Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C11/00—Moulding machines characterised by the relative arrangement of the parts of same
  • B22C11/10—Moulding machines characterised by the relative arrangement of the parts of same with one or more flasks forming part of the machine, from which only the sand moulds made by compacting are removed

Definitions

• the present invention relates to a method of heating one or more elements that come in contact with moulding sand of a string moulding apparatus of the kind set forth in the preamble of claim 1 and to a string moulding apparatus with one or more heated elements that come in contact with moulding sand of the kind set forth in the 10 preamble of claim 12.
• String moulding apparatus relate to foundry machinery in which the moulding sand
• the string moulding apparatus is introduced into the moulding chamber of the string moulding apparatus in order to produce string of vertically parted moulds, of e.g. green-sand.
• string of vertically parted moulds of e.g. green-sand.
• the sand is bonded by a clay binder capable of forming an instant bond on the application of pressure, thus allowing low cycle times.
• Green sand is a mixture of sand and a clay binder i.e. betonite.
• the normal moisture level in the required for an effective bonding is in the range of 3 to 4 weight % but the range can be higher or lower in extreme situations. A too low moisture level leads to insufficient bonding, whereas a too high moisture level can cause damp- explosions of the moulds when the molten metal is poured in.
• the moulding sand is transported to a sand supply unit that supplies the moulding sand to a sand shot system.
• the sand shot system introduces the moulding sand into the moulding chamber by means of compressed air.
• the sand shot system comprises a sand valve and a sand storage container.
• the sand supplied to the sand shot system by the sand supply unit has a temperature above that of the surrounding environment, typically the temperature of the sand is intended to be about 30 to 40 °C but can under certain circumstances be higher.
• the space in the sand storage container is vented. The expansion of the pressurised air
• the moulding chamber has normally a temperature close to that of the surrounding environment, i.e. typically about 20°C.
• the condensed water leads to corrosion of the hardened steel.
• the top surface of the bottom plate usually made of hardened steel, in order for it to have a high wear resistance.
• the wear resistance of the hardened steel is however strongly reduced if the steel is exposed to corrosion since the crystal- and boundary structure is damaged and the hardened steel looses its high wear resisting properties. Thus, the wear-plate will wear faster than is expected.
• This object is achieved by the characterising features of claim 1.
• the hydraulic fluid is flowed through a conduit formed in the bottom plate.
• the conduit is arranged such that the whole bottom plate is heated.
• the conduit is arranged such that an overproportional part of the of the conduit is formed in the part of the bottom plate most remote from the moulding chamber where the last of the previously mould parts remains for the time of one production cycle of the apparatus.
• the bottom plate comprises a support plate supporting a wear plate.
• the conduit is formed in the support plate.
• the top surface of the bottom plate is heated to such an extend that the top surface of the bottom plate that is intended to support the mould parts is heated up to a temperature equal to or higher than the temperature of said mould parts supported by the bottom plate.
• the side surfaces and/or the top surface of the moulding chamber are heated with hydraulic fluid.
• the sand storage container and/or the sand valve are heated with hydraulic fluid.
• Figure 2a is a view on the side of a bottom plate
• Figure 2b is a view on the top of a support plate of the bottom plate.
• the apparatus illustrated in Figures 1a, 1b and 1c comprises a combined mould-making and casting apparatus, e.g. of the DISAMATIC® type.
• This apparatus as such and its mode of operation are well known in the art, and for this reason it is only dealt with broadly in this specification.
• a sand storage chamber 11, adapted to receive sand from a sand supply system (not shown) is used for temporarily storing the moulding sand 10.
• a sand valve 22 comprising a closure member 23 is arranged on top of the sand storage container 11.
• the sand valve is temporarily opened by moving the closure member 23 from a closing position to an open position.
• air under pressure is supplied to the space above the sand 10 by means not shown here through the air inlet/outlet 24 in order to introduce moulding sand 10 into the moulding chamber 1.
• the space above the sand is vented. The expansion of the pressurised air cools the sand storage container and the sand valve.
• the moulding chamber 1 situated as shown below the supply chamber 11 , is limited in the lateral direction by pattern plates which are supported by a squeeze plate 2 and a pivoted squeeze plate 3, respectively.
• Box-less mould parts 8 are made from loose green-sand, i.e. sand with moist ciay as binder, in the moulding chamber 1 defined between a pattern located on a squeeze plate 2 and a pattern located on movable and upwardly pivoted -squeeze plate 3 in a downwardly pivoted position of the squeeze plate 3.
• the sand is compacted between the squeeze plate 2 and the pivoted squeeze plate 3 to form a mould part 8 as shown in Figure 1b.
