CN219459326U - Electromagnetic induction hot plate for vulcanizing machine - Google Patents

Abstract

The utility model discloses an electromagnetic induction hot plate for vulcanizing, which comprises the following components: the device comprises a heated plate body, an electromagnetic coil and a magnetic stripe; an electromagnetic coil is arranged between the heated plate body and the magnetic stripe, and the heated plate body, the coil and the magnetic stripe are separated by a heat insulating plate; the heated plate body is arranged at the top of the bracket, the magnetic stripe is fixed on the bracket, and the electromagnetic coil is bonded into a disc shape through an adhesive and is arranged on the bracket. The principle of eddy current heat generation in the high-frequency alternating magnetic field is utilized in the application, the induction coil, the magnetic stripe shape, the arrangement mode and the plate structure are reasonably analyzed and designed, the problem of heating dead zones is well solved by introducing local heat conduction oil as temperature buffer, and the improved structure has the advantages of high energy utilization rate, higher controllability and higher vulcanization uniformity.

Description

Electromagnetic induction hot plate for vulcanizing machine

Technical Field

The utility model relates to the technical field of vulcanizing machines, in particular to an electromagnetic induction hot plate for vulcanizing.

Background

The traditional flat vulcanization adopts the mode of passing through superheated steam and heating the sidewall by means of steam heat conduction to provide the external temperature of tire vulcanization, but the heat energy dissipation is serious in the whole process, so that the heating efficiency of the traditional flat vulcanization is lower. The steam heating itself is uneven, which can cause uneven vulcanization of the sidewalls.

In the tire vulcanization process, the development of the vulcanization process tends to be efficient and energy-saving, the vulcanization process is subjected to two developments of an isothermal and isobaric vulcanization process and a variable temperature vulcanization process from the technical condition, the vulcanization medium is changed from superheated water to nitrogen, and the vulcanization shaping medium is also changed from single high-temperature steam to a novel nitrogen shaping process. For a hot plate type steam vulcanizing machine, high-temperature superheated water enters the inside of a capsule according to the instruction of an industrial controller PLC to provide internal temperature and internal pressure necessary for vulcanization; the inner cavities of the upper hot plate, the lower hot plate and the die sleeve are filled with high-temperature steam to provide vulcanized external temperature.

The hot plate type steam vulcanizing machine has the advantages in the actual production process:

1) The pressure stability is high in the mold closing process, so that the stress of the tire can be ensured to be uniform everywhere;

2) The steam heating ensures that the capsule has good shaping and stretching properties.

Has the disadvantages that:

1) The equipment damage frequency is high, and particularly, a balance valve, a sizing table and the like;

2) The energy consumption is high, high-temperature steam is introduced into the upper hot plate and the lower hot plate, a large amount of heat energy is lost in the conduction process, and a large amount of water resources, coal, natural gas and other fuels are consumed by adopting steam for heating.

At present, energy-saving transformation of an upper hot plate and a lower hot plate of a steam vulcanizing machine can be mainly divided into four types: adding energy-saving heat preservation device, improving hot plate mechanism, replacing heating medium and changing heating mode. For adding the energy-saving heat preservation device, the principle is that the heat preservation devices are arranged on the periphery of the upper hot plate and the lower hot plate, so that the workshop temperature can be reduced, the heat dissipation can be reduced, the heat isolation is completed by 70-80% through the first air heat preservation device, and the rest heat isolation is completed by the second layer of polyester glass fiber. However, the vulcanizing machine is large in size, so that the heat insulation material used for the whole vulcanizing machine is high in cost and difficult to reconstruct a unit. For the improvement of the hot plate structure, CN201720979U,2011-01-26 refers to an energy-saving hot plate mechanism consisting of a supporting plate and a heat transfer plate, a heater is arranged on the heat transfer plate, the supporting plate is positioned above the heat transfer plate, a vacuum layer for blocking heat transfer and a reflecting layer for reflecting heat are sequentially arranged between the supporting plate and the heater from top to bottom, and the device enables the heat emitted by the heater to be fully utilized. CN201800174U,2011-04-20 refers to an integral hot plate formed by pairing upper and lower main plates, wherein the upper and lower main plates form a curved steam channel between each boss and rib plate, so that the device has good tightness and uniform steam heat transfer. However, although these methods have been advanced in energy saving, the heated state of the contact portion between the tire and the hot plate is improved only for the hot plate mechanism, and the non-uniformity of heating of the tire has not been improved yet. For replacing heating medium, the industry uses conduction oil to replace traditional high temperature steam heating. Although high-temperature steam has good thermodynamic performance, a great deal of heat energy is lost due to process conditions and pipeline arrangement, a steam system can reach the temperature required by vulcanization under relatively high pressure, and a conduction oil system is a low-pressure closed type circulating operation system, so that the heat loss is small theoretically, and the heating temperature of vulcanization can be reached under normal pressure. For changing the heating mode, a far infrared heater, an electric constant temperature heater, an electromagnetic induction heater and the like are mainly used for replacing the high-temperature steam heating hot plate. The far infrared heating device comprises a tank body and a locking device, wherein far infrared is positioned in the pipe body, and the device has high energy utilization rate and small pollution. The electric constant temperature heating method is to place an electric heater between the inner mold and the outer mold and add a heat insulating layer, and the device can ensure the vulcanization quality but has high energy consumption and influences the energy saving effect. In the electromagnetic induction heating method disclosed in CN2798486Y and 2006-07-19, an electromagnetic induction coil is arranged, an alternating magnetic field is generated under the action of alternating current, a closed loop is generated through a steel die, vortex-shaped induction current is formed, and electric energy is converted into heat energy through an in-die resistor to be heated. The heating mode has the advantages of high heat conversion efficiency, rapid heating, environmental protection and the like, but because the electromagnetic heater has high unit price and high maintenance cost, whether electromagnetic radiation is harmful to people or not when electromagnetic wave heating is used for a long time is still to be questioned.

