FR2559079A1 - HALF METAL MOLD FOR SHELL MOLDING - Google Patents

Abstract

A. METAL HALF-MOLD FOR SHELL MOLDING. B. THIS HALF-MOLD 1 INCLUDES A FRONT WALL 2 INCLUDING A SHELL-MOLDED ZONE OF THE SIDE WALLS 3 EXTENDING TO THE REAR OF THE FRONT WALL 2 AND A SUPPORT ELEMENT 4 FORMING THE BASE OF THE SIDE WALLS 3 AND FIXED AT THE BOTTOM OF THESE, THE FRONT WALL 2, THE SIDE WALLS 3 AND THE SUPPORT ELEMENT 4 FORMING A HIGH PRESSURE THERMAL EXCHANGE CAVITY 7, VALVES 8, 9 ARE PROVIDED TO INTRODUCE FLUID UNDER PRESSURE THEREIN AND EVACUATE GAS UNDER PRESSURE. C. THE INVENTION APPLIES TO MOLDINGS.

Description

The invention relates to the "molded metal half-mold"

  molds for shell casts using two mold halves comprising

  each a heat exchange cavity at high pressure.

  Half-molds for shell molding according to the invention

  There is a thin wall between the shell mold area of the mold half and the high pressure heat exchange cavity. This thin wall between the shell molding zone and the heat exchange cavity at

  high pressure covers substantially the entire surface

  taken between the shell molding area and the cavity

  heat exchange at high pressure.

  A high-pressure heat exchange cavity

  sion allows the heat exchange agent contained in this high pressure heat exchange cavity to be maintained in the form of a high temperature liquid with respect to the temperature at which the metal to be molded is introduced. in the mold. A half shell mold having a thin wall of large area between the shell molding area of the half mold and

  the high-pressure heat exchange cavity has been used

  to take advantage of the difference in temperature

  weaker between the metal to be molded and the heat exchange agent in order to evacuate the heat obtained by using a heat exchange agent at temperature

relatively high.

  Molds for molding in a shell

  in use use water at atmospheric pressure.

  as a heat exchange agent to evacuate heat from the shell cavity. Heat exchange is achieved by drilling a series of ducts into the shell block to allow water to flow into this shell block and thereby cool the cavity of the shell.

  shell. When the systems for exchanging

  shell cavity are not under pressure, sufficient cold water must be circulated through the shell block to sufficiently cool the cavity of the shell.

  shell so that the casting metal can be

  jected into the shell cavity, cooled, solidified and extracted. The temperature of the hot metal introduced into the shell cavity varies from one metal to another. Zinc is usually introduced into the molds at about 430 ° C, while aluminum is introduced into the molds at about 650 ° C, the temperature of the circulating water

  normally between 20 C and 95 C. The difference between

  resulting temperature difference between the most

  hot and cold parts of a conventional mold

  that when zinc and aluminum are molded,

approximately 315 ° C. and 540 ° C.

  The heat exchange conduits of the conventional molds are normally spaced at least several centimeters from the mold cavity of the shell and at least several centrimeters from each other, so that the steel between the air ducts Heat exchange and the shell cavity distribute the cooling effect of heat exchange, before the cooling effect reaches the shell cavity. The greater the thickness of the steel between the shell mold cavity and the heat exchange conduits of the conventional molds, the more even the temperature profile in the shell molding cavity is. On the other hand, the greater the thickness of steel between the heat exchange ducts and the shell cavity, the greater the

  the exchange of heat takes place slowly.

  If conventional mold heat transfer ducts are placed near the shell cavity, the risk of thermal fatigue is increased.

  the mold because of the important temperature difference

  aunt occurring on a low thickness. Another

  convenient to place the heat transfer ducts

  in the immediate vicinity of the shell cavity.

  the, is the formation of provocative temperature distortions

  the large differences in temperature between the areas of the shell cavity closest to the ducts

  of heat transfer and the areas of the shell cavity

  the farthest from the shell molding.

  With a mold for shell molding used

  With a heat exchange cavity under pressure, it is possible to raise the temperature of the heat exchange medium to any desired temperature up to 230 ° C. The temperature difference between the shell cavity and the high pressure heat exchange cavity, in the shell molding area of the

  front wall, is significantly smaller than the one

  against with molds cooled by water circulation in conduits of these molds. This lower temperature difference made it possible to manufacture a mold whose mold shell wall does not exceed 0, 85 mm in thickness,

  according to the size of the molding and the heat to be evacuated.

