FR2760680A1 - ASSEMBLY SYSTEM OF THERMOPLASTIC TUBULAR ELEMENTS - Google Patents

Abstract

The present invention relates to a system for assembling a pair of stopper thermoplastic end portions (38, 40) using a transparent sleeve (116) extending around the outer surface of the tubular end portions (38, 40) to assemble and a mandrel (150) on the interior surface. Infrared heating means (136) provide radiant heat through the transparent sleeve (116) to melt and fuse the tubular end portions (38, 40). The tubular end portions (38, 40) can be visually monitored through the transparent sleeve (116) during the welding process.

Description

ASSEMBLY SYSTEM OF THERMOPLASTIC TUBULAR ELEMENTS

  The present invention relates to the assembly of thermoplastic tubular elements. It relates more particularly to a method of welding pairs of tubular end portions without forming a bead at the weld. The process lends itself particularly well to fluoropolymers which can be treated in the molten state by welding, such as

than perfluoroalkoxy (PFA).

  Various means are known for welding the ends of thermoplastic pipes, see for example U.S. Patent No. 4,929,293 issued to Oscar, which uses the positioning of an infrared heating plate between and in front of the tubular end portions to be assembled. Then, the infrared hot plate is removed and the tube joints are then engaged with each other to create the weld. Although such a process produces a high integrity weld on melt processable fluoropolymers, such a weld can leave a deformation or bead on the inner and / or outer surfaces of the

  tubular end parts assembled.

  In many applications, it is not acceptable to have any deformations in the assembled tube, in particular on the interior surface. In sanitary installations used in the food and pharmaceutical industries, the standards of the U.S. Code of Regulations (7 C.F.R. S58.128) require that a pipe be smooth, allow a laminar flow of fluids and be free of discontinuities that can

trap certain materials.

  Traditionally, we use in installations

  sanitary fittings and pipes in stainless steel.

  However, due to corrosion, cost and other problems, pipes and tubing are now used

plastics in these facilities.

  Various welding devices have been developed to carry out the welding of thermoplastic pipes and tubes without internal cord. See, for example, patent No. 5,484,506 issued to DuPont et al. and patent No. 5,037,500 issued to Hilbert, both of which disclose the use of radially expandable internal mandrels to allow engagement of the interior surface of the tubular end portions to be assembled and then allow the mandrel to retract radially to be able to be removed from the pipeline. This type of removable mandrel has a difficulty in that it requires a power cable extending to one end of the pipe. When assembling long sections of pipe, or mounting valves or other fittings, there may not be enough exit points to remove the mandrel. Attempts have been made to use breakable internal mandrels, see U.S. Patent No. 2,963,394 issued to Wilkenson. However, these types of devices produce unacceptable residues and can damage the interior surface of the pipe when these devices are broken for removal. In addition, these welding methods resort to heating the tubular end portions exclusively by conduction. With such heating means, it is difficult to concentrate the heat on the abutting faces of the tubular end portions. In addition, this heating exclusively by conduction generates in the welding tool a large amount of heat which must be dissipated and which delays the moment of withdrawal of the tool from the assembled tubes to proceed to the next weld. This leads

longer cycle time.

  An apparatus for assembling first and second components uses a sleeve substantially transparent to infrared radiation, extending around the outer surface of the tubular end portions abutting the components, and a mandrel positioned within the portions of tubular end. An infrared heating element produces radiant heat through the sleeve to melt and therefore assemble the tubular end portions in abutment. The tubular ends can be rotated in abutment relative to the infrared heating element to ensure uniform fusion and bonding of the joint. The device can be configured as a portable unit with a separable welding head connected to a control unit by means of a cable containing electric lines to supply the heating element, detection lines for thermocouples in the head welding and a pipe

  coolant to cool the welding head.

  Thus, a separate air compressor or hydraulic pump can be placed in the separate control unit remote from the welding head to accelerate the cooling of the welding head and reduce cycle times. The device can also be configured as a bench unit. Either of these configurations can be used to assemble straight pipe sections, to assemble fittings to pipes or tubing, or to assemble pipe coils to

  other pipe sections or accessories.

  Means may be provided to produce axial compression on the tubular end portions in abutment. One aspect of the invention includes compression means comprising a rod extending through the tubular end portions abutting with two engaging portions, each engaging each component and producing a compressive force thereon this. This facilitates the rotation of the components to produce a

  uniform heating by the infrared source.

  A characteristic advantage of the invention is that the use of the transparent sleeve allows the radiant energy concentrated at the end portions in abutment to achieve the weld, causing minimal melting of the thermoplastic material. In addition, the concentration of radiant heat minimizes the heating of the welding head, which minimizes cycle times. Mirrors or concave lenses can focus infrared radiation to

  produce optimal welding performance.

  In the alternative embodiments, the sleeve engaging the outer surface of the pipes can be formed from various quartz-based materials, glass, ceramic materials, or even sapphire. These non-metallic materials have characteristics distinct from traditional metallic sleeves, in that they allow, for example, longer cooling times.

  short after the welding operation.

  The transparent sleeve can be split longitudinally to allow insertion and removal of the tubular end parts or it can be in one piece and mounted on both end parts

  tubular to be assembled before they are brought into abutment.

  After welding, the sleeve can be slid if the outside diameter of the components allows, it can be broken and removed or left on the assembled components. The mandrel can be based on known designs which are radially expandable, see for example U.S. Patent No. 5,037,500 issued to Bruno Hilbert; it can be generally rigid and not extensible and manufactured in polytetrafluoroethylene (PTFE) or in other inert materials. According to one aspect of the invention, it can also be made of a dissolvable material, such as sodium chloride. A fluid such as water can be introduced inside the tubular end portions to

  dissolve and remove the dissolvable mandrel after welding.

  The dissolvable mandrel can be partially or totally dissolvable. Additional components or additives which are not dissolvable can be added to modify its heat transfer characteristics, for example its infrared absorption and infrared reflectivity characteristics. The additives can be metallic, ceramic or

  solid plastics or materials like carbon.