Electromagnetic induction heating replaces the existing steam heating, and electromagnetic induction transformation of the upper and lower hot plates is realized. The structure of the original upper and lower die closing and the capsule operating mechanism are not changed in the reconstruction process, and only the upper and lower hot plates are used as reconstruction objects. Performing electromagnetic induction eddy current loss, energy density and magnetic field density simulation by using SolidWorks three-dimensional modeling software and Ansoft Maxwell electromagnetic simulation software through establishing a temperature model, and performing thermal analysis and thermal calculation according to simulation results to obtain that the heat generation of the hot plate is in direct proportion to the current frequency; the heating dead zone appears in the heating annular region, and the homogenization of hot plate heating can not be realized in pure electromagnetic induction structure transformation.

Disclosure of Invention

In view of this, the utility model is to solve the problems of heating dead zone and uneven vulcanization temperature of electromagnetic induction structure, take heat conduction oil with good thermal stability as heat transfer medium, refer to the steam channel of the upper and lower hot plate originally, redesign the plate body, let in the heat conduction oil in the plate body, make the temperature distribution of the contact surface of plate body and sidewall even.

In order to achieve the above object, the present utility model provides the following technical solutions, including: the device comprises a heated plate body, an electromagnetic coil and a magnetic stripe; an electromagnetic coil is arranged between the heated plate body and the magnetic stripe, and the heated plate body, the coil and the magnetic stripe are separated by a heat insulating plate; the heated plate body is arranged at the top of the bracket, the magnetic stripe is fixed on the bracket, and the electromagnetic coil is bonded into a disc shape through an adhesive and is arranged on the bracket.

Preferably, in the electromagnetic induction hot plate for vulcanization, the magnetic strip has an L-shaped structure.

Preferably, in the electromagnetic induction hot plate for vulcanization, the bracket and the heat insulation plate are made of nonmetallic materials with high temperature resistance, high impact resistance, high electric resistance and good processing manufacturability.

Preferably, in the electromagnetic induction hot plate for vulcanizing machine, the heated plate body has the same size as the lower hot plate of the vulcanizing machine.

Compared with the prior art, the utility model discloses the electromagnetic induction hot plate for vulcanizing, which reasonably analyzes and designs the shape, arrangement mode and plate body structure of the induction coil, the magnetic stripe by utilizing the principle of eddy current heat generation in a high-frequency alternating magnetic field, and well solves the problem of heating dead zone by introducing local heat conduction oil as temperature buffer.

Drawings

In order to more clearly illustrate the embodiments of the present utility model or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present utility model, and that other drawings can be obtained according to the provided drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic view of the structure of a lower hot plate of a steam vulcanizing machine.

FIG. 2 is a schematic view of the lower plate.

Fig. 3 is a schematic cross-sectional view of the present utility model.

Fig. 4 is a schematic diagram of the front view structure of the present utility model.

Fig. 5 is a schematic top view of the present utility model.

Fig. 6 is a schematic view of the structure of the separator of the present utility model.

FIG. 7 is a schematic view of the press-vulcanization mold closing structure of the present utility model.

FIG. 8 is a graph showing the change of the heating temperature of the heat transfer oil according to the present utility model with time.

Fig. 9 is a schematic view of the heat generating process of the modified plate body of the present utility model.

