WO2020234846A1

WO2020234846A1 - Improved method for adjusting a gas flow and system using said improved flow adjustment method

Info

Publication number: WO2020234846A1
Application number: PCT/IB2020/054890
Authority: WO
Inventors: Pan Lei; Maurizio Terzo; Enrico Cortelazzo
Original assignee: Jasic Technology Europe S.R.L.
Priority date: 2019-05-23
Filing date: 2020-05-22
Publication date: 2020-11-26
Also published as: CN114375236A

Abstract

The invention is a method for adjusting the flow rate of a technological gas used in a production system (1) comprising a dispensing station (2) suited to dispense the technological gas, a machining unit (3) using the technological gas dispensed by the dispensing station (2) and conveyance means (4) suited to convey the technological gas from the dispensing station (2) to the machining unit (3). The conveyance means (4) comprise two or more dispensing valves (5, 6, 7) of the on-off type which are arranged in parallel with one another and each of which is configured in such a way that it dispenses a pre-established flow rate of technological gas. The flow rate of the technological gas conveyed to the machining unit (3) is adjusted by selectively opening and closing one or more of the dispensing valves (5, 6, 7).

Description

IMPROVED METHOD FOR ADJUSTING A GAS FLOW AND SYSTEM USING SAID IMPROVED FLOW ADJUSTMENT METHOD.

DESCRIPTION

The invention concerns a method for adjusting the flow rate of a fluid, particularly suited to adjust the flow rate of a gas of any type used in any system.

More specifically, the method that is the subject of the invention is used to adjust the flow rate of a gas, preferably a technological gas or an operating gas, which is used in industrial systems such as, for example, industrial welding systems of the MIG, MAG or TIG type and in plasma welding and cutting systems or laser beam systems.

In general, the invention concerns any industrial system using the above mentioned method for adjusting the flow of a gas, preferably of the technological type.

As is known, the systems listed above use gases of various types, having characteristics that make them suitable for taking actively or passively part in the machining process.

For example, in the TIG welding process the electric arc is protected and insulated from contact with the oxygen present in the external environment through a gas flow generally comprising argon, helium, nitrogen or mixtures of these gases.

Similarly, in the plasma cutting process the plasma jet is produced in a torch in which an electric arc ionizes a gas mixture, for example a mixture of argon and hydrogen.

The plasma jet passes through a calibrated nozzle and is directed towards the material to be cut, which is melted making a cut whose perimeter is determined by the path defined for the torch.

Analogously, in the laser cutting process a laser beam is used, which is focused on the material to be cut and flows along a calibrated nozzle, together with a flow of inert gas or active gas coaxial with it.

The examples mentioned and briefly described above in relation to welding and cutting systems are only some examples of systems in which, during the machining process, it is necessary to convey a controlled gas flow towards the work area.

The gas flow rate used varies according to the type of system and the type of material to be processed, to its characteristics and to other parameters, if any, and therefore it is necessary to equip the systems with devices suitable for supplying variable gas flow rates according to the various needs.

In the known art proportional solenoid valves are used to convey variable gas flow rates to the machining units, wherein said proportional solenoid valves, as is well known, make it possible to modulate the flow rate of the exiting gas in a continuous manner, adapting it to the different needs of the unit that uses them.

More specifically, proportional solenoid valves are provided with a shutter controlled by a solenoid and the gas flow rates supplied by each solenoid valve are proportional to the degree of opening of the shutter, which in turn is proportional to the value of the current that feeds the solenoid and is supplied by an electronically controlled power supply.

The drawback observed in the use of said proportional valves is constituted by their cost, which is considerably high.

Therefore, it is the object of the present invention to provide an improved method for adjusting the flow rate of a gas in a system, wherein said method makes it possible to avoid the use of proportional valves.

It is another object of the present invention to reduce the construction costs of systems including machining units where variable flow rates of technological gas are used.

Furthermore, it is also the object of the invention to provide a production system in which said improved adjustment method is applied.

The objects illustrated above are achieved by the method of the invention according to the main claim, to which reference is made, and whose dependent claims describe details of said method.

The application of the method that is the subject of the invention advantageously makes it possible to reduce the construction costs of production systems in which machining units are present, for example laser beam or plasma welding and/or cutting machines and systems which carry out processing cycles requiring the use of technological gases, also called operating gases, supplied in variable flow rates.