  The core can be heated to a large extent by radiant infrared heat and further heat by conduction the end portions of the pipes to be joined. Another characteristic advantage of the invention is that the mandrel can be dissolved in a solution and can therefore be removed in special installations which would exclude the use of a mechanically inflatable mandrel. Another characteristic advantage of the invention is that the dissolvable mandrel guarantees food safety and does not create unacceptable confinements inside.

of the sanitary installation.

  Another characteristic advantage of the invention is that the use of radiant energy is more efficient than the use of heating essentially by conduction. Infrared radiation can be concentrated by lenses or be reflected and / or

concentrated by mirrors.

  Another characteristic advantage of the invention is that the use of radiant heat allows the use of lighter and more compact welding heads, which facilitates applications not taking place on the bench. In the portable configuration, the welding head is lighter, which improves the portability characteristic. In addition, the lower mass in the welding head allows a

  faster and more efficient cooling.

  Other characteristics and advantages of the invention

  will emerge more clearly on reading the description

  below, made with reference to the accompanying drawings, in which: FIG. 1 is a perspective view of an embodiment of the invention configured in the form of a

portable welding device.

  Figure 2 is a side elevational view of a

  workbench configuration of the invention.

  Figure 3 is a sectional view of a welding head

illustrating the invention.

  Figure 4 is a perspective view of an apparatus for

portable welding head.

  Figure 5 is a rear elevation view of the portable welding head of Figure 4. Figure 6 is a sectional view of the portable welding head apparatus taken along line 6-6 on the

figure 5.

  FIG. 7 is a perspective view of a ceramic insert for a welding head applicable to the device

  shown in Figures 4, 5 and 6.

  Figure 8 is a back view of a half-sleeve.

  Figure 9 is a top plan view of the half

  sleeve shown in Figure 8.

  Figure 10 is a block diagram illustrating the

parts of the control unit.

  Figure 11 is a side elevational view of a

  dissolvable chuck provided with inclusions.

  Figure 12 is an elevational view of the operation

of an aspect of the invention.

  Figure 13 is an elevational view of the operation

of an aspect of the invention.

  Figure 14 is an elevational view of the operation

of an aspect of the invention.

  Figure 15 is an elevational view of the operation

of an aspect of the invention.

  Figure 16 is an elevational view of the operation

of an aspect of the invention.

  Figure 17 is an elevational view of the operation

of an aspect of the invention.

  Figure 18 is an elevational view of the operation

of an aspect of the invention.

  FIG. 19 is a perspective view of an embodiment of

  realization of the invention for use on bench.

  Figure 20 is a sectional view of the mode of

realization of figure 19.

  Figure 21 is a perspective view of another mode

for carrying out the invention.

  Figure 22 is a sectional view of the mode of

realization of figure 21.

  Figure 23 is a perspective view of a rod assembly according to the invention with a pipe section, a

  sanitary accessory and a sleeve on the rod assembly.

  Figure 24 is a sectional view of the rod assembly

in Figure 23.

  Figure 25 is a sectional view of an embodiment of the invention using a lens at the level

  tubular end portions.

  Figure 26 is a sectional view of an embodiment using a lens at the portions

tubular end.

  Figure 27 is a sectional view of a mode of

realization of the invention.

  Figure 28 is a sectional view taken along the

line 28-28 in figure 22.

  Figure 29 is a sectional view similar to Figure 28 with a drive wheel for rotating the

  infrared heating sources.

  With reference to FIG. 1, the drawing represents a portable apparatus for welding thermoplastic pipes, generally designated by the number 20. Said portable welding apparatus is mainly composed of a portable welding head 22, a unit for control 24 and a connection cable 26. With reference to FIG. 2, the drawing represents another apparatus for welding thermoplastic pipes for use on a workbench, designated by the number 30. The workbench welding apparatus 30 has a base 32 which can hold the control unit. The workbench configuration can be used for larger gauge tubes and when there is no need to weld in remote locations. The bench unit of Figure 2 has a pair of tubular end portions 38, 40 which are to be welded together. The tubular end parts can be part of a pipe or a pipe or part of an accessory, a reducer, a valve or any other equipment to be connected. Both the portable welding apparatus 20 and the bench configuration 30 use an outer sleeve which envelops the outer circumferential surface 44 of the tubular end portions. Both have separable parts 48 and 50 which allow access to the receiving part 52 of the welding heads. The separable parts 48, 50 can fold in on themselves in an appropriate manner by means of a joint or can be detachable from each other. Fixing means 60, such as the latch shown in Figure 1, can be used

  to lock the separable parts 48 and 50.

  With more specific reference to Figure 2, the workbench 30 has half-sleeves 64, 66 supported by the welding head 70 which is fixed to the base 32 by a support 72 and further supported by elements auxiliary supports 76, 78 provided with respective support elements

, 82 fixed to the base 32.

  The pipe or tubing sections 36 to be assembled are further supported at a point further away from the welding head by support elements 83, 84. These support elements include tubular blocking elements 86, 88 which extend around and enclose the outer surface 44 of the tube sections 36 by means of the adjustment screws 90. The support elements 96, 98 are axially adjustable relative to the tubular end portions on the base 32 by means of the cranks 94. The elements of support 83, 84 only block the tube sections 36 at the level of the locking elements 86, 88 and use return means 102, configured in the form of helical springs, to produce an axial compression force

  on the tubular end portions 38, 40.

  Referring to Figure 3, the drawing shows a sectional view of a welding head similar to that which can be used in the bench apparatus of Figure 2. This welding head consists of a pair of separable parts of the welding head housing 110, 112 which extend around the tubular end parts 38 and 40. The welding head housing can be made of aluminum or any other suitable material. The configuration of Figure 3 uses a sleeve for engaging the parts

  tubular end made of a pair of half

  116 quartz sleeves which are illustrated in isolation in the

views of Figures 8 and 9.

