FR2503595A1 - METHOD AND APPARATUS FOR PRODUCING CORES - Google Patents

Abstract

THE INVENTION RELATES TO A PROCESS AND AN APPARATUS FOR MAKING CORES IN MOLDING SAND CONTAINING A WATER-SOLUBLE AGGLOMERANT. THE CORE BOX CONSISTS OF TWO SHAPES 11, 23 OF WHICH THE ONE THAT IS ABOVE IS REMOVED AFTER THE CORE SHAPING; THE ASSEMBLY IS THEN COVERED BY A COVER BOX 27 IN WHICH HOT COMPRESSED AIR IS INTRODUCED. THE LATTER PUT INTO THE UNCARDENED CORE AND DRY QUICKLY TO HARDEN IT.

Description

t

  METHOD AND APPARATUS FOR PRODUCING CORES

  The present invention relates to a process

  dice and to an apparatus for producing cores, in the-

  which an uncured core is made of soft sand

  lage containing a water-soluble binder, then is hardened quickly by drying. More particularly, the invention relates to a method and an apparatus

of cores.

  It is well known to make a sand core

  molding containing a water-soluble binder.

  In summary, this known method consists of loading a core box with molding sand containing water-soluble dextrin, then placing and heating the core box in an oven or the like to evaporate the water contained therein. molding sand,

  in order to dry and harden it. But this process con-

  naked using a water-soluble binder is not widely used due to the relatively short time

  long it takes for drying. But during the last

  n the last few years, the process of making cores used

  reading a water soluble binder has been reconsidered

  due to different poblems such as the elimination

  nation of molding sand, the increase in the price of conglomerates and the production of troublesome gases and dangerous gases in shell and core box molding operations, etc. Under these conditions, different studies have been

  made to improve the process of making our

  yals using water-soluble agglomerants.

  In particular, a study was made to improve

  improve the process for producing cores, by different

  his experiences, some of which are explained below

  after. According to one of the experimental methods, the molding sand containing a water-soluble binder

  (water-soluble dextrin or soluble organic resin

  ble in water) is previously heated to a temperature of 80 to 900C in a closed container and it

  is loaded into a core bodte by a hopper. In-

  subsequently, the pressure in the core box is reduced to evaporate the water contained in the molding sand,

  in order to dry and harden it. In this process ex-

  perimental, the hardening time of the core is relatively short but the molding sand which remains in

  the hopper may cool and dry, deteriorating

  thus its characteristics for blowing. According to this method, it is therefore necessary to charge and

  heat the molding sand at each mold operation

  lage to maintain the desired characteristics during blowing. This is very disadvantageous in terms of

work performance.

  In another experimental method, molding sand at normal temperature and containing a water-soluble dextrin is loaded into a core box, and heated compressed air is introduced into the core box to infiltrate through the molding sand in the box to evaporate the water

  and dry and harden the molding sand. But this pro-

  yielded is very long and laborious, especially when

  that the core to be produced is large or of complicated shape. In addition, it is difficult to do

  so that the hot compressed air infiltrates evenly

  lying in all of the mold sand in the

  core box, so it often turns out that some

some parts are not hardened.

  It appeared by various trial and error

  in the experiments explained above, a fact

  expected to know that the molding sand in the box

  with a core consisting of an upper half and a half

  lower part does not come out of shape due to the application of hot compressed air, even if the upper half of the core box is removed, thus exposing half of the uncured molding sand resting on the lower half . This fact is beyond imagination

  specialists in the field, enjoying the common sense

  mun because they would have thought that the molding sand not

  hardened, exposed to compressed air, would deform quickly-

is lying.

  The invention is therefore based on this observation

  tion. It is therefore an object of the invention to provide a method for producing cores using molding sand which contains a water-soluble binder, and consisting in forming an uncured core in molding sand containing the binder soluble in water. water, and

  to dry and harden the core in a short time.

  Another object of the invention is to provide an apparatus for producing cores arranged to form an uncured core using molding sand containing a water-soluble binder, and for

  dry and harden the core in a short time.

  Another object of the invention is to provide an apparatus for producing cores, using a core box consisting of an upper half and

  a lower half, the lower half being

  cé to be removed easily and quickly.

  Other features and advantages of the

  vention will appear during the description which goes

  follow from an exemplary embodiment and with reference to the accompanying drawings in which: Figure 1 is a front view and partly cut away of an embodiment of the invention, Figure 2 is a plan view of the apparatus of FIG. 1, Figure 3 is a side view of the apparatus of FIG. 1,

  Figure 4 illustrates an operation in a pro-

  ceded embodiment of the core according to the invention, in which a lower shape maintaining an uncured core is covered by a cover box and,

  Figures 5 and 6 illustrate the application process.

  cation of hot compressed air in re-

ference.

