CA2704506A1 - Crust breaker with reduced compressed air consumption - Google Patents
Crust breaker with reduced compressed air consumption Download PDFInfo
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- CA2704506A1 CA2704506A1 CA2704506A CA2704506A CA2704506A1 CA 2704506 A1 CA2704506 A1 CA 2704506A1 CA 2704506 A CA2704506 A CA 2704506A CA 2704506 A CA2704506 A CA 2704506A CA 2704506 A1 CA2704506 A1 CA 2704506A1
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- Prior art keywords
- piston rod
- crust
- pressure chamber
- pressure
- cylinder
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
- C25C3/06—Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
- C25C3/14—Devices for feeding or crust breaking
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25D—PERCUSSIVE TOOLS
- B25D9/00—Portable percussive tools with fluid-pressure drive, i.e. driven directly by fluids, e.g. having several percussive tool bits operated simultaneously
- B25D9/14—Control devices for the reciprocating piston
- B25D9/145—Control devices for the reciprocating piston for hydraulically actuated hammers having an accumulator
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25D—PERCUSSIVE TOOLS
- B25D2250/00—General details of portable percussive tools; Components used in portable percussive tools
- B25D2250/221—Sensors
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Mechanical Engineering (AREA)
- Fluid-Pressure Circuits (AREA)
- Percussive Tools And Related Accessories (AREA)
Abstract
A crust breaker for metal melts, has a fluid-actuated, double-acting crust breaking cylinder with a pressure chamber on the cap end, a pressure chamber on the bottom end, a piston, and a piston rod mounted on one side. The piston face on the end toward the piston rod has a lesser effective diameter than the opposed piston face. On the basis of a signal to a valve assembly associated with the crust breaking cylinder, an extension motion of the piston rod can be initiated with a positioning force. A determining mechanism for ascertaining that the metal melt has a crust is provided. On the specification of the determining mechanism, a further extension motion of the piston rod can be introduced with a breaking force that is greater than the positioning force. A sensor for detecting a fully extended state of the piston rod is provided. On the specification of the sensor, a retraction motion of the piston rod can be initiated. The sensor has at least one pneumatic multiposition valve.
Description
CRUST BREAKER WITH REDUCED COMPRESSED AIR CONSUMPTION
BACKGROUND OF THE INVENTION
Field of the Invention The invention relates to a crust breaker for metal melts and to an associated method.
Description of the Prior Art The field in which the present invention is used extends primarily to the technology of aluminum production. In the case of aluminum or related metals, the material is often in the molten, liquid state, which is known by the term melt. For production process reasons, raw materials or additives must be added to the melt from time to time; they are usually of powdered consistency. However, the delivery of these materials is hindered by the fact that a solidified solid layer called a crust forms on the surface and covers the liquid melt beneath it. In practice, so-called crust breakers are therefore employed, in order to break up the solid crust from time to time, so that by suitable delivery means, the aforementioned materials can be scattered into the now exposed liquid melt.
The melt must be broken open, so that the electrolytic production process can be kept going.
The crust breaking cylinder used in the context of the present invention is as a rule a pneumatic work cylinder actuated on both ends, which is installed in stationary fashion above the metal melt in such a way that its piston rod, connected to the piston located inside, protrudes downward and thus forms a push rod, which is provided on the distal end with a chisel for reinforcement. In the retracted basic position of the crust breaking cylinder, the chisel is at a considerable distance above the metal melt. For breaking up the crust, the work cylinder is subjected to compressed air, so that the piston rod moves outward into the breakup position; the chisel strikes the crust and finally breaks it up. Next, the piston rod is moved back into its retracted basic position.
From German Patent Disclosure DE 10 2004 033 964 B3, a device of this generic type for operating a crust breaker of this kind is known. In it, the crust breaking cylinder is moved between the retracted basic position and the extended breakup position on the specification of an electronic control unit, by means of suitable triggering of electropneumatic valves associated with the control unit. For initially extending the piston rod, a valve of the valve assembly is provided, which is located toward the cylinder bottom and which brings about a communication with a supply pressure source, while at the same time a valve, toward the cylinder cap, of the valve assembly also makes a communication with the supply pressure source. Since the difference in the effective diameter of the piston face on the piston rod end, compared to the piston face opposite it, brings about an extension motion of the piston rod at only slight force, it is possible by triggering both valves simultaneously to achieve a low- energy positioning mode of operation, which is employed for moving the piston rod from the retracted basic position until the chisel strikes the crust. Next, by sensor technology, the arrival of the chisel at the crust is ascertained. This is done here by monitoring the electrical potential between the grounded chisel and the existing voltage potential of the melt. To that end, an electric impedance measurement circuit or an electric voltage measurement circuit is integrated with the electronic control unit. If the arrival of the chisel at the crust is ascertained in this way, then the force acting on the crust is increased. This is done by disrupting the communication of the valve on the cylinder cap end with the supply pressure source, so that the contrary force for action toward the cylinder bottom of the crust breaking cylinder is omitted, and the crust breaking cylinder is shifted to the high-energy breaking mode of operation. Once the crust has been broken through, the piston rod returns to its retracted basic position.
Although this special triggering of the crust breaking cylinder by valve technology makes operation of the crust breaker possible in a way that is economical in terms of compressed air, nevertheless the electrical potential inquiry for detecting the crust has only relatively low operating safety for the switchover to the breaking mode of operation. This can be ascribed to the fact that the oxide crust of varying thickness leads to measurement results that are not unambiguous. Moreover, because of the use of electronic components for the potential inquiry, there is an increased vulnerability to error in the field of use in question, because of the great heat and the risk of soiling.
