RU2783626C2 - Welding unit and welding method - Google Patents

Abstract

FIELD: welding.

SUBSTANCE: welding unit is intended for “end-to-end” welding of flexible metal wire. A welding block of the unit is intended for welding of ends of the specified first and second metal wires and formation of a welded joint. Each tool of the unit for processing of the specified welded joint and for testing of the specified welded joint contains an indicator of a completed or uncompleted state for corresponding processing and testing. Before welding process, the first metal wire is clamped in a clamp, indicators of all tools are set to the uncompleted state. The clamp is made with the possibility of release of wire after the transition of all indicators of the mentioned tools to the completed state, which indicates the completion by an operator of all necessary operations and quality control of the welded joint.

EFFECT: unit provides automatization of a welding process and testing with tracking of operations, which are performed during welding; the welding unit provides obtaining a welded joint corresponding to customer’s requirements, while eliminating unintended errors of an operator.

10 cl, 1 dwg

Description

Technical field

The present invention relates to the field of metal wire welding. The metal wire may be a single strand or a wire made up of multiple metal strands. As metals, steel, copper, aluminum or any other metal or alloy can be used, although steel is used as an example in the present description. The metal wire must be bent by hand.

State of the art

Connecting different pieces of metal wire to each other is an unavoidable operation in many processes where metal wire is wound on and off spools. For example, the ends of steel cables, consisting of many steel strands twisted together, sometimes need to be connected to each other. Although various methods of connecting the wire have been proposed, such as tying, twisting (see US3908715) or using a crimp connector or wire braid (WO2013/110360), their common disadvantage is a local increase in the diameter of the wire, which in some cases is invalid.

For example, in the production of tires, a plurality of steel cables are simultaneously spooled on a spool feed frame and fed into a calender where the steel cables are coated with rubber. On the way from the coil to the rubber, the steel cable must pass through narrow holes and dense combs that do not allow the diameter of the steel cable to increase by more than, say, 3%. Any increase in the diameter of the cable at the junction by more than the specified amount will lead to the impossibility of passing the steel cable and its breakage at the junction, or, even worse, to the breakage of the spool frame.

Therefore, welding is still the most preferred method of joining metal wire, in particular the ends of a steel cable, to each other. The requirements that these welds must meet are complex in that the weld must have a diameter no greater than 3% of the original wire rope diameter, must be able to pass small diameter guide pulleys, and must also withstand stretching during processing. .

Unfortunately, steel cables are difficult to weld together because they consist of many thin steel strands that cannot be arranged "end to end", and it is also impossible to provide a flat end surface (unlike metal rods). In addition, the threads are produced from drawn, mechanically hardened steel with a high tensile strength (typically over 2700 N/ ^mm2 ). The steel wire has an elongated pearlite structure. During welding, the ends of the steel wire are first heated slightly below the melting point, and then pressed against each other, after which they are cooled. The resulting metallographic structure upon rapid cooling is martensitic, which is known to be strong but brittle. As a result, the breaking load of the steel cord is never achieved, since the weld is never work hardened, and the breaking load of the weld is about half the breaking load of the steel cable.

By fine-tuning the welding process and the design of the welding machine as described in WO 2015/144427, the Applicant has been able to significantly improve the quality of the welds. However, it is still mandatory to check the weld for its suitability for use, which in the case of a weld means that the weld must have a sufficiently small diameter, be bendable and sufficiently strong. These properties must be confirmed.

The operator may forget one or more of these checks. Forgetting just one of the specified verification operations, for example, checking the diameter when the diameter is larger than the allowable one, can lead to great damage to the consumer. Thus, the authors of the present invention proposed the solution described below.

Disclosure of the essence of the invention

The object of the invention is thus to provide such a welding installation in which the various steps of making and testing the weld cannot be overlooked or forgotten. Another object of the invention is to provide a welding installation in which not the operator, but the installation itself monitors the various operations that must be carried out during the welding process. Yet another object of the present invention is to ensure that each weld meets customer requirements and that unintentional, unintentional errors on the part of the operator of the welding machine are prevented. Another object of the present invention is to provide automation of the welding and testing process. Another object of the invention is to provide a method for operating said welding installation.

