Composite roller bar type roller hearth furnace

Abstract

The application discloses a composite roller bar type roller bottom heating furnace. The heating furnace is provided with a furnace body, comprising: a plurality of steel roller bars, a plurality of ceramic roller bars, and a plurality of groups of eddy current refrigeration bearing seats; the plurality of steel roller bars are arranged in parallel in a material sheet heating area in the furnace body; the plurality of ceramic roller bars are arranged in parallel in a rapid discharging area in the furnace body; the plurality of steel roller bars are respectively supported by the plurality of groups of eddy current refrigeration bearing seats; after the material sheet enters the furnace body, the material sheet is conveyed by the plurality of steel roller bars, and then conveyed by the plurality of ceramic roller bars after passing through the material sheet heating area, and then passes through the rapid discharging area. In this way, the problem of coating corrosion of the ceramic roller bar is solved, and long-term stability of the heating furnace capacity and high qualified rate of products are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hot steel plate conveying, in particular to a composite roller bar type roller hearth furnace. BACKGROUND

[0002] Press Hardening (PD) technology, as one of the mainstream directions of automobile lightweight technology, is applied more and more widely in the manufacturing industry of passenger car body parts.

[0003] The roller hearth furnace is one of the key equipment of the hot forming production line. The roller hearth furnace is used for heating the sheet to completely austenitize and conveying the sheet to the next process. The furnace generally consists of a sheet feeding roller platform, a furnace body, furnace rollers, a sheet discharging roller platform, a heating system and an electric control system. The sheet is fed from the sheet feeding roller platform, conveyed and enters the furnace body, heated in the furnace body, and then quickly conveyed to the sheet discharging roller platform for forming and quenching process.

[0004] The furnace roller refers to a plurality of ceramic rollers (also known as furnace rollers) arranged in parallel across the furnace body. The ceramic roller nodulation is the main cause of furnace failure and thus reduces production efficiency.

[0005] According to statistics, in a certain hot forming production line, about 330 ceramic rollers are equipped for each furnace, and about 180 rollers are damaged due to coating corrosion every year, with a direct economic loss of about 360,000 yuan. There are currently 200 hot forming production lines in China, and 30-50 new production lines are built every year, so replacing the damaged rollers will cause huge direct and indirect economic losses. SUMMARY

[0006] In view of the above problems of the prior art, the present application provides a composite roller bar type roller hearth furnace to solve the problem of coating corrosion of ceramic rollers.

[0007] The composite roller bar type roller hearth furnace provided by the present application is provided with a furnace body, comprising:

[0008] a plurality of steel rollers, a plurality of ceramic rollers and a plurality of groups of eddy current refrigeration bearing seats;

[0009] The plurality of steel rollers are arranged in parallel in the sheet heating area in the furnace body;

[0010] The plurality of ceramic rollers are arranged in parallel in the rapid discharging area in the furnace body;

[0011] The plurality of steel rollers are respectively supported by the plurality of groups of eddy current refrigeration bearing seats;

[0012] After the sheet enters the furnace body, it is conveyed by the plurality of steel rollers, and after passing through the sheet heating area, it is conveyed by the plurality of ceramic rollers, and passes through the rapid discharging area.

[0013] Further comprising: a first roller driving device;

[0014] The plurality of steel rollers are driven by the first roller driving device to rotate at a first rotating speed, so that the material sheet is conveyed at a first linear speed.

[0015] Further comprising: a second roller driving device;

[0016] The plurality of ceramic rollers are driven by the second roller driving device to rotate at a second rotating speed from the first rotating speed, so that the material sheet is conveyed at a second linear speed from the first linear speed; wherein the second linear speed is a positive integer multiple of the first linear speed.

[0017] Further, the steel roller is a hollow structure, which comprises two roller heads at both ends and a roller body between the two roller heads;

[0018] The roller body is used to hold and convey the material sheet;

[0019] The two roller heads are used to be supported by two eddy current refrigeration bearing seats respectively.