  The Figures show a column 1 whose ex-

  upper end comprises a head la with a front end portion projecting horizontally. A cylinder

4 2503595

  riser 2 is attached to a front and bottom side

  of column 1. The cylinder 2 has a rod of pis-

  ton 2a on the upper end of which is attached a lifting table 3. A blowing head 5 is suspended from the lower surface of the head

  above the lifting table 3. The blower head

  ge 5 has an internal bore which receives a

  split chon (not shown) with an angular interval

  the predetermined area formed between the inner peripheral surface of the bore and the outer periphery of the split sleeve. A blowing plate 4 is attached

  on the underside of the blowing head 5. The former

  upper end of the blowing head 5 crosses the head 1a and projects above, so as to communicate with a sand hopper 6. The sand hopper 6 is fixed on the upper surface of the head

  the by an elastic piece 7, so that the vibrations

  tions produced by a vibrator 8 are not trans-

  put in column 1. The numerical reference 9 de-

  signs a sliding door between the blowing head and the hopper 6. The sliding door 9 is coupled by its rear end with the piston rod 10a of a jack 10 which is fixed on the upper surface of the head 1a. The arrangement is such that the communication passage between the blowing head 5 and the hopper

  6 is open and closed when the door cylinder 10 operates

  tion. A top shape 11 of core, made of a

  heat-resistant resin, has on the underside

  a hollow part which communicates with the upper face of this upper shape 11 by blowing holes. The upper form 11 of the core is fixed to the lower face of the blowing head 5 by means of the blowing plate 4 so that the blowing holes of the upper form are aligned with the blowing holes formed in

  the plate 15. Two conveyor beams 13 which sup-

  each carry, so that they can rotate to flanged wheels 12 with a constant pitch, are arranged

  in an intermediate part of the blow molding machine

  setting produced in the manner described, crossing it horizontally. More particularly, the conveyor beams 13 are supported by feet 14 mounted

  vertically on a base, and they have ex-

  right hoppers seen in FIG. 1, extending outside a drying station to be mentioned

  thereafter. The conveyor beams 13 are es-

  facing each other in the perpendicular direction

  in the plane of FIG. 1 to allow the table to

vage 3 to pass between them.

  As shown in Figures 1, 3, a cha-

  riot 18 with molding plate is placed so that

  see move on the conveyor beams 13.

  The carriage 18 with mold plate has an interior chamber 15 which communicates with the upper face of this carriage 18 through a hole 16 and with the outside by

  a discharge hole 10 opening on one side of the cha-

  riot 18. A sealing part 20 provided with a communication hole 19 is glued to the upper surface

  of the mold plate carriage, the communication hole

  tion 19 being formed there in alignment with the hole 16

cited above.

  A lower core shape 23, made of a

  heat resistant resin has on its underside

  there is a housing 21 which communicates with the upper face

  shape 23 by evacuation holes 22 formed therein. The lower core shape 23 is placed on the upper surface of the part

  sealing 20 so that the housing 21 communicates

  than with hole 16 and communication hole 19.

  On one side of the blowing machine is

  arranged a drying station as follows:

  boasts. In other words, the drying station has a

  door-shaped frame 24 on the lower part of the

  which is fixed a jack 25 operating upwards.

  A lifting table 26 is coupled with the end

  upper tee of the piston rod 27a of the electric cylinder

  vateur 25. The lifting table 26 can move up and down in the interval between the two conveying beams 13. A cover box 27 has a lower opening which can surround

  the lower core shape 23. The cover box

  ture 27 is fixed to the door frame 24 by a part

  this support 28. The conveyor beams 13 are sup-

  carried by support legs 9 projecting from the frame

24 in the shape of a door.

  The reference numeral 30 designates a device

  heating element for heating compressed air

  up to a temperature between 60 and 2000C.

  The heating device 30 has on one of its

  sides a common compressed air intake port 31

  having a source of compressed air (not shown)

  mé and, on the other side, an outlet port 32 for

  heated compressed air. The outlet 32 is connected

  connected to an air inlet orifice 27a formed in the wall of the cover box 27 by a pipe and a shut-off valve which are not shown. So the

  heater 30 communicates with the space

  inside of the cover box 27. The nu-

  meric 33 designates a nucleus which remains in the form

lower 23.

  The apparatus produced in the manner described above

  above works as explained below.

