FR2569371A1 - OSCILLATING APPARATUS, METHOD AND SYSTEM FOR FRICTION WELDING OF DIFFERENT THERMOPLASTIC MATERIALS - Google Patents

Abstract

AN APPARATUS AND A PROCESS FOR THE FRICTION WELDING OF ARTICLES OF SIMILAR SHAPE IN DIFFERENT THERMOPLASTIC MATERIALS ARE DESCRIBED BY SUBJECTING THE PARTS TO BE WELDED TO AN OSCILLATORY MOVEMENT COMBINED WITH AN EXTERNAL HEAT SOURCE 37 TO MANUFACTURE TO CAUSE A BEND HERMETIC WELDING BETWEEN THE PARTS.

Description

OSCILLATING APPARATUS, METHOD AND SYSTEM FOR WELDING

  FRICTION OF DIFFERENT THERMOPLASTIC MATERIALS.

  The present invention relates to a method and to

  an apparatus for welding together two shaped parts if-

  milaire of thermoplastic items.

  In particular, the present invention relates to a method and an apparatus for frictionally welding lower and upper parts, made of different, crystalline or amorphous plastics, of a container in order to form a single hermetically welded container. By different plastics is meant thermoplastic materials having different melting temperatures

at least 15 C.

  In the prior art, a method is described for welding together the container parts to form a single container. This method is applicable to thermoplastic containers of cylindrical shape and consists in bringing the two parts of this container against one another, one of them being in rotation at high speed, to release

  by friction the heat necessary to weld the two parts.

  This method is generally called rotational welding and is described in particular in US patents 3,297,504, US Re. 29448

and US 3499068.

  Although this rotary welding method is advantageous compared to methods using cementing, chemical welding, or thermal welding, for example using a laser, an electron beam, radio waves or

  other electrical means, however, it presents the inconvenience

  -2 - deny being limited to cylindrical joints. It is obvious that two non-cylindrical parts of a container cannot be successfully welded by rotation because of the small surface which would be kept in contact while the parts are in

  rotation relative to each other.

  The object of the present invention is to remedy the

  Convenient to this method of rotary welding.

  The subject of the present invention is a method and a

  apparatus for friction welding of thermoplastic containers

  ticks whose parts to be joined are not cylindrical, well

  that the said process and apparatus can also be applied

  quer to the welding of cylindrical parts.

  The present invention also relates to a pro-

  ceded which uses an external heat source combined with an oscillating movement rather than a rotational movement between the parts of the container which must be joined, so as to release by friction the last amount of heat necessary for the

welding of these two parts.

  The present invention also relates to a process

  and a device for welding different plastic materials. The process of the present invention for welding

  at least two parts of thermoplastic articles of confi-

  similar guration with complementary contiguous parts

  fitting tightly, is characterized in that it

is:

  - preheat at least one of these parts in its share: e joln-

  tive; - slide the adjoining parts together to bring them telescopically to join; - Axially oscillate these parts, relative to each other, at a sufficiently high speed and for a period of time sufficient to generate enough heat

  to cause the contacting surfaces to merge and support

age of the parties; and

  - bring the sections to the desired final position and

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  put the cooling of the heated parts.

  The present invention is also described with the aid of drawings in which: - Figures 1 to 3 show sectional profile views of three different types of container seals can be welded using the method of the invention;

  - Figure 4 shows a partial profile view of an appliance

  oscillating welding eye, for low-frequency welding

  quence; - Figure 5 shows a schematic view of a rotary air seal used with the apparatus described in Figure 4;

  - Figure 6 shows a partial profile view of an appliance

  oscillating welding eye, for high-frequency welding

quence;

  - Figure 7 shows a schematic diagram of the ro-

  tative which provides air and electrical power to the appliance

  reil described in Figure 6; - Figure 8 shows a plan view of the rotary system

  input and output of the oscillating welding machine

tions.