[0020] Further, the eddy current refrigeration bearing seat comprises:

[0021] A shell is provided with a cold gas passage, the cold gas passage is provided with a first end and a second end;

[0022] An eddy current refrigeration structure is provided with a compressed gas inlet and a cold gas outlet, the cold gas outlet is in communication with the first end;

[0023] The shell is provided with a bearing mounting hole, the bearing mounting hole is mounted with at least one bearing, the roller head is connected with the bearing, and a cavity is formed between the surface of the roller head and the bearing mounting hole;

[0024] After the compressed gas is sent into the compressed gas inlet, the cold gas is output through the cold gas outlet, the cold gas is transmitted through the cold gas passage, and is discharged into the cavity at the second end.

[0025] Further, when the steel roller is supported to rotate by the two eddy current refrigeration bearing seats oppositely arranged on both sides of the furnace body, the cold gas discharged into the corresponding cavity at the second end cools the inner sides of the two roller heads of the rotating steel roller respectively.

[0026] Further, the second end comprises at least two first type blind holes extending along the radial direction of the bearing mounting hole, and the through end of the first type blind hole is located on the surface of the bearing mounting hole;

[0027] The first end comprises at least one second type of blind hole extending radially along the bearing mounting hole, or at least two third type of blind holes extending axially along the bearing mounting hole.

[0028] Further, when the first end comprises at least one second type of blind hole extending radially along the bearing mounting hole,

[0029] The cold gas passage further comprises a transition part connecting the first end and the second end, and the transition part comprises at least two third type of blind holes extending axially along the bearing mounting hole.

[0030] Further, the heat preservation pipeline is further provided.

[0031] The vortex refrigeration structure further comprises a hot gas outlet.

[0032] After the compressed gas is fed into the compressed gas inlet, the hot gas is output through the hot gas outlet, and the hot gas is delivered to the furnace body through the heat preservation pipeline.

[0033] Further, the vortex refrigeration structure further comprises:

[0034] The ceramic bracket is arranged directly below the steel roller and is used for supporting the steel roller after radial deformation.

[0035] These and other aspects of the present application will become more fully understood in light of the following detailed description of (one or more) embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0036] Various features and aspects of the present application will be further clarified with reference to the following description of embodiments. The drawings are exemplary, some features are not shown in actual scale, and some features in the drawings can omit conventional features in the field of the present application and are not essential to the present application, or additional features are shown which are not essential to the present application. The combination of various features shown in the drawings is not intended to limit the present application. In addition, throughout the specification, the same reference signs refer to the same elements. The specific drawings are as follows:

[0037] Figure 1 It is a perspective view of the composite roller type roller bottom heating furnace in the embodiments of the present application;

[0038] Figure 2 It is a front view of the composite roller type roller bottom heating furnace in the embodiments of the present application;

[0039] Figure 3 It is a perspective view of the vortex refrigeration bearing seat in the embodiments of the present application;

[0040] Figure 4 It is a perspective view of the vortex refrigeration bearing seat in the embodiments of the present application;

[0041] 10. upper loading roller platform; 20. furnace body; 30. eddy current refrigeration bearing seat; 31. housing; 31A. first type blind hole; 31B. second type blind hole; 31C. third type blind hole; 32. bearing mounting hole; 33. mounting stop; 34. eddy current refrigeration structure; 34A. compressed gas inlet; 35. bearing; 36. blocking plug; 40A. upper heater; 40B. lower heater; 50. eddy current refrigeration gas source pipeline; 60. lower loading roller platform; 70. steel roller; 70A. inner roller head; 70B. outer roller head; 70C. bearing section; 80. ceramic roller. DETAILED DESCRIPTION

[0042] The words "first", "second", "third", etc., or "module A", "module B", "module C" and the like in the specification and claims are used only to distinguish similar objects, and do not represent a specific order or sequence of the objects. It is understood that the specific order or sequence can be changed, if permitted, so that the application described herein can be implemented in an order other than that illustrated or described herein.