  Still with reference to FIG. 3, the welding head 70 comprises cooling passages or openings 122 which can be used to circulate a cooling fluid such as air after a weld has been carried out. The housing parts 110, 112 as shown in FIG. 3 each have an internal part 126 and an external part 128 fixed to each other by screws 130 or by other suitable means. The housing parts each have an intermediate part 132 which, in a preferred embodiment, is of a machinable ceramic material, the cooling openings 122 being formed therein. The intermediate part also supports an infrared heating element 136 which, in FIG. 3, is presented in the form of a strip embedded in a cavity 138 of the intermediate part. The cavity 138 is suitably configured to provide an air gap between the element and the sleeve and to direct the infrared radiant heat from the element 136 to the tubular end portions. The radiant heat will pass, to varying degrees depending on the quartz material, the quartz sleeve surrounding and enveloping the parts

tubular end.

  The tubular end portions each have an end face 142, 144 which abuts one against the other

  and how well the end parts will be assembled.

  Inside the end portions is a mandrel 150 made of a soluble material guaranteeing food safety such as sodium chloride or potassium chloride. The mandrel 150 engages the interior surface 154 of the tubular end portions and has a smooth finish of 10 microns or better. An ideal formula for the composition of the mandrel is a mixture of 50% potassium chloride and compacted sodium chloride. The mandrel 150 has an opening 160 configured as a hole extending axially through the mandrel. The mandrel based on the above formula is stable at temperatures above 900 F (482 C) but it is soluble in water, this

  which allows to remove it once the welding has been carried out.

  Referring to Figure 11, the drawing shows another embodiment of the soluble mandrel 150. In this embodiment, components 161 have been added to influence the heat transfer characteristics of the core. These inclusions can be made of metal or other materials. The components are shown embedded in the place where the ends of the pipes will come into abutment. Such inclusions can thus produce an accentuated heating of the end faces both by reflection of infrared radiation and by conduction. The inclusions will normally be segmented to allow easy removal when the nucleus is dissolved. Furthermore, it should be noted that the dissolvable mandrel 150 is also suitable for use with a welding machine with

conventional metal sleeve.

  The housing parts 110, 112 also include

  O-ring grooves 166 for receiving the half

  O-rings 168 to secure the tubular end portions inside the welding head. The support section 72 of the welding head contains a coolant conduit 172 which can convey a fluid such as air into the interior of the weld head, which will pass through the cooling passages 122 to exit through an exhaust port 174. The support structure 72 also contains a power supply line 176 connecting to the infrared heating element 136 and a detection line 178 connecting to a thermocouple 180 to monitor the temperature at desired locations in the

welding head.

  With reference to FIGS. 4, 5, 6 and 7, the drawings represent functionalities of the portable welding head. The portable welding head generally has separable parts 48, 50 connected to each other at the joint 56 and which can be locked using the latch 60. A handle 186 is connected to the part separable lower 50 and has a hole 188 through which the connection cable, not shown in this view, will extend to the elements

of the welding head.

  Referring more particularly to FIG. 4, this drawing does not show either the half-sleeves or the infrared heating element and thus shows the intermediate parts 190, 192 of machinable ceramic material. Intermediate parts provide support for the infrared heating element and may also have locations 196 for desired sensors as well as for cooling passages 198. Figure 4 also shows half-o-rings 202, 204 for engaging

  the tubular end portions.

  Referring to Figures 6 and 7, the drawings show in more detail an appropriate intermediate portion 192. FIG. 6 represents the infrared heating element 136 in position and mounted on the intermediate parts 190, 192. It should be noted that the infrared heating element 136 is separated from the quartz half-sleeves 116. The connection wires for the heating elements are not shown in FIGS. 4, 5, 6 and 7. With reference to FIGS. 8 and 9, the drawings represent the sleeve 116. The sleeve can be produced from a suitable quartz such as GE grade 214 quartz. note that various quartz variants can be used, for example sapphire and ceramic materials, glass, more particularly tempered glass such as Pyrex (Pyrex is a registered trademark of Corning Corporation) and other rigid transparent materials which withstand the temperatures encountered. The use of a non-metallic sleeve less transparent than the GE 214 quartz allows the heating of the sleeve and produces a better

  conduction heating of the tubular end parts.

  The materials which are essentially transparent to infrared radiation nevertheless allow rapid cooling after welding due to the generally lower thermal capacity of these materials compared to steel.

conventional stainless steel.

  Referring to Figure 10, the drawing shows a block diagram of the control unit 24 and its main parts. Generally, the control unit has a control processor 210 which is connected to sensors in the welding head 70 via an input / output portion 214 and also receives instructions from a keyboard or other data input source part 218 and can display data

  or information by means of the display part 220.

  The control unit 24 also includes a supply portion 224 for supplying energy to the heating element in the welding head. In addition, a coolant supply portion 228, configured as a fan, supplies the weld head with coolant, such as forced air or coolant. The cable 26 connecting the control unit 24 to the welding head 22 can use an appropriate connector 230. The control processor can include programmable functions to allow the adjustment of the welding cycle parameters for sizes and types of tubes. as well as the recording of relevant data such as welders, verifiers and welding parameters. This is in addition to the monitoring and control functions of the sensors and functional elements of the welding head and the control unit. These include, among others, the control unit display, the welding head temperature sensors, the sensors for detecting the correct closing and locking of the welding head, the mechanisms electronic lock in the welding head and the heating element in the welding head. The control unit may, through the control processor, provide visual or auditory information at the control unit or the welding head to indicate when the welding head has cooled sufficiently to allow removing the welding head from the welded tubular end portions. In addition, the control unit can control the electronic locking of the welding head on the pipe so that it cannot be removed inadvertently.

  before reaching the appropriate temperature.

  Referring to Figures 12 to 18, the drawings illustrate the operation of the invention. If necessary, a conventional mechanical pipe expander can be used, such as No. 15071, model S, manufactured by Rigid, 400 Clark Street, Elyria, Ohio (USA), designated by the number 260 in Figure 12, on the parts of the tubular end 38, 40 as shown in FIG. 12 to diametrically widen the tubular end faces 142, 144 in order to allow the introduction of a mandrel 150 as shown in FIG. 13. The tubular end parts 38, to be assembled are aligned axially and the mandrel 150 is inserted therein so that the end faces 144, 142 come into abutment as shown in FIG. 14. Normally, as the tubular end parts retract after a few seconds, the mandrel must be inserted quickly after enlargement. Smooth half-sleeves 64, 66 are placed on and secured to the outer circumferential surface 44 of the tubular end portions as shown in Figure 15 to form a sleeve assembly 270. As shown in Figure 16, the welding head 22 is then placed on the

  half sleeves 64, 66 and engagement therewith.

