DE102007023883A1 - Device and method for supplying a core sand magazine in the core shooting machine with moistened shot gas - Google Patents

Abstract

A shot gas supply device (10) for supplying a core sanding machine of a core shooter with a pressurized humidified gas has a pressurized gas reservoir (12) for the humidified gas, which has a gas outlet (18) for supplying the core sand hopper and a gas inlet (16) for filling the pressurized gas reservoir having. Further, the shot gas supply device (10) has a gas humidifier (14) disposed in a gas supply to the gas inlet (16) and which humidifies a gas to the predetermined humidity to form the humidified gas.

Description

The The present invention is concerned with a shot gas supply device and in particular with a shot gas supply device, the it allows a pressurized gas with predetermined, adjustable humidity for a core shooting facility provide.

In More recently, it became necessary to core sands, which used for producing metal casting cores, specifically and with precisely adjustable humidity to moisten the safe and reliable functioning of the whole Kernschießprozesses, so that process, with the a sand core is generated to ensure. This is touching therefore, that for environmental protection reasons currently a change of organic binder bound sand cores to sand cores bound with inorganic binders.

Independently The type of binder used is used in core manufacturing a molding material, a so-called "core sand" filled in a mold, which has a cavity which is the shape of the sand core to be produced has. To get a sufficient fast and even Filling this cavity, the core sand is usually over a plurality of distributed openings, so-called "shot openings", introduced into the mold. This is when filling in each of the shot openings a nozzle ("shot nozzle") introduced, over which the core sand into the cavity is introduced. This introduction is usually done supported by compressed air or compressed gas at high speed, so that one speaks also of injection of the core sand.

Of the Core sand itself is usually completed within a Volume on the side facing away from the mold of the shot nozzle stockpiled, the so-called "shot hood". For introducing the core sand the core sand volume becomes sudden and short Time (within about 500 ms to 800 ms) with one under pressure pressurized gas, which in turn in a compressed gas reservoir is stored. The overpressure becomes the core sand introduced into the mold, the core sand completely is penetrated by the gas, so that the bulk of the introduced Gas through the core sand and through the shot nozzles flows into the mold, from which the shot gas over Vents can escape.

at Process with organic binding materials usually becomes dry air used as shot gas, since these binders after the Introduction of the core sand in the mold by adding an activating gas to be cured.

The Use of this activating gas as well as the use of organic Binder, however, leads to a non-negligible Burden on the workplace or the environment, so that the development core sands with inorganic binders, such as water glass, were driven forward. The inorganic binders harden under the influence of supplied heat, so that waives an activating, polluting the environment gas can be.

For The curing is therefore filled with the core sand Heated mold, or the core sand is in an already preheated Mold introduced. Therefore, a heat must be applied on the core sand before the actual introduction into the molding be avoided to prevent premature curing of the core sand to prevent. Such premature curing, for example in the guns, inevitably leads to that the core shooter clogged and thus the core manufacturing process is interrupted.

This Problem is particularly noticeable in the shot nozzles, which are in the vicinity of the preheated molds of These are heated indirectly. However, the hardened Core sand with inorganic binder even at normal ambient temperature slow out, allowing a cure even within the was observed in the shot hood sand volume.

The Curing can be prevented by moistening the sand wherein the amount of moisture supplied are accurately metered need to allow the production of high quality sand cores. Is too little moisture per unit of time or per sand volume fed, it comes at the particularly temperature-exposed Make still the premature curing and thus clogging the apparatus. But too much moisture supplied, it can come to condensation of moisture, causing it to form drops of the supplied liquid comes, which introduced by the shot nozzles with in the mold and lead to cavities in the sand core. This inevitably has a deterioration in quality the sand cores and thus an increase in rejects in the foundry.

In order to ensure suitable humidification, attempts have been made inter alia to apply enough moisture to the core sand mixture even before it is introduced into the core shooter. In such a process, however, one is dependent on the fact that there are no pro production interruptions may occur because in these waiting times the core sand mixture on the transport route to the core shooting machine or in the silo could lose so much moisture that it can come back to the above-mentioned premature Sandaushärtungen in shot hoods and firing nozzles. In the waiting time occurring during such an interruption, the finished sand mixture from the core shooter and the transport lines to the core shooter would consequently have to be removed. Alternatively, it would have to be re-moistened exactly controlled, ie be humidified again depending on the respective, possibly even seasonally changing, environmental conditions, so that subsequently in the continuation of the core production reproducible high-quality sand cores can be produced. However, both approaches are not feasible with a reasonable cost / benefit ratio.

