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
  • B29C33/00—Moulds or cores; Details thereof or accessories therefor
  • B29C33/56—Coatings, e.g. enameled or galvanised; Releasing, lubricating or separating agents
  • B29C33/68—Release sheets
• • 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
  • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
  • B29C43/02—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles
• • 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
  • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
  • B29C43/32—Component parts, details or accessories; Auxiliary operations
  • B29C43/50—Removing moulded articles
• • 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
  • B29C51/00—Shaping by thermoforming, i.e. shaping sheets or sheet like preforms after heating, e.g. shaping sheets in matched moulds or by deep-drawing; Apparatus therefor
  • B29C51/10—Forming by pressure difference, e.g. vacuum
• • 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
  • B29C51/00—Shaping by thermoforming, i.e. shaping sheets or sheet like preforms after heating, e.g. shaping sheets in matched moulds or by deep-drawing; Apparatus therefor
  • B29C51/26—Component parts, details or accessories; Auxiliary operations
  • B29C51/44—Removing or ejecting moulded articles
• • 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
  • B29C70/40—Shaping or impregnating by compression not applied
  • B29C70/42—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles
  • B29C70/46—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles using matched moulds, e.g. for deforming sheet moulding compounds [SMC] or prepregs
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
  • B29K2105/06—Condition, form or state of moulded material or of the material to be shaped containing reinforcements, fillers or inserts
  • B29K2105/08—Condition, form or state of moulded material or of the material to be shaped containing reinforcements, fillers or inserts of continuous length, e.g. cords, rovings, mats, fabrics, strands or yarns
  • B29K2105/0872—Prepregs
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
  • B29K2105/25—Solid
  • B29K2105/253—Preform
  • B29K2105/256—Sheets, plates, blanks or films

