Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
  • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
  • B29C70/06—Fibrous reinforcements only
  • B29C70/10—Fibrous reinforcements only characterised by the structure of fibrous reinforcements, e.g. hollow fibres
  • B29C70/16—Fibrous reinforcements only characterised by the structure of fibrous reinforcements, e.g. hollow fibres using fibres of substantial or continuous length
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
  • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
  • B29C70/06—Fibrous reinforcements only
  • B29C70/08—Fibrous reinforcements only comprising combinations of different forms of fibrous reinforcements incorporated in matrix material, forming one or more layers, and with or without non-reinforced layers
  • B29C70/081—Combinations of fibres of continuous or substantial length and short fibres
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
  • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
  • B29C70/28—Shaping operations therefor
  • B29C70/30—Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core
  • B29C70/34—Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core and shaping or impregnating by compression, i.e. combined with compressing after the lay-up operation
  • B29C70/345—Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core and shaping or impregnating by compression, i.e. combined with compressing after the lay-up operation using matched moulds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
  • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
  • B29C70/28—Shaping operations therefor
  • B29C70/54—Component parts, details or accessories; Auxiliary operations, e.g. feeding or storage of prepregs or SMC after impregnation or during ageing
  • B29C70/541—Positioning reinforcements in a mould, e.g. using clamping means for the reinforcement

Definitions

• the present invention relates to a method and an installation for manufacturing an object stamped in a thermoplastic composite material.
• the thermoplastic composite material is heated to the stamping temperature before being placed in a sufficient quantity in one of the two parts of a cold compression mold forming part of a stamping press and comprising a fixed mold part and a movable mold part so that it can quickly close against the fixed mold part and strongly compress the composite material to give it the final shape of the product and to suddenly cool the material contained in said mold before the reopening of the latter and evacuation of said stamped and cooled product.
• the process for forming an object by compression of a thermoplastic composite material also called “stamping" consists of cutting ' plates of thermoplastic composites with isotropic characteristics, into blanks of smaller dimensions, to heat a sufficient number of blanks at a temperature such that the thermoplastic material becomes plastic, filling a cold half-mold with said blanks, covering this first half-mold with a second half-mold of corresponding shape, then rapidly closing the mold, under a determined pressure ( from ten to a few hundred bars) to obtain, by compression and deformation of the hot composite material, the desired shape part corresponding to that of the two cold half-molds; after cooling the shape of the part is retained and the part is removed from the mold.
• a determined pressure from ten to a few hundred bars
• thermoplastic object reinforced by stamping is characterized by the discontinuity of the operations for manufacturing the plates on the one hand, and stamping, under a compression press, on the other hand.
• the complete manufacturing process of the product in thermoplastic composite material includes a heating phase of the raw materials for forming the plates, followed by cooling of the thermoformed plates to ambient temperature, then a new heating phase of the blanks before introduction of these in the cold mold of the stamping press.
• Unidirectional long fiber composites generally include the following steps: unwinding of strands of fibers; preheating of the wicks of fibers; impregnation of the wicks of fibers with thermoplastic resins; where appropriate heating of the impregnated fibers; calendering the wicks to obtain an impregnated fiber ribbon; cooling of the ribbon and winding of it on a storage reel.
• the fiber wicks are generally impregnated either with molten thermoplastic polymers or with thermoplastic powders in the form of a fluidized bed of powders, these powders melting under the action of heat.
• the fibers used are of all kinds.
• natural or synthetic, mineral or organic fibers such as glass fibers, metal alloys, carbon fibers, cotton fibers made of cotton, hemp, fibers of polyacrylic resins, polyethylene, polypropylene, polyamides can be used. etc.
• Thermoplastic fibers can also be used provided that their softening temperature is sufficiently higher than the processing temperatures to maintain their fiber structure.
• wicks of fibers are impregnated from molten polymers, it is necessary to melt the thermoplastic polymer before the impregnation of said strands.
