WO2016071799A1

WO2016071799A1 - Thermal treatment apparatus

Info

Publication number: WO2016071799A1
Application number: PCT/IB2015/058242
Authority: WO
Inventors: Antonio Poli
Original assignee: Echo-Term Srl
Current assignee: Echo-Term Srl
Priority date: 2014-11-06
Filing date: 2015-10-26
Publication date: 2016-05-12
Anticipated expiration: 2017-05-06

Abstract

Described is an apparatus for the thermal treatment of metal products, comprising a plurality of electric heating elements (3) designed to be placed against a metal product to be subjected to thermal treatment, an electricity distribution unit (2), connectable to a power supply network and designed to distribute electricity to the electric heating elements (3), the unit (2) comprising a voltage transformer designed to reducing the supply voltage of the electric current supplied to heating elements (3) and a plurality of outlets (5) for connecting the electric heating elements (3).

Description

DESCRIPTION THERMAL TREATMENT APPARATUS.

Technical field

This invention relates to a thermal treatment apparatus.

More specifically, this invention relates to a transportable apparatus for the thermal treatment of metal products.

Background art

A very widespread use of portable apparatuses for thermal treatment is linked to the construction on site of large mechanical structures, such as turbines, reactors, large equipment.

Similarly, a frequent use is in the construction of pipelines, which can be long ones in the case of, for example, gas and oil pipelines, or grouped together on a site such as, for example, those of a refinery or a chemical plant.

Typically, welding joints made for connecting metal parts are subjected to thermal treatment. The aim of these treatments, meaning heating cycles carried out at predetermined times and at predetermined temperatures followed by cooling, which is performed more or less slowly, is that of making a component adopt the desired crystalline structure as well as eliminating the internal stresses which derive from the various speeds of cooling of adjacent parts, to give it those mechanical characteristics which will be most suitable for its use.

Moreover, before the welding, these parts are pre-heated in order to limit any damage connected to the high temperatures which are reached in a short time during the welding. As well as this, the pre-heating avoids the formation of critical crystalline structures and reduces the porosity of the welding. For the execution of these heating activities, regardless of whether it is pre-heating or a more complex treatment cycle, prior art teaches the use of apparatuses comprising an electricity supply unit which supplies, on different channels, a plurality of heating elements, usually coated with ceramic plates which, positioned in contact with the metallic parts, change the thermal status.

Thermocouples designed to measure the temperature of the parts so as to regulate the switching ON/OFF of the relative heating elements, as a function of the treatment cycle to be followed, are positioned at the parts to be heated.

These apparatuses are usually made in a box-shaped form, easy to transport and simple to use, since they are sometimes used by non- specialised personnel and often in difficult conditions.

The prior art thermal treatment apparatuses supply the heating elements, through the above-mentioned supply units, and switch them ON/OFF using suitable contactors controlled by the thermocouples present on the treatment points.

In other words, as a function of the predetermined thermal cycle, the thermocouples, measuring the temperature at the point subjected to the treatment, control the switching ON/OFF of the electricity supply of the heating elements, using the above-mentioned contactors.

Even though the control performed by thermocouples allows the execution of the thermal cycles, it does not allow a more general checking of the operation the apparatus.

More specifically, the prior art apparatuses are not able support the operator either during setup stage of the apparatus (positioning of the heating elements and their connection to the power supply unit) or during the performance of the thermal cycle.

As mentioned above, individuals using these apparatuses are not always an expert and hence may insert a quantity or type of heating element which does not comply with the characteristics of the electricity distribution unit.

For example, if the operator commits errors, either in the number of heating elements connected (in excess of what each channel could tolerate) or in their connection, the operator receives the system response only after a very long time, sometimes hours, when, for example, it has not been possible to reach a predetermined thermal state at a certain point of the treatment zone. Moreover, this problem may not be resolved immediately as it is necessary to wait for the heating elements to cool down before carrying out any activities.

In effect, a thermal cycle which is not completed must be repeated from the start.