  The present invention relates to a mofifica-

  tion and improvement of the apparatus described in the briefs

  vets mentioned above. In order to facilitate the description, we

  will describe the present invention with reference to a single apparatus of a multiple apparatus system such as that described in the patents cited above. With the exception of the modifications

  relating to the single apparatus described in this invention

  tion, the rest of the container formation system is ready

  the same as that described in the patents cited above. Referring to Figure 4, there is shown a single apparatus 10 of the welding system 11, represented by a side elevation view. This unique device 10 is representative

  other devices on the rotary device system

multiple lashes.

  This device includes a drive assembly

4 2569371

- 4 -

  upper 12 mounted by rollers on an upper cam head

13 hours.

  The lower drive assembly 14 is mounted on a lower cam head 15 by a roller device

roller 16.

  The upper assembly 12 is mounted in the head of

  cam 13 by a roller roller device 17.

  The upper cam head 13 generally comprises a vertical and practically circular cam plate 18, in which a peripheral groove 19 has been formed. The groove 19 passes circumferentially around the cam head 13 and

  is arranged to receive the roller roller 17 in an enga-

  relatively adjusted. The groove 19 has fluctuations in the vertical plane as explained in reference 20, so

  to control the vertical movement of the drive assembly

  ment 12 when it is rotating around the cam head 13.

  Similarly, the assembly of the lower cam head 15 comprises a peripheral groove 21 surrounding a generally circular cam head 36 and arranged to

  receive the roller roller 16. The groove 21 has fluctua-

  tions in the vertical plane to ensure vertical movement

  of the lower assembly 14 relative to the upper assembly

laughing 12.

  The lower assembly 14 generally comprises a

  upper vertical shaft 22 to which the tool is attached

  23 intended to receive and fix the lower part of the container to be welded. In addition, the tool 23 has conventional means, such as a device for placing under

  empty, to be able to hang the lower part of the container.

  The shaft 22 is mounted so as to rotate by means of the bearing 39 on a lower axis 45, which in turn is mounted on the roller

  16 of the cam. A pulley 44 or other drive device

  ment, like a gear or a wheel, is fixed on the upper shaft 22 to provide a means for selectively driving in a rotational movement the upper shaft 22 and the tool 23.

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  An external heating element 37 is fixedly attached

  ment by the support 38 on the base 46 of the device. It is

  directed towards the tool 23 and is very close to it.

  The head of the upper drive device 12 is attached by means of a shaft 24 to the roller 17. The roller 17 is mounted so as to be able to pivot on the shaft 24. It has also been mounted on the head of the drive device 12 an air oscillator 25 transmitting its action by means of a

  pivot 26 to an oscillating diaphragm 27 which is fixedly attached

  lying at the head of the drive device 12. The oscillator is provided with a sliding axis 28, extending downwards and on which the shaft of the upper tool 29 to which the tool is attached is attached upper 30. The axis of the tool 29 passes through an air bearing 31 mounted in the bearing housing 32

  which is fixedly attached to the head of the driving device

  12. The air bearing 31 allows vertical slides between the shaft 29 and the drive assembly 12. The tool

  higher 30 has conventional means, such as a

  positive vacuum, to be able to hang the upper part of the weldable container on the lower part which is held in the tool 23. The air supply source 33

  takes the air to level 31, while a second source of air

  air ment 34 sends air to oscillator 25, and a third air supply source 35 sends air to

  diaphragm 27. The oscillating diaphragm 27 is connected to the

  reader 25 so as to adjust the amplitude of the movement oscll-

  lant. In a typical operation, a pair of lower and upper parts of a container are removed from their

  respective battery by means of an appropriate device (not shown

  felt on the drawing). We bring the two parts by means of the

  conveyor system as described in the patents cited above

  front, and so that the lower part is held in the tool 23 and the upper part is held in

  the upper tool 30. The movement of the driving devices

  ment 12 and 14 around the circular cam heads 13 and 36 -6 - causes a vertical movement caused by the cams between the tools 23 and 30, bringing the parts of the container very close

one from the other.

