Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
  • B22D17/20—Accessories: Details
  • B22D17/2007—Methods or apparatus for cleaning or lubricating moulds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
  • B22D17/20—Accessories: Details
  • B22D17/32—Controlling equipment

Definitions

• the subject of the present invention is a method and a device for controlling the poteyage means in an installation for die-casting of metals or metal alloys.
• the present invention relates, in an installation for die-casting of metals or metal alloys, a device which makes it possible to control, that is to say to optimize, the spreading of the cleaning liquid. on the internal faces of the mold used to carry out the molding operation.
• the installation essentially comprises a mold 12 consisting of two respectively movable 14 and fixed 16 parts, part of the internal faces respectively 14a and 16a defining the mold cavity or cavity 18.
• a mold 12 consisting of two respectively movable 14 and fixed 16 parts, part of the internal faces respectively 14a and 16a defining the mold cavity or cavity 18.
• the alloy to be molded is introduced into a container 20 and injected under pressure into the cavity 18 by a system of pistons 22. This is what is shown in FIGS. 1a and 1b.
• the movable part 14 of the mold is removed.
• the part 14 of the extraction rods such as 26 which are slidably mounted in the part 14 of the mold. These rods are controlled simultaneously by a cylinder not shown in the figures.
• an poteyage operation using a potageage ramp 28 which makes it possible to spray on the internal faces 14a and 16a a poteyage liquid forming a film on these faces.
• the boom can be fixed during the spraying step or be moved back and forth. It has a number of spray nozzles.
• poteyage products in particular poteyage products based on solvents or water-dilutable cleaners. These poteyage products in themselves are well known.
• the problem is to adapt the content of poteyage product in the solvent, whether it is water or oil, and the quantity of products which must be sprayed before each casting operation.
• the optimization of the coating operation is decisive because it makes it possible to reduce the force which the ejector 26 must exert in order to demold the part. It is in fact understood that if the stresses are too high, the ejectors or the parts being ejected risk being damaged, which constitutes one of the most important obstacles to the automation of die casting.
• the device for controlling the poteyage means in an installation for die-casting of metals or metal alloys comprising a fixed part of the mold and a movable part of the mold defining an imprint, ejector means for the molded part comprising ejection rods, the displacements of which are controlled by a jack supplied with control liquid and a spraying boom for spraying the coating product on the internal faces of the parts of the mold defining the imprint, and supply means of said ramp in poteyage products
• said control device comprises a single pressure sensor for continuously measuring the pressure of the control fluid in said cylinder, means for recording said pressure as a function of time during the cycle of ejection of the part, and means for comparing said recorded curve with a curve of reference including means for detecting in the recorded curve an overpressure level (B) and means for comparing the value of the pressure of said level with a minimum value (Pm) and with a maximum value (Pm) and means for modifying said spraying of pot
• the principle of the invention is to detect the force which the cylinder must exert to carry out the operation of ejecting the molded part.
• the inventors have shown that the quality and the efficiency of the coating operation are inversely proportional to the effort that the ejection rods had to exert to eject the part from the mold imprint. It will be understood that it is thus possible, with the aid of this reading of variations in pressure, to act on the supply of the mixing boom to optimize the effect of the mixing.
• the control device further comprises means for comparing the pressure curve measured with a maximum pressure and means for triggering an alarm if the pressure measured is greater than the maximum pressure. It is understood that in this way it is possible to operate the molding installation without permanent human supervision since the alarm system informs the attendant of unacceptable operating conditions. It goes without saying that, as a variant, the alarm signal can automatically control the stopping of the injection molding installation.
• the device further comprises means for modifying the supply of the ramp with poteyage product as a function of the comparison between the measured pressure curve and the reference curve.