Detailed Description

The following description of the embodiments of the present utility model will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present utility model, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

Referring to fig. 1-9, an electromagnetic induction hot plate for vulcanizing is disclosed.

When the upper and lower hot plates 2 enter vulcanization heating, the pneumatic cut-off valve firstly introduces compressed air, and the high-temperature steam in the main pipeline is connected to the steam inlet 33 of the hot plate, so that the pipeline arranged inside the hot plate is sequentially filled with the high-temperature steam. The steam pressure sensor can detect the steam pressure of the pipeline and send the steam pressure into the control system, and the switch position of the electric regulating valve can be adjusted according to the detected pressure value through the relation between the steam pressure and the temperature rise. The pneumatic cut-off valve on the branch pipeline is normally open when cutting off the gas, the temperature sensor transmits the detected signal to the PLC, and when the detected temperature is higher than a set value, the pneumatic cut-off valve for controlling the steam to enter is closed by introducing compressed air; when the measured temperature is lower than the set value, the pneumatic cut-off valve controlling the steam to enter will cut off the compressed air to be opened. The steam type upper and lower hot plates 2 have the structure shown in fig. 1, the sizes of the upper and lower hot plates 2 are approximately the same as the distribution of the pipelines for introducing steam inside, and the tire is placed on the lower hot plate 2. The central structure of the tire vulcanizer is also called a bladder 1 handling structure, and functions to load the bladder 1 into the green tire before vulcanization, and to release the tire from the lower mold and strip it from the bead after vulcanization. When the tire is vulcanized, the mold closing, heating and vulcanization are realized by means of the vertical up-and-down movement of the upper mold part, the upper mold is vertically lifted to open the mold after vulcanization, the internal structure of the lower hot plate 2 of the steam vulcanizing machine is shown in figure 2, a closed and recyclable steam channel is formed by the upper plate body, the lower plate body and the internal cavity for the lower hot plate 2, high-temperature steam enters and exits through a steam inlet 33 and a steam outlet 4 which are arranged on the periphery of the lower hot plate 2, and the steam outlet and the steam inlet are separated by a partition plate 8 so as to form an effective steam circulation channel. Firstly, steam enters the hot plate through the steam inlet 33 of the hot plate, and fills the edge position of the hot plate; the cavities at the edge of the hot plate are distributed along the circumference, most of the rest cavities are distributed radially along the radial direction, the central position close to the capsule 1 is sequentially filled with steam after the edges are filled, all the cavities in the hot plate from the steam inlet 33 to the steam outlet 4 are filled, and the lower hot plate 2 can be heated through the high-temperature steam heat exchange hot plate body. The distribution of the cavity channels in the lower hot plate 2 is beneficial to forming an effective steam circulation channel, the available space is large, a large amount of water vapor can be introduced, and the heat exchange efficiency is improved.

In order to further optimize the above technical solution, the present application uses the hot plate 2 as a research object, and it can be seen from fig. 1 and 2 that the pneumatic bladder 1 and its corresponding operating mechanism are installed in the central position, and the hot plate is only responsible for heating the sidewall, and in practical design, the heating of the contact portion between the hot plate and the sidewall is also considered, so that the coil is wound into a space ring shape in design, and its size corresponds to the side surface of the tire. The heating principle of the electromagnetic induction structure of the plate body-coil-magnetic stripe 10 is shown in fig. 3, the rectified high-frequency alternating current passes through the annular induction coil to form a closed alternating magnetic field of the plate body, and when magnetic force lines pass through the plate body, alternating current, namely eddy current, is formed. The eddy current makes the plate body generate heat energy to automatically heat at high speed, so that the purposes of quick temperature rise and uniform heating of the plate body are achieved.

In order to further optimize the above technical solution, for the lower hot plate 2, the electromagnetic induction structure is shown in fig. 4 and mainly consists of three parts: a heating plate body, an electromagnetic induction coil 9 and a ferrite magnetic strip 10. The size of the heating plate body is the same as that of the original lower heating plate 2, the diameter is 1200, and the unit is mm; the electromagnetic coil is wound into a circular ring shape in an Archimedes spiral line mode, and the inner diameter and the outer diameter are respectively 450mm and 900mm; the ferrite magnetic strip 10 has the size of 250×50×15, the unit is mm,15 is in a circular array around the center of the circle, and the number is 8. The heated plate body 7 is separated from the coil and the magnetic strip 10 by a heat insulating plate, and the heat insulating plate prevents the heat of the heated plate from transferring heat to the coil, so that the performance is affected by overheat of the induction coil; on the other hand, the plate body is supported to prevent the coil and the magnetic stripe 10 from bearing pressure. The L-shaped magnetic strip 10 is fixed on the bracket, and the coil is also bonded into a disc shape by the adhesive

On the support, the support serves to fix the relative position of the induction coil and the magnetic stripe 10. In terms of spatial arrangement, the hot plate is located at the uppermost layer as a heating object, the electromagnetic induction coil 9 layer is centered, and ferrite is located at the last layer in view of improving thermal efficiency and reducing magnetic leakage. The ferrite magnetic strip 10 is arranged on the outermost layer, on one hand, the alternating current magnetic field is shielded outwards, and magnetic interference to other ferromagnetic materials is avoided; on the other hand, the magnetic strip 10 can collect magnetic field and increase the magnetic field strength generated by the coil because the magnetic permeability is far higher than that of air.

