MXPA98007511A - Heating coil apparatus with power supplies connected in series to heat it material - Google Patents

Abstract

The present invention relates to an induction heating apparatus for heating material in continuous strips. In a first embodiment, there are two coil sections each having a space at one end for the strip material to pass through a section in and out of the heating apparatus further characterized in that the coil sections are adapted for connection to two power supplies, in such a way that the first power supply is connected through a half turn of each coil section and therefore the second power supply, which is connected through the second half turns of the respective ones coil sections and back to the first power supply, all in series. In a second embodiment, the coil sections are adapted for connection to four power supplies in series, each power supply connected to a respective half turn of the coil sections, so that a half turn is connected between each of the four power supplies. The series connection ensures a uniform amplitude and phase of the electric current applied to the induction heating coil apparatus

Description

HEATING COIL APPARATUS WITH POWER SUPPLIES CONNECTED IN SERIES TO HEAT MATERIAL IN STRIPS FIELD OF THE INVENTION The present invention relates to the general field of heating metals by induction and has a particular utility in the field of annealing and galvanizing of materials in continuous strips by induction of heat.

ANTEGEPENT'S OF A TENVENGIQN For a long time »in the metallurgy industry one practice has been the use of induction heating means to anneal and galvanize metals in continuous strips» like strip steel »with other metal coatings (such as zinc or aluminum alloy). zinc) applied as liquids. The induction heat causes an increased bond in the alloy phases between the strip material and the liquid metal coating. The annealed and galvanized metals have known advantages over galvanized metals as the characteristics of better welding and painting as well as improved corrosion resistance. One of the most demanding applications for annealing and galvanizing metal strips by means of induction heating is to heat a metal strip to approximately 454.4 ° to 565.5 ° C after the strip has been galvanized through a zinc bath. . For example, this type of strip is used extensively in automotive body panels. In the patent of E.U.A. 5,495,094"an induction heating coil apparatus adapted for use with materials in continuous strips was described. One aspect of this invention was the configuration of the induction coil sections of the apparatus, including the provision of a space at one end of the apparatus that allowed the stripped material to pass in and out of the coil apparatus without the need of complex door assemblies. Another aspect of the prior invention was that the coil apparatus could be energized by means of separate power supplies to provide opposite currents in the respective half turns of each full turn section of the apparatus. The reference to the patent of E.U.A. 5.495.094 will give the reader a complete understanding of the above apparatus. A modality of the above invention can be used to illustrate the context of the present invention. With reference to Figure 1 hereof, a perspective view of a coil apparatus according to the present invention can be seen that the coil apparatus 10 is a solenoidal structure containing two coil sections 12 »14. A section 12 forms a full turn coil in the upper half of the apparatus »the other section 14 forms the lower complete turn. The upper spool section 12 contains two complementary half turns 16.18 and the lower spool section 14 contains two complementary half spins 20 »22 to form the complete turns of each section of the apparatus. A first power supply 32 drives the upper half turns 18 and lower half 20 in the front portion of the apparatus shown in figure 1 »a second power supply 34 drives the top half 16 and bottom half turns 22 in the back of the apparatus shown in FIG. Figure 1. A first power supply 32 drives the upper half turns 18 and lower half 20 in the anterior portion of Figure i; a second power supply 34 drives the upper half turns 16 and lower half 22 in the rear portion of the apparatus of figure 1. In the previous invention. a complex configuration of interconnection elements was necessary to make the power supply connections to drive the induction of the coil apparatus. Extension portions 24-26 and interconnecting conductors 28-30 were provided to facilitate the connection of two power supplies to drive the coil apparatus. In practice, these conductors increase the complexity of the coil structure; cause greater electrical resistance and resulting current losses »thus reducing the efficiency of the system; and cause an undesirable reactive voltage drop »requiring higher voltages to be generated by the power supplies. The two power supplies 32. 34 are electrically isolated, but must be operated at equal amplitudes in a 180 ° phase relationship to provide the current flows shown in Figure 1 (by means of access road arrows a and b) to the proper operation of the coil apparatus. The need to maintain the amplitude and phase relationships of power supplies requires additional control circuit and system complexity. The present invention is a modification of the configuration of the coil apparatus and the provision of energy sources for the purpose of improving the overall efficiency of the system while reducing its complexity. The simplified interconnector elements of the present invention allow another improvement over the previous invention. The introduction of flexible components in the interconnection elements makes it possible to widely open the space at the opposite end of the coil apparatus to extract the continuous metal strips. The flexible components in the interconnecting elements also provide the ability to make the space that separates the shunt conductors very small during heating. A smaller space reduces the drop in inductive voltage in the shunt conductors, minimizes the magnetic field of dispersion around the space, and increases the efficiency of induction heating.