  The heating element of the welding assembly is activated by the control unit to supply heat to the junction 232 of the tubular end portions. The heat is applied at a sufficient temperature and for a sufficient time to perform the welding. An axial compressive force, indicated by the numbered arrows 242, 246, can be used to promote welding. It is important that the heating of the junction is limited to the sole realization of the weld to thereby reduce the cycle time and avoid excessive melting of the tubular end parts. The welding head can be removed before the weld is completely cooled, especially if the sleeve assembly 270 is left thereon as shown in Figure 17. The use of the separable sleeve can

  promote a reduction in cycle times by welding.

  When the solder is sufficiently cooled, the sleeve can

then be removed.

  As illustrated in FIG. 18, a fluid, represented by arrow 150, can then be injected into the welded tubular end portions to dissolve and evacuate the mandrel 150. When using an extensible mandrel or a

  other type, it is removed at this stage of the process.

  The apparatus and the process presented lend themselves particularly well to various pipes such as PFA pipes but the invention is applicable more generally to the welding of all thermoplastic materials. With reference to Figures 19 and 20, the drawings show another embodiment of the invention. This embodiment is a workbench configuration and consists mainly of a support structure 302, a drive motor 303, a welding head 304, a first pipe support 308, comprising a first bearing 310, a second pipe support 314, comprising a second bearing 316, and a third pipe support 320, with a third pipe bearing 322. Each pipe support has a lower half 323 and an upper half 324 separable to allow insertion of the pipe. Placed in the pipe supports 308, 316, 320, a first component 326, configured as a pipe section, is fixed in the first pipe support and the third pipe support and is engaged therewith this in a way that allows rotation. A second component 330 is configured as a sanitary accessory, with a second tubular end portion 332. The first component 326 has a first tubular end portion 329. The first tubular end portion and the second portion d the tubular end meet at a stop point 334. The second component 330 is connected to the second pipe support and to the second bearing by means of the adapter 338 configured in the form of a drive hub and through a seal 340. The drive hub 338 rotates in the second bearing 316. The drive hub 338 is engaged with a drive collar 344. A rod assembly 348, extending through the first component and the second component, includes a drive shaft portion 350 which is connected to the drive motor 303. The rod assembly has a first engagement portion 354 which consists of an extension piece remitted 356, a spring 358 and a spring nut 360 which is engaged by thread with a threaded part 362 of the rod 364. A seal 366 is placed between the

  end piece 368 and the first component 326.

  The rod assembly also includes spherical centering members 370 which may be rigid plastic. These centering elements 370 prevent the rod from damaging or scratching the smooth interior surface 372 of the first component 326. The welding head 304 comprises a lower half 374 and an upper half 376 which are hingedly connected at the pivot 378 A mirror reflector 382 surrounds on essentially three sides a nickel-cadmium wire 384 which constitutes the source of infrared radiation 385. Additional screens 388 contain and concentrate the infrared energy generated by the element.

heating 384.

  When the motor 303 rotates, the rod assembly 348 also rotates thanks to the connector 390, the rod 364 is coupled to the drive collar 344 by a pin 345 and makes

  therefore turn the adapter 338 and the second component 330.

  The rod 364 extends through and is connected to the first engagement portion 354. An axial compressive force is applied to the first component and to the second component by tightening the spring nut 360. This type of embodiment is ideal for welding sections of PFA pipes and accessories from 19 mm to 51 mm of

  diameter (three quarters of an inch to two inches).

  A drive insert 392 supports a mandrel 394 and extends to engage the drive hub 338. The mandrel therefore engages the interior surface of both the first tubular end portion and the second tubular end part. Opposite the mandrel with respect to the tubular end parts is a transparent cylindrical sleeve in one piece 396. This sleeve can be made of tempered glass, such as Pyrex, quartz or another rigid material and essentially

  transparent to infrared radiation.

  In the embodiment of Figures 19 and 20, the rod assembly produces an appropriate axial compression on the first and second tubular end portions in abutment 329, 332, which are constrained in space

  between the mandrel 394 and the outer sleeve 396.

  The rod assembly also provides the additional function of rotating the first component and the second component and, therefore, the tubular end portions abutted such that the infrared heat generated by the nickel-cadmium wire 384 is distributed evenly at the stop point. When the welding head is in the closed position, the upper mirror reflector and the heating element 384 are in the position shown in 384.1 by dotted lines. This position makes it possible to provide a gap between the upper and lower heating elements 384.1, 384.2 so that there is a gap 397 forming a manhole through which the operator can observe the stop point and the state of the

  soldering during heating and rotation of components.

  The speed of the motor 303 can be modulated at will by means of

  conventional motor speed controls.

  Axial compression can be adjusted using the spring nut 360. It has been found that the ideal axial compression range of the spring is 20-24 ft-lbs for PFA pipes from 12 to 25 mm (1/2 "to 1"). For 1-1 / 2 "and 2" (37 to 51 mm) PFA lines, an appropriate spring compression value is 54 ft-lbs. The spring can be configured to produce increasing axial compression with axial deformation. When tubular PFA end portions are welded, the components undergo an elongation of a few hundredths of a millimeter (a few thousandths of an inch) when heated and melted. Good welding results are obtained when the axial compression force increases by 10% or more

during this lengthening.

  The embodiment of FIGS. 19 and 20 is ideally suited to the welding of pipe sections to accessories or to components provided with accessories. As clearly shown in the figure, this embodiment uses the end of the first and second components which are opposite the tubular end portions to produce the axial compressive force. In the case of a pipe of great length or of a pipe of smaller size which is not rigid enough to support the axial compression without undergoing a significant deformation, one can use another configuration such as that presented below. The following lines provide an appropriate procedure for welding a PFA pipe section to a PFA sanitary accessory using the device in Figures 19 and 20: 1. Clean the exterior surface, the interior surface and the face of the accessory with isopropyl alcohol and a lint-free cloth in aseptic chamber, then dry these with

clean, dry compressed air.