  The lifting cylinder 2 lifts the lifting table 3 to lift the molding plate carriage positioned on this table 3 to bring the lower form 23

  of core on the carriage 18 in contact with the shape

  of the core 11, thereby forming a horizontally split core box. Next, the door cylinder 10 is actuated to open the sliding door 9 and load the molding sand containing a water-soluble binder from the hopper 6 into the split sleeve of the blowing head 5. Then, the cylinder door is reversed to close the sliding door 9,

  while compressed air is introduced into the -

  blowing head 5 for blowing the molding sand containing a water-soluble binder into the cavity of the core box comprising the upper form 11 and the lower form 23, by blowing holes (not shown) formed in the blowing plate 4 and in the upper form 11. In this regard, it should be noted that the molding sand can be loaded into the cavity in a very regular manner because the compressed air acts first in the space between the inner peripheral surface of the blowing head and the split sleeve. Then, the lifting cylinder 2 is inverted to lower the lifting table 33, thus removing the lower shape 23 from the core of the upper shape

  11. Then, after having left the carriage 18

  that molding mounted on the conveyor beams 13, the lifting table 13 is further lowered to the initial position shown in Figure 1. Then the lower shape 23 of the core is moved with the carriage 18 of molding plate along the conveyor beams 13 to the position of the drying station just above the table 26 and, at the same time, the lifting cylinder 25 is actuated to lift the table 26 and move the carriage 18 of the molding plate upwards until its upper surface is brought into contact with the lower end surface of the cover box 27, via the sealing piece 20, thus covering the lower form 23

  with the cover box 27 in a gas-tight manner.

  Then, the aforementioned shut-off valve (not shown) is opened to admit compressed compressed air into the cover box 27, from the heating device 30. Consequently, the water contained in the core 33 on the lower form 23 evaporates so

as the core 33 dries and hardens.

  Furthermore, hot compressed air infiltrates

  in the unhardened core 33 and it enters the cham-

  bre 15 through the evacuation holes 22, the housing 21, the communication hole 19 and the hole 16. The air is then evacuated outside through the evacuation hole 17. The uncured core 33 dries and hardens quickly because water evaporates in a short time due to direct contact with hot compressed air. After the core 33 has dried and hardened on the lower form 23, the lifting cylinder 25 is inverted to lower the table 26 and leave the plate carriage 18

  molding roll on the conveyor beams 13.

  so that the carriage 18 with the lower form 23 and the hardened core 33 are driven towards one side of the

  discharge station. Then after the removal of the no-

  yau 33 hardened of the lower form 23, the carriage. 18

  and the lower form 23 are moved to the posi-

  right, above the lifting table 3.

  Then the series of operations described above

is repeated.

  In the embodiment described, the movement

  ment of the carriage 18 of molding plate along the conveyor beams 13 is done by the manual force exerted by the operator. However, this is not limiting and the carriage 18 can be moved automatically to the

  by means of a suitable jack device. You must also

  Note that in the present embodiment, the carriage 18 of molding plate has the form of a box but that it is possible to arrange the lifting table 26 with a recessed upper surface while the carriage 18 of plate molding has a form of

flat table with hole 16.

  It is also possible to delete the cha-

  riot 18 of molding plate provided that the table

  vatrice 26 is equipped with an exhaust hole which allows air to escape to the outside through

  the upper surface of the lifting table 26.

  In the present embodiment, the shape

  upper 11 of core is fixed on the lower surface

  of the blowing head 5. This arrangement can be replaced by another, such as the. upper form 11 is located on the upper surface of the support part, so that it can go up and down, or the upper form 11 of the core can be raised and lowered by the lower form

  23 of core driven by means of a jack.

  Needless to say, it is possible to use a suitable metal as a material for the upper form 11 or the lower form 23 of core at

  instead of a heat resistant resin.

  In the embodiment described, the box

  core in which blowing and charging are done

  Molding sand is constituted as a horizontally split core box, comprising two shapes 11 and 23. But this is not limiting. For example, it is possible to assemble two Ilet 23 shapes to form a vertically split core box with blow holes in the vertical slot surfaces of the two shapes. After blowing and loading, the vertically split core box with the molding sand is turned sideways so that the shape

  upper 11 is above the lower shape 23.

  Then, the upper form 11 is removed.

  The core production process according to the invention

  tion, as illustrated in FIG. 5, has been set

  implemented experimentally. The details of this experience

  rience are indicated below, in comparison with the current process for producing cores illustrated by

Fig. 6.

  Mold sand containing two percent dextrin and two percent water was loaded into

  the cavity of a core box comprising a cy-

  the large diameter central indica as shown in Figure 5. Next, the top shape of the core was

25035 9 5

  removed so that the uncured core 33 was left on the lower bore 23 having several discharge holes 22. Next, compressed air at a pressure of 1.5 × 105 Pa, heated to 1200 C at t5 applied on the surface of the uncured core 33. Therefore, the core 33 was dried and hardened in a very short period, 35 seconds. On the contrary, when the production of the core was made according to the current method using the same molding sand and a core box of the split type as shown in FIG. 6, with the compressed air at the same pressure and at the same temperature applied by the upper end opening of the core box, the latter being left unopened, it was necessary

  seconds to dry and harden the core 33.