The objects and advantages listed herein are achieved by a method according to the invention that is described here below with reference to the attached drawing, which is supplied only by way of non-limiting example and in which: - Figure 1 schematically represents a system using the method of the invention.

The method that is the subject of the invention makes it possible to adjust the flow rate of a technological gas or operating gas that feeds a machining unit of a production system of any type.

The method is described here below with reference to Figure 1 , which provides a schematic representation of a production system indicated as a whole by 1. More specifically, the production system 1 comprises a machining unit 3 using a technological gas which is conveyed from a dispensing station 2 to the machining unit 3 by conveyance means 4.

The production system 1 to which reference is made can be either a fixed system or a mobile system comprising one or more machining units 3 of various types, for example machine tools.

Furthermore, the dispensing station 2 can have different configurations, and in the case of large-sized fixed production systems it can comprise a technological gas storage unit or a technological gas production unit while in small-sized mobile systems it simply comprises one or more cylinders.

According to the method of the invention, and independently of the size of the system, the flow rate of technological gas that is conveyed to the machining unit 3 requires the use of two or more dispensing valves 5, 6, 7 belonging to the conveyance means 4.

Obviously, the use of three dispensing valves illustrated in Figure 1 is described only by way of indicative example, as they can be present in any number, provided that there are no fewer than two valves.

As shown in Figure 1 , all the valves 5, 6, 7 are connected to one another in parallel, as their inlet ways 5a, 6a, 7a are all connected to an inlet pipe 8 that communicates with the dispensing station 2 and their outlet ways 5b, 6b, 7b are all connected to an outlet pipe 9 that communicates with the machining unit 3.

Each dispensing valve 5, 6, 7 is of the on-off type and therefore is only able to open and close the flow of the gas from the dispensing station 2 towards the machining unit 3 but cannot modify its flow rate.

According to the method that is the subject of the invention, the adjustment of the flow rate of the technological gas that is conveyed to the machining unit 3 is carried out through the selective opening and closing of one or more of said dispensing valves 5, 6, 7.

According to an embodiment, all the dispensing valves 5, 6, 7 are configured in such a way that they all supply the same pre-established flow rate.

According to a variant embodiment, the dispensing valves 5, 6, 7 are configured in such a way that each of them supplies a pre-established flow rate whose value is different from that of the flow rate supplied by another valve. According to a further variant embodiment, the dispensing valves 5, 6, 7 are configured in such a way that each of them supplies a pre-established flow rate whose value is different from that of the flow rate supplied by another valve and that the values of said flow rates are distributed according to a binary sequence.

More specifically, the dispensing valves 5, 6, 7 are configured in such a way that the relation, in sequence, between the values of their pre-established flow rates is defined according to the power of two. In other words, the flow rate value of each of the dispensing valves 5, 6, 7 is equal to half and/or twice the flow rate value of at least another one of said dispensing valves 5, 6, 7.

Advantageously, this configuration makes it possible to define, as desired, a value of the total flow rate supplied which is substantially variable within the whole interval ranging from zero flow rate, when all of the dispensing valves 5, 6, 7 are closed, and maximum flow rate value, when all of the dispensing valves 5, 6, 7 are open.

The value of the flow rate supplied by each valve is set in advance by applying a calibrated nozzle 5c, 6c, 7c to the outlet way 5b, 6b, 7b of each dispensing valve 5, 6, 7 and the adjustment of the total flow rate supplied and necessary for the operation of the machining unit 3 is obtained through the selective opening and closing of one or more of the dispensing valves 5, 6, 7 through control means.

Preferably, the calibrated nozzle 5c, 6c, 7c is of the removable type, so that it is possible to vary the flow rate supplied by the same dispensing valve by simply changing the calibrated nozzle.

The value of the total flow rate that the conveyance means 4 convey to the machining unit 3 thus varies according to the number of valves that are opened at the same time and to the flow rate that each valve is able to supply depending on the type of calibrated nozzle installed on it.

Furthermore, the total number of flow rates that can be obtained depends on the number of valves installed and on the number of valves that can be opened at the same time.

Said number of flow rates corresponds to the combinations without repetition that can be obtained by using any number of valves which are opened at the same time in all the possible combinations.

Since the dispensing valves used are of the on-off type and therefore can be configured with two positions, the number of obtainable combinations C, corresponding to the number of gas flow rates obtainable by conveniently combining the valves being opened and closed, is provided by the relation:

C = 2"

where n indicates the number of valves used.

