Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
  • B29B7/00—Mixing; Kneading
  • B29B7/30—Mixing; Kneading continuous, with mechanical mixing or kneading devices
  • B29B7/58—Component parts, details or accessories; Auxiliary operations
  • B29B7/60—Component parts, details or accessories; Auxiliary operations for feeding, e.g. end guides for the incoming material
  • B29B7/603—Component parts, details or accessories; Auxiliary operations for feeding, e.g. end guides for the incoming material in measured doses, e.g. proportioning of several materials
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
  • B29B7/00—Mixing; Kneading
  • B29B7/30—Mixing; Kneading continuous, with mechanical mixing or kneading devices
  • B29B7/58—Component parts, details or accessories; Auxiliary operations
  • B29B7/72—Measuring, controlling or regulating
  • B29B7/728—Measuring data of the driving system, e.g. torque, speed, power, vibration
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
  • B29B7/00—Mixing; Kneading
  • B29B7/74—Mixing; Kneading using other mixers or combinations of mixers, e.g. of dissimilar mixers ; Plant
  • B29B7/7476—Systems, i.e. flow charts or diagrams; Plants
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
  • B29B7/00—Mixing; Kneading
  • B29B7/74—Mixing; Kneading using other mixers or combinations of mixers, e.g. of dissimilar mixers ; Plant
  • B29B7/7476—Systems, i.e. flow charts or diagrams; Plants
  • B29B7/748—Plants
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
  • B29B7/00—Mixing; Kneading
  • B29B7/74—Mixing; Kneading using other mixers or combinations of mixers, e.g. of dissimilar mixers ; Plant
  • B29B7/7476—Systems, i.e. flow charts or diagrams; Plants
  • B29B7/7485—Systems, i.e. flow charts or diagrams; Plants with consecutive mixers, e.g. with premixing some of the components
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
  • B29B7/00—Mixing; Kneading
  • B29B7/80—Component parts, details or accessories; Auxiliary operations
  • B29B7/88—Adding charges, i.e. additives
  • B29B7/90—Fillers or reinforcements, e.g. 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
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
• • 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
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
  • B29C48/05—Filamentary, e.g. strands
• • 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

