ES2607833T3 - Device for simultaneous shaping and welding of connecting tubes for compressors using a centering pin; forming and welding procedure of compressor connecting tubes using said device - Google Patents

Abstract

Simultaneous shaping and welding device of connecting tubes for compressors (C), said connecting tubes (1) being defined by substantially cylindrical bodies 5 that are coupled to existing gas through holes in a housing (2) of the compressors (C) , which constitute its suction, discharge and process channels, in which said device comprises: - an upper electrode holder (3) that cooperates with one of the poles of an inverter and transformer assembly; - an upper electrode (4) that cooperates with the upper electrode holder (3) and the upper region of the connecting tube (1); - a lower electrode holder (5) that cooperates with the other pole of an inverter and transformer assembly; - an electrical isolation means (6) that cooperates with the inner surface of the lower electrode holder (5); - a lower electrode (8) that cooperates with a lower electrode holder (5) and the compressor housing (2) (C), and - a centering pin (7) coupled to the inner region of the electrical isolation means (6) and cooperating with the gas through hole of the housing (2) of the compressor (C) and the connecting tube (1) and which is further characterized by: - a stop (10) for applying welding force that cooperates with the upper electrode holder (3) and the upper end of the connector tube (1); and the inner diameter of the lower electrode (9) being equal to or greater than the outer diameter of the upper electrode (4).

Description

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DESCRIPTION

Device for simultaneous shaping and welding of connecting tubes for compressors using a centering pin; method of forming and welding compressor connector tubes using said device

The present invention relates to a device according to the preamble of claim 1 and a method of forming and welding using said device performed simultaneously, tube connectors (also known as spikes) intended primarily for use in compressors. More specifically, the procedure presented herein refers to the simultaneous shaping and welding of copper pipes - used as connectors for suction, procedure and discharge - to the metal housing of hermetic compressors for refrigeration, with the aim of reducing the stages of the production procedure, making it more efficient and economical.

BACKGROUND OF THE INVENTION

As is known in the art, hermetic compressors are devices widely used in refrigeration systems in general, the components being responsible for providing the circulation of the refrigerant fluid through the pipes of the refrigeration systems. The suction and discharge connecting tubes have the function of conducting the refrigerant gas through the compressor housing, connecting the interior of the compressor with the refrigeration system tubes. The procedure connecting tube has the function of being the injection route of refrigerant fluid and / or oil during the installation of the compressor in the refrigeration system. It should be clarified that said connecting tubes are typically made of copper due to the ease of connection by strong welding with the system tubes.

It happens, however, that the correct operation of said equipment also depends on the conditions of perfect sealing between these connecting tubes and the metal housing of the compressor, said copper connecting tubes being produced and the compressor housing generally made of steel, so that said welding procedure becomes significantly complicated.

The best known form of assembly provides the use of brazing of additional materials that are disposed between the hole of the compressor housing and the connecting tube as disclosed, for example, in JP2010038087. Although this document involves the use of a connecting tube without the need for prior conformation, said procedure has, however, the disadvantage of needing the use of welding addition material.

An alternative technique is presented in document CN101780602 (see attached figures 2 and 3), on which the preamble of claim 1 is based, which provides the use of upper and lower electrodes 200 arranged in order to imply the entire surface. outside the connecting tubes 110, these electrodes being responsible for the passage of an electric current of 30,000 to 50,000 amps for about 30 to 80 milliseconds to heat the copper and make it flexible to, by applying a compressive force, weld the copper from the flange of the connector tube 110 on the surface of the housing 2 with which it is in contact. It happens, however, that said procedure requires the existence of a flange (111) in the body of the copper spike, that is, the need for additional steps in the process, making it more complex and more expensive compared to the solution proposed in this document.

Another example of the installation of a connecting tube in hermetic compressors was disclosed in document PI0603392-0, in which some previously formed connecting tubes 110 and also necessarily provided with flanges 111 - which constitute the coupling means of the part - are welded directly into the housing 2 of the compressor C by means of the application of electric current through electrodes 200/201. The disadvantages of this procedure are related to the fact that a previous conformation of the flange 111 is required before the welding operation, which requires an additional complex operation for the production process, and is more expensive compared to the solution proposed in this document.

It should be noted that all the procedures of the current state of the art require the introduction of the ends of the connecting tube 110 into the suction and discharge holes of the compressor C. Therefore, it is observed that the current state of the technique lacks of a welding procedure that, in addition to being more efficient, simple and economical, also allows welding between the "upper" type parts, thus eliminating the need for prior conformation of copper pipes for the production of welding flanges and eliminating the need to use addition material for brazing. The current technique also lacks a procedure that allows the shaping and welding of connecting tubes to the compressor housings to be carried out in a single stage and, therefore, significantly faster and cheaper.