In order to further optimize the technical scheme, the design of the induction coil is as follows:

(1) The cross section of the induction coil calculates the electromagnetic induction coil 9 required for the hot plate in an environment of high temperature, the formation of which is on the one hand the heat conduction of the hot plate generating heat by eddy currents and on the other hand the joule heat generated by the coil itself, so the following considerations must be taken into account in the choice of material for the coil:

1) The coil material is high-temperature resistant and has simple processing process;

2) The coil does not or as little as possible heat during operation.

According to electroengineering theory, the cross-sectional area of the current-carrying wire has the following relation with the magnitude and density of the current passing through the current-carrying wire:

a—the cross-sectional area of the current carrying wire (mm 2); i-the current magnitude (A) of the current carrying wire; j-current density (A/mm 2); p-is added to the coil; v-the voltage (V) applied to the coil. From the above equation, it can be seen that, in the case that the current I passing through the coil is constant, the area of the coil cross section is inversely proportional to the current density, and the larger the current density is, the smaller the calculated cross section area is, and the single copper wire diameter and the number of copper wires on the bonding surface can be determined by the calculated cross section area a. To avoid excessive eddy current heat generated by the coil and improve the quality factor Q of the circuit, the smaller the diameter of the single copper wire is, the larger the winding difficulty is, the higher the processing cost is, the diameter is selected, and the number of copper wires of the bonding surface can be determined according to the sum

(2) The simulation and spatial arrangement of the induction coil eddy fields creates a simple model in the process of studying the spatial arrangement of the electromagnetic induction coils 9: a single annular energizing coil is disposed above the metal plate body in an annular array without a ferrite core. Three-dimensional vortex field eddy current loss simulation is carried out by using AnsoftMaxwell software, and the simulation result can be seen: the eddy current heat losses are densely distributed around the energized coil and have the same shape as the induction coil.

Thus, it can be concluded that: the arrangement in the archimedes spiral line mode can apply a magnetic field to the plate body and generate eddy current heat, but the distance between adjacent coils is required to be small, so that the coils are tightly wound in actual design, dense electromagnetic induction heating is realized in a heating annular area, and the uniformity of heat distribution of a heated area is improved.

(3) The peak voltage born by the enameled wire is higher, usually higher than 600V, and the heat insulation material cannot insulate heat to normal temperature when the enameled wire is used, so that the working environment temperature is higher, and the enameled wire is required to be designed according to the temperature higher than 180 ℃, so that the economical enameled wire with high insulating strength, high temperature resistance and double-layer paint films is required to be selected. Several common enamelled wires were compared for performance according to the above requirements:

TABLE 1 relevant performance parameters of enamelled wires

And finally, adopting the Q (ZY/XY) -2 type polyester imide and polyamide imide composite paint as enameled wires of the induction coil through parameter comparison.

(4) Selection of induction coil adhesive

The electromagnetic induction coil 9 is an archimedes spiral line in space, the service life and the working state of the coil can be directly influenced by the use of an adhesive, and the following requirements are put forward on the adhesive due to the actual high-temperature environment:

1) High temperature resistance, low curing temperature and short curing time;

2) The electric resistance is high;

3) No toxicity or low toxicity;

4) Proper concentration and moderate price.

According to the research on the performance parameters of some binders, the applicability of the materials is comprehensively considered, and the related performance parameters of the alternative materials are summarized in table 2:

table 2 relevant performance parameters of the binder materials

And finally, modified epoxy resin is selected as the binder by combining the vulcanization temperature of the sidewall with the high temperature resistance, the bonding strength degree and the like of the binder.

(5) Measures to avoid overheating of induction coils

In the electromagnetic induction heating process, the induction coil generates joule heat due to the self resistance under the action of high current, and if the corresponding cooling treatment is not performed on the heating of the coil, the continuous temperature rise of the induction coil can lead to the rise of the resistivity, so that more serious temperature rise is caused.