  After the container parts have been brought back

  close to each other, and immediately-

  Before welding them together, the lower tool 23 arrives at its position closest to the external heating element 37 and at the same time undergoes a rotation of one or more complete turns to obtain uniform heating of the part which

  is held. Rotation can be achieved by driving the thumb

  lie 44 using an external V-belt (not shown)

  as described in US Patent Re 29,448 mentioned above

  above. During the rotation of the container part held in the tool 23, an energy source is switched on at

  the heating element 37 which thus emits heat which is di-

  rigged towards the container part. The element 37 can be a heat source of any conventional type such as quartz, infrared or other radiative type heating elements, electrical resistances, microwave or radio wave heating elements, flames obtained using gas or other liquid fuels, jets of hot air or steam, ultrasonic generators, and others

equivalent heating means.

  Several other heating procedures can be used. For example, if the parts of the container have nonclyclical surfaces to be welded, it is necessary that they are marked during or after the rotation, so that the correct alignment of the two parts is preserved after

  the rotation. This can be achieved either by conventional means.

  alignment, mechanical or optical, either by using a gear wheel in place of the pulley 44 and driving it in an exactly controlled rotation at

each cycle of the device.

  Another system is to use a heat source which distributes the heat over almost the entire circumference of the container part, so that it

  there is no longer any need to rotate the tool 23. We can react--

  read this by permanently installing items

  heated on each tool 23, or else having an element

  heated, which unfolds and folds cyclically and

  turn one tool at a time. The deployment and the folding can be carried out vertically or radially or both at the same time, in connection with the rotation of the assembly 14 around

from base 15.

  You can also heat the parts of the pan.

  pient using heating elements placed in or on a

  only one or both tools 23 and 30, generally oriented vertically

  tightly and slightly inward, so as to heat the plastic part held in the opposite tool. For example, an annular radiant heating element or a set of circulating air jets can be placed along the most lower surface of the tool

  and directed mainly towards the position that

  cuts the surface to be welded by friction of the container part

  held in tool 23. These heating elements can be

  automatically switched off by switches associated with the

peripheral groove 19.

  During the movement of the driving devices

  ment 12 and 14 around the device, when they get closer

  in close proximity to each other by the action of canes-

  lures 19 and 21, one or more external heating sources are activated and one or both surfaces to be welded parts of the plastic container are heated around their entire periphery

  using one of the methods described above.

  Since one of the advantages of the present invention is to weld different plastic parts by oscillatory friction, it is preferable to supply most and even all of the heat external to the part formed from the plastic having the highest melting temperature. high. For example, if one part has a melting temperature 45 ° C higher than that of the other part, it is preferable to increase the temperature of the part having the melting temperature 1 to 20 to 70 C beforehand. higher before

  perform oscillatory friction welding.

  When the drive devices 12 and 14, which rotate around the cam heads 13 and 15, have reached a predetermined point in the grooves 19 and 21, the tools 23 and 30 move to their closest position, bringing

  thus the upper and lower parts of the container in con-

  tact with each other. When the two parts of the reci-

  pient come into contact with each other, we send simulta-

  air from the tube 34 to the air oscillator 25,

  causing a low frequency oscillation of the upper part

  pearl of the container, held in the tool 30, and introduced into the lower part fixed to the tool 23. This oscillating movement is sufficient to release enough additional heat between

  the two parts of the container to obtain a tight welded joint

  tick. The number of oscillations necessary to have a suitable welding depends on various parameters including the quantity

  preheating used, the types of plastics used

  the size of the container, as well as the frequency and amplitude of the oscillations. These various parameters are well known to the operator when adjusting the apparatus. So,

  the duration and frequency of the oscillations must be determined

  created so that, when welding begins, the oscillations cease to allow the parts of the container to form a

good welding.

  The air oscillator 25 stops the oscillations in the lowest position so that the parts of the

  container remain completely in contact. Shortly after the cessation

  tion of the oscillations and carrying out the welding, the movement of the driving devices 12 and 14 around the cam heads 13 and 15 by means of the engagement of the rollers 16 and 17 in the grooves 19 and 21, will cause a vertical displacement of the two devices and will allow the removal of the welded container. It will then be transported by conventional means outside

of the welding area.