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OBJECTIVES OF THE INVENTION

Therefore, it is an objective of this invention to provide a device that at the same time performs the conformation of the flange and the welding of the connecting tubes, said connecting tubes being copper pipes lacking a flange and, therefore, not require prior conformation to its connection (welding) to the compressor housing.

It is also an object of this invention to provide a method for the superior welding between copper connecting tubes and the housing, usually of steel, of the compressors.

Another among the objectives of the present invention is to provide a method that simultaneously performs the conformation of a flange and the welding of the connecting tubes, which preferably uses a servomotor as an element for the generation of force and displacement of the connecting tubes against the housing of the compressor.

It is yet another among the objectives of the present invention to provide a method that uses a stop for the application of compression force to the connecting tube.

Another object of the invention is to provide a method in which welding between the connecting tube and the compressor housing is performed by applying a force in the range of 200 to 500 kgf instead of the force of approximately 1100 kgf used for welding. performed using known techniques.

In addition, it is an object of the invention to describe a welding procedure using a guide pin which, in addition to providing alignment between the connector tube and the housing hole, also prevents the constriction of the gas through hole and the connector tube, during the simultaneous forming and welding stages, also avoiding the deformation of the housing caused by the welding force, because it is executed with a lower electrode with a diameter greater than that of the connecting tube.

SUMMARY OF THE INVENTION

The foregoing objectives are achieved by means of a simultaneous forming and welding device of connecting tubes for compressors according to claim 1, said connecting tubes being defined by substantially cylindrical bodies that are coupled to the existing gas orifices in the gas housing. the compressors that constitute its suction and discharge channels.

In one of the main embodiments of the present invention, said device comprises:

- an upper electrode holder that cooperates with one of the poles of an inverter assembly and with transformers;

- an upper electrode that cooperates with the upper electrode holder and the upper region of the connecting tube;

- a welding force application stop cooperating with the upper electrode holder and with the upper end of the connecting tube;

- a lower electrode holder that cooperates with the other pole of an inverter assembly and with transformers;

- an electrical isolation means that cooperates with the inner surface of the lower electrode holder;

- a lower electrode holder that cooperates with the lower electrode holder and with the compressor housing, the inner diameter of the lower electrode being equal to or greater than the outer diameter of the upper electrode, and

- a centering pin coupled to the internal region of the electrical insulating means and cooperating with the gas through hole of the compressor housing and with the connecting tube.

Also according to one of the preferred embodiments of the invention, the lower electrode holder, the electrical isolation means, the lower electrode and the centering pin comprise the lower components of the forming and welding device.

In addition to the upper electrode holder, the upper electrode and the welding force application stopper comprise the upper components of the forming and welding device.

In summary, the device constructed in accordance with a preferred embodiment of the invention comprises means for allowing superior welding between the connecting tube and the compressor housing.

Preferably, the inside diameter of the connecting tube is equal to the diameter of the gas through hole of the compressor housing.

Also in a preferred manner, the welding force application stop of the instant device operates with an intensity within the range of 200 to 500 kgf, more specifically in the range of 330 to 400 kgf

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Preferably, the upper device allows the application of current pulses without simultaneous displacement.

The objectives of the invention are also achieved by means of a method of forming and welding of connecting tubes for compressors comprising the use of a device for forming and welding of connecting tubes for compressor (see claim 9) in order to perform the following stages:

- placing the upper components of the forming and welding device by coupling the upper electrode around the connector tube, until the stop for force application located inside the upper electrode holder reaches the upper edge of the connector tube;

- actuate the displacement mechanism, preferably a servomotor, to provide the approach of the connecting tube to the surface of the compressor housing using as a position parameter the end of the centering pin that passes through the gas through hole of the housing of the compressor;

- activate the compression and welding force and its maintenance during a stabilization time;

- apply the first pulse of electric current with an intensity ranging between 30 and 50 kA, without allowing the movement of the upper device;

- suspend the current application and allow the displacement of the upper device with a consequent increase in the welding force to form the flange;

- apply the second current pulse effectively consisting of the welding time of the piece;

- suspend the current application with the maintenance of the force application to provide a better welding condition;

- move the upper electrode to the resting position.

It should be noted that this method of forming and welding comprises, in summary, means for forming and welding, simultaneously and on site, the flange for welding the connecting tube to the compressor housing.

Brief description of the drawings

The present invention will be described further below based on the drawings. The figures show:

Figure 1 - an elevation view of a compressor provided with connecting tubes for connection to the tubes of a general cooling system;

Figure 2 - a longitudinal section view of a connector tube used in the current state of the art;

Figure 3 - a schematic section view of the components used in the current state of the art for

weld between the copper connecting tubes and the compressor;

Figure 4 - a longitudinal sectional view of a copper tube that can be used to form the connecting tube by the method of the present invention;

Figure 5 - a schematic sectional view of the components used in the method of forming and welding of connecting tubes of the present invention;

Figure 6 - a diagram of the variables of the welding procedure used in the current state of the art; Figure 7 - a diagram of the variables of the forming and welding process of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention will be described below in detail based on the accompanying drawings, which are given a reference number to facilitate understanding.