It is therefore a need for further improvement in both a device and a method for operating a crust breaker of this generic type, in such a way that while maintaining minimal compressed air consumption, the presence of a crust on the aluminum melt can be detected in an operationally safe way, so as to bring about a switchover of the crust breaking cylinder to a breaking mode of operation.
BACKGROUND OF THE INVENTION
Field of the Invention The invention relates to a crust breaker for metal melts and to an associated method.
Description of the Prior Art The field in which the present invention is used extends primarily to the technology of aluminum production. In the case of aluminum or related metals, the material is often in the molten, liquid state, which is known by the term melt. For production process reasons, raw materials or additives must be added to the melt from time to time; they are usually of powdered consistency. However, the delivery of these materials is hindered by the fact that a solidified solid layer called a crust forms on the surface and covers the liquid melt beneath it. In practice, so-called crust breakers are therefore employed, in order to break up the solid crust from time to time, so that by suitable delivery means, the aforementioned materials can be scattered into the now exposed liquid melt.
The melt must be broken open, so that the electrolytic production process can be kept going.
The crust breaking cylinder used in the context of the present invention is as a rule a pneumatic work cylinder actuated on both ends, which is installed in stationary fashion above the metal melt in such a way that its piston rod, connected to the piston located inside, protrudes downward and thus forms a push rod, which is provided on the distal end with a chisel for reinforcement. In the retracted basic position of the crust breaking cylinder, the chisel is at a considerable distance above the metal melt. For breaking up the crust, the work cylinder is subjected to compressed air, so that the piston rod moves outward into the breakup position; the chisel strikes the crust and finally breaks it up. Next, the piston rod is moved back into its retracted basic position.
From German Patent Disclosure DE 10 2004 033 964 B3, a device of this generic type for operating a crust breaker of this kind is known. In it, the crust breaking cylinder is moved between the retracted basic position and the extended breakup position on the specification of an electronic control unit, by means of suitable triggering of electropneumatic valves associated with the control unit. For initially extending the piston rod, a valve of the valve assembly is provided, which is located toward the cylinder bottom and which brings about a communication with a supply pressure source, while at the same time a valve, toward the cylinder cap, of the valve assembly also makes a communication with the supply pressure source. Since the difference in the effective diameter of the piston face on the piston rod end, compared to the piston face opposite it, brings about an extension motion of the piston rod at only slight force, it is possible by triggering both valves simultaneously to achieve a low- energy positioning mode of operation, which is employed for moving the piston rod from the retracted basic position until the chisel strikes the crust. Next, by sensor technology, the arrival of the chisel at the crust is ascertained. This is done here by monitoring the electrical potential between the grounded chisel and the existing voltage potential of the melt. To that end, an electric impedance measurement circuit or an electric voltage measurement circuit is integrated with the electronic control unit. If the arrival of the chisel at the crust is ascertained in this way, then the force acting on the crust is increased. This is done by disrupting the communication of the valve on the cylinder cap end with the supply pressure source, so that the contrary force for action toward the cylinder bottom of the crust breaking cylinder is omitted, and the crust breaking cylinder is shifted to the high-energy breaking mode of operation. Once the crust has been broken through, the piston rod returns to its retracted basic position.
Although this special triggering of the crust breaking cylinder by valve technology makes operation of the crust breaker possible in a way that is economical in terms of compressed air, nevertheless the electrical potential inquiry for detecting the crust has only relatively low operating safety for the switchover to the breaking mode of operation. This can be ascribed to the fact that the oxide crust of varying thickness leads to measurement results that are not unambiguous. Moreover, because of the use of electronic components for the potential inquiry, there is an increased vulnerability to error in the field of use in question, because of the great heat and the risk of soiling.
It is therefore a need for further improvement in both a device and a method for operating a crust breaker of this generic type, in such a way that while maintaining minimal compressed air consumption, the presence of a crust on the aluminum melt can be detected in an operationally safe way, so as to bring about a switchover of the crust breaking cylinder to a breaking mode of operation.
The invention includes the technical teaching of using at least one pneumatic multiposition valve as the sensor for detecting a fully extended state of the piston rod.
The pneumatic sensor may be implemented in the form of a 2/3-way valve or a 2/2- way valve. For details, see the ensuing description of the drawings.
Compared to electronic components, such multiposition valves have the advantage of functioning reliably and sturdily in high-temperature environments. In contrast to the use of standard electronic components, this makes for especially improved process safety.
Moreover, because of the use of corresponding valves, it becomes possible to reduce the complexity of the versions known until now and thus to reduce costs and increase the reliability. In particular, the present device requires only a trigger signal, which can be furnished by a simple triggering device, and moreover functions independently.
Besides the 2/3-way valves and 2/2-way valves mentioned, other types can also be used, as long as they make it possible to realize the teaching of the invention.
Preferably, corresponding multiposition valves, if they are used as sensors, have a tappet control, which cooperates mechanically with a motion of the cylinder piston of a crust breaking cylinder. In the terminal position of the crust breaking cylinder, this cylinder piston contacts the tappet of the multiposition valve and as a result switches the multiposition valve.
In an especially advantageous way, for ascertaining that the metal melt has a crust, the determining mechanism has a timing device, which ascertain that the metal melt has a crust on the basis of a time during which the sensors do not detect a fully extended state of the piston rod. By a corresponding indirect ascertainment that does not rely on the often unevenly built-up crust itself or on its measurement, the process safety of the method can be enhanced still further. The determination in this respect is based on the fact that in the absence of a crust, an extension of a piston rod of a corresponding crust breaking cylinder, having the chisel mounted on its end, takes place entirely within a certain time. Once that time has elapsed, a response of the sensor for detecting a fully extended state should accordingly have happened. If the sensor conversely does not respond, then it can conversely be assumed that the metal melt does have a crust that the chisel is incapable of penetrating.