In order to prevent the induction coil from being excessively high in temperature rise, the coil adopts a copper tube, and water is cooled in the copper tube, so that the temperature rise of the induction coil can be effectively reduced, and the current carrying density of the coil is improved.

For the selection of the copper tube cross section, the ring effect of the alternating current and the arrangement of the coils are considered. The ringing indicates that a maximum current density occurs inside the annular conductor when alternating current flows through the annular conductor. The rectangular section copper tube is closer to the heating element than the current region of the circular section copper tube, so that the gap between the rectangular section induction coil and the heating element is smaller, and a rectangular section copper tube is actually selected.

To further optimize the above solution, the design of the ferrite strip 10

(1) U-shaped ferrite magnetic field simulation

According to the principle of electromagnetic induction, an alternating magnetic field is generated under the action of alternating current, and the alternating magnetic field forms a closed magnetic loop with the hot plate through the ferrite magnetic strip 10, and eddy-current-like induction current is formed in the hot plate. In order to study the distribution of magnetic lines of force passing through the ferrite magnetic stripe 10 in an alternating magnetic field, the process of generating electricity and magnetism is simplified, a coil wound by an Archimedes spiral is simplified into a single electrified solenoid, a U-shaped ferrite magnet is selected for magnetic field simulation, one end of the U-shaped ferrite is wound with the electrified solenoid, a simple model is established, and electromagnetic field simulation is carried out by using Ansoft Maxwell software. Simulation results show that ferrite plays a role in magnetic concentration in the process of generating electricity and magnetism, and the magnetic field distribution at one end close to the electrified coil is obviously denser and more energy than that at one end far away from the electrified coil. Under the action of the ferrite magnets, magnetic induction lines are densely distributed along the arrangement direction of the ferrite magnets, the magnetic fields are highly concentrated, and the magnetic field distribution is weaker as the distance from the ferrite magnets is farther. However, in the practical hot plate modification, the heat-receiving plate body 7 is only separated from the induction coil and the magnetic stripe 10 by a layer of heat-insulating material, magnetic force lines in the magnetic field are relatively dense, so that the rapid temperature rise of the induction metal material can be realized, and the magnetic stripe 10 is reasonably arranged along the circumferential direction, and is arranged in an annular array mode at 45 degrees, 8 magnetic stripes 10 are arranged, so that the uniformity of heating of the induction metal can be realized.

From the simulation results, it can be seen that the different ways of winding ferrite by the coil can have different effects on the distribution of the magnetic field, and the closer the coil is to the magnet and the denser the magnetic force lines and the larger the energy are at the position of the coil where the current is firstly introduced. And the iron metal material has obvious magnetism gathering effect.

(2) Selection of the material of the L-shaped ferrite strip 10

The magnetic strip 10 layer has the functions of shielding magnetic field outwards and gathering magnetic field inwards, so as to further form closed magnetic lines of force to improve magnetic efficiency, reduce magnetic pollution caused by outward leakage of the magnetic lines of force, and combine magnetic field simulation of a U-shaped magnet and structural design of a strip-shaped magnet, and in practice, an L-shaped magnetic strip 10 is adopted as shown in fig. 5.

The choice of ferrite core directly affects the inductance of the induction coil and the quality factor Q of the circuit, i.e. affects the degree of heating of the ferrite core itself during operation, and in turn affects the heating of the hot plate. The ferrite core operates under the conditions of high temperature and high magnetic field, which requires that the ferrite core have a high curie temperature, a low temperature coefficient, a high saturation strength, a low power loss and a proper initial permeability to achieve a corresponding inductance. Through experiments on different ferrite materials, the selection is carried out according to the performance parameters of the ferrite materials. The temperature coefficients of the Mn-Zn, mn-Zn-Cu and Ni-Zn materials are all in the range of-20 to 180 ℃, and according to the researches on Curie temperature, magnetic saturation strength, power loss, initial magnetic permeability and inductance of the materials, the most suitable ferrite core material of the Mn-Zn (A) is considered.

TABLE 3 relevant Performance parameters of ferrite materials

In order to further optimize the technical scheme, the heat insulation plate and the selected heat insulation plate of the bracket mainly ensure that the coil is not influenced by heat conduction of the plate body, the heat insulation plate is positioned in the area where the magnetic field of the induction structure is most concentrated, and particularly the heat insulation plate has the function of heat insulation, so that the material of the heat insulation plate cannot be selected from metal materials capable of generating eddy current heat. 21 in practice, synthetic resin fibers commonly used in factories can be used to insulate heat to 80 ℃.