In accordance with the first object of the invention, a welding installation is provided according to claim 1. In the context of this description, the term "welding installation" is used to denote equipment that includes one or more tools mounted on a single production stand, preferably mobile. This stand moves around the production area to any area where the welding process needs to be performed. An essential part of the welding installation is, of course, the presence on it at least of the welding equipment itself, which in the following we will call the "welding unit".

The welding machine is used to connect the first metal wire to the second metal wire. When using a welding machine, it is important that these first and second metal wires can be manipulated by hand. By this it is meant that the operator must be able to guide the metal wire to any position without applying excessive force. Thus, the use of this invention for welding rods is excluded. Metal cords, i.e. metal wires consisting of several metal threads with a diameter of less than 5 mm, 10 mm and even 12.5 mm can be welded using the proposed welding machine. Metal cords with a diameter greater than 12.5 mm cannot be welded because they are too stiff to be guided by hand. The metal can be any weld metal such as copper, aluminium, high carbon steel, stainless steel, etc. As already mentioned, steel is taken as an example, but nothing prevents the principles of the present invention from being applied to other metal wires.

The welding unit is designed to weld the end of the first metal wire to the end of the second metal wire, resulting in a weld. To further improve and improve the quality of welds, a number of tools are available on the welding machine. The tools can either serve to process a weld (hereinafter referred to as "processing tools") or to test a formed weld (hereinafter referred to as "testing tools"). The welding installation has at least one or more of these tools. Each of these tools has a "tool indicator". Before starting the welding process, the tool indicators are set to the "incomplete" state. After using a tool, its tool indicator is set to the "completed" state.

A characteristic feature of the welding machine is that it contains a clamp that clamps the first metal wire before the welding process. After the clamp is closed, all instrument indicators are set to the incomplete state. There must be sufficient distance between the closed clamp and the end of the first wire so that the end of the first wire can be easily manipulated with all other tools.

Welding is carried out by clamping the end of the first metal wire in the first welding jaw and the end of the second metal wire in the second welding jaw. The welding clamps can be individually moved along a common guide rail and can be activated with direct or alternating current. The ends of the first and second metal wires are precisely placed in the welding jaws so that their ends exactly match each other when the jaws are moved towards each other. To this end, grooves less than half the diameter of the metal wire are provided in the welding clamps, which serve to accurately align the ends of the metal wires relative to each other.

After the ends of the metal wires are aligned and clamped, an electric current is passed through the point of contact, and the metal wire begins to melt due to the higher resistance at the point of contact of the ends of the wires. When the melting temperature of the metal wire is almost reached, the clamps are pressed against each other at a contact distance. A ball of molten metal forms between the clamps. There are no more individual threads in this ball, as they all merge into a molten ball.

Once the clamps have been pressed together, the current is switched off or at least significantly reduced (see WO 2015/144427, various electric current welding technologies). The weld ball is cooled and the welding is completed. Obviously, since the ends of the metal wires were pressed against each other, while the mass of material remained unchanged, the diameter of the weld is larger than the diameter of the metal wire.

Although the present example deals with electric welding, other welding methods such as flash butt welding or gas welding are not excluded.

After welding, further finishing of the weld seam with machining tools is necessary. Processing tools are, for example:

- As already mentioned, the diameter of the resulting weld is larger than the diameter of the metal wire. To avoid problems during post-processing, it is necessary to repeatedly adjust the diameter of the weld. To do this, for example, a weld can be placed between two semi-cylindrical hammer blocks and hammered until the desired diameter is reached (first diameter adjustment tool). An alternative tool for correcting the diameter is, for example, a grinding or abrasive tool, with which the excess mass of material is removed around the circumference in the area of the weld.

- Annealing tool for annealing the weld Indeed, when steel is used, the metallographic structure of the weld is a martensitic structure, which is hard and brittle. To improve its properties, it is useful to anneal the weld at a temperature of 500°C to 700°C. The resulting recrystallized martensite is more ductile.