  The shell molding area generally includes all parts of the front wall that receive the material

hot molding.

  The lower temperature difference between the shell cavity and the high-pressure heat exchange cavity also increased the surface area

  of the high-pressure heat exchange cavity is

  contacting the mold shell area of the front wall. The surface area of the thin wall is the mold shell area of the front wall receiving the hot liquid. Due to the surface increase of the high pressure heat exchange cavity coming into contact with the mold mold shell area, it is possible

  to obtain both a larger heat exchange area

  and a better temperature profile in the

molding shell of the mold.

  Parts that are molded into shell molds have an infinite variety of shapes and thicknesses. The amount of hot metal to be cooled increases with the thickness of the parts to be molded, decreases with the thinness of the part to be molded and depends

  directly from the surface of the molding. By using

  With a high pressure heat exchange cavity and a high temperature heat exchange agent, it is possible to adapt the configuration of the main heat exchange wall in the high pressure heat exchange cavity to produce on the shell mold part of the mold a temperature profile substantially conforming to the heat to be evacuated from different

  parts of the part being molded.

  It is necessary to evacuate a greater amount of heat from the thicker parts of the room in progress

  of molding while a quantity of

  their weakest of the thinnest parts of the piece being molded. By exactly inverse profiling the thickness of the inside of the main heat exchange part of the wall of the cavity

  heat exchange at high pressure, so as to adapt to

  As a result of the heat dissipation from different parts of the shell molding area, a cooling profile can be obtained to remove more heat from the molding parts requiring greater heat loss during solidification, and less heat

  parts of the molding requiring less loss of heat.

  their for solidification. Another difficulty related to the ducts of

  elongated tubular heat transfer of the conventional molds

  However, the continuous passage of water in these ducts causes the formation of sludge or scale on the side walls of the ducts. This problem may be partly

  resolved by conditioning or treating the cooling water

  before using it. Tartar or sludge reduces

  the normal heat transfer between water and

  mold and thus cause irreversible heat distribution

  regular in the mold. This must be treated permanently to remove scale or sludge

  to maintain a satisfactory heat transfer.

  With a heat exchange agent under pres-

  such as for example water, it suffices to add

  in the heat exchange cavity a sufficient quantity of water

  It is used to replace the heat exchange vapor produced by each injection of metal into the shell cavity. As a result, sludge or scale deposits do not occur and the above problem does not arise in the heat exchange cavity under pressure.

  The object of the invention is to solve the problems

  above-mentioned problems and concerns, for this purpose, a half-

  metal mold for shell molding, half mold

  characterized in that it comprises a front wall, comprising

  both a shell molding area, side walls extending rearward of the front wall, a support member closing the base of the side walls, means for securing the support member to the bottom of the walls

  lateral walls, the front wall, the side walls and the

  support forming a heat exchange cavity at high pressure a valve for introducing fluid under

  pressure in the heat exchange cavity at high pressure

  and a valve for discharging pressurized gas from the high pressure heat exchange cavity.

  The invention will be described in detail in

  FIG. 1 is a sectional view of the fixed mold, and FIG. 2 is a sectional view of the stationary mold comprising means for maintaining aligned the

two halves of the mold.

  Referring to Figure 1, this represents

  a half-mold 1 comprising a front wall 2, side walls 3 and a support element 4. The support element 4 is attached to the bottom of the side walls 3 by bolts 5. A thin high-pressure seal 6 capable of withstanding high temperatures and pressures, is mounted between the bottom of the side walls 3 and the Savant support member that the bolts 5 are securely fixed. A high pressure heat exchange cavity 7 is formed between the front wall 2, the walls

  3 and the support element 4. A

  8 is provided in the side wall 3 to add fluid into the high pressure heat exchange cavity 7 when necessary. An outlet valve 9 is provided in the side wall 3 for evacuating gas from the high pressure heat exchange cavity 7 after each

molding operation.