Definitions

• the invention relates to the field of manufacturing composite materials by molding processes employing closed molds.
• the invention relates to a method of preforming a semi-finished plastic product used to manufacture a plastic product.
• thermosetting materials such as SMC
• thermoforming process compression with a thermoplastic material
• reinforced plastics thermosetting or thermoplastic
• These materials consist of reinforcing fibers mixed with a polymer resin.
• These reinforcements comprise glass or carbon fibers, for example. These fibers can be cut or continuous.
• SMC with a high degree of reinforcement, especially greater than or equal to 50% by weight, to manufacture semi-structural composite parts.
• the preforming consists in giving a rough shape to the semi-finished product by means of a specific equipment, different from the equipment necessary for molding the finished part.
• the preforming equipment does not necessarily incorporate the definitive shapes of the part, unlike the manufacturing mold.
• the preforming equipment usually operates under conditions of pressure, temperature, and time different from those used for molding the finished part. For example the temperature for the preforming of the preform is less than that used during the molding of the finished part. Due to a lower temperature than in the manufacturing mold, there is no creep or polymerization of the resin.
• vacuum preforming a preforming process known as "vacuum preforming” is known. This process uses a membrane, called a vacuum tarpaulin, placed on the side of SMC. Then the air is evacuated, resulting in the plating of the sheet against the wall of the mold, bringing with it the side of SMC placed between the sheet and the mold.
• cold stamping Another known method of compression preforming in which a semi-product made of plastic material is placed in punch-die type preforming equipment. Then the equipment is closed to apply pressure on the semi-product, while remaining at a moderate temperature, such as the ambient temperature.
• this preforming step has a major disadvantage: the preform adheres to the surface of the preforming means after shaping. This adhesion makes it difficult for the robot to pick up the preform and insert it into the manufacturing mold. This adhesion makes it difficult to eject the preform out of the mold. In addition, this adhesion causes a fouling of the preforming means.
• the SMC flank may tear.
• the object of the invention is to remedy these drawbacks by providing a method for preforming a semi-finished product made of plastic material, in which non-stick membranes are inserted between the semi-finished product and the mold walls.
• the method according to the invention thus comprises the following steps:
• At least one nonstick membrane is arranged opposite a wall of a preform mold
• the semi-product made of plastic material is placed opposite the non-stick membrane, so that the release membrane is positioned between the semi-finished product and the wall;
• the mold thus preformed is removed from the mold.
• the release membrane is nonstick vis-à-vis the wall of the preform mold and vis-a-vis the semi-product.
• the membrane may contain silicone and / or stearates and / or fatty substances and / or maleic anhydrides.
• the part thus preformed can be ejected from the wall of the mold by detaching the membrane from the wall.
• the membrane can be peeled off the wall by applying a pressure between the membrane and the wall. It is also possible to detach the membrane from the wall by reshaping the membrane.
• the air gap is produced between the membrane and the wall before closing the mold in order to press the membrane on the wall, then the membrane is taken off the wall by reintroducing air between the membrane. and the wall.
• the membrane may be flat or have the shape of the wall.
• a punch-die type preform mold is used, the first membrane being located between the semi-finished product and a first wall of the mold, and a second non-stick membrane being located between the semi-finished product and a second wall of the mold.
• the second membrane may contain silicone and / or stearates and / or fatty substances and / or maleic anhydrides.
• the temperature inside the preforming mold is the ambient temperature.
• thermosetting material of the SMC type can be used as a plastic material.
• FIG. 1 illustrates, for a first embodiment, the introduction into the preforming mold (MP) of the semi-finished product (SP) made of plastic material and a release membrane (PM).
• MP preforming mold
• SP semi-finished product
• PM release membrane
• FIG. 2 illustrates, for a second embodiment, the introduction into the mold preforming (MP) of the semi-finished product (SP) made of plastic material and the two non-stick membranes (PM, SM).
• MP mold preforming
• SP semi-finished product
• PM, SM two non-stick membranes
• FIG. 3 illustrates the closed state of the preforming mold (MP), when the punch (PO) presses the die (MA).
• Figure 4 illustrates the opening start of the preform mold (MP).
• Figure 5 illustrates the preform (PF) output of the preform mold (MP).
• FIG. 6 illustrates the embodiment in which the preformed part (PF) is ejected from the matrix (MA) by detaching the first membrane (PM) from the matrix (MA).
• Figure 1 which describes the various steps of the method according to the invention.
• This method of preforming a semi-finished product (SP) made of plastic material comprises the following steps:
• At least one nonstick membrane is arranged opposite a wall of a preforming mold (MP);
• the semi-finished product (SP) is placed in plastic material facing the non-stick membrane (PM), so that the release membrane (PM) is positioned between the semi-finished product (SP) and the wall;
• a pressure is applied to press the semi-finished product (SP) against the wall of the preforming mold (MP), to give a shape to the semi-finished product (SP);
• the part thus preformed and called the preform (PF) is removed from the mold.
• the nonstick membrane (PM) is attached to a membrane support (SU). It can be a frame to which the membrane is fixed (by means of metal eyelets for example).
• This support (SU) can be fixed on the mold. It can also be mobile vertically and / or horizontally.
• the support (SU) can for example be mounted on moving means, to be moved.
• SP semi product
• SP semi-product
• the support is moved so as to remove the preform on the membrane from the mold.
• Another support comprising a nominee flank and a membrane is then taken to introduce the semi-finished product and the membrane into the mold.
• the release membrane (PM) may be arranged facing the wall of the preforming mold (MP) at each molding cycle, either on a fixed support to the mold, or on a mobile support.
• the release membrane (PM) is permanently positioned on or above the wall of the mold.
• the non-stick membrane (PM) can be introduced into the mold (MP) with a flat shape. It is then deformed during pressurization (closure of the mold or when an air gap is applied).
• the release membrane (PM) can also be introduced into the mold (MP) having the same shape as that of the wall of the mold with which it is in contact.
• a "vacuum preforming" method in which the pressure is applied by carrying out the vacuum under a tarpaulin (BV) placed against the semi-finished product on the side opposite to the wall of the mold, so that the tarpaulin slates the semi-product against the wall of the mold.
• the pressure is ceased by ceasing the vacuum.
• FIG. 1 illustrates the introduction into the preforming mold (MP) of the semi-finished product (SP) made of plastic material and the non-stick membrane (MP).