• the adaptation of the coating parameters is done automatically as a function of the difference which exists between the measured curve of the pressure in the control cylinder of the ejector and an optimal pressure curve. .
• the invention also relates to a method for controlling the coating means which is characterized in that the pressure of the control fluid is measured, throughout the duration of an ejection cycle. of the ejector cylinder, said measurements are recorded and action is taken on the coating parameters to optimize the measurement curve of said pressure.
• FIG. 1 - Figures la to ld, already described, illustrate an injection molding installation of known type;
• FIG. 2a shows a molding installation provided with the device for controlling the poteyage means according to a first embodiment of the invention;
• FIG. 2b shows an example of a variation curve of the pressure of the control fluid in the control cylinder of the ejector
• FIG. 3 shows a second embodiment of the control device for automatic adaptation of the coating parameters.
• FIG. 2a we will describe a first embodiment of the control device of the coating system.
• This figure shows the two parts 14 and 16 of the mold as well as a molded part 24.
• the ejector rods 26 are also shown, which are mechanically connected to the rod 30 of a control jack 32.
• the jack 32 is supplied with control fluid by the inputs 34 and 36.
• a pressure sensor 38 is permanently mounted on the jack 32 to measure the pressure prevailing in the control cylinder.
• the sensor 38 which can be of any suitable type delivers an analog signal which is converted into digital information possibly by the converter 40.
• a processing circuit 42 makes it possible to record and memorize the different pressure values as a function of time during all an ejection cycle.
• the corresponding curve can be displayed on a control monitor such as 44.
• the processing circuit 42 also includes comparison means which will be explained later. Also shown in Figure 2a, the movable poteyage ramp 28 which is supplied from a reservoir of poteyage liquid 46 via one or more control valves 48.
• FIG 2b there is shown as a function of time t the pressure P measured by the sensor 38.
• the pressure curve has a first pressure peak A which corresponds to the arrival of the control oil in the jack. This peak is not significant of the ejection efforts.
• control device makes it possible, for each operation, to check whether the maximum pressure value does not increase compared to the optimal value defined previously. In this case, it would then be necessary to modify the coating parameters as indicated above.
• the treatment device can permanently compare the maximum pressure corresponding to the bearing B with a minimum value Pm of admissible pressure and with a maximum value PM of admissible pressure. If the maximum measured pressure value exceeds the pressure range between Pm and PM, the processing circuit 42 triggers an alarm circuit 50 which can supply a visual alarm on the monitor 44 or an audible alarm 52.
• the control device also allows monitoring of the effective operation of the mold ejection system.
• the processing circuit 42 comprises means for comparing the maximum pressure of the control liquid corresponding to the plate B with a set value. If a deviation greater than a predetermined value is detected, the processing circuit 42 activates a control circuit 60 which makes it possible to control the modification of certain spraying parameters for the spraying liquid.
• the control circuit 60 controls the valve 48 for regulating the supply of the spraying boom 28 and for example a supply line 62 with solvent for the spraying product in the container 46.
• the parameters can be automatically modified to find optimal spraying conditions without manual intervention being necessary. We thus enslave the poteyage phase.

Applications Claiming Priority (4)

Publications (2)

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• 1995
  • 1995-01-26 FR FR9500876A patent/FR2729876B1/fr not_active Expired - Fee Related
• 1996
  • 1996-01-25 US US08/875,566 patent/US6073676A/en not_active Expired - Fee Related
  • 1996-01-25 WO PCT/FR1996/000126 patent/WO1996022852A1/fr active IP Right Grant
  • 1996-01-25 AT AT96901853T patent/ATE178821T1/de not_active IP Right Cessation
  • 1996-01-25 EP EP96901853A patent/EP0809555B1/de not_active Expired - Lifetime
  • 1996-01-25 JP JP8522684A patent/JPH10512810A/ja active Pending
  • 1996-01-25 DE DE69602083T patent/DE69602083D1/de not_active Expired - Lifetime
• 1997
  • 1997-07-07 CA CA002209779A patent/CA2209779A1/fr not_active Abandoned

Non-Patent Citations (1)

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