The above-mentioned circumstance is not even to be considered too negative if, even though it results in the loss of hours-work, does not adversely affect the condition of the metal product in question.

On the other hand, it sometimes occurs that the incorrect execution of the thermal treatment/pre-heating cycle generates, for example, stresses such as to deform the metal product or alter its characteristics in an unacceptable manner, thus causing considerable economic losses.

Also with regard to other problems, the thermal treatment apparatuses of known type have not been found to be fully satisfactory. Consider, for example, the case of an overload on a channel for supplying the heating elements; under these circumstances the overload on a channel would cause the overheating of the power transformer of the power supply unit, with consequent switching OFF of the power supply on all the channels.

Also in this case, the result would be to adversely affect, at best, the execution of the treatment cycle, or, in the worst case, the condition of the product. Disclosure of the invention The aim of this invention is to provide a thermal treatment apparatus for metal products which is free of the above-mentioned drawbacks and is, at the same time, structurally simple and practical and effective to use.

The technical features of the invention, in accordance with the above mentioned aim, may be clearly inferred from the contents of the appended claims, in particular from claim 1 and, preferably, from any of the claims directly or indirectly dependent on claim 1 .

Brief description of drawings

The advantages of the invention are more apparent from the detailed description which follows, with reference to the accompanying drawings which illustrate a preferred, non-limiting example embodiment of the invention and in which:

- Figure 1 is a schematic perspective view from above of a thermal treatment apparatus made according to this invention;

- Figure 2 is a block diagram of a preferred embodiment of the apparatus according to this invention.

Detailed description of preferred embodiments of the invention

As illustrated in Figure 1 , the numeral 1 denotes in its entirety a preferred embodiment of an apparatus for the thermal treatment of metal products. The apparatus 1 comprises a unit 2 for the distribution of electricity and a plurality of heating elements 3.

The heating elements 3, of a substantially known type, basically comprise a metal conductor cable 3a covered by combined ceramic elements 3b, which are able to provide a certain flexibility to the heating elements 3. This flexibility is necessary to allow the heating elements 3 to adapt to the shape of the metal product to be subjected to thermal treatment which they are placed against. Contact between the heating elements 3 and the product is in fact necessary in order to transmit to the latter, by conduction, the heat required for performing a predetermined thermal treatment.

The distribution unit 2 is box-shaped and has four wheels 4 emerging underneath at the corners of a relative quadrangular base 2b.

The distribution unit 2 is designed to be connected to an electricity network, not illustrated, for distributing electricity to the above-mentioned heating elements 3, after variation of the parameters of the incoming electricity supply.

More specifically, the unit 2 comprises a power transformer, of known type and not illustrated nor described further, to adapt the voltage supplied to the heating elements 3.

The above-mentioned and not illustrated transformer is designed to lower the input voltage to the value required for the output current, which is normally low voltage.

Preferably, based on the standard values widespread in the sector, the output voltage from the unit 2 is equal to 60 V. Alternatively, this output voltage may adopt different values, such as, for example, 80 V.

Again with reference to the global standards in the sector, all the heating elements 3 are substantially equal, in terms of electrical characteristics, absorbing 2,70 kW at 60V.

As illustrated in Figure 1 , at a relative first lateral face 2I, the power supply unit 2 has six outlets 5 for coupling respective power supply cables 6 of the heating elements 3.

Each outlet 5 constitutes the outlet to the outside of a relative electricity distribution channel, inside unit 2.

On another relative lateral face 2m, advantageously adjacent to 2I which supports the outlets 5, the unit 2 has six panels 7 for controlling respective channels connected to the above-mentioned channels 5.

There is therefore a correspondence between each panel 7, the respective electricity distribution channel and the relative outlet 5. The apparatus 1 also comprises means for check and control of the electricity flowing along the above-mentioned channels and through each outlet 5.

The above-mentioned check and control means comprise, for each distribution channel, a respective inductive sensor, not illustrated, designed to detect the passage of current through the related outlet 5. The above-mentioned check and control means comprise, for each distribution channel, a programmable micro-controller, also not illustrated, designed to measure the instantaneous values of the electric current flowing along each channel and through the related outlet 5.