- Another processing tool can be, for example, a coating tool, such as a bath containing an electrolyte, or even a brush, with which the area of the weld is covered with, for example, copper to maintain adhesion on the seam. Indeed, any metal coating, such as the brass coating of a steel cable, will melt and penetrate into the weld, and will no longer be only on the outside of the weld.

After using any of the above processing tools, its corresponding tool indicator is set to the "completed" state.

Finishing a weld may require different combinations of machining tools. These combinations are selected depending on the use of the weld and metal cord. Possible combinations are:

- "a", "b" or "c" separately;

- "a and b", "a and c", "b and c" and;

- "a and b and c".

However, the above list of processing tools is not exhaustive, and other processing tools may also be added without departing from the scope of the invention.

In some cases, it may be that the weld, after processing with certain machining tools, is already suitable for further use. When all the necessary processing tools have been used, and thus all tool indicators are set to the completed state, the clamp opens and releases the first metal wire. This weld can be wound back onto the spool of the first or second metal wire and the manufacturing process can be continued.

However, in many cases it is necessary that the weld meet certain requirements in order to be able to carry out further processing operations. Thus, according to another preferred embodiment of the present invention, prior to removal from the clamp, the weld is tested with certain testing tools.

Possible testing tools are, for example:

- Diameter tester to check wire diameter. It can be in the form of a calibration hole through which the weld must pass, or in the form of a measuring (possibly optical) device that determines whether the diameter of the weld corresponds to the required value. If the weld passes the test, the test tool indicator is set to the "completed" state;

- Tester for testing the weld for bending. Such a tester can be made, for example, in the form of a wheel of a certain diameter, through which the weld must pass without breaking. Detection of rotation of the given wheel is used to bring the test tool indicator to the "completed" state;

- Tester for testing the weld for tensile strength. In such a tester, a specified tensile load is applied to the weld, which is considered sufficient for further use of the weld. Of course, this given load must be less than the tensile strength of the metal cord. If the weld can withstand this specified load, the test tool indicator is set to the "completed" state;

- Alternatively or additionally, the electrical resistance of the weld can be tested. This can be important when welding metal cords that need to conduct electricity. If the weld passes the electrical resistance test, the test tool indicator is set to the completed state.

- Alternatively or additionally, the weld can be color tested. The color of a weld is an indicator of whether it has been coated.

As with processing tools, the above list of test tools is not exhaustive, and other tests may also be added without departing from the scope of the invention.

In addition, depending on the intended future use of the weld, it may be sufficient to perform only individual tests such as "d", "e", "f" or "g". Alternatively, two or more tests may be required, such as "d and e", "d and f", "d and g", "e and f", "e and g", or "f and g". In addition, combinations of three tests, such as "e and f and g", "d and f and g", "d and e and g" or "d and e and f", or even all tests may be required. , such as "d and e and f and g".

In the preferred embodiment of the present invention, subsequent testing is automated to eliminate the possibility of any operator error. For example, after welding is completed, the weld is clamped in a tensile strength tester containing bend test wheels, a diameter tester, and/or a color tester. After a predetermined load is applied to the weld, it is guided to bending wheels under stress control during diameter measurement.

In addition, any combination of processing tools ("a" - "c" above) with testing tools ("d" - "g" above) is possible as long as at least one of the testing tools or processing tools is available. A total of 2 ⁷ -1 is possible, i.e. 127 combinations.

It is possible that after the operator's first attempt, the weld will not pass the test. In this case, further processing of the weld may be useful, but in such a case, before correcting the weld, the selective processing tools and testing tools must first be set to an incomplete state. To this end, the welder includes a reset button that selectively resets the tool indicators to an incomplete state without opening the clamp.

For example, all indicators of processing tools and testing tools can be set to an incomplete state. In this case, the operator can only cut the weld and repeat the operation. Alternatively, only the test tool indicator can be set to the incomplete state. For example, if a weld fails a diameter test, further processing of the weld by grinding may allow the diameter test to pass. Of course, after this, all other required tests must be carried out, since a decrease in the diameter of the weld can lead to a decrease in its strength. Therefore, it is recommended to reinstall all indicators of the testing tools together.