  The front wall 2 has a shell molding area 10 for receiving the hot molding liquid. The central portion of the shell molding area is part of the shell cavity in which the object to be mold is formed. The shape of the front wall 2 and the shape of the shell molding zone 10 may vary from one mold to another depending on the shape of the object to be molded. The thin wall 11 between the shell molding zone 10 and the high-pressure heat exchange cavity 7 may have a thickness down to 7.6 mm depending on the size and configuration of the molding part and, by following, according to the amount of heat to be discharged from the different parts of the shell molding zone 10. In the half-mold 1 shown in FIG. 1, a column 12 is formed in the high-pressure heat exchange cavity 7 for provide additional support for the front wall 2. A rod

  ejection 13 passes through the column 12.

  FIG. 2 shows two mold halves 14 and 15 in the closed position, so as to form a shell cavity 16. The half of the mold 14 is fixed to a block 17 itself attached to one of the plates 18 of the shell molding machine that drives half of

  mold 14 to the mold half 15 in the closed position

  ture. or away from it in the open position. In the same way, the mold half 15 is attached to the block 19 itself attached to the other plate 20 of the shell molding machine, which entralates the mold half 15 to the mold half 14 in the closed position , or away from it in the open position. The mold half 14 comprises a front wall 21, side walls 22

  and a support member 23. A heat exchange cavity

  that at high pressure 24 is formed between the front wall

  21, the side walls 22 and the support member 23.

  The mold half 15 comprises two or more rods of

  25 and 26 retained respectively in cushions

  27 and 28 to hold the mold halves 14 and 15

  aligned. When the mold halves 14 and 15 are closed,

  As shown in FIG. 2, the shell cavity 16 is formed between the shell cavity areas 29 and

  Respective mold halves 14 and 15.

  When the mold halves 14 and 15 are in the closed position, the hot molding metal is introduced through the orifice 31 and the air is discharged through the vent 32 until the shell cavity 16 and the excess -plein 33 are filled with hot molding fluid. The hot molding metal is introduced at a pressure of up to kg / cm 2 and at a temperature of about 4300 ° C. in the case of zinc and under a pressure of up to 350 kg / cm 2

  and at a temperature of 650 C in the case of aluminum.

  When the molding is carried out with zinc, the high pressure heat exchange cavity 24 contains a heat exchange fluid 34 under pressure at a temperature up to 2300C. It's the same for half of

mold 14.

  With a temperature difference of approximately 205 ° C., when zinc is molded in the shell cavity 16 and the heat exchange fluid 34 is in the high-pressure heat exchange cavity 24, the heat passes through. by the shell cavity area 29 to reach the heat exchange fluid 34 thereby causing the vaporization of a small portion of this heat exchange fluid. Steam escapes into the atmosphere through a pressure control valve, as indicated

in Figure 1.

  When the molding is solidified, the mold halves 14 and 15 are spaced from each other by the plates 18 and 20, and then the molding is ejected from the shell mold cavity by ejection rods such as the rods 13, 36 and other similar rods not shown

on the drawing.

  An additional advantage of the high pressure heat exchange cavity 24 is that before the start of the molding operation, the exchange fluid

  of heat 34 may be heated under pressure and the temperature

  The clearance of each of the half-molds can be raised to 230 ° C or any other desired temperature before starting the molding. The temperature of the mold can be controlled by a combination of pressure controls of the inlet valve 8 and the outlet valve 9 of the

  high-pressure heat exchange cavity 7, in association with

  with an immersion heater placed in

  the high pressure heat exchange cavity 7.

  Although the invention has been shown and described in a particular embodiment, it is obvious to those skilled in the art that precise construction details may vary from object to object.

  to another intended to be molded.

Claims (17)