  Figure 5 gives a schematic representation of the rotary air seal to which the air inlet tubes 33, 34 and 35 have been connected. Figure 5 shows the rotary seal 40 having a

  outlet 41 of the air intake tube to be connected with the supply tube

  35 of the diaphragm, a second outlet 42 of the stopper tube

  air line to be connected to the air supply tube 34 to the oscillator and a third outlet 43 of the air supply tube to be connected

  to the tube 33 for supplying air to the air bearing. As the disposi-

  tifs 12 and 14 are rotating around their -

  respective cam head 13 and 15, the outputs 41 and 43 of the tube

  of air supply communicate with the various supply tubes

  tion to bring in sufficient air in due time

  in the various organs which must be supplied with air.

  In this embodiment, the oscillating device

  tion consists of a pneumatically controlled oscillator. he

  this is a low frequency oscillator, i.e.

  about 50 to 500 cycles per second and more particularly 120

at 240 cycles per second.

  In the case where one wishes an oscillation at more

  high frequency, an electrically controlled oscillator is used

  than. Frequencies of the order of 50 to 50,000 cycles per second are thus reached, and more particularly of the order

  from 20,000 to 40,000 cycles per second.

  Figure 6 shows a second embodiment

  of the present invention. This mode of execution is particularly

  commonly used to weld parts of vessels

  pient with high frequency oscillations. In the present embodiment, the drive device of the first embodiment has been replaced by a drive device 100 at high frequency. This drive device is mounted on similar cam heads 13 and 15 by means of roller rollers 16 and 17. The drive device 100 comprises an upper drive body 101 and a lower drive body 102. The body 101 has a support 102 on which is mounted an ultrasonic transducer 104 located in a

  vertical plane. The transducer 104, which works electrically-

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  mert, is connected to a source of electricity by the connection 105. At the lower part of the transducer 104, there is a pivot 106 which ensures the connection with the upper shaft 107 of the transducer. The air bearing 108, connected to the body 101, supports

  the shaft 107 so as to slide it in the vertical plane.

  A tool 109 is provided located at the lower end of

  the shaft 107, for hanging the upper part of the container.

  The tool 109 preferably has an internal cavity similar in shape to that of the top of the container to be welded. On the lower body 102 is mounted a lower shaft 110 having at its upper end a tool 111 for hanging the part

  bottom of the container. Tool 111 has an inter-

  not similar in shape to the bottom of the container

  pient to solder. Tools 109 and 111 have means

  conventional to fix tightly the parts of the container.

  Tool 111 can be rotatably mounted on the

  bearing 112 and include a drive pulley or a

  grenage 113. Although a pulley 113 has been shown, it is

  holds a more precise rotation thanks to an exact location in

  replacing pulley 113 with a gear to weld parts

non-circular ties.

  An external heating source 114 of the type described above, or its equivalent, is placed on the stationary central column of the apparatus for the intermediary of the chassis.

  115. The heating source 114 is directed towards the carrier

  object of the tool which has received the plastic part having the highest melting temperature. The heat source can be fixed either to one of the tools 109 and 111, or be an integral part thereof; it can also be retractable, whether vertically or radially. These different heating techniques eliminate the need to provide the

rotation means 112 and 113.

  In a usual operation, the mobile assemblies

  the 100 revolve around their respective cam head 13 and with the rollers 16 and 17 engaged in the grooves 20 and 21. This rotary movement associated with the normal movement of the cams i- 11 - 2569371

  results in a vertical spreading and moving movement

  lower and upper trees relative to each other. At some point, tools 109 and 111 are spaced from each other, and the top of a plastic container is

  housed in tool 109 while the foot of the plastic container

  that is housed in the tool 111, by means of suitable devices

  tional. An additional movement of the rollers in their respective grooves serves to bring the upper and lower shafts towards each other by translation until the time when the lower and upper parts of the plastic container are

  in close proximity to each other. The heating element ex-

  114 is then activated, and heating of the

  around the preselected part of the container either in

  dragging this last part in a rotational movement, either by heating it with an annular heating element, thus

as described above.