In an advantageous feature of the invention, the timing device has at least one pneumatic time function element. Pneumatic time function elements of the kind known in the prior art have the advantage of great reliability over electronic time function elements, which as noted can be vulnerable to error, especially in the particular environment in which they are used. Corresponding pneumatic time function elements may have an adjustable response time, for instance by using a controllable throttle check valve.
In an advantageous feature of the present invention, the positioning force with which the crust breaking cylinder initially extends the cylinder rod is therefore less than the breaking strength of a crust. As a rule, the crust breaking cylinder comes to a stop once the chisel contacts the crust. The fully extended state is thus not attained, which in effect leads to non-response of the sensor and to response of the determining mechanism, delayed by the timing device.
Advantageously, the piston rod of the crust breaking cylinder can be fully extended with the positioning force whenever there is no crust present. This characteristic brings about an especially advantageous economy in terms of the air or fluid required, since in this case the cylinder rod is extended with only slight air consumption until the fully extended state is detected by the sensor; after that, it can be returned to its original position.
In an advantageous feature, for bringing about the extension motion of the piston rod with the positioning force, a pressure chamber on the cap end and a pressure chamber on the bottom end of the crust breaking cylinder can be subjected to pressure;
conversely, for bringing about the extension motion with breaking force, it is possible for only the pressure chamber on the bottom end of the crust breaking cylinder to be subjected to pressure. Moreover, to bring about the retraction motion, it is possible for only the pressure chamber on the cap end of the crust breaking cylinder to be subjected to pressure.
Especially advantageously, for the imposition of pressure and for the pressure reduction of the respective pressure chambers, one multiposition valve, in particular air-actuated, for each is provided; it communicates on the supply pressure side with a supply pressure source. By the use of compressed-air-actuated multiposition valves, it is possible in this connection to dispense entirely with electronic components, which as noted above can sometimes be vulnerable to error.
Moreover, in an advantageous feature, a pneumatic signal with a maximum duration by which the extension motion of the piston rod can be initiated can be generated by a first valve assembly on the basis of an electrical signal to it. It should be understood that an electrical signal can be furnished to a first valve assembly at a spatial distance from a breaking cylinder. Only relatively sturdy pressure lines are required for the communication with the second valve assembly that is tasked directly with controlling the crust breaking cylinder.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be better understood and further objects and advantages thereof will become more apparent from the ensuing detailed description of preferred embodiments taken in conjunction with the drawings, in which:
Fig. 1 is a schematic view of a crust breaker for metal melts in an especially preferred embodiment of the invention;
Fig. 2 is a schematic view of a crust breaker for metal melts in a further especially preferred embodiment of the invention; and Fig. 3 is a schematic view of an arrangement for furnishing a trigger pulse in an especially preferred embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In Fig. 1, a crust breaking cylinder 1, which is embodied on the order of a pneumatic cylinder that can be acted upon on both ends, is disposed in stationary fashion above a metal melt 2 in a smelting device 12 that is coated with a solid crust 3. The crust breaking cylinder is disposed in a cylinder unit 21 to which a valve assembly 20 is assigned.
A piston rod 4 of the crust breaking cylinder 1, with a chisel disposed on its distal end, is provided for breaking up the crust 3 by subjecting the crust breaking cylinder 1 to pressure means. The valve assembly that acts on the crust breaking cylinder 1 has first a multiposition valve 6 on the cylinder cap end and also a multiposition valve 7 on the cylinder bottom end. Both valves 6 and 7 are embodied for example as compressed-air-actuated, monostable, spring-restored 3/2-way valves. One work line each extends from the work connections of the multiposition valves 6 and 7 to the pressure chamber 60 on the cylinder cap end and to the pressure chamber 70 on the cylinder bottom end of the crust breaking cylinder 1. On the supply pressure side, both multiposition valves 6 and 7 are in communication with a common supply pressure source 8.
The triggering of the two multiposition valves 6 and 7 is effected with influence from a position sensor 10, which is preferably also embodied as a multiposition valve, in particular with tappet actuation, and from a pneumatic time function element 11 and a two-way valve 9.
On the specification of the triggering, the crust breaking cylinder 1 is moved between a retracted basic position and an extended breakup position. The positioning motion takes place in various phases of operation, as explained below.
The multiposition valve 7 on the side toward the cylinder bottom is switched by furnishing a signal or pressure pulse A to a signal line or line 100, with a duration of 1 to 4 seconds, for instance, via the two-way valve 9, which furnishes an OR
functionality. As a result, via the lines 101, 102, the pressure chamber 70, toward the cylinder bottom, of the crust breaking cylinder 1 is subjected to pressure from the supply pressure source 8.
Simultaneously, the pressure chamber 60 on the cylinder cap end is acted upon by pressure from the supply pressure source 8 via the lines 103, 104 and 105 as well as the multiposition valve 6 on the cylinder cap end, so that as a result of the prevailing difference in the effective surface areas on both sides of the piston, a slow, low-energy positioning mode of the piston rod 4 is brought about. The energy of the piston motion suffices to move the piston rod 4, with the chisel 5 mounted on it, as far as the crust 3, but not for breaking through the crust 3. The cylinder therefore first comes to a stop when the chisel 5 arrives at the crust 3.
The position sensor 10 is preferably disposed such that it is switched only upon a full extension of the piston rod 4, that is, when the terminal position possible for the cylinder is reached. If a crust 3 is present, and therefore the piston rod 4 with the chisel 5 does not extend fully, then the position sensor 10 is not switched.