BRIEF DESCRIPTION OF THE INVENTION The present invention is a coil apparatus for continuous strips of induction heating material. The coil apparatus contains two coil sections in which the complementary half turns of the electrical conductors form two complete turns of solenoid for the material in induction heating strips. A space is provided at one end of the coil apparatus of the strip material to pass through the edge in and out of the coil apparatus. The configuration of the coil sections is adapted for connection to two AC power supplies which are connected in series with the coil sections to each other to ensure the uniform phase and the amplitude of the current applied to the coil apparatus. In a second preferred embodiment of the invention, the coil sections are adapted for connection to four power supplies in a series configuration. More particularly, the invention is an induction heating apparatus for heating the continuous strip material containing a solenoid coil apparatus for the induction by heating containing pr mers and second coil section. Each bobbin section contains first and second complementary half-turns that form an effective complete roll of coil through which the material can pass in strips. The coil sections are arranged longitudinally spaced apart in the direction of the path of the strip material through the apparatus. The first half turn of the first coil section and the first half turn of the second coil section are connected to one end of the apparatus by a first branch conductor. The second half turn of the first coil section is in the same way supplemented at the same end of the apparatus to the second half turn of the second coil section by a second shunt conductor. The shunt conductors are separated from one another by a variable space or a fixed space of sufficient dimension to allow the strip material to pass in and out of the apparatus through the space formed in this manner at said end of the apparatus. The apparatus further contains first and second alternating current power supplies, each with two terminals for connection to the coil apparatus. The first power supply is connected at its first terminal to the first half turn of the first coil section and the other terminal to the second half turn of the first coil section »making said connection at the end of the apparatus opposite the end which It has the conductors in derivation. The connection can be flexible or rigid. The second power supply is in the same way connected to its first terminal to the first half turn of the second coil section, and in the other terminal to the second half turn of the second coil section. The connection of the two power supplies to the coil apparatus forms an electrical circuit in series for the current passing through the coil apparatus at a given time from the first power supply to the first half turn of the first coil section , through a shunt conductor and the first half turn of the second coil section within the second power supply, then from the second power supply within the second half turn of the second coil section to a shunt conductor at the second half turn of the first coil section and returning to the first power supply, said current returns to its address at another time corresponding to an opposite cycle of the AC power supplies. In a second preferred embodiment, a solenoid coil apparatus for induction heating contains first and second coil sections, each coil section containing first and second complementary half-turns that form an effective complete roll of coil through which the material can pass in strips. The coil sections are arranged longitudinally spaced from each other in the direction of the path of the strip material through the apparatus and where each of the half turns of the respective coil sections is separated from each of the other half turns. not being connected to any of them. In this mode there are four power supplies »each connected in electrical series with a half turn of the respective half turns of the coil sections, so a single half turn is connected between each of the power supplies. The connection of the power supplies to the half coil turns is from a first power supply terminal until the first half turn of the first coil section to a second power supply »from the second power supply to the first medium return of the second coil section to a third power supply »from the third power supply to the second half turn of the second coil section to the fourth power supply, and from the fourth power supply to the second half turn the first coil section back to the first series power supply.

For the purpose of illustrating the invention, forms which are preferred herein are shown in the drawings, however it is understood that this invention is not limited to the precise arrangements and instruments shown. Figure 1 is a perspective view of a coil apparatus according to the prior art. Figure 2 is a perspective view of a coil apparatus in accordance with the present invention. Figure 3a is a schematic diagram of the electrical configuration of the coil apparatus of Figure 1. Figure 3b is a schematic diagram of the electrical configuration of the coil apparatus of Figure 2. Figure 4a is a schematic diagram of the electrical circuit of an induction heating coil activated by an inverted power supply of energized current. Figure 4b is a schematic diagram of the electrical circuit of an induction heating coil activated by a supply of inverted voltage fed power. Fig. 5 is a schematic diagram of the electrical circuit of the coil apparatus of Fig. 2. Fig. 6 is a perspective view of one embodiment of a coil apparatus in heating strips adapted for four power supplies. Figure 7 is a schematic view of the electrical configuration of the coil apparatus of Figure 6. Figure 8 is a schematic view of the electrical circuit of the coil apparatus of Figure 6. Figures 9a and 9b illustrate a top view of a symmetrical coil apparatus according to the invention, showing flexible interconnection elements allowing the closed and open positions, respectively. Figures 10a and 10b illustrate a top view of an asymmetric coil apparatus according to the invention, showing flexible interconnection elements allowing closed and open positions.