• a "compression preforming” method is used in which the pressure is applied by closing the punch-die mold. According to this embodiment, the pressure is stopped by opening the punch-die type mold.
• a second membrane insofar as each face of the semi-product is in contact with a wall of the mold: the first membrane (PM) being located between the semi-product product (SP) and a first wall (PO) of the mold (MP), and the second non-stick membrane (SM) being located between the semi-finished product (SP) and a second wall (MA) of the mold (MP).
• At least the first non-stick membrane (PM) is arranged opposite the punch (PO) of the preforming mold (MP);
• At least the second nonstick membrane (SM) is arranged facing the matrix (MA) of the preforming mold (MP);
• the semi-finished product (SP) is placed in plastic material opposite the two non-stick membranes (PM, SM), so that the semi-finished product (SP) is inserted between the two membranes (PM, SM);
• the preforming mold (MP) is closed
• the mold is opened and the piece (PF) thus preformed is ejected; and the part thus preformed and called the preform (PF) is removed from the mold.
• Figure 2 illustrates the introduction into the preform mold (MP) of the plastic semi-finished product (SP) and the two non-stick membranes (PM, SM).
• the second membrane (SM) is introduced into the mold permanently.
• the second non-stick membrane (SM) is also attached to a membrane support (SU) of the same type as that of the first membrane (PM).
• the second non-stick membrane (SM) can be inserted between the wall of the preform mold (MP) and the semi-finished product (SP) at each use of the mold, either on a fixed support to the mold or on a mobile support.
• the second non-stick membrane (SM) is permanently positioned in the mold.
• the second non-stick membrane (SM) can be introduced into the mold (MP) with a flat shape. It is then deformed during pressurization (closing of the mold).
• the second release membrane (SM) can also be introduced into the mold (MP) in the same shape as the wall of the mold with which it is in contact.
• FIG. 3 illustrates the closed state of the preforming mold (MP), when the punch (PO) presses the die (MA).
• Figure 4 illustrates the opening start of the preform mold (MP).
• Figure 5 illustrates the preform (PF) output of the preform mold (MP).
• a preform mold is an equipment comprising a fixed matrix (MA) and a movable punch (PO).
• a mold does not necessarily include a heating element, insofar as it is not a question of molding the finished part, but of forming a preform intended to be introduced into a manufacturing mold.
• the PM and SM membranes have a percentage of elongation allowing them to conform to the shapes of the mold.
• membrane having the capacity to lengthen when subjected to the same constraints as the semi-product in the preforming equipment makes it easier to demold the preform, allowing the part to be ejected after opening. of the mold.
• the MP membrane has a return elasticity, allowing it to resume its original shape.
• PM and SM membranes are nonstick membranes for preforming temperatures and semiproduct (SP) materials. These temperatures are generally between 0 ° C and 150 ° C, preferably between room temperature and 100 ° C, and more preferably between room temperature and ⁇ ' ⁇ ). So :
• Adhesion is the set of physico-chemical phenomena that occur when two materials are brought into intimate contact, to create a mechanical resistance to separation. Once the contact is established, the energy needed to achieve the separation is called adhesion energy.
• adhesion is governed by four types of phenomena: physical, mechanical, chemical and diffusive.
• the specialist knows, depending on the semi-product used and the material forming the wall of the mold, to determine a material to meet this non-stick need.
• membranes (PM, SM) containing silicone can be used in the process according to the invention, because they are known for their non-stick properties with respect to plastic resins and plastic preform molds.
• These membranes may also contain, as non-sticking agent, stearates, fatty substances (soaps, etc.), maleic anhydrides, etc.
• the membranes are silicone membranes having a thickness of 1 mm and 5 mm.
• the PM membrane is used to eject the preform (PF) from the mold (MP), as illustrated in FIG. 6 for the second embodiment.
• the method comprises a step during which the matrix (MA) is ejected from the preformed part (PF) by detaching the PM membrane from the matrix (MA).
• the matrix (MA) is ejected from the preformed part (PF) by detaching the PM membrane from the matrix (MA).
• Figure 6 it is observed that the first membrane (PM) is detached from the matrix (MA), ejecting the preform (PF).
• the membranes are membranes containing silicone and having an elongation percentage of between 100 and 800%.
• This PM membrane can be detached from the wall of the mold by applying a pressure between the membrane (PM) and the wall (MA, PO) with which it is in contact.
• the pressure can be applied by local ejectors, the membrane then distributing the forces applied by these ejectors.
• the pressure can also be applied by injecting a gas, such as air, between the mold wall and the PM membrane. Due to its elastic property, the membrane hangs, ejecting the preform from the mold.
• a gas such as air
• This membrane (PM) can also be detached from the matrix (MA) by recovering the shape of the first membrane (PM).
• the PM membrane must also have the following property: a return to rest of the membrane allows the membrane to return to its original shape.
• Elastomeric, silicone or latex membranes are membranes having this property.
• the air gap is produced between the first membrane (PM) and the matrix (MA) before closing the mold (MP).
• SP semi-product
• This operation is intended to press the first membrane (PM) on the matrix (MA), thus preventing the piece from sticking to the mold.
• this operation also makes it possible to predict the ejection of the preform (PF). Indeed, after opening the mold, the first membrane (PM) is removed from the matrix (MA) by reintroducing air between the first membrane (PM) and the matrix (MA).
• the preforming mold (MP) there is kept inside the preforming mold (MP) an ambient temperature during the preforming of the part.
• the semi-product (SP) made of plastic material may be of thermoplastic material or thermosetting material.
• it may be thermosetting material type SMC.
• a loading plan is made outside the mold, by stacking at least a semi-product and a first non-stick membrane (PM) on a mobile support;
• PM non-stick membrane
• a second non-stick membrane is permanently disposed between the other movable wall of the preforming mold (MP) and the semi-finished product; iv. the preforming mold (MP) is closed, and at least part of a new loading plan outside the mold is simultaneously produced on a second support (a new loading plan is made at least partially in masked time of the molding) ;
• preform PF

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

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

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Family Cites Families (10)

• 2013
  • 2013-12-24 FR FR1363567A patent/FR3015339B1/fr not_active Expired - Fee Related
• 2014
  • 2014-12-22 CN CN201480073151.8A patent/CN106132657A/zh active Pending
  • 2014-12-22 EP EP14833518.5A patent/EP3086913A2/de not_active Withdrawn
  • 2014-12-22 WO PCT/FR2014/053513 patent/WO2015097397A2/fr active Application Filing
  • 2014-12-22 US US15/107,154 patent/US20170001339A1/en not_active Abandoned

Non-Patent Citations (2)

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