The bracket plays a role in fixing the relative positions of the coil and the magnetic stripe 10 in the electromagnetic induction structure of the plate body, the coil and the magnetic stripe 10, and as the metal in the alternating magnetic field can generate eddy current, the bracket material cannot be a metal-selected plastic material which meets the structural design, and the requirements are that:

1) High temperature resistance, no deformation after long-time use at high temperature of about 80 ℃, and softening temperature of 200 ℃;

2) The impact resistance is high;

3) The electric resistance is high;

4) The processing technology is good. Based on these requirements, the properties of some plastic materials were compared:

table 4 relevant performance parameters of the stent plastic material

The comparative PBTP type plastics in the table above were selected for use as scaffold materials.

4. Selection of the material of the heat-receiving plate body 7

In the electromagnetic induction structure, the heat receiving plate 7 is the object of eddy current heating. When high-frequency current passes through the induction coil, the current generates a strong high-frequency resonance magnetic field near the coil, and a plate body close to the induction coil generates iron loss heat, and the calculation formula is as follows:

P _υ ＝P _h +P _c +P _e ＝K _h f(B _m ² +K _c (fB _m ) ² +K _c (fB _m ) ^1.5 (3-2)

wherein P is _υ -core loss (W); p (P) _h -hysteresis loss (W); p (P) _c -eddy current loss (W); p (P) _s -excess core loss (W); k (K) _h -hysteresis loss factor, related to ferromagnetic substance material; k (K) _c -eddy-current loss coefficient, related to resistivity and geometry of the ferromagnetic substance; k (K) _s -an excess core loss factor; f-operating frequency (Hz); b (B) _m -saturation induction (T) of ferromagnetic substances.

The higher the working frequency f and the saturation induction intensity, the larger the conductor thickness, the lower the resistivity and the larger the heat conduction coefficient, and the larger the heat generated by the conductor and the faster the heat generation. Magnetic permeability also plays an important role in terms of eddy current heating. When selecting the material of the heat-receiving plate body 7, iron, aluminum and Q45 commonly used in practice are used as the study objects, and preliminary selection is made for magnetic permeability and heat conductivity, respectively. In terms of magnetic permeability, magnetic media are classified into paramagnetic, diamagnetic, and ferromagnetic. When the induction coil generates a high-frequency alternating magnetic field, the antimagnetic (copper and the like) generates an induction magnetic field which is opposite to the antimagnetic under the action of an external magnetic field, so that the electron magnetic moment vector of the antimagnetic is approximately zero, and the paramagnetic (aluminum and the like) also generates the same effect; the magnetic field in the ferromagnetic substance is superposition of the external magnetic field intensity and the induction magnetic field intensity, the value after superposition is far greater than the original external magnetic field intensity, and the synthetic magnetic field condition of the magnetic medium is shown in figure 5, so that the iron is easier to form a strong synthetic magnetic field under the action of the external magnetic field relative to the aluminum, and larger vortex is obtained, thereby meeting the requirement of rapid temperature rise. Aluminum is used as paramagnetic material, the internal composite magnetic field is close to zero and cannot be fixedly magnetized, but eddy current can be formed in metal, so that the magnetic field is passively formed, and when alternating current disappears, the eddy current effect disappears, and the magnetic field correspondingly disappears. Considering that the purpose of replacing the heating mode with electromagnetic induction heating is to improve the heat efficiency to save energy, the heat transfer capability during the heating of the plate body affects the actual heating condition, and the heat transfer coefficients of the candidate materials at normal temperature are shown in table 5:

TABLE 5 relevant performance parameters of plate materials

It can be seen from the table that aluminum has a much higher thermal conductivity than iron and better heat transfer properties. Iron and aluminum have advantages and disadvantages in combination with magnetic conductivity and heat conductivity coefficient, and are selected by combining with factors such as bearing capacity, rust speed and the like.

In order to further optimize the technical scheme, the heat transfer oil is used for replacing the traditional high-temperature steam, and although the traditional high-temperature steam has good heat transfer performance, a great amount of heat loss can be caused by the phase change of the steam; and for the heat conduction oil, the cyclic heating is a closed forced circulation process, so that a higher temperature can be obtained under a lower pressure, and the heat efficiency is high, the temperature rise is fast and the energy-saving effect is good in the circulation process. The design temperature of the upper and lower hot plates of the steam vulcanizing machine is 203.5 ℃, the working temperature is 188 ℃, the initial temperature is 20 ℃, the heat conductivity coefficient is 58W/(mm. DEG C.), the specific heat capacity is 460J/(Kg. DEG C.) and the density is 7.8Kg/m3.

Considering the highest use temperature of the conduction oil, model YD-300 was selected for the study of the heating mode using the conduction oil as a medium, and specific heat capacity and density values at different temperatures are shown in table 6, which increase with increasing temperature, but decrease with increasing temperature.