There in industrial production a completely trouble-free Operation also does not correspond to reality, is the Use of pre-moistened sand less promising, or inevitably leads to disruptions in the production process.

The German utility model 20 2006 010 504 U1 proposes, within a compressed air tank, in which the firing air of the core shooter is stored to perform a compressed air humidification characterized in that there is liquid water within the compressed air tank. The compressed air is introduced either above the water level in the compressed air tank or below the water level, so that the newly introduced compressed air is first passed through the water to be moistened during the introduction. In both cases, the moisture absorbed by the compressed air or the water taken up during the firing process should be returned to the core sand mixture (sand, binder and optionally also activators or promoters).

Both Alternatives of humidification have disadvantages. Will the compressed air only passed over the water reservoir leads this leads to an uncontrolled and insufficient water absorption of the gas or air, since the time between two firing operations in industrial core production is not sufficient for the setting a thermal equilibrium between the water and the gas to allow for a reproducible amount of liquid Water could enter the gaseous phase to moisten the shot air. A resulting insufficient Humidification then leads in particular to the core production of core binders bound with inorganic binders, as before described that the core sand at exposed sites in the Core shooter (especially within the firing hood and the shot nozzles) as a result of the curing process of the sand in the tool required heat input into the Tool or the molded part and the resulting heat radiation in the firing hood / shot nozzles hardens too quickly. The means it evaporates from the existing sand moisture too fast too much and the sand hardens too fast out. This has the input described consequences of production disruption or production interruption.

Becomes the compressed air passed through the water reservoir, also turns no thermal equilibrium between gas and liquid one. Rather, it can lead to the uncontrolled entrainment of come a lot of water. This leads to subregions in the shot hood, the shot nozzles and also in the mold be washed out when the moisture from a supersaturated Compressed air condenses. The result is the mis-production of sand cores.

The Entrainment of water is also favored, among other things, when trying to air in the highly dynamic range of System to moisten. As already mentioned, it takes a shot, within which the core sand transports into the mold is only between 500 ms to 800 ms. In this short period of time will be So the compressed air tank partially emptied and its Content is about the shot nozzles in the molding transported. As a result, high gas velocities occur as well within the evacuated pressure vessel, the cause significantly more water from the compressed air can be transported than at a dew point adjusting Thermodynamic equilibrium would be the case as the water be carried along by the fast flowing gas downright can.

Becomes the liquid inside the compressed air tank heated to increase the evaporation rate, results the problem that is inside the compressed air tank forming a temperature gradient, i. H. at the bottom of the compressed air tank with the liquid is at a higher temperature as at the other end of the compressed air tank. this leads to Make sure that parts of the warm area of the compressed air tank evaporating liquid at the other end of the container condense again, leaving itself inside the container no uniform humidity setting. This allows the moisture supplied to the core sand, d. H. the amount of moisture per air volume, can not be controlled precisely. As synonymous with use The heater is trying to keep the air in the highly dynamic area of the air Systems to moisten, it comes in addition to the continue problems described above.

The present invention has the object to provide a shot gas supply device which makes it possible to provide shot gas with a predetermined humidity to use it within a core shooter.

These The object is achieved by a device according to of claims 1 or 7 and by a method solved according to claim 9.

some Embodiments of the invention is the knowledge basis that a core sand magazine with a humidified gas predetermined Moisture can be supplied when a shot gas supply device is used, which is a compressed gas reservoir and a Gasbefeuchtungs device having. The compressed gas reservoir has a gas outlet for supplying the core sand magazine and a gas inlet for filling of the compressed gas reservoir. The humidifier for humidification of the gas is in a gas supply to the gas inlet of the Compressed gas reservoir arranged. That means the gas will moistened before it is stored in the compressed gas reservoir.

The Humidification therefore takes place at one point in the gas duct instead, in which no discontinuous states prevail. The place of humidification is therefore not in the high dynamic range of the system, there are no abrupt changes in the system Flow rate of gas or gas pressure instead of.

