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
  • B22D17/14—Machines with evacuated die cavity
  • B22D17/145—Venting means therefor
• • 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
  • B22D17/14—Machines with evacuated die cavity

Definitions

• the present invention relates to a suction valve device for evacuating gas from a mold, in particular a mold for casting under pressure of liquid metals, or for injecting a plastic material.
• a differential valve for the evacuation of gas from a die casting mold of liquid metals is described in European Patent EP 936009.
• the die casting of liquid metals makes it possible to manufacture molded parts of complex metal alloy form such as than alloys of aluminum, magnesium, zinc, zamak or other injection materials. It is important to inject the still liquid metal into the mold very quickly to ensure that the mold fills completely with a minimum of solidification of the metal caused by contact with the mold wall, also to ensure homogeneous properties after the solidification of the injected material.
• the suction valve makes it possible to evacuate the air contained in the mold before and during the injection of the liquid material into the mold, the valve being connected to a vacuum tank to create a partial vacuum in the cavity by suctioning air out of the mold.
• the valve Because of the injection speeds, the valve must be reactive and very accurate, while being reliable and economical. Due to a possible clogging of the valve and wear of certain parts during its use, it is desired to have a valve that keeps maintenance costs low and can be exchanged quickly for replacement or for cleaning.
• Molds for the die casting of liquid metals comprising a valve device for gas evacuation are described for example in US Patents 4,691,755 and US 4,997,026.
• the valve is disposed at the top of the mold, the axis of displacement of the piston of the valve being vertical and perpendicular to the axis of movement of the opening of the mold to extract the casting.
• the axis of movement of the piston of the valve is parallel to the plane of separation (also called joint plane) of the two parts of the mold.
• the valve device for gas evacuation is thus disposed above the two parts of the mold, these two parts being separable for extraction of the casting.
• a disadvantage of this configuration is that the mold must have a device for raising the valve device to separate the two mold parts.
• an object of the invention is to provide a gas evacuation valve device of a die casting mold or plastic injection mold, which is reliable and allows a controlled and rapid evacuation air and other gases in the mold.
• a gas vent valve device of a die casting or plastic injection mold which is easy and economical to maintain and replace. It is advantageous to provide a suction valve device for a die-casting or injection mold which allows a quick and easy exchange of worn, fouled or damaged parts and which allows the easy cleaning of soiled parts by the circulation of the dirty gas during suction (lubricants, grease, combustion gas). In particular, it is advantageous to provide a valve device for a die casting or injection machine that reduces the downtime of the machine when replacing or servicing parts of the valve.
• a suction valve device for a die casting or plastic injection machine, comprising a body with a valve chamber comprising a suction chamber and a pilot chamber, and a slide valve mounted in the valve chamber.
• the sliding valve comprises a first part with a head of valve cooperating with a valve seat on the body for opening and closing the valve, and a second portion comprising a piston mounted in the control chamber, the control chamber being connected to fluidic control connections to exert a force on the piston to control the opening and closing of the valve.
• the second valve part and the first valve part are aligned on the same axis in the direction of movement of the slide valve, transverse to the separation plane of the molds, the first and second parts of the slide valve being separable.
• first and second portions of the slide valve are secured together by a detachable fastener.
• first and second parts of the sliding valve are fixed together by being screwed to each other, for example by having a male thread on one part engaged in a female thread in the other part.
• the valve device according to the invention reduces the downtime of the machine during maintenance of the valve, for example for cleaning or replacing the valve head, while increasing the reliability of the device. Indeed, by arranging the valve device so that the direction of movement of the piston is transverse to the separation plane of the molds, and having the valve valve separable valve head and configured to allow the head out of valve on the side of the mold face, we can quickly remove the valve head without intervening on the control chamber by performing very simple operations. Furthermore, with this configuration it also avoids having to move the valve device during the opening of the mold, thus avoiding the need for a cylinder or other system for moving the valve device.
• valve device according to the invention being compact and inexpensive, the user will have the opportunity to obtain a spare valve device for rapid exchange during a maintenance operation.
• the valve device according to the invention can be inserted into the mold at choice positions, unlike conventional molds as described in US 4,691, 755 and US 4,997,026 which must be disposed at the periphery of the mold.
• the invention makes it possible to maximize the suction section for faster gas evacuation of large cavities, thanks to its control device which allows rapid and extremely safe closing even for a very large suction section.