PESCRTPqSQ FROM A? N? NCIQN Referring now to the drawings, in which similar reference numerals indicate similar elements, FIG. 2 illustrates a form of coil apparatus for heating material in continuous strips 50 in accordance with the present invention. The coil apparatus 50 has upper sections 52 and a lower coil 54 which. together, they form a two-turn solenoid coil apparatus for heating the material in continuous strips »the upper spool section 52 contains two complementary half turns 56» 58 which, in combination, operate as one complete revolution of the solenoid coil apparatus 50. In the same way »the lower spool section 54 contains two complementary half turns 60 as 62. The respective half turns of the spool sections are arranged in such a way that they extend transversely towards the longitudinal axis of the piece of material in strips (not shown in the figure) and on both sides of it. The turned meds 56 »58 containing the upper spool section 52 are not connected to each other at any point, nor the half turns 60. 62 of the lower spool section 54 are connected together. Further, as shown in FIG. 2, the upper half turn 58 in the front part of the upper bobbin section is connected to the lower half turn 60 of the front part of the lower bobbin section 54 of the apparatus 50 through a bypass conductor 64. Similarly, the upper half turn 56 at the rear of the upper spool section 52 (of FIG. 2) is connected to the lower half turn 62 of the lower section 54 at the rear of the coil apparatus 50 through a bypass conductor 66. A space 68 between the respective branch conductors 64 »66 permits movement of the material in continuous strips (not shown) inside and outside the coil apparatus 50. The described configuration establishes the current flow in the coil apparatus in two paths, which are connected in series through of two power supplies 74. 76. The flow of current at a given time is shown by means of the arrows in Figure 2. The current can flow from the lower half-turn 60 to the upper half-turn 58 at the front of the apparatus a through conductor 64. This pattern ensures that the current moves in opposite directions on the front of the device. The same configuration at the rear of the apparatus produces the same result in the upper half turns 56 and lower 62 connected by a lead 66. It can also be seen in figure 2 that the current flows in opposite directions in the two half turns 56 58 of the upper section of coil 52. The same is true of the current in half turns 60, 62 of the lower spool section 54. The opposite current flows in the respective half turns of each spool section which create longitudinal electromagnetic fields through which the piece of strips material passes (not shown). This leads to the maximum and concentrates the eddy currents induced in the workpiece which »on the contrary» cause efficient heating. The coil apparatus 50 is configured for the connection of power supplies to the end opposite the space 68. Each of the four half turns 56 »58. 60. 62 of the upper and lower coil sections 52. 54 contains a conductor of extension 70 terminating in a terminal 72 for connection to one of two power supplies 74. 76. A first power supply 74 is connected to terminals 72 of the upper coil section 52; the second power supply is connected to the terminals 72 of the lower coil section 54. The connection of the power supplies and the coil sections thus form a single electric circuit in series. The connection of the power supplies to the coil assembly is simplified by the placement of the coil elements, extension conductors, and terminals. The energy loss and voltage drop attributable to this connection are reduced to a minimum compared to the previous form of coil apparatus described in relation to figure 1. There is a series circuit, which ensures equal current in all the Coil segments and an adequate phase relationship through the apparatus because the same current flows both in the power supplies and in the coil segments. With rence to Figures 3a and 3b schematically illustrate the difference between the circuit configurations of the apparatus of Figure 1 and that of Figure 2. In Figure 3a. the current paths of the energy supplies 32. 34 are electrically isolated from one another. Each one carries the current in a half turn of the respective upper and lower coil sections. This configuration has the disadvantages that it requires complex circuits to maintain a precise phase and amplitude control in the two power supplies so that they correctly energize the coil apparatus. The configuration of the present invention provides a significant difference and an advantageous placement. In figure 3b. which schematically illustrates the electrical configuration of Figure 2. the first power supply 74 carries the current (the arrow in the figure) into the first half turn 56 of the upper section of the coil, through the branch conductor 66 inward from the half turn 62 which is connected to the second power supply 76. The second power supply 76 carries the current through two other half turns 60 »58 and back to the first power supply 74. The power supplies they are connected in series to each other. with half turns also connected in series. A major advantage of this configuration is that the series connection of the power supplies and the coil elements ensures that the current will be the same and of the correct phase in all the coil elements. The same current flows in all power supplies and in all coil segments in a series circuit. The induction heating energy supplies 74. 76 include resonance charge capacitors that. when connected to the present induction coil apparatus (Figure 2) they form a resonant series circuit. The natural frequency of this circuit is established by the formula F = l / 2tr -f LC The power supplies must have the capacity of operation when they are connected in series with others. This means that all power supplies are synchronized with each other and the resonant current of the series circuit. There are two basic inverted circuit configurations commonly used for induction heating power supplies. Here they are referred to as fed current and powered voltage. Both configurations can be connected in series and can be used in the modalities described. The power supply configurations of fed current and fed voltage are illustrated in Figures 4a and 4b respectively. The output of the power inverter 80 is connected through a capacitor 82 which. together with the induction heating coil 84. forms a resonance circuit. The capacitor 82 is commonly divided into two equal sections in series with the connection to the midpoint connected to an electrical ground, as illustrated in FIG. 4a. The output of the supplied voltage inverter 86 is connected to an isolation transformer 88 having a secondary winding 90 which commonly has a center cover ground connection. As illustrated in figure 4b. the secondary winding 90 of the transformer 88 is connected in series with the circuit consisting of the capacitors 92. 