  The plastic parts are then brought

  in contact by a telescopic movement caused by the rods-

  lures 19 and 21. At this time, the transducer is supplied with electricity by connection 105, thus causing movement

  high frequency oscillatory of the shaft 107, which makes os-

  blink the top of the container, creating forces

  friction, which release a large amount of heat and

  put hermetic welding of the lower and upper parts

  container. The continuous movement of the in-

  dragging around the cam heads then separates the upper and lower shafts from each other, and allows

  removal by known means of the welded container.

  Figure 7 shows a schematic diagram of the rotary joint located near the central longitudinal axis of the complete assembly. In Figure 7, we have represented by

  references 112 and 113 the electricity supply circuits

  tricity. An air supply is connected to the rotary air seal

  114 to supply air to bearing 108 in a semi-

  similar to that described in Figure 5. In addition, the tools 109

  and 111 are equipped with conventional means, such as a device

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  tif vacuum, or a mechanical mechanical device to fix the container parts during the welding step

by oscillations.

  Figure 8 shows a plan view of the system

  supply 200 of the welding device. The feeding system

  mentation comprises a rotary input device such as a star wheel 201 which distributes the containers in the various devices 10, and an output wheel 202 comprising a

  star wheel to remove containers that have been welded.

  We show in this Figure an oscillating welding system

  multi-device, having ten individual devices 10

welding.

  Figures 1 to 3 show the various joints that can be welded using the assembly of the invention, as well as parts of rigid plastic containers. Figure 1 shows a view of a partial section of the part

* upper 301 of a container which is welded to the lower part

  lower 302 with the assistance of the heating element 37. This type of seal is generally called compression shear seal. The outside diameter of the lower part 302

  is a few thousandths of a millimeter wider than the dla-

  inner meter of the upper part 301. We force the part

  tie 301 above the part 302 so as to cause an air tight tightening, and then the oscillation between the

  two parts, causes, thanks to the heat previously supplied

  negates and to the heat of friction, a sufficient fusion of the ma-

  thermoplastic materials to form a hermetic seal

between them.

  Figure 2 shows a view of a partial section-

  the joint between two plastic items, such as the two parts of a container, or the wall of a container and the bottom of a container. This type of seal is generally called a seal.

  directional energy. In this type of joint, we make os-

  close the side wall 401 of a part of the container between the

  flanges 402 and 403 for the bottom of the container 404. Pre-

  ference, there is a small difference between the wall 401 and the

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  distance between edges 402 and 403, to obtain heat

  sufficient to weld the bottom of the container to the wall 401.

  Figure 3 shows another mode of execution of

  the upper tool 501 for tightening the cross-section 502 of the

  container. Section 502 of the container should be friction welded to the bottom 503 of the container. In this particular embodiment, a wedge wedge 504, connected

  to a first cam path located on the upper cam head

  lower 13, hooks the container section 502. The part 504 is made in the form of a wedge at the base, but in a divergent direction, and a sealing ring 505, which can slide, is situated around my outer periphery of the fixing member cut into a wedge shape. A second cam path located on the upper cam head directs the vertical movement of the fixing member 505 downward on the member 504 cut in the corner of

  so as to obtain internal compression of the container part

  pient 502. The period of time required to travel the first and second cam paths is such that the member 505

  descends on member 504 to compress part 502 of the reci-

  downward on the part 503 of the container, just after this part 503 has entered the region of the edge 502 A. Then, the member 505 is lowered to compress the wedge 504 and

  the part 502 of the container on the part 503 of the container.

  After this downward movement of member 505,

  oscillations in the whole upper assembly to make oscillation-

  place the container part 502 on the part 503 and release

  enough friction heat to weld the two parts together

container ties together.

  The friction welding system of the present invention is particularly advantageous for welding parts.

  non-circular thermoplastic container ties and

  of different thermoplastic materials. The present invention

  tion uses an axial oscillatory movement, in contrast to

  the conventional rotary motion of lifting devices

  rotation dage. The oscillatory movement being a movement-

  translation rather than rotational movement, this

- 14 -

  allows friction welding of containers of almost any transverse shape. In addition, preheating

  of one or both parties brings several appreciable advantages

  bles to container manufacturing processes. An advantage

  already mentioned is the welding of different plastics

  tes with significant differences in melting temperatures.