[0043] The term "comprising" as used in the specification and claims should not be interpreted as limiting to the elements listed after it; it does not exclude other elements. Thus, it should be interpreted as specifying the presence of the stated features, integers, components or groups but does not preclude the presence or addition of one or more other features, integers, components or groups thereof. Thus, the expression "a device comprising means A and B" should not be interpreted as being limited to a device consisting only of means A and B.

[0044] The phrase "one embodiment" or "an embodiment" appearing in the specification is intended to mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the application. Thus, the appearances of the phrase "in one embodiment" or "in an embodiment" in various places in the specification are not necessarily all referring to the same embodiment, but can refer to different embodiments. Furthermore, the particular features, structures, or characteristics can be combined in any suitable manner in one or more embodiments.

[0045] Some vehicle body parts are made of high-strength steel sheets. The strength of high-strength steel sheets usually reaches 1300-1500 MPa. Because of its high strength, it cannot be formed by cold bending, and is usually hot formed and quenched after heating. To avoid oxidation during heating, the hot-formed steel sheet can be coated with a hot-dip Zn-Al-Si coating or a hot-dip Al-Si coating.

[0046] Generally, each roller in the furnace passes through the bearing seat embedded in the furnace body at both ends, supported by the bearing arranged in the bearing seat. When the roller bottom heating furnace heats the hot forming steel plate coated with a coating, the furnace temperature of the sheet heating zone is often as high as 950℃, and the roller body temperature of the roller rotating in situ also reaches 950℃. The product after the coating of the sheet is melted will adhere to the ceramic roller, destroy the organization structure of the ceramic (such as the main component of the coating is aluminum silicon, the ceramic roller is a porous structure, mainly composed of silicon oxide and aluminum oxide, which is similar to the compatible product after melting) and form nodules or cause partial area material loss. After the roller size changes, it will cause the instability of the sheet conveying, and in severe cases, it will cause the front and rear stacking of the sheet or the large deflection of the sheet and cannot be transferred to the next process, ultimately affecting the yield and qualification rate of the product. Finally, when the corrosion is more serious, the roller will break and malfunction. If the broken roller is not replaced in time, the broken roller will swing under the drive of the roller driving device, which may continuously roll and impact the through hole on the side wall of the furnace body, damage the heat insulation layer or the heat preservation layer of the furnace body. The broken roller may also hit the lower heater below the roller way, causing damage to the lower heater.

[0047] Therefore, the application provides a composite roller type roller bottom heating furnace. In different areas of the furnace body, according to the melting characteristics of the coating, rollers made of heat-resistant steel and ceramic are selected respectively. In the front half of the heating furnace, steel rollers made of heat-resistant steel are selected to avoid the corrosion problem of the original ceramic rollers. The problem of the broken ceramic roller hitting the heater arranged below the roller way can also be avoided. In the rear half of the heating furnace, ceramic rollers are used to meet the requirement of rapid sheet discharge. In this way, the use of rollers made of two materials is beneficial to prolong the service life of the roller, reduce the operating cost of the heating furnace, improve the equipment operation stability and production efficiency.

[0048] The composite roller type roller bottom heating furnace in the embodiment of the application will be described in detail below with reference to the accompanying drawings.

[0049] As shown in Figure 1 and Figure 2 , the composite roller type roller bottom heating furnace of one embodiment of the application comprises a feeding roller platform 10, a furnace body 20, an upper heater 40A, a lower heater 40B, a plurality of steel rollers 70, a plurality of ceramic rollers 80, an eddy current refrigeration bearing seat 30, a discharging roller platform 60 and an eddy current refrigeration gas source pipeline 50.

[0050] As shown in Figure 1 and Figure 2As shown, the plurality of steel roller bars 70 are arranged side by side in the sheet heating area inside the furnace body; the plurality of ceramic roller bars 80 are arranged side by side in the rapid discharge area inside the furnace body; the plurality of steel roller bars 70 are respectively supported by a plurality of groups of eddy current refrigeration bearing seats 30; after the sheet enters the furnace body, it is conveyed by the plurality of steel roller bars 70, and after passing through the sheet heating area, it is conveyed by the plurality of ceramic roller bars, and passes through the rapid discharge area.