Accordingly, a check is made as to whether the chisel 5 arrives at the crust 3 of the metal melt 2; to do so, by a kind of terminal position detection, a position sensor 10, integrated for instance with the cylinder cap of the crust breaking cylinder 1 and in cooperation with the piston inside the crust breaking cylinder 1, ascertains whether the extended breakup position of the crust breaking cylinder 1 has been reached.
If the piston rod 4 with the chisel 5 does not extend fully because of the presence of a crust 3, then the device functions as follows:
No switching of the position sensor 10 embodied as a multiposition valve takes place. Because of the switched valve 7, the two-way valve 9 therefore continues to be supplied with pressure from the supply pressure source 8 via the line 106, so that even if the signal A continues to be absent, this valve remains switched.
The pneumatic sensor may be implemented in the form of a 2/3-way valve or a 2/2- way valve. For details, see the ensuing description of the drawings.
Compared to electronic components, such multiposition valves have the advantage of functioning reliably and sturdily in high-temperature environments. In contrast to the use of standard electronic components, this makes for especially improved process safety.
Moreover, because of the use of corresponding valves, it becomes possible to reduce the complexity of the versions known until now and thus to reduce costs and increase the reliability. In particular, the present device requires only a trigger signal, which can be furnished by a simple triggering device, and moreover functions independently.
Besides the 2/3-way valves and 2/2-way valves mentioned, other types can also be used, as long as they make it possible to realize the teaching of the invention.
Preferably, corresponding multiposition valves, if they are used as sensors, have a tappet control, which cooperates mechanically with a motion of the cylinder piston of a crust breaking cylinder. In the terminal position of the crust breaking cylinder, this cylinder piston contacts the tappet of the multiposition valve and as a result switches the multiposition valve.
In an especially advantageous way, for ascertaining that the metal melt has a crust, the determining mechanism has a timing device, which ascertain that the metal melt has a crust on the basis of a time during which the sensors do not detect a fully extended state of the piston rod. By a corresponding indirect ascertainment that does not rely on the often unevenly built-up crust itself or on its measurement, the process safety of the method can be enhanced still further. The determination in this respect is based on the fact that in the absence of a crust, an extension of a piston rod of a corresponding crust breaking cylinder, having the chisel mounted on its end, takes place entirely within a certain time. Once that time has elapsed, a response of the sensor for detecting a fully extended state should accordingly have happened. If the sensor conversely does not respond, then it can conversely be assumed that the metal melt does have a crust that the chisel is incapable of penetrating.
In an advantageous feature of the invention, the timing device has at least one pneumatic time function element. Pneumatic time function elements of the kind known in the prior art have the advantage of great reliability over electronic time function elements, which as noted can be vulnerable to error, especially in the particular environment in which they are used. Corresponding pneumatic time function elements may have an adjustable response time, for instance by using a controllable throttle check valve.
In an advantageous feature of the present invention, the positioning force with which the crust breaking cylinder initially extends the cylinder rod is therefore less than the breaking strength of a crust. As a rule, the crust breaking cylinder comes to a stop once the chisel contacts the crust. The fully extended state is thus not attained, which in effect leads to non-response of the sensor and to response of the determining mechanism, delayed by the timing device.
Advantageously, the piston rod of the crust breaking cylinder can be fully extended with the positioning force whenever there is no crust present. This characteristic brings about an especially advantageous economy in terms of the air or fluid required, since in this case the cylinder rod is extended with only slight air consumption until the fully extended state is detected by the sensor; after that, it can be returned to its original position.
In an advantageous feature, for bringing about the extension motion of the piston rod with the positioning force, a pressure chamber on the cap end and a pressure chamber on the bottom end of the crust breaking cylinder can be subjected to pressure;
conversely, for bringing about the extension motion with breaking force, it is possible for only the pressure chamber on the bottom end of the crust breaking cylinder to be subjected to pressure. Moreover, to bring about the retraction motion, it is possible for only the pressure chamber on the cap end of the crust breaking cylinder to be subjected to pressure.
Especially advantageously, for the imposition of pressure and for the pressure reduction of the respective pressure chambers, one multiposition valve, in particular air-actuated, for each is provided; it communicates on the supply pressure side with a supply pressure source. By the use of compressed-air-actuated multiposition valves, it is possible in this connection to dispense entirely with electronic components, which as noted above can sometimes be vulnerable to error.
Moreover, in an advantageous feature, a pneumatic signal with a maximum duration by which the extension motion of the piston rod can be initiated can be generated by a first valve assembly on the basis of an electrical signal to it. It should be understood that an electrical signal can be furnished to a first valve assembly at a spatial distance from a breaking cylinder. Only relatively sturdy pressure lines are required for the communication with the second valve assembly that is tasked directly with controlling the crust breaking cylinder.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be better understood and further objects and advantages thereof will become more apparent from the ensuing detailed description of preferred embodiments taken in conjunction with the drawings, in which:
Fig. 1 is a schematic view of a crust breaker for metal melts in an especially preferred embodiment of the invention;
Fig. 2 is a schematic view of a crust breaker for metal melts in a further especially preferred embodiment of the invention; and Fig. 3 is a schematic view of an arrangement for furnishing a trigger pulse in an especially preferred embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In Fig. 1, a crust breaking cylinder 1, which is embodied on the order of a pneumatic cylinder that can be acted upon on both ends, is disposed in stationary fashion above a metal melt 2 in a smelting device 12 that is coated with a solid crust 3. The crust breaking cylinder is disposed in a cylinder unit 21 to which a valve assembly 20 is assigned.