This allows the gas with high accuracy and completely reproducibly applied with an adjustable amount of moisture.

at an embodiment of the invention is to the gas completely saturated with moisture, d. h., the gas is moistened until at the temperature of the gas the thermodynamic equilibrium between the liquid and the gaseous phase of the liquid, the is used for humidification sets.

at Some embodiments of the invention will be an already pressurized gas humidifies. That is, an under A gas above a pressure above the ambient pressure is moistened.

at a further embodiment of the present invention, Therefore, a gas humidification device has a temperature control device for varying the temperature of the gas to the dew point and thus the amount of moisture that is absorbed and transported by the gas can adjust exactly according to the laws of thermodynamics.

In front the discussion of further embodiments of the invention, It should be noted that in the context of this application and the Description of the invention as gas to understand any gas mixture which is used to supply core shooting machines can. It does not have to be a monoatomic gas Rather, any gas mixtures, such as air, in question and should be understood by the term gas. On similar The term moisture is understood to mean not limited to water to be understood. Rather, it is meant by the term moisture gaseous phase of any liquid be understood, which lends itself to mixed core sands to become. This can be, for example, water or an activator / moderator, the core sands can be mixed to, depending from its concentration, the hardening of the core sand to accelerate or possibly prevent.

Essential is that in some embodiments of the invention possible, humidified gas of a predetermined humidity, which can be adjusted and reproduced exactly to produce in order to supply a shotgun device.

at a further embodiment of the invention has the temperature control device of the gas humidifier Heating element in the form of a microwave radiator. This has the big one Advantage that by means of microwaves the entire volume within the gas humidifier evenly heated can be, so that ensures that no temperature gradients can occur within the gas humidifier. This allows a uniform humidification of the Gases are ensured.

at a further embodiment of the present invention Both the temperature of the compressed gas reservoir and the temperature the gas supply between the gas humidifier and the compressed gas reservoir at a temperature regulated or on heated a temperature which is above that temperature, which is set within the gas humidifier (dew point temperature). Thus it can be prevented that the exact humidification of the gas or the exact amount of moisture transported by the gas it is reduced that parts of the liquid condense again, before the humidified gas is fed to the core sand hopper becomes.

preferred Embodiments of the present invention will be below, explained with reference to the accompanying figures. Show it:

1 a schematic representation of a shot gas supply device;

2 a schematic representation of a core shooting machine;

3 a further schematic representation of a core shooting machine; and

4 a schematic representation of a method for supplying a core sand magazine with humidified gas.

1 schematically shows a shot gas supply device 10 for supplying a core sanding magazine of a core shooter with a pressurized humidified gas of predetermined humidity. The shot gas supply device 10 includes a compressed gas reservoir 12 for the humidified gas and a gas humidifying device 14 that in a gas duct to a gas inlet 16 the compressed gas reservoir 12 is arranged. The compressed gas reservoir 12 has a gas outlet fernern 18 for supplying the core sand magazine.

According to some embodiments of the invention, the humidification of the gas prior to storing the humidified gas in the compressed gas reservoir 12 performed to allow the humidification, ie the amount of liquid transported by the gas set exactly.

1 Thus, the concept of the arrangement of apparatus and method for controlled humidification and tempering (heating and / or cooling, depending on the requirements of the respective environmental conditions) of the compressed air or a gas or gas mixture required for the subsequent core manufacturing process.

The compressed air or gas humidification system is installed in the supply line to the compressed gas tank (or compressed air reservoir, boiler, buffer, reservoir) required for the core production process. The compressed air, respectively the gas or gas mixture, is in the supply line to the compressed air tank 12 controlled and tempered (ie, heated or cooled) by means of suitable equipment and with a liquid such as softened / demineralized / deionized water so moistened that the air or the gas is always saturated. Humidification of the gas in the gas humidifier 14 is thus carried out in some embodiments, that the volume of the gas humidifier 14 and that the gas within that volume is at a temperature corresponding to the desired humidification of the gas when it is laden with moisture until its (temperature dependent) saturation.