Since one end of the metal wire remains fixed in the clamp of the welding machine, dangerous situations can occur if the other end is still wound on the machine's spool. As a safety measure, it is highly recommended to provide an emergency circuit in the design that will immediately open the clamp when activated. A possible emergency circuit is, for example, an emergency button that the operator can press when needed. Even better, the clamp opens automatically when a certain threshold voltage is reached on the clamp, detected by an emergency circuit, for example, using strain gauges installed at the bottom of the clamp.

To avoid misuse of the emergency circuit (for example, to remove a non-compliant weld), the clamp may contain a cutter that cuts the first metal wire before removal. In this case, there is no other choice but to make a new weld. Such a cutter provides an additional safety improvement, since the connection between the first metal wire and the second metal wire is surely broken, and therefore, accidents due to falling or entangling of the wire are eliminated.

According to a second aspect of the present invention, methods for controlling the above-described welding machine are provided. Welding plant management includes the following operations:

- Providing a first metal wire which, for example, comes out of the production machine, and a second metal wire, which, for example, is wound on a coil coming from the production machine;

- Clamping the first metal wire in the clamp of the welding machine while setting all tool indicators to the incomplete state;

- Performing welding by the operator using the welding unit of the welding installation;

- Final processing of the formed weld with the help of processing tools;

- Opening the clamp and releasing the first metal wire, provided that all tool indicators are in the completed state.

Additionally, during operation (d"), the weld can be tested with the test tools after processing with machining tools and before opening the clamp, i.e. the indicators of the machining tools and the indicators of the testing tools must be in the "completed" state.

If something goes wrong during processing or testing of the weld, the reset button can be pressed to repeat any operation after step (b) but before step (e) of releasing the first metal wire from the clamp.

In the event of a safety hazard for the operator, an emergency circuit is activated which re-opens the clamp. The activation of the emergency circuit can be performed by the operator or automatically, for example, when there is too much force on the clamp. In addition, the clip may be provided with a cutter which also cuts off the first metal wire whenever the emergency circuit is activated. This can completely eliminate the risk of entanglement, since there is no longer any connection between the first and second metal wires.

Brief description of the drawings

On FIG. 1 shows an embodiment of a welding installation.

Implementation of the invention

On FIG. 1 shows an exemplary embodiment of a welding machine according to the present invention. It is exemplary in the sense that, as noted in the Summary of the Invention, numerous combinations of processing tools and testing tools are possible. In this example, only one combination is described.

The welding machine 100 includes a stand 122 provided with wheels and able to move across the floor of the manufacturing facility. The welding machine includes a clamp 102, a welding block 104, processing tools 106, 108, and testing tools 110, 112, and 114, described in more detail below. The control unit 116 monitors the state of the status indicators of the various tools and controls the clamp through the line 102'. The design of the welding plant will be described together with the control method to be observed.

The first metal wire 150, for example, its end, comes directly from a wire-making machine, such as a cable-making machine. The second metal wire 150', for example, the end of the metal wire supplied to the spool of the winding machine, is withdrawn. A sufficient length of the first metal wire passes through the clamp 102 and the clamp 102 is closed by the operator. This action sets all instrument indicators to an incomplete state.

First, a weld is formed in the welding block 104. The first metal wire is clamped in the welding jaw 105 and the second metal wire is clamped in the welding jaw 105'. Clamps 105 and 105' are located exactly on the same axis. A weld is formed (depicted as a dot).

The first processing tool is an annealing tool 106. This annealing tool includes two contact pins 107, 107', which allow heating of the wire with electric current. After using the annealing tool 106, the tool indicator of the annealing tool 106 is set to the completed state along line 106'.

The second processing tool is the diameter adjustment tool 108 . In this case, this tool is a hammer-type tool that hammers the weld seam by tapping until the weld has reached the required diameter. After using the hammer tool, its indicator is set to the "completed" state along the line 108'. The weld is now ready for testing.

The first testing tool is the diameter testing tool 110, which measures the diameter of the weld. If the weld diameter is not correct, this is signaled by red light 111. This may require some additional impact hammering 108, but this does not change the status of the hammer tool indicator. If the weld diameter is correct, the lamp 111 turns green and the tool indicator is set to the "completed" state along the line 110'.