• the methods of manufacturing unidirectional tapes require a heating phase to melt the thermoplastic impregnation material and shape the tape, followed by cooling.
• thermoplastic composites After cooling, the thermoplastic composites are relatively rigid; the need to wind the unidirectional ribbon on reels of a diameter compatible with storage and transport, requires cala ⁇ drer the ribbon in relatively small thickness.
• thermoplastic resin • wicks of fibers impregnated with a thermoplastic resin, to place this hot filiform thermoplastic composite on a mandrel in a mold of suitable shape and then to allow to cool gradually all the fibers deposited on the mandrel so that a bond is established rigid between said fibers thanks to the cooled thermoplastic material.
• the assembly formed of threadlike thermoplastic composite constitutes the finished product and can be removed from the mandrel. If necessary, this assembly formed of filiform thermoplastic composite can be subjected to a stamping operation in a second mold after prior heating of said assembly.
• the object of the invention is to propose a method of manufacturing an object stamped in a thermoplastic composite material, a method of the type initially mentioned and which avoids the drawbacks listed previously.
• thermoplastic composite material at least partially a filiform composite ' with long fibers, mutually parallel and impregnated with a thermoplastic material, is used as the thermoplastic composite material
• this filiform composite is preheated and it is continuously passed through a temperature regulation chamber to give it the stamping temperature, - said filiform composite is then continuously introduced into the first cold mold part of the stamping press until a predetermined quantity of filiform composite is deposited there, - said filiform composite is cut when said quantity is reached in the first part of the mold and the section of the filiform composite comprised between the cut end and the outlet of the temperature regulation enclosure is momentarily immobilized, while said filiform composite is continued to be supplied regulatory enclosure,
• the running speeds of the filiform composite are chosen upstream and downstream of the control enclosure so that the length of the filiform composite delivered into the first mold part during a mold supply period is equal to the sum resulting from the lengths of filiform composite introduced into the regulation enclosure during, on the one hand, the period of feeding the mold and, on the other hand, the period of interruption of the feeding of the mold and immobilizing the section of filiform composite between the mold and the outlet of said enclosure.
• the object of the invention can also be achieved because:
• a filiform composite with long fibers which are parallel to one another and impregnated with a thermoplastic material, is used, - this filiform composite is preheated and continuously passed through a temperature control chamber to give it the stamping temperature,
• the said filiform composite is then continuously introduced into the first part of the mold of a heated pre-mold which, if necessary forms part of a pre-stamping press, until a predetermined quantity of filiform composite is deposited there,
• the said filiform composite is cut out when the said quantity is reached in the first part of the pre-mold and the section of the filiform composite is temporarily immobilized between the cut end and the outlet of the temperature regulation enclosure, while we continue to supply filiform composite to said control enclosure, - we store in this enclosure the quantity of filiform composite contained and arriving in said enclosure during the stopping of the supply of filiform composite to the first part of pre-mold until resumption of supply of the same or another first part of pre-mold, - the running speeds of the filiform composite are chosen upstream and downstream of the enclosure regulation so that the composite strand length charged into the first pre-part mold for a period f of the pre-mold power is equal to the sum resulting from lengths e filiform composite introduced into the control enclosure during the one hand, the pre-mold feeding period and, on the other hand, the period of interruption of the feeding of the pre-mold and immobilization of the section of filiform composite between the pre-mold and the outlet of said enclosure,
• the hot blank or preform is rapidly transferred, if necessary with the hot pre-mold, to the first part of the cold mold of the stamping press, and
• the present invention also relates to an installation for manufacturing an object stamped in a thermoplastic composite material of the type comprising from upstream to downstream in the direction of movement of said composite material:
• thermoplastic material a store of long fiber reels, if necessary impregnated with a thermoplastic material
• a movable head for distributing impregnated and heated fibers; and, - a stamping press comprising at least a first part of a cold mold intended to receive the filiform composite and a second part of a vertically movable cold mold, placed directly above the first part and intended to cooperate with the latter to produce an object stamped in threadlike thermoplastic composite.