As high gas temperatures mean that more moisture can be transported, for example, a heater within the gas humidifier 14 be attached to increase the amount of water absorbed respectively the absorbed liquid. If required by the process, cooling may alternatively be provided to transport a lower amount of moisture than would be the case due to the ambient temperatures or the temperature of the delivered gas without cooling. Thus, via a simple temperature control, the moisture transported by the gas can be set exactly, without the amount of moisture transported through the inside of the compressed gas reservoir 12 to distort existing high-dynamic processes.

To prevent some of the moisture of the gas in the gas supply to the compressed gas reservoir 12 or on the walls of the compressed gas reservoir 12 condenses itself again and thus distorts the desired amount of moisture transport, the gas supply to the gas inlet 16 and the compressed gas reservoir 12 optionally with a temperature control device 20 be coupled to the temperature of the gas supply and the compressed gas reservoir 12 above the dew point temperature of the humidified gas.

At largely constant ambient conditions can be dispensed with such a trace heating, as long as the process result is not compromised. This is especially not the case when the ambient temperature is reliably higher than that in the gas humidifier 14 set dew point or the temperature set there.

Of the The purpose of such a trace heating is in other words, the respective required saturation temperature of the compressed air / the Gas / the gas mixture and thus the moisture content of the compressed air / the Keep gas / gas mixture largely constant and to a To prevent condensation of humidity.

2 shows an embodiment of a core shooter that a Schussgasversorgungsvorrichtung 10 as they are in 1 is shown. The core shooter further includes a core sand hopper 24 inside which the core sand is located and that with the gas outlet 18 the compressed gas reservoir 12 connected is. The core sand magazine 24 includes the core sand, which over the at the bottom of the core sand magazine 24 located firing nozzles 26a to 26c can be introduced into a mold, not shown. If the ambient conditions make it necessary to provide additional heat tracing and thermal insulation that supports the desired process result, then a gas connection may also be required 28 between the compressed gas reservoir 12 and the core sand magazine 24 be connected to a temperature control to the temperature of the gas connection 28 to keep above the dew point temperature.

In the in 2 schematically shown core shooting machine so the pipes between humidifying and compressed air tank and between compressed air tank and shooting device and the compressed air tank itself are insulated and provided with a heater to ensure that the moisture content of the gas, which in the gas humidifier 14 is set exactly, not by condensation of moisture on the way to the core sand magazine 24 is falsified.

3 showed a detailed view of a core shooting machine based on the schematic representation of 2 , Therefore, functionally identical elements are provided with the same reference numerals, so that the descriptions of similar or functionally identical elements can be mutually applied to each other. Incidentally, this applies to all functionally similar or identical components in different figures.

In 3 For example, a core shooter is shown which uses air as a shot gas and demineralized water as a humidifying liquid.

At the in 3 The embodiment shown, the gas humidifying device 14 a water softening system 40 to locally produce the demineralised water used for humidification.

The wetting air to be moistened becomes the gas moistening device 14 via a valve 42 supplied from an external compressed air supply. The moistened shot air is via a gas supply 44 to the gas inlet 16 the compressed gas reservoir 12 directed. This in 3 shown sand magazine 24 has two separately controllable partial magazines, so that by means of the sand magazine 24 at the same time two different molds can be filled with molding sand. In order to exploit the possibility of separate control, are in 3 two gas supply lines 46a and 46b between the compressed gas reservoir 12 and the sand magazine 24 provided, these on the gas connections associated firing valves 48a and 48b each with a chamber of sand magazine 24 are connected. gas supply 44 and the gas connections 46a and 46b and the compressed gas reservoir 12 are in the 3 shown embodiment with a temperature control device shown schematically 20 connected to keep the temperature of these components at a temperature above the dew point of the humidified gas.

To vent the sandpit 24 or the separate chambers of the sandpit 24 to allow, are also two vent valves 50a and 50b provided with their respective assigned chambers of the sandpit 24 are connected.

Further, a shot vent cleaning valve 52 with the sand magazine 24 and an external compressed gas source connected. Over the line between the shot ventilation cleaning valve 52 and the sand magazine 24 is also a pressure switch 54 connected to the sand magazine, the pressure in the sand magazine 24 monitored during the vent after the shot. By means of the pressure switch 54 So the venting process is monitored so that, for example, from a pressure level in the sand magazine 24 From about 0.1 bar overpressure the vent can be considered complete, whereupon then the sand magazine 24 with firing hood up and is driven to the side. At the same time a possible gassing device can be moved over the tool to be clamped with this and z. B. Hot air to harden the cores in the tool to lead (possibly also in addition to the tool heating).