[0051] Specifically, each steel roller bar 70 is supported by a corresponding group of two eddy current refrigeration bearing seats 30 arranged on both sides of the furnace body 20 after passing through the furnace body 20.

[0052] Generally, after the normal temperature sheet enters the furnace body through the feeding roller platform 10, it is gradually heated in the sheet heating area and heated to a preset temperature, and the coating of the sheet is melted at the end of the sheet heating area. In the rapid discharge area, the sheet is kept warm and is rapidly conveyed, and after passing through the end of the rapid discharge area, the sheet is rapidly conveyed to the discharging roller platform 60 outside the furnace body. That is, the chamber inside the furnace body, the sheet heating area is before the rapid discharge area, and the rapid discharge area is before the sheet heating area.

[0053] Generally, the plurality of steel roller bars 70 arranged side by side in the sheet heating area constitute a first group of furnace rollers and support the sheet. For example, 150 to 250 steel roller bars 70 are arranged in the sheet heating area.

[0054] Specifically, the heating furnace further comprises: a first roller bar driving device; the plurality of steel roller bars 70 are driven by the first roller bar driving device to rotate at a first rotating speed, so that the sheet is conveyed at a first linear speed.

[0055] Specifically, the first roller bar driving device comprises a first driving motor and a first chain; each steel roller bar is provided with a sprocket at its driving end, and all the steel roller bars are driven in series by the first chain. In this way, each steel roller bar rotates at a first rotating speed in situ, and the sheet located in the sheet heating area is conveyed along the first group of furnace rollers at a first linear speed.

[0056] In some embodiments, in the sheet heating area, a lower rotating speed can be set according to process requirements to achieve the need for sufficient heating.

[0057] Specifically, a tensioning structure can also be provided, and the tightness of the first chain can be adjusted at any time through the tensioning structure, which will not be described again.

[0058] Above, in the sheet heating area of the first half of the heating furnace, the use of steel roller bars avoids the corrosion problem of ceramic roller bars after the coating of the sheet is melted.

[0059] Generally, the plurality of ceramic roller bars 80 arranged in parallel in the rapid discharge area constitute a second group of in-furnace roller and support the sheet. For example, 150 to 250 ceramic roller bars 80 are arranged in the rapid discharge area.

[0060] Specifically, the heating furnace further comprises: a second roller bar driving device; the plurality of ceramic roller bars 80 are driven by the second roller bar driving device to rotate at a second rotational speed from the first rotational speed, so that the sheet is transported at a second linear speed from the first linear speed; wherein the second linear speed is a positive integer multiple of the first linear speed.

[0061] Specifically, the second roller bar driving device comprises a second driving motor and a second chain; each ceramic roller bar is provided with a sprocket at the driving end thereof, and all the ceramic roller bars are driven in series by the second chain. In this way, each ceramic roller bar rotates in situ to transport the sheet located in the rapid discharge area along the second group of in-furnace rollers. Specifically, a tensioning structure can also be provided, and the tightness of the second chain can be adjusted at any time through the tensioning structure, which will not be described here.

[0062] Specifically, the second driving motor drives each ceramic roller bar to rapidly increase from the first rotational speed to the second rotational speed, so as to transport the sheet transported to the rapid discharge area along the second group of in-furnace rollers at the second linear speed.

[0063] The speed control strategy of the second driving motor is illustrated by taking a group of sheets transported from the heating area to the discharge roller platform through the rapid discharge area. Generally, the sheet will undergo a transition process from being completely supported by the steel roller to being completely supported by the steel roller. In this transition process, the sheet experiences a state of being supported by at least one steel roller, and finally switches to a state of being supported by at least one ceramic roller after being simultaneously overlapped on at least one adjacent steel roller and at least one ceramic roller. In order to realize the smooth transition of the sheet on the roller, the second driving motor first drives the ceramic roller to rotate at the first rotational speed to transfer the workpiece from the coating melting zone of the heating area to the rapid transport area. After detecting that the sheet has left the steel roller and is completely supported by the ceramic roller, the second driving motor accelerates from the first rotational speed to the second rotational speed and drives the ceramic roller to rotate at the second rotational speed, so that the sheet is transported to the discharge roller platform at the second linear speed.