The process of simultaneous shaping and welding object of the present invention is aimed at the proper fixing of copper connector tubes 1 to the housing of the hermetic compressors 2, said connector tubes 1 (Figure 4) defined by substantially cylindrical bodies and with external surfaces rectilfneas and uniforms 11 (unlike the connecting tubes 110 of the current state of the art (Figure 2), which must necessarily be pre-assembled to be mounted with flanges 111 to act as a welding surface of the housing 2).

As can be seen in details in the attached figure 5, the shaping device of the present invention is composed, superiorly by an upper electrode holder 3 that acts connected to one of the poles of the inverter and transformer assembly, which keeps coupled, at its end , an upper electrode 4 of substantially cylindrical conformation that engages the upper region of the connecting tube 1. The lower component of the forming device comprises a lower electrode holder 5 connected to the other pole of the inverter assembly and transformers, said lower electrode holder houses a means of electrical insulation 6, centering pin 7 and a lower electrode 8 whose inner diameter is equal to or greater than the outer diameter of the upper electrode 4, in order to prevent the electric current supplied by electrodes 4 and 9 from being applied to the inner point and outside of the housing 2, which could cause premature wear of the centering pin.

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For comparative purposes, it should be clarified that as can be seen in the attached figure 3, in the welding procedure used in the current state of the art, the lower electrodes 201 and upper 200 overlap during welding, resulting in too high heating. which, sometimes, finally also affects the structure of the compressor housing itself, in addition to reducing the service life of centering pin 203, as explained above.

In addition, the current technique requires two separate stages to install the connecting tubes to the compressor housings: a previous stage of forming the same to make the flange, and another to weld the already flanged tubes to the compressor housing. In the proposed invention, the two procedures are carried out simultaneously in a single stage of the procedure, making it faster and cheaper.

As can be seen in Figure 5, with the device and procedure presented here, the welding is done from the top, so that it is possible to use connector tubes 1 with an internal diameter equivalent to the diameter of the gas through hole to which it will be connected the same. With said configuration, the welding surface of the connector tube 1 therefore becomes its lower edge, eliminating the need for the existence of a flange that requires prior conformation of the copper tube. In the present technique, in addition to being necessary the existence of a previously formed flange in the connecting tube, its end must have a diameter that allows its coupling to the male-type hole of the compressor housing (see Figure 3).

In addition to this facility, it should be noted that the use of the centering pin 7 prevents the copper, once made ductile through the passage of electrical current of the electrodes 4 and 9, to find passage and deform the inner region of the hole of the housing 2 , that is, it does not obstruct the passage of gas and, therefore, does not interfere with the performance of the compressor.

Another important point in this document refers to the compression force used to implement the procedure. In the welding processes of the present technique, a compression force of an intensity of approximately 1100 kgf is required. During the application of this force intensity, the application of a single current pulse of 30 to 50 kA is made. The diagram illustrated in Figure 6 graphically shows the variables current, force and displacement of the upper electrode of the known procedures.

In the process of the present invention, due to the construction of the welding device and the preferential use of a servomotor, the compression force necessary for welding the connecting tube 1 preferably comprises from 200 to 500 kgf (i.e., much lower than the one demanded by known procedures). In addition, in the proposed procedure, welding is carried out in two stages, namely, applying two current pulses: the first impulse to heat the copper, making it more flexible, facilitating the stage of forming the flange, and the second Impulse for effective welding. The diagram in Figure 7 schematically illustrates the variables used in the procedure, in addition to illustrating the effects of each stage of the procedure.

Therefore, the stages of the process of forming and welding of connecting tubes for compressors object of the present invention are:

- placing the inner region of the housing 2 of the compressor C in the lower components of the forming and welding device, so that the centering pin 7 is mounted in the through hole of fluid;

- place the connector tube 1 inside the upper electrode 4, until the stop for force application 10 located inside the upper electrode holder 3 reaches the upper edge of the connector tube 1;

- actuate the servomotor to provide the approach of the connecting tube 1 to the surface of the compressor housing 2, using as a position parameter the end of the centering pin 7 that passes through the gas through hole of the compressor housing C;

- activate the compression and welding force, and the maintenance of said force during a stabilization time;

- apply the first pulse of electric current with an intensity ranging from 30 to 50 kA, without allowing the displacement of the upper device, this stage can be called preheating time;

- suspend the current application and the assigned displacement of the upper device with the consequent elevation of the welding force for the conformation of the flange;

- apply the second pulse of current that will effectively consist of the welding time of the piece;

- suspend the application current with maintenance of the force application to provide a better welding condition;

- move the upper electrode to the resting position.