  2. Push the cleaned accessory onto the PTFE 338 drive hub, make sure that the seal

  is in place between the accessory and the hub.

  3. Clean the PTFE mandrel with alcohol and dry it with compressed air, examine the presence

  possible imperfections and signs of wear.

  4. Install the PTFE mandrel in the accessory until it reaches the drive hub

in PTFE.

  5. Push the stainless steel drive insert through the PTFE mandrel and the drive hub until the ball trigger engages the groove of the insert

drive.

  6. Gently slide the cleaned Pyrex sleeve over the accessory until it reaches

the shoulder of the accessory.

  7. Completely air dry the accessory

and the rod assembly.

  8. Place the accessory / hub assembly in the groove of the second pipe support on the part

right of the welding tool.

  9. Clean the inner surface, the outer surface and the face of the PFA pipe with alcohol and a cloth, then dry it with

compressed air.

  10. Lay the pipe in the first and third pipe supports on the left side of the welding tool and gently slide the end of the pipe into the Pyrex sleeve until it is face to face with the 'accessory. 11. Insert the aluminum drive collar into the holes on the back of the PTFE drive hub, turn and align the hole in the drive spindle with the hole in the insert

  stainless steel drive.

  12. Close and lock all the pipe supports on the accessory / rod assembly and the

driving in PFA.

  13. Slowly install a drive rod of appropriate length into the open end of the line, passing through the stainless steel drive insert to the drive motor. Care should be taken to avoid scratching the inner surface of the PFA pipe. 14. Install the drive spindle through the drive collar, the steel insert

  stainless steel and the drive rod.

  15. Install the seal on the front of the end piece. Install the end piece on the threaded part of the rod and in the open end of the PFA pipe. Install the spring

  in the cavity on the back of the end piece.

  Install the spring washer into the exposed end of the spring and advance the spring nut

up to the spring washer.

  16. Tighten the spring nut until the back of the spring washer is flush with the back of the workpiece

end.

  17. Start the drive motor and check whether the attachment and the pipe turn freely. Gently lower the top half

  from the welding head to position.

  18. Position the variable supply on the setting

  supply appropriate to the size of the product.

  19. Switch on the heating element until the zone of molten material has penetrated the entire thickness of the wall of the pipe up to the PTFE mandrel, then switch off the heating element. 20. Let the assembly rotate while the welded end parts cool, then stop the drive motor and gently raise the upper half of the heating head to release it. 21. Loosen the spring nut and remove the drive pin. 22. Slowly remove the aluminum rod and drive collar. Care should be taken to avoid scratching the inner surface of the

driving in PFA.

  23. Unlock all pipe supports and remove the pipe / welded accessory assembly, place the assembly in the core extractor device. 24. When the welded assembly has cooled, remove the assembly comprising the drive hub, the mandrel and the stainless steel drive insert from the weld joint with a device.

  suitable mechanics (for example, a forceps

  back and forth available from the firm De-Sta-Co,

n TC-640).

  25. Check the state of cleanliness and wear of the PTFE mandrel; if necessary, clean it with isopropyl alcohol and polish it with a lint-free cloth or replace it with a

new insert.

  26. Remove the Pyrex sleeve and check its cleanliness; if necessary, clean and repolish

this one with a cleaner.

  27. Inspect the solder joint again.

  Referring to Figures 21, 22, 23 and 24, the drawings show another embodiment in which the axial compression of the tubular end parts is again provided by the rod assembly 348 but o the first part of setting socket 354 engages with the interior surface 372 of the first component. This allows the attachment of an accessory as a second component 330 to a coil 410 as shown on the motorized coil reel 411. This specific embodiment is particularly suitable for PFA pipes of 6 mm and 12 mm (1/4 "and 1/2") in the sense that these pipes are flexible so that the first engagement point must be relatively closer to the end portions in abutment than on pipes of larger diameter. These PFA pipe sizes can be coils with which it is very difficult, even

impossible to weld.

  Referring to Figures 23 and 24, the drawings show details of the rod assembly 348 in combination with the first component 326 and the second component 330 as well as the sleeve 396. This embodiment has a first engagement portion 354 comprising a widener 412 of elastomeric or rubber material, a drive nut 414 for compressing the rubber widener, a pair of locknuts 416 and a thrust washer 418. The adjustment of the first engagement part is accomplished by rotating the rod 364, for example using a suitable tool engaging the end 422, for example conventional button nuts. This causes the drive nut 414 to move axially along the rod 364 while the locknuts 416 remain fixed on the rod, which compresses the expander and causes a radial expansion of

the elastomeric expander 412.

  The rod 364 extends through a hole 426 in the mandrel 394 and extends through and engages the second engagement portion 432 which includes an end piece 436 and a drive hub, a damping and locking gasket 438, a spring 442, a thrust washer 444 and a wing nut 446 with a

  threaded hole 448 which engages on a threaded part 450.

  Once the expander 412 is in engagement with the interior surface 372 of the first component 326, the mandrel, the sleeve and the second component 330 being in place, the joint 438 and the end piece 436 are assembled on the rod 364. with the spring 442, the washer 444 and the wing nut 446. The wing nut is rotated to compress the spring 442 which produces an axial compression on the end portions in abutment 329, 332 which are both retained radially between the mandrel 394 and the sleeve 396. The inside diameter of the sleeve can be a few hundredths of a millimeter (a few thousandths of an inch) greater than the outside diameter of the tubular end portions to facilitate assembly and to compensate for the tolerances of the diameters exteriors of a

given conduct.

  Still with reference to FIGS. 21 and 22, the rod assembly with the first and second components 326, 330 mounts in the first, second and third pipe supports 308, 314, 320 and can rotate therein. The rotation of the rod assembly with the first and second components fixed thereto is ensured by a drive junction 460 comprising drive bars 462, a plate 464 which is fixed relative to the drive bars, a spring 468 and a movable connection plate 472 which slides on the drive bars 462 and

  is forced to couple to motor 303.

