneumatic drives, or mechanical and/or electromechanical drives, respectively.

19. Orbital friction welding apparatus according to any one of claims 6 to 17 having more than one (n > 1) friction welding head for welding workpieces having any cross-section at said joint face, whereby circular motion energy provided by said friction welding head is vertically transmittable to said joint face, said workpieces being subjected to axial compression,

it is characterized in that

The workpieces are each placed at an angle or T-shaped to each other and comprise pipe branches leading away from the longitudinal pipe direction, or structural bars extending from the transverse beams,

a plurality of friction welding heads are fixedly mounted on the longitudinal pipe or transverse beam respectively at a longitudinal axis plane, which is perpendicular to the longitudinal axis of the pipe branch or the structural rod respectively,

more than one (n > 1) friction welding heads are fixed at the track level around the pipe branch or the structural bar respectively,

a virtual composite orbital friction axis is formed by superposition of vibrations of a plurality (n) of friction axes of each friction horn, which pass through the center of mass area, and

the friction welding heads on both sides of the connecting surface oscillate at the same friction frequency, whereby the friction welding heads on one side of the connecting surface oscillate with respect to those on the other side of the connecting surface with an opposite operating phase and a predetermined phase difference, so that a linear relative movement between the workpieces occurs at the connecting surface.

20. Orbital friction welding apparatus according to any one of claims 6 to 18,

it is characterized in that

The apparatus is used in a welding operation for workpieces having a length substantially greater than their effective cross-sectional width (L > D).

21. Orbital friction welding apparatus according to any one of claims 6 to 18,

it is characterized in that

The apparatus is used in a workpiece welding operation where the effective cross-sectional width is substantially greater than its length (D > L).

22. Orbital friction welding apparatus according to any one of claims 6 to 18,

it is characterized in that

The apparatus is used in welding operations of workpieces made of composite material, where the thrust is controlled in time/distance.