94 and with the induction heating coil 96 which forms a resonant circuit. One of the power supplies connected to an induction coil device, as described herein, must be connected to an electrical ground to minimize the voltage across all coil sections, interconnections, and power supply connections. This is an important feature where the induction heating coil apparatus is used in an environment where arcing or corona discharge could present a hazard. Fig. 5 is the electrical schematic of the first arrangement shown in Fig. 2 where the power supplies are of the configuration of the supplied voltage inverter. Another preferred embodiment of the invention is illustrated in Figure 6. This coil apparatus 100 contains two coil sections 102 »103 having complementary half turns 104» 106 »108» 110 in a solenoidal configuration for the material in continuous heating strips (not shown). At a first end of the apparatus »the extension portions 112 drive the terminals 114 to which two power supplies 116» 118 are connected. In contrast to the previously described embodiment of Figure 3. the opposite end of the apparatus has no shunt conductors connecting the upper coil sections 102 and lower 103. On the other hand, the configuration of Figure 6 enables the connection of two power supplies plus 120. 122 to the device. At the end of each of the four respective half turns 104, 106, 108. 110 of the apparatus, the extension conductors 124 carry the terminals 126 which are connected to the power supplies 120. 122. In the described embodiment, the conductors of extension 124 are placed at a right angle perpendicular to the plane of the workpiece of the strip material (not shown) which moves through the coil apparatus. This positioning provides a longitudinal space 125 between the pairs of the extension conductors. Strip material (not shown) is placed inside and removed from the coil apparatus by a section through space 125. Other arrangements of these extension conductors are possible. The configuration of extension leads 124 and terminals 126 at the second end of the apparatus is such that each of the power supplies 120. 122 is connected to a half turn of the upper spool section 102 and the adjacent half turn of the lower spool section 103. In this embodiment of the invention, the total voltage applied to the induction heating coil apparatus is approximately 4 times the output voltage of each power supply, and the total power sent to the coil is four times the output of each power supply. The ability to send this higher voltage and higher power is especially important when heating very wide metal strips. In this case. the longer coil opening that requires accommodating the wide strip results in a higher coil inductance and thus requires higher coil voltage. The electrical configuration resulting from the apparatus of Figure 6 is another arrangement connected in series of the power supplies and coil elements. Referring to Figure 7. the configuration is illustrated schematically showing the four power supplies and the two coil sections. At a given time, the current in the apparatus is carried from the first power supply 116. to a half turn 104 of the upper section 102. within a second power supply 122 to a half turn 110 of the lower coil section 103 , within a third power supply 118"of another half turn 108 of the lower spool section 103. within the fourth power supply 120. then to another half turn 106 of the upper spool section 102 and back to the first supply 116. In the next cycle of the four AC power supplies, the direction of the current flow is reversed but continues to be in series through each of the half turns of the coil apparatus and the power supplies. . The power supplies used in the embodiment of the invention shown in Figures 6 and 7 are powered current inverter supplies. The power supply of the power inverter was described above and illustrated in Figure 4a. Figure 8 is the electrical schematic of the second positioning of the coil apparatus as shown in Figures 6 and 7 »where the energy supplies shown are powered current inverters. As in the previously described embodiment of the invention, at least one of the power supplies must be connected to an electrical ground to minimize the voltage in all the coil sections, interconnects and power supply connections. Figures 9a and 9b illustrate the use of the flexible interconnection component 170 between the power supplies 74 and 76 and the half coil turns 56. 62 »58» and 60. Figure 9a shows the coil apparatus and the strips 78 in FIG. the heating position, with conductors in branch 64 and 6G close to one another. This configuration improves the performance of the coil by reducing the inductive voltage drop in shunt conductors 64 and 66 and minimizes the scattered magnetic field around the space 68. Figure 9b illustrates the coil apparatus with interconnecting components 170 flexed to provide a wide space 68 between the shunt conductors 64 and 66. In this position, the metal strip 78 can easily pass through the space 68 to enter or remove it from the heating position inside the coil apparatus. Another arrangement, illustrating the use of an electrically flexible conductive junction 200 between the interconnecting components 70. is shown in Figures 10a and 10b. The coil apparatus shown is asymmetric with flexible joint 200 provided in the interconnecting components 70 of only one half of the coil apparatus. Figure 10a illustrates the coil apparatus and the strips 78 in the closed heating position. Figure 10b illustrates the coil apparatus with the flexible joint 200 in the interconnecting elements 70 being open to allow the half of the coil to move to provide a wide gap 68 between the shunt conductors 64 and 66. With interconnecting elements 70 in your position, the strip 78 can easily be inserted or removed from the heating position of the coil. The present invention may be modalized in other specific forms without departing from the spirit and attributes of the essential thereof and "therefore, reference should be made to the appended claims" rather than to the above specification as indicated in the scope of the invention. invention.