  Another is that preheating reduces the interference fit between the parts to be welded, which reduces

  the gap and the destructive forces in the weld region

  re. Thanks to preheating, frequencies can also be used.

  these weaker welds which reduce the stresses in the final weld. The present invention also describes

  embodiments and devices for bone welding-

  cillations, both low frequency and high frequency, of different thermoplastic materials. Although this

  invention has been described with reference to modes of execution

  tion, it is understood that this does not constitute a limitation. Thus, for example, although it is indicated that the transducer is electrically controlled and that an air oscillator is used, it is obvious that other means can be used, such as for example a hydraulic control and a mechanical production of the oscillations. So also, although we indicate that we oscillate the

  upper part of the container in contact with the lower part

  of this container, it is obviously possible to make

  oscillate the lower part, or even the two parts in

  seems. All these modifications are therefore part of the

this invention.

  Although the process of the present invention has been described for the welding of container parts made of material

  thermoplastic in general, it is understood that these terms

  in particular, styrene resins, polystyrene, polypropylene, polycarbonate, high or low density polyethylene, polyethylene terephthalate, or

  polyethylene glycol terephthalate.

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Claims (22)

CLAIMS:   1. Method for welding at least two parts of thermoplastic material of similar configuration having complementary adjoining parts sealingly adapted, characterized in that it consists in - preheating at least one of these parts in its adjoining part ; - slide the adjoining parts together to bring them telescopically to join; - Axially oscillate these parts, relative to each other, at a sufficiently high speed   and for a sufficient period of time to   generate enough heat to cause the contact surfaces to merge and the parts to be welded; and - bring the sections to the desired final position   and allow cooling of the heated parts.   2. Method according to claim 1 characterized in that the parts of thermoplastic material are dimensioned so that there is a slight difference between them to allow them to be arranged clamping.   3. Method according to any one of the claims.   1 and 2, characterized in that parts of organic thermoplastic material having slightly different melting temperatures are used, and that the part having the   highest melting temperature.   4. Method according to any one of the claims   1 to 3, characterized in that a container is formed ,.   from two parts of thermoplastic material, of non-circular cross section, each part being held by clamping in a support, both   parts aligned axially and capable of telescopic engagement   scopically, the welding area of these parts being   heated before telescopically engaging them. 69371 - 16 -   5. Method according to any one of the claims   1 to 4 characterized in that the configuration parts   similar are plastic, crystal-   lines or amorphous, different and whose melting temperatures differ from more than 15 C and which are chosen from polystyrene and styrenic resins, polyethylene, polypropylene, polyethylene terephthalate.   6. Method according to any one of the claims   tions 1 to 5, characterized in that the oscillation movement at a frequency of 50 to 50,000 cycles per second. 7. Apparatus (10) for oscillating friction welding of a thermoplastic polymer compound to another compound consisting of a different thermoplastic polymer, characterized in that it comprises   - a first support (30) adapted to attach a pre-   mier compound to be welded comprising a first attachment device and a first receptacle for receiving the first compound, - this first support being mounted on a tool (29) adapted for a sliding axial movement, and - this tool being mounted on a movable assembly (12); - an oscillation device (25) connected to this first tool (30) and to this movable assembly (12) and arranged   so as to oscillate this first axial tool (30) -   ment relative to this movable assembly (12); - a second support (23) attached to the shaft support (22) and adapted to hold a second article to be welded to the   first, this second support (23) being aligned axially-   ment with the first support (30) and being very pro-   che of the latter, this second support (23) comprising   a receptacle for receiving this second article.   - a device to move axially and re-   here the first and the second support in a movement such that they meet telescopically; - 17 -   - an external heat source (37) mounted near at least one of the supports (23 or 30) and arranged to direct the heat against a welding surface of a   compound held in the support located nearby.   8. Apparatus according to claim 7 characterized in that the support (23) located near the heat source (37) is adapted to rotate around its vertical axis.   9. Apparatus according to any one of the claims   tions 7 and 8, characterized in that it comprises a dis-   positive (44) to rotate the support (23) to pro-   ximity of the heat source (37).   