  With reference to FIGS. 21, 22, 23 and 24, the following lines present suitable steps for making a weld with this specific embodiment: 1. Mount the PFA pipe in a serpentine (first component), centered around the tube. aluminum 479 from the coil reel. Extract the end of the PFA pipe to the end of the aluminum tube on the coil reel and introduce it into the clamps on the welding tool. Close the tube supports (3) on the PFA tube at the end of the aluminum tube of the coil reel 481, slide over the alternating openings of the aluminum tube on the

tube supports.

  2. Clean the inner surface, the outer surface and the face of the PFA pipe with alcohol and a cloth and dry it with

compressed air.

  3. Dry the rod assembly and introduce it into the PFA pipe, starting with

the rubber expander.

  4. Screw temporary nuts (2) (not shown) and lock them on the rod, then turn the wing nut clockwise to widen the rubber inside the PFA tube , turn until the rubber is sufficiently compressed and expanded

to block PFA driving.

  5. Remove the temporary button nuts.

  6. Clean the outer surface, the inner surface and the face of the accessory (second component) with isopropyl alcohol, a lint-free sanitary cloth and dry them with clean, dry compressed air. 7. Push the cleaned accessory onto the PTFE drive hub, make sure that the seal is

  securely in place between the accessory and the hub.

  8. Clean the PTFE mandrel with alcohol and dry it with compressed air, examine the presence

  possible imperfections and signs of wear.

  9. Install the PTFE mandrel in the accessory until it reaches the drive hub

in PTFE.

  10. Carefully slide the cleaned Pyrex sleeve over the accessory and hub assembly, preferably with a compressed air system to maintain cleanliness. 11. Completely air dry the accessory and hub assembly and the end of the pipe

in PFA.

  12. Carefully slide the rod through the components and the Pyrex sleeve over the pipe

in PFA.

  13. Examine the possible presence of dirt on the

  area to be welded, repeat steps if necessary.

  14. Install the spring / washer assembly on the back

  of the hub assembly, then a button nut.

  15. Tighten the wing nut until the

  spring washer is flush with the hub.

* 16. Place the accessory / hub assembly in the groove in the second pipe support on the part

right of the welding tool.

  17. Close and lock all the pipe supports on the accessory and hub assembly and the

driving in PFA.

  18. Compress the drive junction by hand and insert it between the drive hub and the drive motor, the side with a square section shaft facing the motor. First insert the three drive bars into the holes in the hub. Then turn the drive joint by hand until the shaft is

  square section enters the engine.

  19. Gently lower the upper half of the head

heated to position.

  20. Position the variable supply on the setting

  supply appropriate to the size of the product.

  21. Simultaneously start the two drive motors (one on the coil reel and the other on the welding tool) and observe the direction of rotation of the welding motor driving motor; if the drive motor of the coil reel turns in the opposite direction, force it to change direction by stopping it by hand, it will automatically change direction.

22. Switch on the heating element.

  23. When the zone of molten material has penetrated over the entire thickness of the wall of the pipe up to the PTFE insert and begins to form against the PTFE mandrel a flat of about 6 mm

  (1/4 ") wide, turn off the heating element.

  24. Allow the assembly to rotate to allow it to cool, then stop the drive motors and gently raise the upper half of the head

heated to release it.

  25. Compress and remove the drive junction assembly.

  26. Remove the wing nut and the spring.

  27. Unlock all pipe supports and

remove the entire welded tube.

  28. Remove the drive hub and the gasket

the end of the accessory.

  29. Screw button nuts (2) onto the rod and lock them in position, then turn the buttons anticlockwise

  watch to release the rubber expander.

  30. Push the rod into the PFA pipe to release it. 31. Place the welded end in an extractor device and extract the PTFE mandrel and the rod assembly. Set the rod assembly aside making sure that the PTFE mandrel

don't touch anything.

  32. Slide the Pyrex sleeve on one side of the

  solder and inspect the solder joint.

  Referring to Figures 25, 26, 27, and 28, the drawings illustrate various embodiments using infrared radiation to carry out the welding process. Figure 25 is a sectional view through a mandrel 394, tubular end portions abutting 329, 332, and a sleeve 396. This embodiment adds lenses 470 to the basic configuration shown in Figures 19, 20 , 21 and 22. Although represented in section in the form of half-moons, the lenses extend

  circumferentially and coaxially around the sleeve 396.

  The lenses act to concentrate the infrared energy supplied by the infrared source 472 which is represented

  as comprising a pair of nickel heating wires-

  cadmium 476 mounted inside a glass envelope

  480 with 482 gold plating on the exterior surface.

  The lens made of glass or the like can be suitably formed and configured so that its focal point is located at various desired locations within the assembly. For example, at a point 485 outside the stop point 334 or at a point 486 in the center of the thickness of the tubular wall 488 or at a point 490 on the interior surface of the tubular wall

  488, or even slightly inside the mandrel 394.

  With more specific reference to FIG. 26, the drawing represents an additional embodiment in which the focusing lens is either adjacent to the sleeve 396, or integrated into the sleeve 396. With reference to FIG. 27, the drawing represents an embodiment where the infrared heating source 472 is an infrared laser, the laser beam widens to provide heat over a slightly larger area compared to conventional infrared lasers. These lasers are suitably provided with lenses 492 which produce a heat zone which extends circumferentially around the abutment point. Multiple 472 lasers can be used to provide full coverage and promote uniformity of fusion and

  assembly of the tubular end portions in abutment.

  Referring to Figures 28 and 29, the drawings show sectional views illustrating several aspects of the invention. In FIG. 28, the infrared heating source 472 extends essentially around the sleeve, as shown in the embodiments of FIGS. 19, 20, 21 and 22. With regard to these embodiments, the source of infrared can be a nickel-cadmium wire that extends around the sleeve in two sections. The sections open at a hinge point 510. To guarantee uniform heating of the stop point of the tubular end parts, either the rod assembly is rotated, and therefore the components to be welded, as illustrated by arrow 514, or the source of infrared 472 can be rotated as illustrated by arrow 516. The rotation of the tubular end portions relative to the source of infrared can also be performed as shown in Figure 29 with a simple gear drive rotating a frame 520 on which are fixed the sources of infrared 472. The sources of infrared in this figure illustrate possible configurations counting

  three 524 diffuse infrared lasers.