• the dispensing head comprises, on the one hand, drive and distribution means as well as, on the other hand, cutting means for the filiform component and that the device for regulating the temperature comprises an enclosure in which a buffer unit is provided for temporarily storing the quantity of filiform composite entering said enclosure during the stopping of the means for driving the filiform component in the dispensing head.
• FIG. l, 2a_, 3a ⁇ show a plan view of some stamped objects in thermoplastic composite material capable of constituting applications of the invention, objects such as window frame, car door reinforcement, tennis racket;
• Figures 1b, 2b_, 3Jb represent the same three objects, with the representation of the paths of the filiform composites in the molds corresponding to the objects according to Figures la_ to 3a_;
• FIG. 4 is a diagram of an installation for implementing a method according to the invention.
• FIG. 5a_ and 5b_ schematically represent a device for regulating the temperature provided with a buffer unit for the temporary storage of fibers, wicks, bundles or impregnated ribbons;
• FIG. 6a_ and 6 show schematically, respecti ⁇ vely, a stamping press using two first lower mold parts allowing the implementation of a method according to the invention and comprising two loading stations;
• FIG. 7a_ and 7] Î show an installation comprising two stamping presses each comprising two loading stations, and a feed robot for two stations, one of the two stations being part of a first press and the another post from the second press;
• FIG. 9 shows a fourth variant of possible deposition trajectories of the material to be stamped
• FIG. 10a_ to 10 _f show schematically the successive ⁇ sion of the operations for preparing a hot uncompressed blank of filiform thermoplastic composite
• FIG. 13 is a plan view of a cross section through the dispensing head along the broken line XIII-XIII of FIG. 12.
• FIGS. 1b, 2JD and 3] D show the directions of the paths of the filiform thermoplastic composite with unidirectional fibers 1 during deposition of the latter in a first mold part suitable for enabling the objects of FIGS. La_, 2a_ and 3a_, respectively , this in accordance with the invention, between a starting point 2 of the deposit and an end point 3 of this deposit, in order to produce the frames 4, 5 and 6 of said objects, respectively. It would not, however, depart from the scope of the invention to deposit the filiform composite with unidirectional long fibers along other paths.
• filiform composites means composites having an almost infinite dimension in one direction relative to the dimensions in the other two directions, their fibers being impregnated or embedded in a thermoplastic material.
• the section of filiform composites can be circular, square, rectangular, or correspond to more complex shapes. What characterizes a filiform composite is the existence of a dimension in one direction very much greater than the dimensions in the other directions. For example, a wire, a continuous bar, a ribbon, a strip, are filiform products despite the diversity of the sections, the length being able to be considered as infinite compared to the width.
• the composite is cut and the feeding, that is to say the running of the filiform composite is momentarily interrupted at said level. first part of cold mold.
• the first part of the mold having been filled with the necessary quantity of filiform thermoplastic composite with long fibers unidirectional, at the stamping temperature, that is to say hot, and following the chosen path, is closed quickly using the second cold mold part and vertically movable.
• the quantity of thermoplastic composite deposited in the first part of the mold is compressed and under the effect of the compression rapidly fills the entire chamber delimited by the two parts of half-molds. and cools and freezes almost instantly on contact with the internal walls of the cold compression mold.
• the cooled stamped part is removed from the mold.
• the term cold mold or part of cold mold it should be understood that this mold is at a temperature of the order of 50 to 70 ° C., in contrast to the hot molds used for cooking products of ther odurable material.
• the long fibers, continuously impregnated with a thermoplastic material and brought to the stamping temperature are brought together to form a bundle, which is deposited in a first part of the mold, along the path chosen, by the dispensing head provided on an arm, or on a carriage whose movement in space is programmable.