Advantageously, the above-mentioned and not illustrated programmable micro-controller is designed to transmit a signal representative of the number of heating elements 3 electrically connected to the respective outlet 5.

As illustrated in Figure 1 , the check and control means comprise, for each channel, positioned at the respective control panel 7, a unit 8 for visually indicating the above-mentioned signal representing the number of heating elements 3.

Advantageously, the visual indicating unit 8 comprises a LED (Light Emitting Diode).

At the outlet 5, for each channel, the distribution unit 2 also has a connection 9 for a respective thermocouple 10.

In known manner, the thermocouple 10 is used to check the temperature in the zone of the metal product subjected to thermal treatment.

The apparatus 1 also comprises, housed inside the unit 2, for each channel, a respective computerised unit, not illustrated, for managing the thermal treatment programs of the heating elements 3.

In other words, each above-mentioned and not illustrated computerised unit for management of the thermal treatment programmes manages, by means of suitable contactors positioned on each channel, the switching

ON and OFF of the electricity supply to the outlets 5 and, therefore, to the heating elements 3 connected to it, so as to perform, step by step, the selected heating/cooling programme.

Basically, each computerised unit supplies electricity to the heating elements 3 of the relative channel to perform a predetermined thermal treatment programme, continuously monitoring, through the thermocouples 10, the thermal state of the product undergoing thermal treatment.

As illustrated in the block diagram shown in Figure 2, a low voltage supply line (preferably 400 V three-phase) carries voltage to the distribution unit 2 of the apparatus 1 .

A main switch, schematically illustrated with a block G, intercepts this power supply line inside the unit 2.

Downstream of the main circuit breaker G there is the above-mentioned transformer, shown with a block T, and designed to adapt the input voltage up to the desired value of 60 V.

Downstream of the transformer T there are the above-mentioned means for checking and controlling the electricity flowing through each of the outlets 5.

More specifically, the block marked with S/M represents, for each outlet 5, the above-mentioned inductive sensors, designed to detect the passage of current, and programmable micro-controller, designed to measure the instantaneous values of the electric current flowing.

Downstream of the above-mentioned block S/M there is a block marked P which represents the signalling and protection device (the inductive sensor mentioned above falls within the signalling and control devices). Between these devices there is the above-mentioned unit 8 for visually indicating the signal representing the number of heating elements 3.

The signalling and protection devices also comprise, for each channel, and therefore each outlet 5, a switch, not illustrated in detail, designed to interrupt the flow of electricity along a predetermined channel if the programmable micro-controller detects a fault along the line connected to that specific canal.

Downstream of the above-mentioned signalling and protection devices there are the user devices consisting of the heating elements 3.

The diagram of Figure 2 also illustrates the presence of a control panel Q, consisting in practice of the set of the above-mentioned control panels 7, and by the above-mentioned computerised unit for managing the thermal treatment programs, represented here by a block U.

The diagram of Figure 2 shows a further element of the distribution unit 2, represented by a block REC, comprising an apparatus for recording the temperatures measured by the thermocouples 10, that is, the trend of the thermal cycles.

In use, the apparatus 1 according to this invention, thanks to the means for checking and controlling the electric flowing through each outlet 5, and in particular the above-mentioned and not illustrated programmable microcontroller, allows a continuous control to be made on the functionality of each channel and the activities of the heating elements 3 active on that canal.

In effect, the apparatus 1 , thanks to the check and control means, performs a continuous control on the electrical line of each channel and already after just a few seconds from there being an electric current on each channel, it measures the load, in terms of absorbed power.

After measuring the load installed on each channel, which have for the heating elements 3, as mentioned above, standard absorbed power ratings (2.7 kW for each heating element supplied at 60 V or 3.6 kW for heating elements supplied at 80 V), the microcontroller deduces the number of heating elements 3 actually installed and transfers a corresponding signal to the visual indicating unit 8.

In the case of the preferred embodiment illustrated in Figure 1 , wherein the visual indicating unit 8 comprises a LED, the latter emits a respective signal representing the number of heating elements electrically connected to the respective outlet 5.