• the pivoted squeeze plate 3 is conveyed forward and pivoted upwards to the position as shown in Figure 1c, after which the mould part 8 is conveyed by the squeeze plate 2 to abut against the mould string formed by previously produced mould parts 8.
• the newly produced mould part 8 is then further pushed out until the mould string is conveyed over a distance corresponding to the thickness of T of a mould part 8 in the direction indicated by an arrow A.
• the mould part 8 is conveyed out of the moulding chamber 1 by the squeeze plate 3 it slides over the bottom plate 5.
• the mould cavity 9 is cast with a molten metal through an inlet 21 , which may be on a side or bottom wall of the mould below the level of the mould cavity 9, by means of a casting device, e.g. a ladle 20. It will be appreciated that the casting of the mould cavity 9 must take place while the mould string is stationary, i.e. within the intervals between each time the squeeze plate 2 advances the mould string through a distance corresponding to the thickness of a mould part 8 in the direction A.
• a linear hydraulic actuator arrangement comprising a linear hydraulic actuator 12 for driving the squeeze plate and a linear hydraulic actuator 13 for driving the pivoted squeeze plate 3, is adapted to move the squeeze plate and the pivoted squeeze plate 3 towards each other under high pressure for the mould part forming operation and move the squeeze plates 2,3 back and forth in the other steps of the production cylce.
• the hydraulic linear actuator 12 is directly connected to the squeeze plate 2 at one end and connected on the other end to a stationary block 6 which is integral with the base frame of the string moulding apparatus.
• the linear hydraulic actuator 13 is connected at one end to the pivoted squeeze plate 3 through push-pull rods 18 and at the other end connected to the stationary block 6.
• the linear hydraulic actuators 12, 13 are supplied with hydraulic fluid under pressure, preferably hydraulic oil, by a hydraulic system comprising a valve system 14, a pump 15, and a reservoir or tank 16.
• the hydraulic fluid is returned from the hydraulic actuators 12 and 13 and/or the valve system 17 through a return conduit 17.
• the return conduit 17 is connected to a conduit 7 in the bottom plate 5. By flowing the warm hydraulic fluid through the bottom plate 5, the heat in the hydraulic fluid is transferred to the bottom plate 5. When the hydraulic fluid leaves the conduit 7 it is returned to the hydraulic fluid to the tank 16.
• the return conduit also hydraulic fluid to a conduit (not shown) in side plates and the top plate 4 of the moulding chamber.
• the return conduit 17 further conveys hydraulic fluid to a conduit in the walls of the sand storage container 11 and/or the sand valve 22.
• the return conduit 17 also conveys hydraulic fluid to a conduit (not shown) in the squeeze plate 2 and to a conduit (not shown) in the pivoted squeeze plate 3.
• the bottom plate 5 is shown in detail.
• the bottom plate is built up of a support plate 5a and a hardened steel wear plate 5b. This construction is used since the mould parts 8 are conveyed slidingly over the bottom plate 5.
• the sand of the mould parts 8 has a high abrasive effect which causes the conveying surface of the bottom plate to wear out. Therefore the wear- plate 5b is made of hardened steel.
• the wear resistance of the hardened steel is however strongly reduced if the steel is exposed to corrosion. When such a steel corrodes the boundary structure and the crystal structure are is damaged and the hardened steel looses its high wear resisting properties.
• the wear-plate 5b will wear faster than is expected when the bottom plate is not heated. Further the corrosion takes also place between the wear-plate and the bottom thereby forming rust.
• the wear plate 5b is worn out it is exchanged with a new wear-plate 5b.
• the conduit 7 is arranged in the bottom plate 5a, in a groove in the top surface of the support plate 5a.
• the groove is sealed by the wear plate 5b that is fixed on top of the support plate 5a.
• the hydraulic fluid can either be conveyed in the groove itself or in a tube arranged in the groove.
• the path that the conduit 7 follows is chosen such that the whole bottom plate 5 is warmed up, whereby the path is chosen such that the part of the bottom plate 5 most remote from the moulding chamber 1 , i.e. there where the last of the previously produced mould parts 8 rests, receives overproportional part of the heat from the hydraulic fluid.
• the path of the conduit 7 in that part of the bottom plate forms a serpentine pattern.
• the bottom plate 5 is heated up to such an extent that the top surface of the bottom plate 5, normally formed by the top surface of the wear plate 5a, is heated up to such an extent that it has a temperature equal to or higher than the temperature of the sand mould parts supported by the bottom plate.
• the warm hydraulic fluid is conveyed in a tube arranged in the groove in the support plate 5a.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Furnace Charging Or Discharging (AREA)
• Casting Devices For Molds (AREA)

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• 1999
  • 1999-06-09 JP JP2001503006A patent/JP2003501270A/ja active Pending
  • 1999-06-09 AU AU42570/99A patent/AU4257099A/en not_active Abandoned
  • 1999-06-09 EP EP99973895A patent/EP1198313A1/de not_active Ceased
  • 1999-06-09 WO PCT/DK1999/000310 patent/WO2000076691A1/en not_active Application Discontinuation

Non-Patent Citations (1)

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