  With reference to FIGS. 19 and 28, another important advantage of the use of transparent sleeves is that it is possible to provide a manhole 550 through which one can monitor the progress of the weld, which makes it possible to adjust parameters during welding, for example the amount of infrared energy generated, the welding time

and the cooling time.

  The present invention can be implemented in other specific forms without departing from the spirit or essential attributes thereof. It should therefore be considered that the present embodiment must in all respects be perceived as being illustrative and not restrictive

  and reference should be made to the appended claims

  rather than the above description to define the scope

of the invention.

Claims (40)

  1. A method of assembling a pair of tubular end portions (38, 40) of melt-processable fluoropolymers, each of the end portions (38, 40) having an interior surface (154), a outer surface (44) and an end face (142, 144), characterized in that it comprises the steps consisting in: placing the tubular end parts (38, 40) in abutment against each other ; threading a hollow cylindrical sleeve (116) essentially transparent to infrared radiation around the tubular end portions (38, 40); engaging the interior surfaces (154) of the tubular end portions (38, 40) with a mandrel (150); and providing the abutting end portions (38, 40) with infrared heating energy sufficient to melt and merge said abutting end portions (38, 40) into an assembly. 2. Method according to claim 1, characterized in that it further comprises the step of producing an axial compression on the two end parts (38, 40) while the heating energy is supplied. 3. Method according to claim 1, characterized in that the sleeve (116) is split longitudinally into a plurality of parts, which allows to move at least part of the sleeve (116) to wrap the tubular end parts (38 , 40). 4. Method according to claim 1, characterized in that the infrared heating energy is supplied by an infrared heating source (136) positioned circumferentially around the sleeve (116), the method   further allowing rotary movement of the tubular end portions abutting (38, 40) and / or the infrared heating source (136) to provide the tubular end portions abutting (38, 40) with uniform heat .   5. Method according to claim 1, characterized in that the hollow cylindrical sleeve (116) is breakable and in that the assembly is allowed to cool before breaking the breakable sleeve (116) to release the sleeve (116) from the 5 tubular end parts in abutment and assembled (38,). 6. Method according to claim 1, characterized in that the assembly is allowed to cool and in that the   sleeve (116) on the tubular end portions in abutment and assembled (38, 40).   7. Method according to claim 1, characterized in that it further comprises the step of producing a   axial compression on the two end portions (38, 40) while the heating energy is supplied and further increasing the level of axial compression while the heating energy is supplied.   8. Method according to claim 1, characterized in that the first end part (329) is part of a first component (326) and the second end part (332) is part of a second component (330 ), the method further comprising the step of producing axial compression by means of a rod assembly (348) extending axially through the two end portions (329, 332) at the same time, the rod assembly (348) having a first engagement portion (354) for engaging the first component (326) and a second engagement portion (432) for engagement with the second component ( 330). 9. Method according to claim 8, characterized in that the first component (326) is an elongated pipe section and in which the first engagement part (354) of the rod assembly (348) comprises a part of radially expandable cylindrical lock (412), the method further comprising the step of engaging the lock portion (412) with the interior surface of the first end portion (329) to produce the axial compression.   10. The method of claim 8, characterized in that the first component (326) has an end opposite the first end portion (329), the method comprising the step of positioning the engagement portion (354 ) of the rod assembly (348) against said end to produce a compressive force on the two parts from end to end (329, 332).   11. Method according to claim 10, characterized in that the rod assembly (348) comprises a rod (364) extending axially through the end portions (329, 332), the rod (364) being in engaged with one of the two engaging portions (354, 432) through a spring (358), the method further comprising the step of compress the spring (358).   12. The method of claim 1, characterized in that the sleeve (116) is visually transparent, the method further comprising the step of visually monitoring, through the sleeve (116), the process of the melting of the parts d end (38, 40) .20 13. The method of claim 1, characterized in that it further comprises the step of concentrating the infrared energy emitted by the heating source by infrared (136).   14. Method according to claim 13, characterized in that the concentration of the infrared energy takes place at the level of the tubular end portions in abutment (38, 40) to assemble.   15. The method of claim 1, characterized in that it further provides the step of providing the   mandrel (150) heating energy by infrared.   16. Method for monitoring the welding of a pair of tubular end parts (38, 40), characterized in that it comprises the steps consisting in: placing the tubular end parts (38, 40) in abutment l 'one against the other; thread a substantially transparent hollow cylindrical sleeve (116) around the tubular end portions (38, 40);   providing the abutting end portions (38, 40) with infrared heating energy; and monitoring the progress of the welding by visually observing, through the transparent sleeve (116), the end portions in abutment (38, 40). 17. A method of assembling a first component (326) having a first tubular end portion (329) to a second component (330) having a second tubular end portion (332), the end portions ( 329, 332) being composed of melt processable fluoropolymers, each of the end portions (329, 332) having an inner surface (372), an outer surface (44) and an end face (142, 144 ), characterized in that it comprises the steps consisting in: placing the tubular end parts (329, 332) in abutment against one another; positioning a hollow cylindrical sleeve (116) around the tubular end portions (329, 332); engaging the interior surfaces of the tubular end portions (329, 332) with a cylindrical mandrel (394); inserting a rod assembly (348) axially through the two end portions (329, 332) and through the mandrel (394), the rod assembly (348) including a first engagement portion (354) for engaging the first component (326) and a second engagement portion (432) for engaging the second component (330); compressing the tubular end portions into abutment (329, 332) with a compressive force produced by the rod assembly (348); and supplying the abutting end portions (329, 332), through the sleeve (116), with heating energy   sufficient to melt and merge said end portions into abutment (329, 332).   18. The method of claim 17, characterized in that it further comprises the step of heating the tubular end portions in abutment (329, 332) by infrared radiation by means of an infrared source ( 136) positioned outside the sleeve (396) and to diffuse said infrared radiation through the sleeve (396).   