Claims (6)

NOVELTY OF THE INVENTION i REIVI DICTIONS

1. - An induction heating apparatus for heating material in continuous strips contains: a solenoid coil apparatus for induction heating containing first and second coil sections »each coil section contains first and second complementary half turns forming a coil full effective return through which the material can pass in strips »where the coil sections are arranged longitudinally, separated one from the other in the direction of the path of the strip material through the apparatus» the first half turn of the first coil section and the first half turn of the second coil section being connected to one end of the apparatus by means of a first shunt conductor, the second half turn of the first coil section being in the same way connected in the same end of the apparatus to the second half turn of the second section of coil for a second conduct or in derivation, said conducting conductors being separated from each other by a space of sufficient dimension to allow the strip material to be placed and removed from one side of the apparatus through a space thus formed at said end of the apparatus; and said apparatus further contains first and second alternating current power supplies each with two terminals for connection to the coil apparatus, the first power supply being connected at its first terminal to the first half turn of the first coil section and in the other terminal to the second half turn of the first coil section, said connection is made at the end of the apparatus opposite the end having leads in derivation, said second power supply being in the same way connected in its first terminal to the first half turn of the second coil section and in the other terminal to the second half turn of the second coil section »said connection of the two power supplies to the coil apparatus form an electrical circuit in series for the current which passes through the coil apparatus at a given time from the first power supply to the first half turn of the first coil section, up to a conductor in series and the first half turn of the second coil section within the second power supply, then from the second power supply within the second half turn of the second coil section to a conductor in Bypassing the second half turn of the first coil section and returning to the first power supply, said current returns its address at another time corresponding to an opposite cycle of the alternating current power supplies.

2. An induction heating apparatus for heating material in continuous strips contains: a solenoid coil apparatus for induction heating contains first and second spool sections »each spool section contains first and second complementary half turns forming a complete turn effective coil through which the strip material can pass »further characterized in that the coil sections are disposed longitudinally» spaced apart from each other in the direction of the path of the strip material through the apparatus »and further characterized because each of the half turns of the respective winding sections is separated from each other of the half turns and not connected to any of them; and four power supplies, each power supply respectively connected in electrical series with a half turn of the respective half turns of the coil sections, so that a half turn is connected between each of the respective power supplies.

3. The induction heating apparatus according to claim 2. further characterized because the connection of the power supplies to the half turns of the coil is from a first power supply terminal until the first half turn of the first coil section to a second power supply »from the second power supply to the second power supply first half turn of the second coil section to a third power supply »from the third power supply to the second half turn of the second coil section to the fourth power supply» and from the fourth power supply to the second half return of the first coil section back to the first series power supply.

4. The induction heating apparatus according to claim 3. further characterized in that the connections between the first power supply and the turns of the coil and the connections between the coil turns and the fourth power supply include an element electrically conductive flexible.

5. The induction heating apparatus according to claim 1 »further characterized in that the connection between the power supplies and the coil turns contain at least one electrically conductive flexible element.

6. The induction heating apparatus according to claim 5 »further characterized in that the connection between the power supplies and the coil turns include a flexible electrically conductive connection.