TABLE 6YD-300 values of heat transfer oil specific heat capacity and Density at different temperatures

The flow rate of the heat conduction oil in the heating furnace tube is generally 2-4m/s, and the heat conduction oil is in a laminar flow state due to the fact that the flow rate is too low according to fluid mechanics knowledge, so that the service life of the heat conduction oil is shortened; when the flow rate is increased to a certain value, the heat transfer efficiency of the heat conduction oil is greatly improved when the heat conduction oil is in flocculation flow, but the pressure on the pipe wall is increased when the flow rate is too high. The flow rate of the heat transfer oil is generally 1.5m/s.

According to an empirical formula, the relationship between cure temperature and cure time can be formulated:

in the formula, the vulcanization time when the temperatures of T1 and T2 are T1 and T2 respectively, K is a vulcanization temperature coefficient, and 2 is usually taken. From this empirical formula, it is estimated that the vulcanization time between vulcanization temperatures is reduced by half when the vulcanization temperature is increased by 10 ℃.

When the upper and lower hot plates of the tire are clamped, the direct contact heat transfer between the hot plates and the sidewalls occurs in an annular region between 450mm and 780mm in diameter. The position 390mm away from the center of the plate body is inward a closed heating area formed after die assembly, and outward is a hot plate area which is not directly contacted with the heat for heat exchange with the air. As shown in FIG. 7, 390mm from the center of the plate belongs to a cold-hot junction area, the temperature distribution gradient is large, the change is complex, and the thermal analysis is selected.

The transient temperature field analysis of the initial temperature of 20 ℃ is carried out at the position 390mm away from the center of the plate body, the change of the temperature with time is shown as figure 8, the temperature curve heated by the heat conduction oil is in an upward convex shape, the temperature rise is faster, and the increase with time is smooth. Therefore, the heat conducting oil can meet the requirements of high heat efficiency, temperature rise, energy saving and the like. In addition, the heat conduction oil is heated without pressure operation, and the control is relatively simple and easy.

Before transformation, the induction coil and the magnetic stripe are combined to generate an alternating magnetic field above, the plate body generates induced electromotive force to generate heat by eddy current, and the direct heating of the plate body is utilized to heat the sidewall during die assembly; however, after the modification, the internal structure of the board body is designed, as shown in fig. 9, which corresponds to dividing the board body into three layers: an induction heating layer, a heat conducting oil layer and a conduction heating layer. The heat conducting oil is used as a heat medium, and the induction heating layer generates eddy current heat, but the heat conducting oil is heated by the induction heating layer due to uneven temperature distribution caused by arrangement of magnetic strips and coils, so that the heat conducting oil has good heat stability as the heat medium, and the temperature distribution to the metal surface of the conductive layer is even.

Two heating stages before modification: an electromagnetic induction heating plate body and a plate body heat the side surface of the tire; three heating stages after modification: the lower part and the lower part of the electromagnetic induction heating plate body are transferred to the upper part and the upper part through heat conduction oil to heat the side surface of the tire.

In the heating of a steam type hot plate, heat conduction oil replaces steam by the advantages of good heat stability, quick temperature rise, high heat efficiency and the like, and is heated in a heating furnace and is introduced into the hot plate under the pressure action of a hydraulic system. In this context, the heat transfer oil is used as a good heat medium to homogenize the heating of the plate body, so as to improve the phenomenon of uneven heating of the outside of the annular region caused by the electromagnetic induction direct heating plate body. The difficulty of the hydraulic system is increased by combining the structural design, and the heat conduction oil which is locally static is added in practice

The application is mainly aimed at improving and optimizing the heating dead zone of electromagnetic induction, and local heat conduction oil is introduced for temperature buffering. Firstly, the superior performance of heat conduction oil in the existing heat conduction oil heating system of the vulcanizing machine is researched; then, combining the heating requirement of an induction structure and the performance parameters of the heat conduction oil, and selecting Therminol VP-1 type, a static state and decoking measures for the heat conduction oil in an optimized structure; finally, the simulation of the optimized structure proves that the improved electromagnetic induction structure can improve the energy utilization rate and lead the tire to be heated uniformly.

The transformation of electromagnetic induction heat conduction oil of a hot plate of a steam vulcanizing machine is proposed according to the problems of large energy consumption and uneven heating of tire steam vulcanization in actual production. Compared with the original steam vulcanizing machine hot plate, the principle of eddy current heat generation in a high-frequency alternating magnetic field is utilized in the method, the shape, arrangement mode and plate body structure of the induction coil and the magnetic stripe 10 are reasonably analyzed and designed, the problem of heating dead zones is well solved by introducing local heat conduction oil as temperature buffer, and the improved structure has the advantages of high energy utilization rate, higher controllability and higher vulcanization uniformity. By studying the structure in this application, the following conclusion was reached:

1) The following hot plate 2 is a study object, and the electromagnetic induction structure selects a mode that the plate body, the induction coil and the magnetic stripe 10 are sequentially arranged from top to bottom so that the magnetic field is gathered above and isolated below, thereby effectively improving the utilization rate of the alternating magnetic field and avoiding magnetic pollution from being generated outwards.