The second testing tool is the bend testing tool 112 112. This tool is a rotary wheel 112 on which the weld is moved back and forth to check if it is ductile enough to withstand bending. After performing a sufficient predetermined number of back and forth movements on the wheel 112, the indicator of this tool is set to the "completed" state.

Thereafter, the weld is subjected to a strength test in a tensile strength tester 114. The clamps 114 apply a tensile force to the weld. After the specified load (depending on the specific metal wire) is reached, the indicator of the tensile tester is set to the completed state. If the seam breaks before the specified load is reached, the tool indicator will of course not be set to the "completed" state. If other deviations are detected during tensile tests, such as broken threads in a weld, the indicator of this tester will remain in an incomplete state even when trying to repeat the failed test. In this case, there is no other choice but to cut the weld and reshape it after resetting all tool indicators to the incomplete state using the reset button 120.

After the indicators of all tools move to the completed state, the clamp 102 is automatically opened and the weld can be wound onto the take-up spool. The use of a clamp guarantees the precise and correct execution of all operations (by the principle of "poka yoke" or "error protection").

In the event of an emergency (e.g. wire entanglement), the clamp can be automatically opened by means of an emergency circuit, which in this embodiment is activated by the emergency button 118. The clamp can also be provided with a cutter that cuts off the first metal wire so that no hooking loops were formed.

Although the proposed welding apparatus and welding method has been considered mainly for steel wire rope, nothing prevents the application of this welding apparatus or welding method to other metal wires.

Claims (19)

1. Welding machine for welding the first flexible metal wire with the second flexible metal wire, containing a welding unit for welding the ends of the specified first and second metal wires and forming a weld, as well as at least one tool for processing the specified weld and at least one a tool for testing the specified weld, each of which contains a tool indicator to indicate the completed or incomplete status for the respective processing and testing, characterized in that the welding installation includes a clamp for clamping said first metal wire before the welding process, wherein said clamp is configured to release said first metal wire after the indicator of each of the used processing tools and each of the used testing tools passes to the completed state. 2. Welding machine according to claim 1, characterized in that said one or more processing tools are selected from the group consisting of an annealing tool for annealing a weld, a tool for coating a weld, and a tool for adjusting the diameter of a weld. 3. Welding machine according to claim 1, characterized in that said one or more testing tools are selected from the group consisting of a diameter tester of said weld, a bend tester of said weld, a tensile tester to determine the tensile strength of said weld, a tester for determining the electrical resistance of said weld, and a color tester for determining the color of said weld. 4. Welding installation according to any one of paragraphs. 1-3, characterized in that it is provided with means for selectively resetting the tool indicators to a position indicating an incomplete state, containing a reset button. 5. Welding installation according to any one of paragraphs. 1-4, characterized in that it additionally contains an emergency circuit, upon activation of which the specified clamp for the first metal wire opens. 6. Welding machine according to claim. 5, characterized in that it further comprises a cutter designed to cut said first metal wire before releasing the clamp when said emergency circuit is activated. 7. The method of welding the first flexible metal wire with the second flexible metal wire using a welding machine according to any one of paragraphs. 1-6, which includes the following operations: (a) providing a first flexible metal wire and a second flexible metal wire; (b) clamping said first metal wire in said clamp of said welding machine and setting the indicators of all tools to an incomplete state, while the length of the wire between the specified clip and the end of the first metal wire is sufficient to accommodate the end of the first metal wire in the welding block and manipulation tools for subsequent processing and testing of the resulting weld; (c) butt-welding the ends of said first and second metal wires with said welding block to form a weld; (d) passing said weld through said machining tools to finish said weld; (d') testing said weld in said testing tools; (e) releasing said first metal wire from said clamp, provided that the indicators of all tools used are in the completed state. 8. The method of claim 7, further comprising at any point in time after step (b) and before step (e) the step of selectively resetting said tool indicators to an incomplete state by activating a reset button in case not all of the tool indicators have changed to completed state. 9. The method according to claim 7 or 8, further comprising, whenever step (b) is performed, the step of activating the emergency circuit. 10. The method of claim 7, wherein operation (d') is performed automatically.

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