• the detachable fixing member comprises a pin inserted transversely into a bore passing through the first and second parts of the sliding valve.
• the body comprises openings on either side of the sliding valve configured to allow the axial displacement of the pin during the opening respectively closing the valve.
• the openings in the body may be closed by screws mounted in threaded holes in the body configured to arrange the end of the screws at a slight clearance from the ends of the pin to allow the pin to slide.
• the fixing member comprises a screw, for example a screw aligned with a central axis in the sliding valve passing through one of the parts and engaging the other part with a thread.
• the valve device may advantageously comprise a sleeve mounted in the chamber of the body, the sleeve defining a sliding guide and sliding surface, and the valve seat, the sleeve being removably mounted to the body.
• the body comprises a first portion and a second portion, the first portion being removably mounted to the second portion, the first portion comprising a connection for connection to a vacuum generating system, and the second part including the control chamber.
• the piston has an opening face with a larger surface than a closing face on the other side of the piston, configured to apply a differential pressure on the compensating piston at least in part to a pressure on the valve head during gas evacuation.
• the valve head has a conical surface complementary to a conical surface of the valve seat.
• valve head has a cylindrical surface complementary to a cylindrical surface in the valve seat.
• a die casting system comprising a die casting machine with a valve device, and a vacuum generating system comprising a volume vacuum tank larger than a volume of gas vacuum from a mold mounted on the machine.
• the vacuum generation system comprises at least one main valve for controlling the opening and closing of the connection between the reservoir and the valve device.
• the vacuum generating system includes a plurality of main valves between the vacuum tank and the valve device, the main valves being controllable for delayed opening or closing to control the suction flow rate.
• the vacuum generation system comprises a valve connected to the atmospheric pressure in order to reduce the flow rate of the suction during a first injection phase.
• a method of casting under pressure of a liquid metal disposed in a tank connected by an outlet to a mold-shaped cavity comprises a first step of aspirating gas from the mold and the reservoir at a first speed and simultaneously reducing the volume in the chamber of the reservoir, and a second step of withdrawing gas at a second speed greater than the first speed when the volume of the chamber is smaller, and possibly a third gas suction step at a third speed greater than the second speed when the volume of the chamber is very small or when the liquid begins to be injected into the cavity of the mold.
• the variation of the suction velocity can advantageously be controlled at least in part by the degree of opening of the valve of the valve device.
• the variation of the suction speed can advantageously be controlled at least partially by a plurality of main valves of a vacuum generation system comprising a vacuum tank connected to said mold, the plurality of valves The main ones are arranged between the vacuum tank and the valve device and can be independently controlled for delayed opening or closing to control the suction flow rate.
• the second suction step can be started when the liquid metal to be cast has not yet entered the mold cavity. If a third stage of gas aspiration is implemented, it can intervene when the volume filled with liquid metal in the chamber of the tank is very small or when the liquid begins to be injected into the mold cavity.
• the increase of the suction speed can be achieved in three or more stages of speed variation by controlling the degree of opening of the valve of the valve device, and / or by controlling the opening of one or more several main valves of a vacuum generation system.
• the variation of the suction speed can therefore also be controlled at least in part by a valve system connected to the reservoir of a vacuum generation system.
• one or more suction sections of one or more outlet channels connecting the mold cavity with the valve device are configured to create a pressure drop at the gas flow rate as a function of the the volume of gas to be sucked in order to be able to use the valve device for a plurality of liquid volumes with volumes that can vary by an order of magnitude.
• Fig. 1 is a schematic illustration of a die casting or plastic injection system according to one embodiment
• Fig. 2a is a sectional view of a suction valve device according to a first embodiment with a cylindrical valve head and a cylindrical coupling with a pin with the piston;
• Fig. 2b is a sectional view of a valve device according to one embodiment with a cylindrical valve head and a fork-shaped coupling with pin with the piston;
• Fig. 2d is a sectional view along line 11-11 of FIG. 2c;
• Fig. 3a is a sectional view of a valve device according to a second embodiment of the invention.