A piston rod 4 of the crust breaking cylinder 1, with a chisel disposed on its distal end, is provided for breaking up the crust 3 by subjecting the crust breaking cylinder 1 to pressure means. The valve assembly that acts on the crust breaking cylinder 1 has first a multiposition valve 6 on the cylinder cap end and also a multiposition valve 7 on the cylinder bottom end. Both valves 6 and 7 are embodied for example as compressed-air-actuated, monostable, spring-restored 3/2-way valves. One work line each extends from the work connections of the multiposition valves 6 and 7 to the pressure chamber 60 on the cylinder cap end and to the pressure chamber 70 on the cylinder bottom end of the crust breaking cylinder 1. On the supply pressure side, both multiposition valves 6 and 7 are in communication with a common supply pressure source 8.
The triggering of the two multiposition valves 6 and 7 is effected with influence from a position sensor 10, which is preferably also embodied as a multiposition valve, in particular with tappet actuation, and from a pneumatic time function element 11 and a two-way valve 9.
On the specification of the triggering, the crust breaking cylinder 1 is moved between a retracted basic position and an extended breakup position. The positioning motion takes place in various phases of operation, as explained below.
The multiposition valve 7 on the side toward the cylinder bottom is switched by furnishing a signal or pressure pulse A to a signal line or line 100, with a duration of 1 to 4 seconds, for instance, via the two-way valve 9, which furnishes an OR
functionality. As a result, via the lines 101, 102, the pressure chamber 70, toward the cylinder bottom, of the crust breaking cylinder 1 is subjected to pressure from the supply pressure source 8.
Simultaneously, the pressure chamber 60 on the cylinder cap end is acted upon by pressure from the supply pressure source 8 via the lines 103, 104 and 105 as well as the multiposition valve 6 on the cylinder cap end, so that as a result of the prevailing difference in the effective surface areas on both sides of the piston, a slow, low-energy positioning mode of the piston rod 4 is brought about. The energy of the piston motion suffices to move the piston rod 4, with the chisel 5 mounted on it, as far as the crust 3, but not for breaking through the crust 3. The cylinder therefore first comes to a stop when the chisel 5 arrives at the crust 3.
The position sensor 10 is preferably disposed such that it is switched only upon a full extension of the piston rod 4, that is, when the terminal position possible for the cylinder is reached. If a crust 3 is present, and therefore the piston rod 4 with the chisel 5 does not extend fully, then the position sensor 10 is not switched.
Accordingly, a check is made as to whether the chisel 5 arrives at the crust 3 of the metal melt 2; to do so, by a kind of terminal position detection, a position sensor 10, integrated for instance with the cylinder cap of the crust breaking cylinder 1 and in cooperation with the piston inside the crust breaking cylinder 1, ascertains whether the extended breakup position of the crust breaking cylinder 1 has been reached.
If the piston rod 4 with the chisel 5 does not extend fully because of the presence of a crust 3, then the device functions as follows:
No switching of the position sensor 10 embodied as a multiposition valve takes place. Because of the switched valve 7, the two-way valve 9 therefore continues to be supplied with pressure from the supply pressure source 8 via the line 106, so that even if the signal A continues to be absent, this valve remains switched.
Thus the pneumatic time function element 11 also continues to be acted upon by pressure via the line 107. The pneumatic time function element 11 has an adjustable throttle check valve 111 as well as an air or energy reservoir 114. If the pressure in the energy reservoir 114 reaches a sufficiently high value, for instance after approximately 2 seconds, the switching of the multiposition valve 115 that is also provided is effected.
This is because after this time elapses, the fully extended breakup position of the crust breaking cylinder 1 should have been expected, if no crust 3 had been present.
The time can be varied by way of adjusting the throttle of the throttle check valve 111.
Based on the switching of the valve 111 after the time has elapsed, the multiposition valve 6 on the cap end is switched via the line 108 by means of being subjected to pressure from the supply pressure source 8.
The pressure chamber 60 on the cap end is as a result vented via the line 105 and the switched multiposition valve 6 on the cap end. Thus the contrary force on the piston of the crust breaking cylinder 1 disappears, so that the crust breaking cylinder, as a result of the pressure that continues to be present on the bottom side, acts with its full force on the crust 3 to break through it.
The position sensor 10 is now switched as a result of the thus fully extended piston of the crust breaking cylinder 1. Thus via the line 106, no further pressure is applied to the two- way valve 9. The multiposition valve 7 on the bottom end returns to its outset position. The pressure chamber 70 on the bottom end is no longer supplied from the supply pressure source 8 and is vented. Simultaneously, the time function element 11 becomes pressureless, so that the multiposition valve 6 on the cap end returns to its outset position. The pressure chamber 60 on the cap end therefore enters into communication with the supply pressure source again, so that the piston rod 4 with the chisel 5 is moved inward. Thus the outset position as shown in Fig. 1 is attained once again; the system is available for a new cycle.
If from the beginning there is no crust 3, then the cylinder trips the position sensor before the response of the time function element 11, so that the cylinder returns to its outset position as in the previous paragraph.
In Fig. 2, a device for operating a crust breaking cylinder for metal melts is provided which corresponds essentially to the embodiment described above, as shown in Fig. 1.
However, instead of the two-way valve 9, the device has a check valve 9'.
Instead of the position sensor 10 of Fig. 1 in the form of a 3/2-way valve, the position sensor is provided here in the form of a 2/2-way valve 10'. The function of the device is also equivalent essentially to what is described above, with the changes shown. If the position sensor 10 is switched because the crust breaking cylinder 1 has reached its terminal position, then the trigger pressure of the multiposition valve 7 on the bottom end is rescinded, since the line 106 is no longer subjected to supply pressure from the supply pressure source 8. The multiposition valve 7 on the cylinder bottom end thus returns to its outset position, as shown in Fig. 2, if no signal is present any longer.
From the form of the embodiment as shown in Fig. 2, further advantages result:
By the use of a 2/2-way valve instead of a 3/2-way valve, further simplification of the arrangement can be attained. Optionally, by the use of a sturdier (more heat-stable) 2/2-way valve, the reliability of the system can be increased still further here.