Definitions

• This invention relates to a system for supplying a plurality of different components in controlled amounts and component conditions to a molding machine. More particularly, the invention relates to a system for drying a plurality of different particulate molding composition components, 0 maintaining the state of dryness of the components throughout the system, blending the particulate components and mixing the components with a reinforcing component to obtain a uniform mixture of all components and feeding the mixture to a molding machine.
• Fiberglass which is used to reinforce the molded parts is 5 delivered from the manufacturer in the form of chopped bundles.
• the bundles tend to be broken apart foraiing "fuzzballs" which cause system pluggages and over-rich areas of fiberglass which detract from the molded article properties.
• the fine fibers from the bundle break up, o blocking air filters and transport lines.
• the system of the present invention permits combining multiple components in precise ratios while at the same time drying and maintaining the dryness of the ingredients throughout the proportioning, transport, mixing and feeding operations. Handling of the chopped fiberglass 5 is conducted in such a way as to keep fibrillation and "fuzz ball" formation of the fiberglass to a minimum.
• the system of the present invention comprises a plurality of holding bins for the particulate molding material components. Each component requires its appropriate drying condition. Separate dryer hoppers are provided for each component. Each hopper has its own heater control which adjusts the temperature of the conditioned air, i.e., dehumidified air, prior to its entry into the individual drying hopper.
• the transport system from the drying hoppers to the molding machine is supplied with conditioned air.
• An air transport loop is included which utilizes dehumidified air provided by a dehumidifying dryer, filter and compressor.
• the drying hopper for each component is equipped with a special discharge valve to allow pickup of the discharged contents with dry air for transport to smaller inventory supply bins which are a part of a compact gravimetric weigh unit.
• bins empty by gravity to vibratory pan feeders which deliver the feed from the respective bins to a weigh hopper which is suspended from a precision weighing strain cell.
• the weigh hoppers are filled to their precise weights through automatic feedback control between weigh cells and amplitude and timing controls to vibratory pan feeders.
• a transport hopper is designed with steep sides to handle the components which have widely different physical properties and handling characteristics.
• the hopper is ellipto-conical in shape and will have a vertical forward wall and a steep (70°) sloping rearward wall arranged in a f ⁇ istro-elliptical pattern.
• the preweighed components are then transported via a pneumatic conveying (venturi) system using conditioned air to a holding hopper located adjacent a molding machine.
• a pneumatic conveying (venturi) system using conditioned air to a holding hopper located adjacent a molding machine.
• the particulate components which have been preweighed and held in the holding hopper are released to a mixer. It is important to release the particulates into the mixer prior to introducing fiberglass to eliminate excess tumbling which could produce fiberglass "fuzzballs".
• the fiberglass component is handled in a very special and careful way to avoid fibrillation of the fiberglass bundles and to prevent the formation of "fuzzballs".
• the chopped fiberglass is received from the supplier in a bulk container, preferably in large bulk bags which typically weigh 1000 to 2000 lbs.
• Fiberglass is fed to a weigh hopper until the correct weight is achieved in accordance with a control set point and in accordance with a set ratio and other set ratios for other ingredients.
• the discharge gate of the fiberglass weigh hopper is opened.
• a purge air sealed gate valve is opened momentarily allowing flow of the measured fiberglass charge into the mixer.
• Reinforcing components in addition to or in lieu of fiberglass may be used in the system.
• a horizontal shaft type mixer with internal lifting and directional 0 elements causes all the components within the mixer to be gently tumbled together so as to create a homogenous mixture with limited rotations and controlled speed of the apparatus.
• the separate handling of the fiberglass using only gravity (except for the vibratory feeder) to unload and direct the fiberglass down into the mixer is important to preserve the integrity of the 5 fiberglass bundles thereby reducing fibrillation to a minimum.
• FIGURE is a schematic diagram showing a preferred embodiment of a component supply system according to the invention.
• DETAILED DESCRIPTION OF THE INVENTION o
• Transport air is supplied to the dryer hoppers from 5 master dryer unit 28 through line 18.
• Conditioned (dry) air is supplied to the dryer hoppers from dryer 110 through heaters 112, 114, 116 and 118 which are located in conditioned air supply lines 120, 122, 124 and 126.
• the particulate components may include thermoplastic polymers among which are polyesters and polyamides, toughening agents, various additives such as viscosity reduction agents, colorants, mold release agents, antioxidants, UV light stabilizers and flame retardants. Recycled thermoplastic polymer such as recycled bottle resin from postconsumer polyethylene terephthalate soft drink bottles may also be used.
• the components When the components have reached the desired level of dryness, they are transported through feed lines 40, 42, 44 and 46 by conditioned air to inventory supply bins 50, 52, 54, and 56. Each bin employs one vertical wall and steep angled side walls to promote the evacuative flow of its particular contents.
• Each feeder's receiving port is loosely connected through a coated flexible sock to its individual feed bin and similarly at its exit to weigh hoppers 60 and 60' to prevent ingress of room air, excess loss of purge air, and the escape of any particulate material.
• a central controller On command from a central controller, predetermined amounts of the components as determined by gravimetric weigh units 48 and 48' are fed to weigh hoppers 60 and 60'.
• Each hopper is suspended from a weigh cell 58 and 58' controlled to yield an accurate weight for those components designated to pass through it.
• a total charge could be 50 lbs (22.7 kg) composed of components, respectively, of 35%, 35%, 25% and 5% from inventory bins 50, 52, 54 and 56.
• Separate weigh hoppers 60 and 60' provide for simultaneous weigh-up and an increase in cycle speed.