10. Apparatus according to any one of the claims.   tions 7 to 9, characterized in that the heat source (37) is adapted to distribute the heat over the entire   circumference of the part to be heated.   11. Apparatus according to any one of the claims.   tions 7 to 10, characterized in that the heat source (37) is chosen from the group comprising radiant heaters, jets of hot air or steam, infrared, radio wave or microwave heaters,   flame heaters and ultrasonic heaters.   12. Oscillating system for friction welding   of two parts made of thermoplastic polymers   ques different, characterized in that it includes   - an upper mandrel (30) for holding a first article   plastic key in a vertical axial orientation   wedge; - a lower mandrel (23) for holding a second   plastic article in an axial orientation ver-   ticale in alignment with the first mandrel (30); - At least one of the mandrels (23 or 30) being adapted to be subjected to a rapid oscillatory axial movement; - at least one of the mandrels (30 or 23) being adapted to be subjected to a substantial vertical displacement; - a device for axially moving one of the mandrels - 18 - (23 or 30); and   - a heat source (37) for applying heat   their exterior to the plastic article held in one of the mandrels (23 or 30), this heat source (37) being disposed near one of the mandrels (23 or 30).   13. Oscillating system according to claim 12, characterized in that the mandrel (23 or 30) located near the heat source (37) is suitable for rotate around its vertical axis.   14. Oscillating system according to any one of   claims 12 and 13 characterized in that the source   heat (37) is adapted to turn circumferentially-   around the mandrel (23 or 30).   15. Oscillating system according to any one of   claims 12 to 14 characterized in that the source   heat (37) is an integral part of one of the mandrels   (23 or 30) and is directed towards the other mandrel (30 or 23).   16. Oscillating system according to any one of   claims 12 to 14 characterized in that the source   heat (37) is an integral part of one of the mandrels (23 or 30) and is directed towards the plastic article   held in this same mandrel (23 or 30).   17. Oscillating system according to any one of   claims 12 to 16 characterized in that the source   heat (37) is selected from the group comprising   radiant heaters, jets of hot air or fan   fear, infrared, radio or microwave heaters, flame heaters and heaters ultrasonic.   18. Assembly comprising several apparatuses (10) for   friction welding according to any one of the claims   cations 7 to 11, characterized in that it comprises - a stationary base (46); - an upper assembly (12) mounted on this base (46); - A lower assembly (14) also mounted on this base (46) and below the upper assembly (12); 693f1 - 19 -   - these assemblies (12 and 14) being kept in line-   circumferential to each other on this basis (46); - At least one of these assemblies (12 or 14) being able to move axially from back to front relative to the other assembly (14 or 12), thanks to a displacement device; - a selective device for supplying power for the actuation of the oscillation device and of the support of each welding device, so as to move the first support from back to front   between a first position where the articles in ma-   all plastic are separated and a second position where the articles telescopically engage one another; and - a heat source (37) arranged to direct the heat selectively to at least one of the two supports (23 or 30) of each appliance (10) and adapted to distribute the heat over the entire circumference of the part of the article to be heated maintained in one of the supports (23 or 30) and this before the articles are not engaged one in the other;   - an oscillation device suitable for oscillating only-   LEMENT when the supports are in this engagement position, this oscillation device comprising means for adjusting the frequency and the amplitude of the oscillation to maintain the articles in telescopic engagement during their oscillation. 19. Assembly according to claim 18 characterized in that the heat source (37) is fixedly mounted on this assembly and that at least one of the supports (23   or 30), in each device (10), is suitable for turning   ner around its vertical axis when it passes near heat source (37). -20-   20. Assembly according to any one of the claims.   tions 18 and 19 characterized in that the source of cha-   their (37) is located on at least one of the supports (23 or 30) in each device (10).   21. Assembly according to claim 18 characterized   in that the heat source (37) is mounted in a   mobile on this assembly and is arranged to move reciprocally on either side of a position located near at least one of the supports (23 or 30).   22. Assembly according to claim 21 characterized   in that the heat source (37) is adapted to band the supports (23 or 30). By proxy from VERCON, Inc. the representative: Cabinet R. Baudin.