For example, according to a preferred embodiment, the above-mentioned LED flashes once to signal the presence, on the respective channel, of one heating element 3, flashes twice to signal the presence of two heating elements 3 and three times to signal the presence of three heating elements 3 connected on that channel.

Advantageously, this type of signalling, not using written characters, does not to be translated into the language known by the operator.

From this simple signalling, the operator immediately receives, during a first switching ON of the apparatus 1 , the correctness, or otherwise, of the relative activities.

For example, if three heating elements have been connected on a channel and the LED flashes twice, signalling the recognition of only two heating elements 3, it will be deduced that a heating element 3 is not correctly installed or is faulty and further checks will therefore be made.

On the other hand, if the signal emitted by the LED agrees with the number of heating elements installed, the operator will receive confirmation of the correct activity and may proceed to the final activation of the thermal treatment cycle.

Another functionality of the microcontroller is that of disconnecting the load on a predetermined channel if the number of heating elements is greater than that allowed. In this case, the signal emitted by the LED advantageously, by way of an example, consists of a series of fast flashing lights.

The invention thus fulfils the proposed aim and achieves important advantages.

A first advantage is that the operator is immediately aware, at the start of the thermal treatment cycle, of the presence of any problems regarding the connection to or faults in the heating elements. A second advantage is due to the opportunity, by using this diagnosis, of avoiding damage to the internal components of the machine.

Another advantage linked to the use of the apparatus according to this invention is that it avoids overloads even during the thermal treatment. If in effect, for example, an overload occurs during the thermal cycle, the check and control means protect the apparatus by isolating only the channel in which the overload has been generated, the remaining channels continuing to be supplied normally. This is not the case with machines currently on the market, in which a similar situation determines the switching OFF of the power supply of the entire machine.

Claims

1 . An apparatus for the thermal treatment of metal products, comprising:

- a plurality of electric heating elements (3) designed to be placed against a metal product to be subjected to thermal treatment,

- an electric energy distribution unit (2), connectable to a power network and designed to distribute said energy to said plurality of electric heating elements (3), said unit (2) comprising a voltage transformer designed to regulate the supply voltage of the electric current supplied to said heating elements (3) and a plurality of outlets (5) for the connection of said plurality of electric heating elements (3), characterised in that it comprises check and control means for the electric energy flowing through each of said outlets (5).

2. The apparatus according to claim 1 , characterised in that said check and control means comprise, for each of said outlets (5), an inductive sensor designed to detect the passage of current through the outlet (5).

3. The apparatus according to claim 1 or 2, characterised in that said check and control means comprise a programmable micro-controller designed to measure the instantaneous values of the electric current flowing through each of said outlets (5).

4. The apparatus according to claim 3, characterised in that said programmable micro-controller is designed to transmit a signal representative of the number of heating elements (3) electrically connected to the respective outlet (5).

5. The apparatus according to claim 4, characterised in that said check and control means comprise, for each of said outlets (5), a unit (8) for visually indicating said signal representative of the number of heating elements.

6. The apparatus according to claim 5, characterised in that said visual indicating unit (8) comprises a LED.

7. A method for implementing a thermal treatment on a metal product, comprising the steps of:

- preparing an apparatus according to any one of claims 1 to 6,

- positioning a plurality of electric heating elements (3) at a metal product to be subjected to thermal treatment,

- connecting said electric heating elements (3) to an electric energy distribution unit (2) of said apparatus,

- activating check and control means for detecting the electric load flowing through each of said outlets (5).

8. The method according to claim 7, characterised in that it comprises the step of detecting the passage of current through an outlet (5) of said unit and transmitting a signal representative of at least the number of heating elements (3) electrically connected to said outlet (5).

9. The method according to claim 8, characterised in that it visually indicates the number of heating elements (3) electrically connected to an outlet (5) of said unit (2).

10. The method according to claim 8 or 9, characterised in that it visually indicates overloading of an outlet (5) of said unit (2).