• the dispensing head advantageously moves on a template representing the path of deposition of the filiform thermoplastic composite.
• FIG. 4 represents the diagram of an installation allowing the implementation of the process which is the subject of the invention, in which the deposition of the filiform composite in the mold is carried out by a dispensing head mounted on an arm articulated in space.
• This installation comprises from upstream to downstream, in the direction of movement or of travel of the filiform composite material: - a magazine A comprising a number of coils 7 from which long fibers 1 are drawn off which in the case of the example are not not yet impregnated with a thermoplastic resin;
• thermoplastic material or resin a device for heating and impregnating B of the long fibers 1 with a thermoplastic material or resin, the impregnation being able to be made with a liquid thermoplastic material provided in a tank or else with a pulverulent thermoplastic material to form the filiform composite;
• thermoplastic material in the powder state in the case where the impregnation is carried out with a thermoplastic material in the powder state
• a movable dispensing head T mounted on a movable carriage or on an articulated arm F and serving to deposit the hot, thermoplastic, filiform composite, with unidirectional long fibers in a first part of a cold mold;
• a cold mold G comprising a first lower cold mold part and a second cold mold part, vertically movable, arranged above the first mold part and intended to come to cooperate with the latter to produce by stamping a composite object filiform thermoplastic, and
• a stamping press H which receives the two cold mold parts and ensures the closing of the mold and the compression of the composite contained therein under pressure, necessary.
• the non-impregnated fibers are withdrawn from the reels 7 of the magazine A and are impregnated in the device B; thermoplastic resin, if it has not been deposited on the fibers to the liquid state, is melted in the device C; this is the case where the impregnation in the device B was carried out with a product in the powder state; the fibers then forming the thermoplastic composite with unidirectional long fibers are pulled or entrained by the drive device D and optionally simultaneously compacted into one or more bundles 8; the temperature of the thermoplastic composite and more particularly of the resin is optionally adjusted in the device E (by heating or by cooling) at the stamping temperature.
• the bundle 8 or the fibers 1 then pass over the articulated arm F, or a carriage carrying the dispensing head T whose movement in space is programmable; this dispensing head T comprises drive means such as at least one drive roller 21, a support board 22 disposed vertically in a passage cavity 23 of the head T in an axial plane of said head T next to d 'an ejection opening or mouth 24, as well as springs 25 intended to urge said driving roller 21 elastically against a bearing face of said board 22.
• drive means such as at least one drive roller 21, a support board 22 disposed vertically in a passage cavity 23 of the head T in an axial plane of said head T next to d 'an ejection opening or mouth 24, as well as springs 25 intended to urge said driving roller 21 elastically against a bearing face of said board 22.
• This dispensing head T also comprises quick cutting means 26 which are arranged in the passage cavity 23 above and near the ejection mouth 24 and below the drive roller 21, next to the support board 22 which in this case serves as a counter-support for the cutting edges of the means cutting 26, the fibers or fiber bundles 8 running along the support board 22 and being clamps between the latter and the periphery of the drive roller 21.
• the bundle 8 is cut and its advancement through the head T is stopped when l the amount of composite deposited in the first part of the mold corresponds to the amount necessary to fill the mold chamber, this chamber being delimited by the interior walls of the two cold mold parts.
• the deposition of the filiform composite in the first mold part must be carried out in a very short time which is of the order of ten seconds to avoid premature cooling of the filiform composite material.
• the mold is then closed under pressure by the descent of the mold part H press upper; thanks to the compression of the hot filiform composite material in the mold G, this material is forced against the cold walls of the mold chamber where it freezes quickly following the cooling which it undergoes; the part thus stamped is demolded after cooling thereof and opening of the mold G.
• the withdrawal of the fibers 1, the impregnation of the fibers. 1 and their transport or advancement to the regulating device E continue normally and are not interrupted.