Therefore, at the end of the process, the lower end of the copper connector tube 1 that was formed during the heating provided by the application of electrical current pulses has settled around the gas through hole of the compressor housing and, due to the force applied by the stop, he agreed to it.

The process object of the present invention also has the advantage that, thanks to being shaped at the site, it causes the welding material to be an integral part of the material / body of the connecting tube, thus minimizing the existence of weak points prone to damage. or breaks that could compromise the efficiency of the equipment.

It is noteworthy that, although preferred constructive forms of the present invention have been shown, it is understood that any omission, substitution, inversion of electrical poles and constructive changes can be made by a technician versed in the subject, without departing from the scope of protection required.

10 It should be understood, however, that the description given based on the preceding figures refers only to some of the feasible embodiments for the system of the present invention, while its actual scope is set forth in the appended claims.

Claims (10)

5 10 fifteen twenty 25 30 35 40 Four. Five 1. Simultaneous forming and welding device of connecting tubes for compressors (C), said connecting tubes (1) being defined by substantially cylindrical bodies that are coupled to existing gas through holes in a housing (2) of the compressors (C) , which constitute its suction, discharge and procedure channels, in which said device comprises: - an upper electrode holder (3) that cooperates with one of the poles of an inverter and transformer assembly; - an upper electrode (4) that cooperates with the upper electrode holder (3) and the upper region of the connecting tube (1); - a lower electrode holder (5) that cooperates with the other pole of an inverter and transformer assembly; - an electrical isolation means (6) that cooperates with the inner surface of the lower electrode holder (5); - a lower electrode (8) that cooperates with a lower electrode holder (5) and the compressor housing (2) (C), and - a centering pin (7) coupled to the inner region of the electrical insulating means (6) and cooperating with the gas through hole of the compressor housing (2) (C) and the connecting tube (1) and which It is also characterized by: - a welding force application stop (10) cooperating with the upper electrode holder (3) and the upper end of the connecting tube (1); and the inner diameter of the lower electrode (9) being equal to or greater than the outer diameter of the upper electrode (4). 2. Device according to claim 1, characterized in that the lower electrode holder (5), the electrical isolation means (6) the lower electrode (8) and the centering pin (7) comprise the lower components of the forming device and welding. 3. Device according to claim 1, characterized in that the upper electrode holder (3), the upper electrode (4) and the welding force application stop (10) comprise the upper components of the forming and welding device. Device according to claim 1, characterized in that it comprises means for allowing the upper weld between the connecting tube (1) and the housing (2) of the compressor (C). 5. Device according to claim 1, characterized in that the inside diameter of the connecting tube (1) is equal to the diameter of the gas through hole of the housing (2) of the compressor (C). 6. Device according to claim 1, characterized in that the welding force application stop (10) operates with the intensity within the range of 200 to 500 kgf. 7. Device according to claims 1 and 6, characterized in that the welding force application stop (10) operates with the intensity within the range of 330 to 400 kgf. 8. Device according to claim 1, characterized in that the upper device allows the application of current pulses without simultaneous displacement. 9. Method of forming and welding of connecting tubes for compressors, characterized in that it comprises the use of a device for forming and welding of connecting tubes (1) for compressors (C) according to any one of claims 1 to 8 to perform The following stages: - placing the inner region of the housing (2) of the compressor (C) in the lower components of the forming and welding device, so that the centering pin (7) is mounted in the fluid through hole; - place the upper components of the forming and welding device by means of the coupling of the upper electrode (4) around the connecting tube (1), until the stop for force application (10) located inside the upper electrode holder (3) reach the upper edge of the connector tube (1); - actuate the movement mechanism, preferably a servomotor, to provide the approach of the connecting tube (1) to the surface of the housing (2) of the compressor (C) using as a position parameter the end of the centering pin (7) that passes through the gas through hole of the compressor housing (C); - activate the compression and welding force, and maintain it for a period of stabilization; - apply the first pulse of electric current with an intensity ranging between 30 and 50 kA, without allowing the movement of the upper device; - suspend the current application and allow the displacement of the upper device with a consequent increase in the welding force to form the flange; - apply the second pulse of current which, in fact, consists in the welding time of the piece; - suspend the current application with the maintenance of the force application to provide a better welding condition; - move the upper electrode to the resting position. 10. Method of forming and welding of connecting tubes for compressors according to claim 9, characterized in that it comprises means for welding and forming, simultaneously and on site, the flange for welding the connecting tube (1) to the housing (2 ) of the compressor (C). 10