19. The method of claim 18, characterized in that it further provides the step of moving in a manner allowing rotation either (a) the source of infrared (472), or (b) the parts d the tubular end in abutment (329, 332), so that the end portions in abutment (329, 332) are heated uniformly. 20. The method of claim 17, characterized in that it further comprises the step of varying the axial compression force produced by the rod assembly (348).   21. Apparatus for welding a first tubular end part (38) of a first component and a second tubular end part (40) of a second component, the end parts (38, 40) being in abutment in an axial alignment, characterized in that it comprises: a support structure (72); a hollow cylindrical sleeve (116), supported by the support structure (72), intended to extend circumferentially around the end portions in abutment (38, 40), the sleeve (116) being made of an essentially transparent material infrared radiation; and30 a source of infrared radiation (136), supported by said support structure (72) and positioned   radially outward from the cylindrical sleeve (116), to allow infrared radiation to pass through said sleeve (116) to melt and merge the end portions into abutment (38, 40).   22. Apparatus according to claim 21, characterized in that it further comprises a mandrel (150) insertable inside the tubular end portions in abutment (38,) to prevent the formation of an internal bead during the heating and melting the tubular end parts (38, 40).   23. Apparatus according to claim 22, characterized in that it further comprises a rod assembly (348) comprising a rod (364) configured and positioned so as to extend axially inside and through parts of the tubular end in abutment (329, 332) and through the mandrel (394), the rod assembly (348) having a first engagement portion (354) on said rod (364) for engaging the first component (326) and a second engagement portion (432) on said rod (364) for engaging the second component (330), at least one of said engagement portions (354, 432) being able to move to the other engaging part   (432, 354), which allows the tubular end parts (329, 332) to be placed in axial compression.   24. Apparatus according to claim 23, characterized in that it further comprises a spring (442) engaging one of said engaging portions (354, 432) to produce axial compression on the tubular end portions ( 329, 332). 25. Apparatus according to claim 21, characterized in that the sleeve (116) is split longitudinally to allow the placement and removal of the sleeve (116) on   the tubular end parts (38, 40) to be assembled. 26. Apparatus according to claim 21, characterized in that the sleeve (116) is visually transparent.   27. Apparatus according to claim 26, characterized in that the apparatus and the source of infrared (136) are configured so that there is a line of sight from the exterior of the apparatus, through the sleeve (116), to the tubular end portions in abutment   (38, 40), which makes it possible to visually monitor the welding.   28. Rod assembly (348) intended to produce an axial compression on a first component (326) and on a second component (330), each component (326, 330) having a tubular end portion (329, 332), said end portions (329, 332) being in axial alignment, the rod assembly (348) being characterized by a rod (364) intended to extend axially through the pair of tubular end portions in abutment (329, 332), a first engagement portion (354) connecting to said rod (364) and being positioned to engage the first component (326), a second engagement portion (432) connecting to said rod (364) and being positioned to engage the second component (330), a clamp and a return member being adjustably connected to said rod (364) for moving the engaging elements (354 , 432) towards each other, which produces axial compression on the pair of tubular end portions in abutment (329, 332). 29. Rod assembly (348) according to claim 28, characterized in that the first engagement part (354) comprises a radially extensible blocking element (412).   30. Rod assembly (348) according to claim 28, characterized in that it further comprises a mandrel (394) intended to radially support the tubular end portions 25 in abutment (329, 332) inside those here, the rod (364) extending through the mandrel (394), the   mandrel (394) being positioned between the first engaging portion (354) and the second engaging portion (432).   31. Sleeve (116) for transferring heat in order to merge a pair of tubular end parts (38,) in axial alignment and in abutment, said sleeve (116) being characterized in that it is dimensioned as a function of the diameter exterior of said tubular end portions (38, 40), said sleeve (116) being visually transparent and substantially transparent to infrared radiation, thereby diffusing infrared radiation through the sleeve (116) to said end portions tubular in abutment (38, 40).   32. Sleeve (116) according to claim 31, characterized in that said sleeve (116) is composed of one of the following elements: tempered glass, quartz or sapphire. 33. Sleeve (116) according to claim 31, characterized in that the sleeve (116) is split longitudinally into   a plurality of sections to allow placement of the sleeve (116) around the tubular end portions (38,10 40) and removal therefrom.   34. Sleeve (116) according to claim 31, characterized in that the sleeve (116) is formed in one piece.   35. Sleeve (116) according to claim 34, characterized in that the sleeve (116) is breakable, which makes it possible to break the sleeve (116) to allow the withdrawal of the sleeve (116) after welding.   36. Welding system for assembling a pair of melt-treatable tubular end portions (38, 40), the tubular end portions (38, 40) comprising an end face (142, 144) , an outer surface (44) and an inner surface, characterized in that it comprises: a welding head (70) comprising: a housing (110, 112) which can be opened to allow the insertion and removal of the parts tubular end (38, 40) to be assembled; a sleeve (116) supported in the housing (110, 112), the sleeve (116) being for engaging the outer surfaces (44) of the tubular end portions (38, 40); a heating element (136) positioned outside the sleeve (116) and intended to provide heat for welding the tubular end portions (38, 40); an electrical supply (176) for supplying the heating element (136); and a soluble core insertable into the tubular end portions (38, 40), the soluble core having an outer surface which matches the inner surface of the   tubular end portions (38, 40).   37. Welding system according to claim 36, characterized in that the soluble core is composed of sodium chloride. 38. Welding system according to claim 36, characterized in that the sleeve (116) is essentially   transparent to infrared radiation and the heating element (136) produces infrared radiation intended to pass through said sleeve (116).   39. Chuck (150) for use in welding systems in which abutting tubular end portions (38, 40) are positioned between said chuck (150) and a sleeve (116) engaging the exterior end parts in abutment (38, 40), in which the heat passes through the sleeve (116) to melt and merge the end parts (38, 40), the mandrel (150) being characterized in that it is soluble in a fluid to allow its removal from the welded end portions (38, 40).   40. Mandrel (150) according to claim 39, characterized in that the mandrel (150) is composed of sodium chloride.