Moreover, as a result of the switching of the 2/2-way valve, the line 106 is not abruptly ventilated, as a result of which a pressure drop that might be disadvantageous for the multiposition valve 7 on the bottom end is avoided. A corresponding pressure drop, in the least favorable case, could lead to the unwanted switching over of this valve 7.
Moreover, the use of the check valve 9' instead of the two-way valve 9 makes it possible to avoid an impact on such a two-way valve 9, or in other words to avoid repeated switchovers.
As shown in conjunction with the description of Figs. 1 and 2, a trigger signal A of limited duration is required for operating the corresponding devices.
Fig. 3 in a schematic illustration shows an arrangement for furnishing this kind of trigger signal or pressure pulse that can advantageously be used in implementing the invention. The device is identified overall by reference numeral 30.
For operating the device, a supply pressure source 8', which may be identical to the supply pressure source 8 of Figs. 1 and 2, and electric trigger means for furnishing an electrical pulse E are provided. The device furthermore has an electrokinetically actuatable 3/2-way valve 31. A pneumatic time function element 32, which in its function corresponds essentially to the pneumatic time function element 11 described above and shown in Figs. 1 and 2, is also provided. In particular, the pneumatic time function element 32 has a throttle check valve with an energy reservoir and also has a pressure-actuatable 3/2-way valve 33 that can be switched over.
The mode of operation of the device 30 will now be described. If the device receives an electrical pulse E, it causes a switchover of the 3/2-way valve 31. As a result, the line 301is subjected to pressure. As a result of the position shown of the 3/2-way valve 33, this pressure is output directly, via a line 302, as a trigger pulse A.
Simultaneously, the pneumatic time function element 32 is subjected to pressure. Once the requisite pressure for switching over the 3/2-way valve 33 is reached in the energy reservoir of the pneumatic time function element 32, the latter switches over, so that the line 302 is terminated by the valve 33, and a line 303 is vented via an air outlet 304.
The function of the device 30 can thus be viewed as a limitation of the maximum duration of the trigger pulse A. If the duration of the electrical pulse is less than the switching time of the time function element 32, then the duration of the trigger pulse A is equivalent to that of the electrical pulse E.
Conversely, if the duration of the electrical pulse E exceeds the switching time of the time function element 32, then the latter limits the duration of the trigger pulse A to a maximum time which can be defined by the adjustment of the throttle valve of the time function element.
The foregoing relates to preferred exemplary embodiments of the invention, it being understood that other variants and embodiments thereof are possible within the spirit and scope of the invention, the latter being defined by the appended claims.
This is because after this time elapses, the fully extended breakup position of the crust breaking cylinder 1 should have been expected, if no crust 3 had been present.
The time can be varied by way of adjusting the throttle of the throttle check valve 111.
Based on the switching of the valve 111 after the time has elapsed, the multiposition valve 6 on the cap end is switched via the line 108 by means of being subjected to pressure from the supply pressure source 8.
The pressure chamber 60 on the cap end is as a result vented via the line 105 and the switched multiposition valve 6 on the cap end. Thus the contrary force on the piston of the crust breaking cylinder 1 disappears, so that the crust breaking cylinder, as a result of the pressure that continues to be present on the bottom side, acts with its full force on the crust 3 to break through it.
The position sensor 10 is now switched as a result of the thus fully extended piston of the crust breaking cylinder 1. Thus via the line 106, no further pressure is applied to the two- way valve 9. The multiposition valve 7 on the bottom end returns to its outset position. The pressure chamber 70 on the bottom end is no longer supplied from the supply pressure source 8 and is vented. Simultaneously, the time function element 11 becomes pressureless, so that the multiposition valve 6 on the cap end returns to its outset position. The pressure chamber 60 on the cap end therefore enters into communication with the supply pressure source again, so that the piston rod 4 with the chisel 5 is moved inward. Thus the outset position as shown in Fig. 1 is attained once again; the system is available for a new cycle.
If from the beginning there is no crust 3, then the cylinder trips the position sensor before the response of the time function element 11, so that the cylinder returns to its outset position as in the previous paragraph.
In Fig. 2, a device for operating a crust breaking cylinder for metal melts is provided which corresponds essentially to the embodiment described above, as shown in Fig. 1.
However, instead of the two-way valve 9, the device has a check valve 9'.
Instead of the position sensor 10 of Fig. 1 in the form of a 3/2-way valve, the position sensor is provided here in the form of a 2/2-way valve 10'. The function of the device is also equivalent essentially to what is described above, with the changes shown. If the position sensor 10 is switched because the crust breaking cylinder 1 has reached its terminal position, then the trigger pressure of the multiposition valve 7 on the bottom end is rescinded, since the line 106 is no longer subjected to supply pressure from the supply pressure source 8. The multiposition valve 7 on the cylinder bottom end thus returns to its outset position, as shown in Fig. 2, if no signal is present any longer.
From the form of the embodiment as shown in Fig. 2, further advantages result:
By the use of a 2/2-way valve instead of a 3/2-way valve, further simplification of the arrangement can be attained. Optionally, by the use of a sturdier (more heat-stable) 2/2-way valve, the reliability of the system can be increased still further here.
Moreover, as a result of the switching of the 2/2-way valve, the line 106 is not abruptly ventilated, as a result of which a pressure drop that might be disadvantageous for the multiposition valve 7 on the bottom end is avoided. A corresponding pressure drop, in the least favorable case, could lead to the unwanted switching over of this valve 7.
Moreover, the use of the check valve 9' instead of the two-way valve 9 makes it possible to avoid an impact on such a two-way valve 9, or in other words to avoid repeated switchovers.