  This comparison shows that according to the invention it is possible to shorten the time necessary to dry and harden the uncured core to about a quarter (1/4) of the time required with the current process. This

  shorter time also allows a remarkable reduction

  consumption of hot compressed air.

he

Claims (5)

CLAIMS I - Process for producing cores, characterized in that it essentially consists of loading mold sand containing a water-soluble binder into the cavity of a core box constituted by first and second forms ( 23, 11) of which at least the first (23) comprises one or more discharge holes (22) establishing communication between the interior and exterior surfaces of said first form, in order to produce an uncured core, to be removed the second form (11) of said core box to leave said uncured core supported on said inner surface of said first form, to cover said uncured core on said inner surface with a cover box (27), introducing heated compressed air into said cover box so that said air infiltrates said unhardened core supported on said interior surface from the exposed surface of said unhardened core and escapes towards the outside said cover box by said one or more discharge holes, in order to harden said uncured core.   2 - Method according to claim 1, character-   laughed at in that it further consists in placing said   first form (23) supporting on its inner surface the   said uncured core, on the upper surface of a support plate (28) provided in its upper surface with a discharge hole opening into the atmosphere, to place said cover box (27) on said upper surface of said plate support so as to cover said unhardened core, and to cause said compressed and heated air introduced into said cover box to infiltrate said unhardened core   hardened from the exposed surface of this core and cir-   flows through said outlet hole (s) so as to escape towards the outside of the cover box through said outlet hole in said support plate   3 - Apparatus for making a core, character-   laughed at in that it includes a core box made up   by first and second forms (23, 11), the first of which   at least one (23) has one or more drainage holes (22) for establishing communication between the interior surface and the exterior surface of said first form, a blowing head (5) arranged to load said core box with molding sand containing a water-soluble binder, a lifting table (3) movable up and down by   relative to said blowing head and arranged for lowering   ser said first shape so that said uncured core is supported by said inner surface of said first shape, leaving the second shape (11) released from said core box-, a conveying device   (13) arranged to horizontally move said pre-   first form (23) mounted on said lifting table, a lifting table (26) movable upwards and towards the   bottom, while supporting said first shape (23) ame-   born on it by said conveying device, said   lifting table with drainage holes   clogging in the atmosphere, from its upper surface   upper, a cover box (27) open at its face   lower and disposed above said ele table   vation so as to be in contact with it when it moves upwards, thus covering said core   uncured supported on said inner surface of the   said first form (23) and a source (30) of compressed air   mé et chauffée arranged to deliver hot compressed air into said cover box so that this air infiltrates said uncured core from the exposed surface of this core and then circulates through said   or said discharge holes (22) so as to escape   finally perishes in the atmosphere through said evacuation holes   cuation in said elevation table.   4 - Apparatus for producing characteristic cores   sé in that it comprises a core box constituted by first and second forms (23, 11) of which at least   the first (23) has one or more drainage holes   tion (22) establishing communication between the inner surface and the outer surface of said first   form (23), a blowing head (5) arranged for charging   manage said core box with molded sand   holding a water-soluble binder, a lifting table (3) movable up and down relative   to said blowing head and arranged to lower the   said first form (23) so that said uncured core is supported by said inner surface of said first form leaving said second form (II) of said core box free, a mold plate (18) arranged to be mounted on said lifting table while supporting said first form, said plate   of molding being provided with drainage holes   plugging into the atmosphere from its upper surface   a conveyor device (13) arranged to   horizontally placing said molding plate from said lifting table, an elevation table (26) movable upwards and downwards while supporting said molding plate which is brought to it by said   conveyor device, said molding plate sup-   bearing in turn on its upper surface said pre-   form supporting the uncured core, a cover box (27) open at its underside and disposed above said lifting table so as to be engaged by said molding plate when the latter   is moved upward to cover said no-   uncured yau supported on said inner surface of said first form, and a source (30) of compressed and heated air arranged to deliver hot compressed air into said cover box, so that said air   infiltrates said uncured core from its over-   exposed side and then flows through said one or more   evacuation holes to finally escape into the atti-   mosphere through said drainage holes.   j5 5 - Apparatus according to claim 3 or 4, characterized in that said second form (11) has one or more blowing holes and is fixed to the   underside of said blowing head. i4   6 - Apparatus according to claim 4, charac-   characterized in that said mold plate (18) has an interior chamber, said discharge holes comprising a first hole leading from the top surface of said mold plate to said   inner chamber and a second hole leading from there   said interior chamber towards the atmosphere.   7 - Apparatus according to claim 4, character-   laughed at in that it further comprises a sealing part   tee (20) with a communication hole (19), said sealing piece being disposed on the upper surface   of said molding plate, with said commu-   information maintained so as to communicate with said   discharge hole in said molding plate.