• Fig. 3b is a sectional view of a valve device according to a variant of the embodiment of FIG. 3a;
• Figs 4a-4d schematically illustrate die casting or plastic injection systems according to different variants:
• FIG. 4a represents the variant illustrated in FIG. 1, wherein the die casting machine is connected to a vacuum tank by a main valve;
• FIG. 4b illustrates a variant where the machine is connected to a vacuum tank without a main valve
• FIG. 4c illustrates a variant where the machine is connected to a vacuum tank by a main valve, the tank being connected to the ambient air by a second valve;
• Fig. 4d illustrates an alternative wherein the die casting machine is connected to a partial vacuum tank by a plurality of independently or sequentially controlled valves;
• Fig. 4e illustrates a variant where the die casting machine is connected to a partial vacuum tank by two valves of different sizes controlled independently or sequentially.
• a die casting or plastic injection system 1 comprises a die casting or injection machine 2, a vacuum generating system 6 and a gas suction valve device 4 mounted on the machine 2 and communicating with the vacuum generation system 6 through a gas discharge connection 24.
• the vacuum generation system comprises a reservoir 14 forming a chamber with a volume greater than the volume of gas in the mold to be sucked, the chamber being connected to a vacuum pump (not shown) creating a partial vacuum in the tank.
• the vacuum generating system may further comprise a main valve 16 which can be controlled to open and close the conduit interconnecting the valve device to the reservoir 14.
• the vacuum generation system allows the air to be evacuated from the mold very quickly before and during the injection of a liquid material into the mold.
• the die-casting or injection machine 2 comprises a reservoir 8 with a chamber 5 for containing the liquid material to be poured or injected 3, a mold 12 defining a cavity of shape 1 1 to form the casting, the cavity of form 1 1 being in communication with the valve device 4 disposed at the top of the mold on one of the parts of the mold.
• the mold comprises at least two parts 12a, 12b separable in order to be able to remove the molded part.
• the valve device is configured to be disposed on one of the parts 12a of the mold and is oriented so that the axis A of a sliding valve 20 of the device (defining the direction of movement of the slide valve) is transverse to the separation plan P of the molds.
• the transverse direction is perpendicular to the separation plane P of the mold parts.
• the transverse direction may however comprise an angle other than perpendicular (90 °) to the plane of separation P, for example an angle between 90 ° and 45 °, without departing from the scope of the invention.
• the chamber 5 comprises an inlet 7 for filling the chamber 5 with the liquid 3, and an outlet 9 between the chamber 5 and the shaped cavity 11 for the passage of the liquid from the chamber 5 to the shaped cavity 11 during the step of casting or injection.
• the reservoir 8 comprises a piston 10 for pushing the liquid 3 of the chamber 5 into the mold cavity 1 1.
• the liquid material is a liquid metal such as an alloy of aluminum, magnesium or other injected metals, the machine being suitable for the die casting of metals.
• Other materials such as plastics could also be injected by a method according to the invention, and it is also conceivable to replace the tank of liquid material 8 with other liquid supply systems.
• the liquid material 3 is poured through the inlet 7 into the chamber 5 of the tank 8. Then the piston 10 advances to close the inlet 7. Then, the valve device is opened and the air contained in the mold cavity 1 1 is sucked by the vacuum generation system 6, the main valve 16 being at this moment also open, and simultaneously the piston 10 is advanced first to raise the level of liquid material 3 in the chamber 5 of the tank 8 and then to push the liquid 3 into the mold cavity 1 1.
• the valve of the device 4 is closed just before the complete filling of the mold cavity 1 1, or when the liquid material is in one or more outlet channels 15 connecting the mold cavity 1 1 to the valve device 4, the shape cavity being preferably completely filled, the closing moment being configured to prevent liquid 3 injected into the mold reaches the height of the valve before closing. Indeed, the closing moment of the valve is configured to prevent injection liquid through the valve, which would have the effect of blocking the valve.
• the combination of gas suction of the valve by the vacuum generation system on one side and the pressure exerted by the piston 10 in motion makes it possible to inject the liquid material 3 at a very high speed into the cavity of form 1 1 and to fill all the parts of the cavity 1 1 in a lapse of time of one order or two orders of magnitude of thousandths of a second.
• the suction speed control is carried out by the valve device 4.
• the vacuum generation system 6 does not include any valves and suction control is performed only by the valve device 4.
• the vacuum generation system 6 further comprises an exhaust valve 17 which partially opens the duct between the main valve 16 and the vacuum tank 14 to the ambient air to increase the pressure and thus reduce the pressure. vacuum suction effect in the first injection phase.
• the exhaust valve 17 is preferably smaller than the main valve 16, i.e., the exhaust valve has a diameter or flow section smaller than the flow diameter or section. of the main valve 16.