The shot ventilation cleaning valve 52 is triggered synchronously with the shot, ie via a port L1 is during the shooting process and by time delay also something in the venting time into additional compressed air in the sand magazine 24 blown. This leaves the lines and the pressure switch 54 Sand magazine free of dirt.

Further shows 3 in dashed line pneumatic control lines 56 , which serve to control the individual valves or to provide an operating pressure required for their operation. The operating pressure is by means of a pressure regulator 58 set. The control may be purely pneumatic, but other control mechanisms may be used, such as electrical signals or messages transmitted on a data bus.

In the in 3 embodiment shown, the gas humidifying device 14 a closed volume 60 on, through which the gas to be humidified or the air to be humidified is passed. Within this volume 60 is an evaporative body 62 Arranged with the water of the water softening system 40 is wetted and preferably has a large surface, so that the evaporation of the water is promoted. Furthermore, the gas humidifying device 14 a schematically illustrated temperature control device 64 for varying the temperature of the air or the humidified air. The Temperaturre geleinrichtung 64 can be implemented in a variety of ways, such as by a resistance wire heater or a microwave.

In the in 3 shown case, the supply of softened water is regulated by the volume 60 Contains a sensor that points to the liquid that attaches to a bottom of the volume 60 collects, is sensitive. If no liquid is detected, additional water is added. This has the further advantage that the presence of a liquid phase is also an indication that the volume 60 At the set temperature, the gas is saturated with moisture. The presence of the fluid or fluid level within the volume 60 can thus be used in a further embodiment to regulate the flow rate of the gas to ensure that the gas within the residence time in the volume 60 is saturated.

The whole in 3 shown system, which is connected to the gas humidifier 14 connects, ie the gas supply 44 , the compressed gas reservoir 12 and the gas connections 46a and 46b are provided with a heater which is connected to a temperature control to prevent condensation of liquid from the gas. Both the heating and the temperature control are in 3 only shown schematically.

The humidified air is supplied via the gas supply 44 in the compressed gas reservoir 12 transported, the pressure in the gas supply 44 from a pressure regulator 66 controlled and kept constant.

Another pressure regulator 68 controls the pressure of the gas within the compressed gas reservoir 12 , This allows the pressure to the required conditions, such as the used core sand or the desired speed of filling the molds einzustel len. In addition, by means of the pressure regulator, for example, an excessively high pressure can be prevented by opening a venting valve when a permissible maximum pressure is exceeded. Pressures in which a transfer of the sand reliably succeeds, for example, between 3 bar and 8 bar.

For the filling or shooting of the core sand, the shot valves 48a and 48b open, leaving the humidified gas from the compressed gas reservoir 12 in the sand magazine 24 flows and shoots the core sand into the molds by the sudden overpressure.

By the basis of the 1 to 3 described embodiments and the process and apparatus arrangements shown therein is thus always exactly at the right time (ie, exactly at the time of shooting the sand) enough or exactly the required amount of moisture in the core sand binder mixture (possibly also additional promoters or may contain activators) introduced. As a result, both washing out and premature curing of the core sand can be reliably avoided in order to obtain sand cores of the desired reproducible quality.

4 shows a schematic representation of an example of a method for supplying a Kernsandmagazin a Kernschießmaschine with a humidified gas of predetermined humidity.

It is first in a humidification step 70 humidify the gas to the predetermined humidity to form humidified gas. The humidified gas is stored in a storage step to make it available to a core sand hopper. The fact that the gas is first moistened before it is stored with precisely set humidity in a reservoir in which strongly dynamic conditions prevail makes it possible to adjust reproducibly and precisely metered the amount of moisture that the subsequent process requires or prevent premature curing of a core sand mixture charged with the humidified gas.