• the temperature control device E comprises an enclosure 27 in which a buffer unit 28 is provided for temporarily storing, for example by increasing the path of the fibers 1 or bundles 8, the quantity of thermoplastic composite. filiform entering the regulating device E, that is to say in the enclosure during the stopping of the drive means 21 of said filiform composite in the dispensing head T.
• the speed of travel of the section of fibers or filiform composite upstream of the enclosure 27 of the regulation device is chosen and that of the section of fibers or filiform composite 1 or 8 downstream of said enclosure 27 so that the length of the composite filiform cut into the first mold part by the dispensing head T during a continuous feeding period of the mold G is equal to the sum of the lengths resulting from the lengths of filiform composite introduced into the enclosure 27 of the regulating device E during, on the one hand, the period of supply of the mold G by the dispensing head T and, on the other hand, the period of interruption of the supply of the mold G by said head T and of immobilization of the section of filiform composite comprised between the mold, or more precisely said the dispensing head T, and the outlet of the enclosure 27 of the regulation device E.
• the speed of travel of the section of filiform composite in downstream of the enclosure 27 is greater than that of the section upstream of said enclosure 27, the section of composite downstream of the enclosure 27 runs intermittently while the section of composite upstream of the enclosure 27 runs so continuous and the quantity of filiform composite entering the enclosure 27 during a period of stoppage of the section of filiform composite downstream of the enclosure 27 is stored there temporarily until the supply of the mold is resumed. to say the travel of the downstream section of filiform composite through the dispensing head T.
• the method according to the invention is therefore remarkable by loading the mold G almost continuously with a continuous preparation of the hot filamentary thermoplastic composites with long unidirectional fibers delivered directly into the cold stamping mold. .
• the buffer unit 28 comprises several fixed return rollers 9a and several return rollers movable in translation 9b between two extreme points, one of which is close to the fixed roller 9a and the other distant of the last.
• the return rollers 9a, 9b are arranged with a horizontal axis and are parallel to one another.
• the movable rollers 9b are guided along vertical parallel paths in vertical guides 9c receiving the lateral ends 9d of said rollers 9b.
• Return springs not shown, urge the dancer rolls 9b in a position in which they are the farthest from a fixed roller 9a and in which the fibers or fiber bundles 1.8 contained in the enclosure 27 of the regulating device E are slightly stretched.
• a pair of drive rollers 29 can be provided at the outlet from the enclosure 27, this pair of drive rollers 29 being stopped or running at the same time as the drive roller 21 of the dispensing head T .
• the fibers or bundles of fibers pass at the entrance to the enclosure 27 first on a fixed roller 9a and then wind, from upstream to downstream of their path, alternately around a movable dancer roller 9b and a fixed roller 9a before passing if necessary, at the outlet of the enclosure 27, between the rollers of a pair of drive rollers 29.
• the buffer unit 28 may also be constituted by any other similar device allowing the temporary storage of the composite, such as a conveyor belt, on which the filiform composite is deposited continuously at the exit of its production line, then taken up continuously at the downstream end of the conveyor belt to feed the mold via the dispensing head T secured to the articulated arm or the carriage.
• the buffer unit 28 for the temporary storage of the thermoplastic filiform composite with unidirectional long fibers (dancer return rollers, conveyor belt, work tables on slide or other), it is possible to maintain the temperature of the composite being in the regulating device E and its buffer unit 28 during the waiting period and / or regulating the temperature by a heating, infrared or other ramp provided in said device E. It is also possible, as a variant, to use two first half-mold parts in tandem and feed one of them when the other is closed and in the stamping position and vice-versa.
• the stamping press H is equipped for example with a second mold part or punch mounted on the upper movable plate and with two lower work tables mounted on slides, on which the first two mold parts are arranged.
• the press opens, the assembly of the two tables slides laterally so that the first part of the mold containing the part which has just been stamped is outside and next to the press frame H and that the other first mold part or matrix which has just been filled with a determined quantity of composite is again under the second upper mold part.