As shown in conjunction with the description of Figs. 1 and 2, a trigger signal A of limited duration is required for operating the corresponding devices.
Fig. 3 in a schematic illustration shows an arrangement for furnishing this kind of trigger signal or pressure pulse that can advantageously be used in implementing the invention. The device is identified overall by reference numeral 30.
For operating the device, a supply pressure source 8', which may be identical to the supply pressure source 8 of Figs. 1 and 2, and electric trigger means for furnishing an electrical pulse E are provided. The device furthermore has an electrokinetically actuatable 3/2-way valve 31. A pneumatic time function element 32, which in its function corresponds essentially to the pneumatic time function element 11 described above and shown in Figs. 1 and 2, is also provided. In particular, the pneumatic time function element 32 has a throttle check valve with an energy reservoir and also has a pressure-actuatable 3/2-way valve 33 that can be switched over.
The mode of operation of the device 30 will now be described. If the device receives an electrical pulse E, it causes a switchover of the 3/2-way valve 31. As a result, the line 301is subjected to pressure. As a result of the position shown of the 3/2-way valve 33, this pressure is output directly, via a line 302, as a trigger pulse A.
Simultaneously, the pneumatic time function element 32 is subjected to pressure. Once the requisite pressure for switching over the 3/2-way valve 33 is reached in the energy reservoir of the pneumatic time function element 32, the latter switches over, so that the line 302 is terminated by the valve 33, and a line 303 is vented via an air outlet 304.
The function of the device 30 can thus be viewed as a limitation of the maximum duration of the trigger pulse A. If the duration of the electrical pulse is less than the switching time of the time function element 32, then the duration of the trigger pulse A is equivalent to that of the electrical pulse E.
Conversely, if the duration of the electrical pulse E exceeds the switching time of the time function element 32, then the latter limits the duration of the trigger pulse A to a maximum time which can be defined by the adjustment of the throttle valve of the time function element.
The foregoing relates to preferred exemplary embodiments of the invention, it being understood that other variants and embodiments thereof are possible within the spirit and scope of the invention, the latter being defined by the appended claims.
Claims (19)
1. A crust breaker for metal melts, comprising a fluid-actuated, double-acting crust breaking cylinder with a pressure chamber on a cap end of the cylinder, a pressure chamber on a bottom end of the cylinder, a piston, and a piston rod mounted on one side of the piston, in which a piston face on an end toward the piston rod has a lesser effective diameter than an opposed piston face;
a valve assembly associated with the crust breaking cylinder and operable on the basis of a signal, for initiating an extension motion of the piston rod with a positioning force;
determining means for ascertaining that the metal melt has a crust; the piston rod being further extendable on a specification of the determining means, for introducing a breaking force that is greater than the positioning force; and sensor means for detecting a fully extended state of the piston rod, the sensor means having at least one pneumatic multiposition valve for initiating, on a specification of the sensor means, a retraction motion of the piston rod.
a valve assembly associated with the crust breaking cylinder and operable on the basis of a signal, for initiating an extension motion of the piston rod with a positioning force;
determining means for ascertaining that the metal melt has a crust; the piston rod being further extendable on a specification of the determining means, for introducing a breaking force that is greater than the positioning force; and sensor means for detecting a fully extended state of the piston rod, the sensor means having at least one pneumatic multiposition valve for initiating, on a specification of the sensor means, a retraction motion of the piston rod.
2. The device as defined by claim 1, wherein the determining means have timing means for ascertaining that the metal melt has a crust on a basis of a time during which the sensor means do not detect a fully extended state of the piston rod.
3. The device as defined by claim 2, wherein the timing means have at least one pneumatic time function element.
4. The device as defined by claim 1, wherein when no crust is present, the piston rod is fully extendable by means of the positioning force.
5. The device as defined by claim 2, wherein when no crust is present, the piston rod is fully extendable by means of the positioning force.
6. The device as defined by claim 3, wherein when no crust is present, the piston rod is fully extendable by means of the positioning force.
7. The device as defined by claim 1, wherein for bringing about the extension motion of the piston rod with the positioning force, the pressure chamber on the cap end and the pressure chamber on the bottom end of the crust breaking cylinder are subjected to pressure; for bringing about the extension motion of the piston rod with the breaking force, only the pressure chamber on the bottom end of the crust breaking cylinder is subjected to pressure; and for bringing about the retraction motion of the piston rod, only the pressure chamber on the cap end of the crust breaking cylinder is subjected to pressure.
8. The device as defined by claim 2, wherein for bringing about the extension motion of the piston rod with the positioning force, the pressure chamber on the cap end and the pressure chamber on the bottom end of the crust breaking cylinder are subjected to pressure; for bringing about the extension motion of the piston rod with the breaking force, only the pressure chamber on the bottom end of the crust breaking cylinder is subjected to pressure; and for bringing about the retraction motion of the piston rod, only the pressure chamber on the cap end of the crust breaking cylinder is subjected to pressure.
9. The device as defined by claim 3, wherein for bringing about the extension motion of the piston rod with the positioning force, the pressure chamber on the cap end and the pressure chamber on the bottom end of the crust breaking cylinder are subjected to pressure; for bringing about the extension motion of the piston rod with the breaking force, only the pressure chamber on the bottom end of the crust breaking cylinder is subjected to pressure; and for bringing about the retraction motion of the piston rod, only the pressure chamber on the cap end of the crust breaking cylinder is subjected to pressure.