• the tank 14 of the vacuum generation system is connected to the valve device 4 by two or three valves 16a, 16b, 16c or more which make it possible to increase the suction speed as a function of the number of open valves.
• a single valve is for example open and then, when the piston is advanced enough to eliminate the unfilled volume in the tank 8, the second, see the third valves are open to increase the section of suction through the valves and increase the gas suction speed of the mold.
• the vacuum tank 14 of the vacuum generating system is connected to the valve device 4 by two valves 16a, 16b of different sizes - a small valve 16a and a large valve 16b - which make it possible to increase the suction speed by function of the opening of the small valve 16a or the large valve 16b or both simultaneously.
• the advantage of this system is its simplicity of control, since there are only two valves to be controlled, while allowing to optimize the slow and fast suction speeds by the dimensioning of the small valve 16a, respectively the large valve 16b.
• the small valve 16a In the first suction phase, the small valve 16a is open and then, when the piston is advanced enough to partially eliminate the unfilled volume in the tank 8, the large valve 16b is open, to increase the suction section and increase the gas suction flow of the mold.
• the large valve may advantageously have a diameter greater than 2.5 cm and the small valve a diameter less than 1, 6 cm and greater than 0.5 cm.
• a combination of the embodiments of FIGS. 4c and 4e is possible, namely, the valve 17 connected to the atmospheric pressure is a small valve and the main valve 16 a large valve.
• the suction section of the channel or outlet channels the mold connecting the cavity 1 1 with the valve device 4 may be varied to vary the resistance to gas suction and to limit the amount of metal in the falls.
• a valve configured for large molds and extraction rates can be used, also for smaller molds by reducing the suction section of the channel or outlet channels of the mold.
• the suction capacity of the valve device or the main valves can advantageously be reduced by the methods described above.
• the valve device comprises a body 18 with a first portion 28 defining a first block, and a second portion 30 defining a second block, a sliding valve 20 mounted in a valve chamber 21 formed in the body 18 and a valve seat 22 , 22 'cooperating with a valve head 44, 44' of the sliding valve to close, respectively open, the valve.
• the valve head 44 ' may have a conical surface complementary to a conical surface of the valve seat 22' as illustrated in Figures 2c to 3b, or the valve head 44 may have a cylindrical surface complementary to a cylindrical surface in the valve seat 22 as illustrated in Figures 2a, 2b.
• the valve chamber 21 comprises a suction chamber 21b and a control chamber 21a.
• the control chamber 21a is connected to fluidic control connections 26a, 26b, one connection 26a being for closing the valve and the other 26b for opening the valve.
• the fluidic connections may in particular be connected to a pneumatic or hydraulic system that can vary the pressure in the connections 26a and 26b in order to advance and retract the sliding valve.
• the suction chamber 21b is connected to the gas discharge connection 24 connected to the vacuum generation system 6.
• valve head is separable from the valve piston in a manner to exit the valve head from the side of the separation plane P of the mold without intervening on the control chamber 21a.
• a sleeve 32 may be inserted into a cavity in the body 18, the valve 20 being slidably mounted in the sleeve 32, the sleeve 32 also defining the valve seat 22, 22 '.
• the sleeve 32 is advantageously removably mounted in the body 18 so that it can be replaced or cleaned in maintenance operations.
• the sleeve can also be made of a different material to that of the body with optimal properties to decrease the frictional forces and improve the sealing of the valve seat 22.
• the sleeve 32 which is subject to significant wear due to the movements repetitive of the sliding valve and in repeated contact with the liquid on the side of the valve head 44 can be exchanged at low cost and without exchanging the body 18.
• the sleeve 32 can be held in the body by means of a circlip 46 or other removable fastening means such as screws.
• the sliding valve comprises at least two separable parts, a first part 34 with a valve head 44, 44 'cooperating with the valve seat 22, 22', and a second part 35 comprising a piston 38 slidably mounted in the pilot chamber 21a of the valve chamber 21.
• the first and second sliding valve portions are secured together with a releasable attachment means 36, 36 '.
• the valve head is separable from the valve piston in a manner that allows the valve head to be pulled out from the face side of the mold part (separation plane side P) without intervening on the pilot chamber.
• first and second parts of the sliding valve are fixed together by being screwed to each other, for example by having a male thread on a part engaged in a female thread in the other part.
• This last variant can especially be used for small molds or for plastic injection molds.