With reference to the case described herein, in which the dispensing valves 5, 6, 7 are n = 3, the resulting number of combinations C is the following:

C = 2ⁿ = 2³ = 8

The valves can thus be arranged in 8 different combinations and thus provide 8 different total flow rates including the flow rate 0 corresponding to the condition in which all the valves are closed.

It will thus be possible for the user to use the number of valves which is most suitable so that, after having combined their opening and closing, they are suitable for providing the desired flow rates.

The measurement of the flow rates is carried out by measuring the difference between the pressure values upstream and downstream of each dispensing valve 5, 6, 7 through a differential pressure gauge indicated by 5d, 6d, 7d in Figure 1.

In practice, the total flow rate of technological gas that the dispensing valves 5, 6, 7 supply to the machining unit 3 can be changed by conveniently modifying the combination of the valves that are open at the same time and providing them with suitable calibrated nozzles 5c, 6c, 7c in such a way as to adapt the flow rate to the type of machining process.

For this purpose, the dispensing valves are preferably solenoid valves controlled and managed by a control system of the known type which allows them to be selectively opened and closed.

In this way, the gas flow rate can be adjusted without using proportional valves which are more expensive and more difficult to manage compared to the dispensing valves 5, 6, 7 of the on-off type. As far as the productive unit 3 is concerned, this can be any machine using a flow rate of technological gas for its operation such as, for example, a welding machine or a machine for cutting materials.

More specifically, in the case of welding operations the machines in question can be TIG, plasma or laser beam welders, and in the case of material cutting operations the machines can be of the plasma or laser beam type, too.

Based on the explanation provided above, it can be understood that the method that is the subject of the invention and the system implementing it achieve the set objects.

In particular, the lower cost of the on-off dispensing valves compared to that of the proportional valves ensures savings in system construction costs.

In practical application, the method and the system that are the subjects of the invention can be subjected to modifications and variants that are neither described nor mentioned herein but that must be certainly considered protected by the present patent, provided that they fall within the scope of the following claims.

Claims

1 ) Method for adjusting the flow rate of a gas, preferably of the technological type, which is used in a production system (1 ) comprising:

- at least one dispensing station (2) suited to dispense said technological gas;

- at least one machining unit (3) using said technological gas dispensed by said dispensing station (2);

- conveyance means (4) suited to convey said technological gas from said dispensing station (2) to said machining unit (3), said conveyance means (4) comprising two or more dispensing valves (5, 6, 7) of the on-off type arranged in parallel with each other and each configured in such a way as to dispense a pre-established flow rate of said technological gas, the adjustment of the flow rate of said technological gas that is conveyed to said machining unit (3) being obtained through the selective opening and closing of one or more of said dispensing valves (5, 6, 7),

characterized in that said dispensing valves (5, 6, 7) are configured in such a way that each of them dispenses a pre-established flow rate whose value is different from that of the flow rate of another valve, the values of said pre- established flow rates being distributed according to a binary sequence.

2) Method according to claim 1 , characterized in that said dispensing valves (5, 6, 7) are configured in such a way that the relation, in sequence, between the values of their pre-established flow rates is defined according to the power of two.

3) Method according to any of the preceding claims, characterized in that in each one of said dispensing valves (5, 6, 7) said pre-established flow rate of technological gas is determined by a calibrated nozzle (5c, 6c, 7c) applied to the outlet way (5b, 6b, 7b) of the dispensing valve.

4) Method according to any of the preceding claims, characterized in that it comprises control means for controlling the selective opening and closing of said dispensing valves (5, 6, 7).

5) Method according to claim 4, characterized in that the measurement of said flow rate is made through the differential measurement of the pressure upstream and downstream of each one of said dispensing valves (5, 6, 7).

6) Production system (1 ) comprising at least one machining unit (3) using a technological gas coming from a dispensing station (2) and conveyed to said machining unit (3) through conveyance means (4) comprising two or more dispensing valves (5, 6, 7) of the on-off type connected in parallel with one another, characterized in that said system (1 ) is configured to implement the method for adjusting the flow rate of said technological gas according to any of the claims from 1 to 5.

7) System (1 ) according to claim 6, characterized in that said machining unit (3) is a laser cutting machine for cutting materials.

8) System (1 ) according to claim 6, characterized in that said machining unit (3) is a plasma cutting machine for cutting materials.

9) System (1 ) according to claim 6, characterized in that said machining unit (3) is a welding machine.