10. The device as defined by claim 4, wherein for bringing about the extension motion of the piston rod with the positioning force, the pressure chamber on the cap end and the pressure chamber on the bottom end of the crust breaking cylinder are subjected to pressure; for bringing about the extension motion of the piston rod with the breaking force, only the pressure chamber on the bottom end of the crust breaking cylinder is subjected to pressure; and for bringing about the retraction motion of the piston rod, only the pressure chamber on the cap end of the crust breaking cylinder is subjected to pressure.
11. The device as defined by any one of claims 1 to 3, wherein the pressure chamber on the cap end and the pressure chamber on the bottom end are pressurized on the basis of the signal, the determining means control a pressure reduction in only the pressure chamber on the cap end; and pressurizing of the pressure chamber on the cap end and in addition a pressure reduction in the pressure chamber on the bottom end is controlled by the sensor means.
12. The device as defined by claim 11, wherein multiposition valves associated with the respective pressure chambers which on a supply pressure side communicate with a supply pressure source control the pressurizing and pressure reduction.
13. The device as defined by claim 12, wherein the multiposition valves are activated by compressed air.
14. The device as defined by claim 1, wherein on a basis of an electrical signal to a first valve assembly, a pneumatic signal with a maximum duration can be generated by the first valve assembly for output to a second valve assembly, by which the extension motion of the piston rod is controlled.
15. The device as defined by claim 2, wherein on a basis of an electrical signal to a fust valve assembly, a pneumatic signal with a maximum duration can be generated by the first valve assembly for output to a second valve assembly, by which the extension motion of the piston rod is controlled.
16. The device as defined by claim 3, wherein on a basis of an electrical signal to a first valve assembly, a pneumatic signal with a maximum duration can be generated by the first valve assembly for output to a second valve assembly, by which the extension motion of the piston rod is controlled.
17. The device as defined by claim 14, further comprising an electrical unit for generating the electrical signal.
18. The device as defined by claim 15, further comprising an electrical unit for generating the electrical signal.
19. A method for operating a mist breaker for metal melts as defined by claim 1, which includes the following steps of:
initiating an extension motion of a piston rod of a crust breaking cylinder of the crust breaker with a positioning force;
ascertaining that the metal melt has a crust by determining means, and if it is found that the metal melt has a crust, initiating a further extension motion of the piston rod with a breaking force that is greater than the positioning force; and initiating a retraction motion of the piston rod after detection by sensor means of a fully extended state of the piston rod, wherein a pneumatic multiposition valve is used as the sensor means,.
initiating an extension motion of a piston rod of a crust breaking cylinder of the crust breaker with a positioning force;
ascertaining that the metal melt has a crust by determining means, and if it is found that the metal melt has a crust, initiating a further extension motion of the piston rod with a breaking force that is greater than the positioning force; and initiating a retraction motion of the piston rod after detection by sensor means of a fully extended state of the piston rod, wherein a pneumatic multiposition valve is used as the sensor means,.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE102009021669.3 | 2009-05-16 | ||
| DE200910021669 DE102009021669A1 (en) | 2009-05-16 | 2009-05-16 | Crust breaking device with reduced compressed air consumption |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2704506A1 true CA2704506A1 (en) | 2010-11-16 |
Family
ID=42979212
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2704506A Abandoned CA2704506A1 (en) | 2009-05-16 | 2010-05-14 | Crust breaker with reduced compressed air consumption |
Country Status (3)
| Country | Link |
|---|---|
| CA (1) | CA2704506A1 (en) |
| DE (1) | DE102009021669A1 (en) |
| FR (1) | FR2945548A1 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103266333A (en) * | 2013-05-24 | 2013-08-28 | 嘉兴朴厚气动控制技术有限公司 | Crust breaking device |
| CN103397346A (en) * | 2013-08-05 | 2013-11-20 | 甘肃工大电子科技有限公司 | Automatic checkout device for bottoming of crust-breaking hammer of aluminum electrolytic cell |
| CN105940148A (en) * | 2014-01-27 | 2016-09-14 | 力拓艾尔坎国际有限公司 | Device for drilling crust of cryolite bath, that can be positioned on periphery of electrolytic cell |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103452934A (en) * | 2013-08-18 | 2013-12-18 | 杭州哲达科技股份有限公司 | Special intelligent air saving instrument and air supply method for crust breaking cylinder |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102004033964B3 (en) | 2004-07-14 | 2006-03-30 | Bosch Rexroth Ag | Device for operating a crust-breaking arrangement for metal melts comprises a valve arrangement having a valve for withdrawing a piston rod and for forming a connection to an injection pressure source |
-
2009
- 2009-05-16 DE DE200910021669 patent/DE102009021669A1/en not_active Withdrawn
-
2010
- 2010-05-10 FR FR1053613A patent/FR2945548A1/en not_active Withdrawn
- 2010-05-14 CA CA2704506A patent/CA2704506A1/en not_active Abandoned
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103266333A (en) * | 2013-05-24 | 2013-08-28 | 嘉兴朴厚气动控制技术有限公司 | Crust breaking device |
| CN103266333B (en) * | 2013-05-24 | 2016-01-13 | 嘉兴朴厚气动控制技术有限公司 | Crust breaker |
| CN103397346A (en) * | 2013-08-05 | 2013-11-20 | 甘肃工大电子科技有限公司 | Automatic checkout device for bottoming of crust-breaking hammer of aluminum electrolytic cell |
| CN103397346B (en) * | 2013-08-05 | 2015-09-30 | 甘肃工大电子科技有限公司 | Aluminum electrolytic cell crust-breaking hammer head is automatic detection device on earth |
| CN105940148A (en) * | 2014-01-27 | 2016-09-14 | 力拓艾尔坎国际有限公司 | Device for drilling crust of cryolite bath, that can be positioned on periphery of electrolytic cell |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2945548A1 (en) | 2010-11-19 |
| DE102009021669A1 (en) | 2010-11-18 |
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