• the first portion 34 of the sliding valve 20 is removed from the side of the active face of the mold, that is to say the side of the separation plane P of the mold parts, when the mold is open.
• the second block of the valve has a very long life, since it is completely separated from the suction chamber 21b and protected from any dirt from the liquid injected into the mold.
• the second part of the sliding valve is also less subject to wear than the first valve part which slides in the sleeve and which engages the valve seat 22, 22 '.
• the piston 38 is, in the illustrated example, in the form of a cylindrical disc slidably mounted in the control chamber 21a which comprises a valve opening side 41 communicating with the opening fluidic control connection 26b, and a side closing 43 communicating with the opening fluidic control connection 26a.
• a fluid for example air for a pneumatic system, is injected into one or the other of the connections depending on the direction of movement desired to apply pressure on the opening side.
• the pressure is differential insofar as the surface of the closing side face 42 is smaller than the surface of the opening side face 40 of the piston 38, the advantage being to be able to regulate the differential pressure more finely, in particular to better control the closure of the valve and increase the positioning stability of the sliding valve.
• the differential pressure makes it possible in particular to compensate the pressure on the valve head 44, 44 'during the evacuation of gas.
• a differential pressure is not desired, a non-differential variant as illustrated in FIG. 3b where the bearing surface of the opening and closing sides of the piston 38 is equivalent or substantially equivalent.
• the control chamber 21a is separated from the suction chamber by a wall 48 mounted in the second body portion 30, an axis 50 of the second sliding valve portion passing through a passage in the wall 48 to interconnect the piston 38 to the first portion 34 of the sliding valve 20.
• the clearance between the passage and the axis is very small in order to limit or eliminate a loss of pressure between the closing side of the control chamber 21a and the suction chamber 21b .
• the axis 50 of the second sliding valve part is housed in a hole or fork corresponding to the rear of the first valve part, the fixing member in the embodiments of Figures 2a-2d being in the form of a pin 36 passing through a bore in the first portion and in the second valve portion.
• the body may comprise apertures 52 on either side configured with an axial length A1 to allow axial movement of the pin 36 from an open position to a closed position of the valve.
• the openings 52 may be closed by flat-bottomed screws mounted in screw holes in the body on either side of the pin and leaving a slight clearance with the ends of the pin to allow its movement.
• the two screws are removed on either side and the pin 36 is pushed on one side so that it can come out of the other side and then simply remove the first part of the valve axially. valve.
• the first valve part can therefore be separated very easily and very quickly, the pin nevertheless ensuring a very robust and rigid connection between the first and second valve parts.
• the first portion 28 of the body 18 can be separated from the second portion 30 by loosening screws 56 and removing the pin 36 as described above, the separation to remove the sleeve 32 is therefore also very simple and fast.
• the body has no opening on either side of the sliding valve, the pin being thus retained by the seat of the valve, or by an O-ring placed in a groove made in the valve. the position of the pin.
• the first and second sliding valve portions are secured together by means of a screw 36 'extending axially from the rear of the slide valve. If rear access is difficult or not desired, it is also possible to have a central screw which is inserted from the side of the valve head 44 engaging a thread into the second portion 35 of the sliding valve.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Moulds For Moulding Plastics Or The Like (AREA)
• Details Of Valves (AREA)
• Control Of Fluid Pressure (AREA)
• Molds, Cores, And Manufacturing Methods Thereof (AREA)

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Applications Claiming Priority (2)

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• 2011
  • 2011-06-09 CH CH00978/11A patent/CH705077B1/fr not_active IP Right Cessation
• 2012
  • 2012-06-01 EP EP12735014.8A patent/EP2718044B1/de not_active Not-in-force
  • 2012-06-01 CN CN201280028404.0A patent/CN103619510B/zh not_active Expired - Fee Related
  • 2012-06-01 HU HUE12735014A patent/HUE031772T2/en unknown
  • 2012-06-01 ES ES12735014.8T patent/ES2614473T3/es active Active
  • 2012-06-01 US US14/123,937 patent/US9050653B2/en not_active Expired - Fee Related
  • 2012-06-01 CA CA2837528A patent/CA2837528C/fr not_active Expired - Fee Related
  • 2012-06-01 PL PL12735014T patent/PL2718044T3/pl unknown
  • 2012-06-01 WO PCT/IB2012/052781 patent/WO2012168841A2/fr active Application Filing

Non-Patent Citations (1)

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