• the feeders of the weighing units are preferably covered pan high frequency vibrating units although auger feeders could be used.
• pan feeders have the general advantage of delivering very uniformly under precise control at the lip whereas auger feeders have the disadvantage of slugging slightly as material from each thread pitch is delivered. Consequently, the range of precision of each auger is limited more so than a vibrating pan feeder.
• Weigh hoppers 60 and 60' are filled to their precise weights through automatic feedback control between weigh cells and amplitude and timing controls to vibratory pan feeders.
• the two or more components designated for each weigh hopper are fed in sequence. Both weigh hoppers can be operated in sequence or at the same time.
• the charges are automatically dropped into a scale collection hopper 64 by the opening of flapper valves 62 and 62' on the bottom of the respective weigh hoppers.
• the combination of weigh hoppers, flapper valves and collection hopper is referred to herein as a confluencing means. Dry air is supplied to the confluencing means to prevent ingress of atmospheric air.
• Hopper 64 is designed with steep sides to appropriately handle the components fed thereto which have widely different physical properties and handling characteristics.
• this hopper is ellipto-conical in shape and will have a vertical forward wall and steep (70°) sloping rearward wall arranged in a frustro-elliptical pattern.
• the preweighed components are transported via a pneumatic conveying (venturi) system 66 and feed line 68 using dry air to a dry air purged holding hopper 70 located proximately above an injection molding machine 96.
• a pneumatic conveying (venturi) system 66 and feed line 68 using dry air to a dry air purged holding hopper 70 located proximately above an injection molding machine 96.
• a fiberglass source, bulk bag 80 is suspended from a holding rack which is supported by superstructure 72 and travelling crane 74.
• drawstrings on bag 80 can be untied and the bag's downspout placed inside a funnel to discharge apparatus 84.
• the large sacks are characterized by a bottom seal composed of an inner tubular funnel tied together with a drawstring device and with outside flaps which are also operated with a drawstring device and tied with a knot.
• the filled sack is lowered onto the top surface of a discharge box 88 which contains a flexible rubber seal which envelopes the discharge area of the sack.
• Steep sides, one vertical, on the discharge box direct the fiberglass to a sock sealed vibratory covered pan feeder 85.
• the feeder directs the fiberglass into a separate weigh hopper 86.
• This weigh hopper is supported from the superstructure with a weigh cell. Fiberglass is allowed to enter the weigh hopper 86 until the correct weight is achieved in accordance with a control set point and in accordance with set ratios with the other ingredients.
• Reinforcing components in addition to or in lieu of fiberglass, such as mineral fibers, carbon fibers and aramid fibers, mica, glass or ceramic spheres and the like may be used in the system and fed to weigh hopper 86 as described above.
• Mixer 90 is placed proximately above the feed throat of molding machine hopper 94.
• Ingredients which have been fed from inventory supply hoppers 50, 52, 54 and 56 and from the fiberglass feed source 80 are gently tumbled together and after a homogenous mixture is obtained are released by a contoured-discharge slide gate valve 92 on command from a central control station to machine hopper 94.
• a contoured-discharge slide gate valve 92 By locating the mixer proximately above molding machine 96, segregation of the components due to differences in solids flow characteristics of the components is not allowed to occur. Also, fuzzball formation and glass breakage is held to a minimum.
• particulate components It is critical that mixing of the particulate components and fiberglass be carefully controlled. As indicated earlier herein, the particulates should be fed into the mixer prior to feeding the fiberglass; however, with careful control the different materials may be fed simultaneously to the mixer.
• a high efficiency magnetic grate 95 is located at the bottom of machine hopper 94 to remove any magnetic tramp materials that might have entered the system with components or from machinery breakdown.
• the high efficiency magnet allows for wider spacing of bars in the grating permitting free flow of the components.
• the mixture of components is fed, via plug (gravity) flow into the moveable portion 98 of injection molding machine 96 where the plastic components are melted and blended with the other components after which the mixture is fed to tool 100 to form a molded part.
• the system can be fully automated and can be programmed to deliver the precise quantities of the various components desired for a particular product to a molding machine.
• An essential requirement for the successful operation of the system and obtaining quality molded parts is providing dry air for the transport of components.
• Air is fed to the system through supply line 102 through filter 78 to heat exchanger 104.
• Master dryer unit 28 includes a dew point meter 106 as well as other controls to deliver conditioned air to the system. Purge air can be supplied by a separate dryer 108 through feed line 38.
• the purge air dryer supplies dehumidified blanketing air to various system units thereby preventing ingress of nearly all room (ambient) air into the system.
• Modifications to the system can be made.
• the air supply and drying means could be combined in a single master unit, and inventory supply bins could be eliminated with the particulate components being fed directly to associated weighing and confluencing means adjacent the fiber glass supply source. Accordingly, the invention should be understood to include embodiments which can be made without departing from the principle of the invention set out in the appended claims.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)

Applications Claiming Priority (2)

Publications (1)

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• 1992
  • 1992-03-25 JP JP5516479A patent/JPH07505096A/ja active Pending
  • 1992-03-25 AU AU22243/92A patent/AU2224392A/en not_active Abandoned
  • 1992-03-25 EP EP92914185A patent/EP0640031A1/de not_active Withdrawn
  • 1992-03-25 WO PCT/US1992/002141 patent/WO1993018899A1/en not_active Ceased
  • 1992-03-25 BR BR9207107A patent/BR9207107A/pt not_active Application Discontinuation

Non-Patent Citations (1)

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