• the second upper mold part is closed again on the filled die, the other die is discharged during this time from the finished part and filled with a new quantity of composite.
• This mode of operation requires working with a press comprising two dies mounted in tandem on the work tables and by a punch mounted on the movable plate, or alternatively, according to the drawing of the part, by two punches mounted in tandem movable in translation. horizontal on the work table and by a die mounted on the movable plate vertically above the punch located in the press.
• FIGS. 7a_ and 7l ⁇ represent an installation comprising two presses Hl and H2 each comprising two loading stations 12,13 or 14,15 situated on either side of the frame of the corresponding press Hl or H2.
• the two stamping presses H1, H2 are preferably arranged one opposite the other so that one or the other of the lateral loading stations 12,13 (or 14,15) of a press , for example Hl, is located opposite one or the other of the loading stations 14,15 (or 12,13) of the other press, for example H2.
• each press is associated with a pair of first cold mold parts 16a, 16b and 17a, 17b movable in horizontal translation on rails 16c or 17c between a compression or stamping station in which the one of the first two mold parts 16a, 16b or 17a, i7b 'integral with one another is in vertical alignment with and below the second cold mold part 16d or 17d of the same stamping press Hl or H2, and one of the two loading stations 12,13 or 14,15 located on either side of an Hl or H2 press on the horizontal path of said pair of first mold parts 16a, 16b or 17a , 17b.
• a dispensing head Tl carried by the free end of an articulated arm of a robot 18a disposed midway between the loading stations 12 and 14.
• a similar arrangement is provided for the loading stations 13 and 15 of the two presses H1 and H2, to which corresponds the position T2 of the dispensing head and the position 18b of the robot.
• the dispensing head Tl can pivot around a vertical axis from the loading station 12 to the loading station 14 and the head T2 can pivot from its position above one of the loading stations 13,15 to the other.
• the cutting means 26 of the dispensing head comprise at least one cutting blade 26a_, for example of the oscillating type, disposed inside the cavity 23 downstream of the drive roller 21 and near the mouth ejection 24. If it is desired to debit the filiform composite 1.8 into sections of more or less long composite, it is possible to provide a plurality of oscillating cutting blades 26a_ superimposed and guided along parallel and oblique paths from top to bottom in the direction of the support board 22. Thus, when the cutting edges of the cutting blades 26a_ shear the filiform composite 1,8 against the support board 22, they simultaneously push the upstream end of the cut composite section towards the ejection mouth 24 and pull the next composite down.
• the deposition in the mold of the filiform thermoplastic composite with unidirectional long fibers is carried out along a path which reinforces the desired directions.
• the deposition in the mold of the thermoplastic filiform composite with unidirectional long fibers is carried out along a trajectory which restores, in the part molded in compression, the isotropy of the characteristics .
• thermoplastic filiform composite with unidirectional long fibers is deposited along the contours of the rectangle, then in continuous spirals, as shown schematically in FIG. 9, there will be obtained, after stamping, a part whose characteristics of the central panel 19 are isotropic, except for the rectangular contour 20, where the characteristics are reinforced and anisotropic.
• the product being made up of filiform composite the deposition of this composite in the mold can be carried out in a precise and easy way by using for the dispensing head a support such as an arm or a carriage moving on a template. Likewise, it is relatively easy to measure the quantity of composite deposited, by measuring the length of composite delivered at the level of the distributor head by associating with the drive roller 21 a rev counter the diameter of said roller 21 and the section of the composite being known. Finally, cutting a thread-like composite at the level of the dispensing head T at the end of loading a first mold part is a simple operation.
• the heating being carried out continuously on filiform thermoplastic composites with long unidirectional fibers, and these composites being immediately immediately deposited hot in the mold, without resumption of handling, the surface defects of the stamped parts are avoided; it is well known that these surface defects cause numerous rejects which are very difficult to avoid when, in the known methods, the blanks are heated and handled, when they are still hot, in order to load the mold of the press.