Even though in the previous embodiments, the humidification gas mainly using an evaporative body is the use of an evaporation body not necessarily required in the context of the invention. Rather, it can the gas be humidified in any other way that is reproducible Humidification or saturation of the gas used allows. It is conceivable, for example, fine mist for moistening liquid to be used, through which the gas passes can be. Furthermore, the gas can, for example via a Liquid levels are passed, if sufficient Time is available, that is above the surface the liquid level the thermodynamic equilibrium can form, so that the gas at a set temperature is saturated.

As already mentioned, to adjust the dew point or the setting of the temperature of the gas to be humidified within the gas humidifying any heating or Kälteein Direction can be used, which allows to heat or cool the gas to an adjustable temperature to determine the recorded moisture content over the temperature. In particular, both cooling and heating may be provided within the gas humidifier to provide a system that can flexibly respond to any possible environmental condition.

The geometric arrangement of the individual components in the 1 to 3 is shown, is only to be understood as an example. In particular, it is not necessary that the gas humidification device is arranged spatially separated from the compressed gas reservoir. Rather, it is also possible, for example, to carry out the gas moistening device as an integrated element of the compressed gas reservoir, as long as it is ensured that the moistening is not carried out in the dynamic range of the system in which pressure conditions or flow velocities change rapidly. This can be achieved for example by a valve between the gas humidifier and the compressed gas reservoir.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 202006010504 U1 [0012]

Claims (12)

Shot gas supply device ( 10 ) for supplying a core sand magazine ( 24 ) a core shooter with a humidified gas of predetermined humidity, comprising: a compressed gas reservoir ( 12 ) for the humidified gas, which has a gas outlet ( 18 ) for supplying the core sand magazine ( 24 ) and a gas inlet ( 16 ) for filling the compressed gas reservoir ( 12 ), and one in a gas feed to the gas inlet ( 16 ) arranged gas humidifying device ( 14 ) for moistening a gas to the predetermined humidity to form the humidified gas. Shot gas supply device ( 10 ) according to claim 1, wherein the gas humidifying device ( 14 ) is adapted to moisten the gas to a saturation moisture corresponding to the temperature of the gas. Shot gas supply device ( 10 ) according to one of claims 1 or 2, in which the gas humidifying device ( 14 ) a temperature control device ( 64 ) to change a temperature of the humidified gas. Shot gas supply device ( 10 ) according to claim 3, wherein the temperature control device ( 64 ) has a microwave radiator for heating the humidified gas. Shot gas supply device ( 10 ) according to one of the preceding claims, comprising a further temperature control device ( 20 ) to a temperature of the gas supply between the gas humidifying device ( 14 ) and the gas inlet ( 16 ) and / or a temperature of the compressed gas reservoir ( 12 ) so that it is above the dew point of the humidified gas. Shot gas supply device ( 10 ) according to one of the preceding claims, in which the gas humidifying device ( 14 ) an evaporator body impregnated with a liquid used for moistening ( 62 ), which in a gas-flow volume ( 60 ) of the gas humidifier ( 14 ) is arranged. Shot gas supply device ( 10 ) according to one of the preceding claims, wherein the gas humidifying device ( 14 ) is adapted to moisten a standing under a pressure above the ambient pressure gas. Shot gas supply device ( 10 ) according to claim 7, wherein the gas humidifying device ( 14 ) is designed to moisten a standing under a pressure between 3 bar and 8 bar gas. Shot gas supply device ( 10 ) according to one of the preceding claims, with the following additional feature: one with the compressed gas reservoir ( 12 ) connected to a predetermined pressure of the humidified gas in the compressed gas reservoir ( 12 ). Core shooter having the following features: a shot gas supply device ( 10 ) according to any one of claims 1 to 9; and one with the gas outlet ( 18 ) associated core sand magazine ( 24 ). Core shooter according to claim 10, wherein a gas connection ( 28 ) between the gas outlet ( 18 ) and the core sand magazine ( 24 ) with a temperature control device ( 20 ) is connected to the temperature of the gas connection ( 28 ) so that it is above the dew point of the humidified gas. Method for supplying a core sand magazine ( 24 ) of a core shooter ( 10 ) with a humidified gas of predetermined humidity, comprising the steps of: humidifying a gas to predetermined humidity to form the humidified gas; and storing the humidified gas to provide the humidified gas to supply the core sand hopper.