2) By researching the eddy current loss and the energy density of the three-dimensional eddy current field of the electromagnetic induction structure, the eddy current distribution characteristic is obtained: an annular heating area corresponding to the induction coil area is formed on the plate body, the unit energy density distribution is octagonal along with the magnetic stripe 10, and the unit energy density decreases from inside to outside, so that a heating dead zone is necessarily generated.

3) And the heat conduction oil is introduced into the heating device to buffer the temperature between the plate body and the heated tire, so that the heat imbalance caused by direct contact heating is avoided, and the heat conduction oil has the characteristics of quick temperature rise and higher heat stability, so that the heating dead zone problem can be remarkably improved as a heat medium.

4) The PID control idea is adopted to realize more accurate control of the temperature in vulcanization heating. Through study and research on the improvement of electromagnetic induction heat conduction oil of a steam vulcanizing machine hot plate, which is the subject of the utility model, finally, the aim of realizing efficient heating by electromagnetic induction is basically achieved, and the heat uniformity is realized by combining simulation software such as basic theory deduction, ansys, ansoftMaxwell, matlab simulink and the like and simulation and analysis of modeling software such as CAD, UG and the like, further optimizing the structure and finding out a mode for solving a heating dead zone. And the response speed of the system is researched through researching the control thought, so that the control mode of the electromagnetic induction technology is more reasonable.

Based on the research of the application, the actual test can be carried out on the electromagnetic induction heat conduction oil transformation of the steam vulcanizing machine hot plate by constructing an experimental platform, and the design of the induction coil, the shape of the ferrite magnetic stripe 10 and the temperature control system are further optimized. Through the following experiments, mainly consider:

1) Problems of distribution density of coils and number of magnetic strips 10: through the arrangement of the Archimedes spiral lines with the same density of the coils and the annular array of 8 magnetic strips 10, the efficient heating of an annular heating area is basically realized, but the heating dead zone appears, so that the plate body is heated to present non-uniformity, and although local heat conduction oil is introduced as a heat transfer medium, the number of the magnetic strips 10 and the distribution density of the coils at different positions still need to be continuously tested and adjusted in the design process, so that the heat generation is better.

2) Heat dissipation problem of coil and mechanical structure design problem of whole induction structure: in this context, the temperature of the coil surface is reduced by means of water cooling of a rectangular-section copper tube, but the feasibility is still to be tested in practice. The improvement needs to consider reasonable assembly of the heat insulation plate to the bearing capacity of the plate body, the structure of the bracket for fixing the coil and the magnetic stripe 10 and the mechanical structure in space.

3) Temperature control problem: in the method, the temperature model transfer function is approximated to a first-order inertia link and a pure hysteresis link is connected in series because the whole heating process is heated in a complex manner and the specific numerical value is unknown, so that the stability of the system is ensured and PID parameter calculation is convenient, the pure hysteresis link is approximated to the first-order inertia link, and finally, the overshoot of the system is reduced and the system is more stable. However, in practice, the determination of parameters in the transfer function is performed by performing a least square method calculation, and the calculation mode of the PID correction parameters is also more complicated.

4) Determination of electromagnetic induction power supply power: it is theoretically necessary to determine the power consumed by the temperature rise to 188±n ℃ and the power required to maintain a constant temperature. But in practice it still needs to be tested.

In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant points refer to the description of the method section.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present utility model. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the utility model. Thus, the present utility model is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (3)

1. A vulcanizer electromagnetic induction hotplate, comprising: the device comprises a heated plate body, an electromagnetic coil and a magnetic stripe; an electromagnetic coil is arranged between the heated plate body and the magnetic stripe, and the heated plate body, the coil and the magnetic stripe are separated by a heat insulating plate; the heated plate body is arranged at the top of the bracket, the magnetic stripe is fixed on the bracket, and the electromagnetic coil is bonded into a disc shape through an adhesive and is arranged on the bracket.

2. The vulcanizer electromagnetic induction hotplate of claim 1, wherein the magnetic strip is an L-shaped structure.

3. The vulcanizer electromagnetic induction hotplate of claim 1, wherein the heated plate body is of a uniform size as the lower hotplate of the vulcanizer.