R E V E N D I C A T I 0 N S CLAIMS   1) Metal mold half-mold for co-molding   keel, half-mold characterized in that it comprises a   front king (2) having a shell molding area, side walls (3) extending rearwardly from the front wall, a support member closing the base of the side walls, means for securing the support element (4)   bottom of the side walls, the front wall, the side walls,   and the support member forming a high pressure heat exchange cavity, a valve (8) for introducing pressurized fluid into the high pressure heat exchange cavity and a valve (9) for discharging the gas under pressure.   pressure of the heat exchange cavity at high pressure.   2) A half-mold according to claim 1, characterized in that the front wall of the shell molding area is thin and the bottom of the shell molding area of the front wall forms the top of the cavity   heat exchange at high pressure.   3) Half-mold according to claim 1, characterized in that the thickness of the front wall of the shell molding zone is inversely proportional to the amount of heat to be removed from the shell portion to mold.   4) Half-mold according to one or the other   Claims 1 and 2, characterized in that the thickness   of the front wall of the shell molding area is as thin as possible given the pressure of the   metal and the shape of the part to be molded.    ) Half-mold according to one or the other   Claims 1 and 2, characterized in that the thickness   of the front wall of the shell molding area is between 8.4 and 12.7 mm.   ) Half-mold according to one or the other   claims 2 and 3, characterized in that the surface of   the thin wall is essentially the same in the two shell molding areas of the front wall and the   heat exchange cavity at high pressure.   ) Half-mold according to one or the other   Claims 1 and 2, characterized in that it comprises   a heat exchange agent in which the pressure in the high-pressure heat-exchange cavity is maintained at a level such that the boiling point of the heat-exchange medium corresponds to the temperature   to which the mold must be maintained.   8) Half-mold according to one or the other   Claims 1 and 2, characterized in that it comprises a   heat exchange agent in which the pressure of the high pressure heat exchange cavity is maintained at a level such that the boiling point of the agent   heat exchange is between 130 and 260 C.   9) Half-mold according to any one of   Claims 1 to 3, characterized in that the element of   support is firmly attached to the side walls by a series of bolts with interposition of a seal.    ) Half-mold according to claim 2, characterized in that one or more hollow columns   containing ejector pins, are mounted in the cavity   heat exchanger tee at high pressure.   11) Half-mold according to claim 10, characterized in that the hollow columns are part integral of the front wall.   ) Half-mold according to claim 10, characterized in that one or more columns through the pressure chamber to reach the front wall of way to support it.   13) Half-mold according to claim 12, characterized in that the columns form an integral part from the front wall.   140) Half-mold according to claim 1,   characterized in that it comprises a front wall comprising   as a shell molding zone, side walls secured to the front wall and running towards the rear thereof, the front wall and the side walls integral therewith being formed of a same metal block, a ele-   support for closing the base of the side walls.   means for securely attaching the support member to the bottom of the side walls, the front wall, the side walls and the support member forming a high pressure heat exchange cavity, an inlet valve for introducing fluid under pressure at high temperature in the pressure vessel, and an outlet valve for   remove the pressurized gas from this pressure vessel.    A half mold according to claim 14, characterized in that the front wall of the shell molding area is thin, and the bottom of the shell molding area of the front wall forms the top of the cavity   heat exchange at high pressure.   - 16) Half-mold according to one or the other   Claims 14 and 15, characterized in that the thickness   of the front wall in the shell molding area is inversely proportional to the heat to be evacuated from the part of shell to be molded.   17) Half-mold according to one or the other   Claims 14 and 15, characterized in that the thickness   of the front wall of the shell molding area is as thin as possible given the pressure of the   metal and the shape of the part to be molded.   18) Half-mold according to one or the other   Claims 14 and 15, characterized in that the thickness   from the front wall, in the shell molding area, is between 8.4 and 12.7 mm.   19) Half-mold according to one or the other   Claims 14 and 15, characterized in that the surface   of the thin wall is essentially the same in the shell molding area of the front wall and in the cavity   high pressure heat exchange.    ) Half-mold according to one or the other   Claims 14 and 15, characterized in that it comprises   a heat exchange agent in which the pressure of   the high pressure heat exchange cavity is now   held to a level such that the boiling point of the agent   heat exchange rate corresponds to the temperature at which the the mold must be maintained.   21) Half-mold according to one or the other   Claims 14 and 15, characterized in that it comprises   a heat exchange agent in which the pressure of   the high pressure heat exchange cavity is now   naked at a level such that the boiling point of the agent   heat exchange is between 130 C and 260 C.   22) Half-mold according to one or other of the   claims 14 and 15, characterized in that the element   support is firmly attached to the side walls by a series of bolts with interposition of seal.   23) Half-mold according to one or the other   claims 14 and 15, characterized in that one or more   hollow columns containing ejector pins,   pass through the heat exchange cavity at high pressure.   24) Half-mold according to one or the other   claims 14 and 15, characterized in that the colonists   hollow are an integral part of the front wall.    ) Half-mold according to one or the other   claims 14 and 15, characterized in that one or more   several columns pass through the pressure chamber for   reach the front wall so as to support it.   26) Half-mold according to any one of   claims 14, 15 and 25, characterized in that the   columns are an integral part of the front wall.