• the impregnation of the fibers, on the one hand, and the deposition in the stamping mold of the filiform thermoplastic composites with long unidirectional fibers on the other hand, being carried out in a continuous operation the balance energy consumption is clearly improved, since heating, then cooling of the composite in a separate impregnation operation, and then reheating of the composite for loading the stamping mold are avoided.
• the pre-mold 30 is obviously also mobile in translation between the supply station below the dispensing head T and the preform unloading station 32 which is unloaded as a whole from the inverted pre-mold 30 by gravity, pneumatic thrust or any other suitable means.
• the hot or heated pre-mold 30 where the first by cold mold tie of the stamping press can receive at least one layer or ply of filiform composite cut into more or less long discontinuous sections and at least one layer or ply of continuous filiform composite, the discontinuous composite layer being preferably arranged on the inner wall of the hot pre-mold or that of the first part of the cold mold of the stamping press.
• the layer or ply of composite with continuous fibers is placed on the layer or ply of composite with cut or staple fibers in contact with the internal wall of the first part of the cold mold.
• the composite with long fibers is advantageously deposited in the hot pre-mold or in the first part of the cold mold along a path and a drawing whose location corresponds to that which said long fibers will occupy in the final product, so as to extend therein in a direction oriented in a preferred direction of anisotropy of said product after stamping.
• thermoplastic composite material As is schematically indicated on the figures lia to llç_.
• a cold continuous filiform composite 37 is cut into shorter or longer sections using a pair of shorter or longer rollers using a pair of drive rollers 36a_, 36b_, one of which (36a_ ) has on its periphery a number of oblique cutting blades 38 and is resiliently biased against the other drive roller 36j.
• These sections of cold filiform composite made up of fibers impregnated with a thermoplastic material are cut into the bottom of a pre-mold 39 whose inner wall 40 is heated and whose bottom consists of an ejection piston 41.
• This pre -mould 39 is articulated on a horizontal axis 42 so that it can be tilted 180 between a loading position (FIG.
• this blank 35 is transported in its pre-mold 39 to the top of the first part of the cold mold 44 where, after tilting of the pre-mold 39 (FIG. 11) it is unloaded in block in the first part of the cold mold 44 of the stamping press.
• the cut composites can be deposited in the cold mold:
• the two types of materials are deposited simultaneously.
• a hot mass of chopped fiber composite can be deposited in a single operation onto which the continuous long fiber composite is deposited, thereby increasing the thermal inertia of the assembly.
• the visible part which may, depending on the case, be constituted by the bottom or the surface of the loaded mold
• the visible part is essentially constituted by composite with cut fibers or by a matrix not loaded with fibers.
• the surface appearance is improved by switching from the continuous long fiber composite to the cut fiber composite and to the uncharged fiber matrix.
• the search for the optimal surface condition can therefore lead to the addition of the uncharged matrix to the visible part of the finished part (bottom or surface of the mold).

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Composite Materials (AREA)
• Mechanical Engineering (AREA)
• Textile Engineering (AREA)
• Casting Or Compression Moulding Of Plastics Or The Like (AREA)
• Moulding By Coating Moulds (AREA)

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Cited By (11)

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• 1988
  • 1988-12-06 FR FR8815988A patent/FR2639867B1/fr not_active Expired - Lifetime
• 1989
  • 1989-12-05 MC MC@@@@D patent/MC2143A1/xx unknown
  • 1989-12-05 WO PCT/FR1989/000628 patent/WO1990006226A1/fr not_active Application Discontinuation
  • 1989-12-05 EP EP19900900916 patent/EP0447479A1/de not_active Withdrawn
  • 1989-12-05 CA CA 2004599 patent/CA2004599A1/fr not_active Abandoned

Patent Citations (6)

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