[0064] In this way, in one rapid transport cycle, each ceramic roller rotates at the first rotational speed in situ and then rotates at the second rotational speed. Specifically, the second rotational speed is 6 to 10 times the first rotational speed. For example, the second rotational speed of the ceramic roller rotating in situ is 300 revolutions per minute, and the second rotational speed of the steel roller rotating in situ is 30 revolutions per minute.

[0065] In some embodiments, in the rapid discharge area, a servo motor can be used to achieve precise speed control, control the roller to start and stop quickly, and meet the requirements of rapid discharge.

[0066] In the above, in the rapid discharge area of the second half of the heating furnace, ceramic rollers are used. The ceramic rollers have good high-temperature strength, small thermal deformation, and good straightness, which can improve the straightness of the material sheet transmission, increase the speed of the material sheet transmission, and meet the process requirements of the material sheet rapid discharge from the furnace to the discharge platform.

[0067] In this way, a complete heating and conveying process is as follows: the material sheet is fed from the feeding roller platform, enters the furnace body, is heated and slowly conveyed to the rapid discharge area in the material sheet heating area under the conveying of the first group of furnace rollers, and the product after the coating of the material sheet is melted and adheres to the surface of the steel roller, and then gradually falls into the furnace bottom; the steel roller rotates at high speed, and the material sheet is rapidly discharged from the furnace to the discharging roller platform under the conveying of the second group of furnace rollers.

[0068] Specifically, the steel roller 70 has a hollow structure, which includes two roller heads at both ends and a roller body between the two roller heads; the roller body is used to hold and convey the material sheet; and the two roller heads are respectively supported by two eddy current refrigeration bearing seats.

[0069] Specifically, the steel roller 70 has a variable cross-section structure, for example, the outer diameter of the roller body (such as 70mm to 100mm) is greater than the outer diameter of the roller head (such as 25mm to 50mm).

[0070] Specifically, the steel roller 70 has a large length-diameter ratio, for example, the length of the steel roller 70 is 2500mm to 4000mm.

[0071] Specifically, the steel roller 70 is cast from 310S heat-resistant steel and has a through hole arranged along the central axis, and heat insulation materials can be filled at both ends of the through hole to avoid heat dissipation from the inside of the furnace to the outside of the furnace.

[0072] Specifically, the steel roller 70 is cast using a mold, and after the outer cylindrical surface is machined, the shape tolerances such as straightness and roundness deviation can be well controlled.

[0073] In this way, the steel roller is made of 310S austenitic chromium-nickel stainless steel, which is heat-resistant steel and has good force transmission. It can withstand the corrosion of the product after the coating is melted. As mentioned above, the first rotation speed is low, the centrifugal force generated during rotation is small, and no obvious radial deformation occurs during rotation. It is reliable to use at a furnace temperature of up to 950℃ and is not easy to corrode and break, and is durable.

[0074] Therefore, adopting a hollow structure, i.e., hollow steel rollers, can reduce weight and rotational inertia, saving the electrical energy and cost of driving their rotation. Furthermore, during furnace operation, steel rollers with large length-to-diameter ratios exhibit significant deflection and poor high-temperature stiffness; hollow steel rollers reduce radial deformation and sagging. In addition, the linear velocity in the heating zone of the material is low. Although steel rollers have lower high-temperature stiffness than ceramic rollers, they still meet the application requirements.

[0075] Compared to using a stainless steel sleeve to prevent corrosion of ceramic rollers, using hollow steel rollers to prevent corrosion by coating molten products is a simpler and more interchangeable solution. Steel rollers also have a longer service life, which helps improve production efficiency and reduce operating costs throughout their entire life cycle.

[0076] To ensure that the height and density of the material sheets remain constant within the furnace, the outer diameter of the ceramic roller is the same as that of the steel roller, and the spacing between adjacent steel rollers is the same as that between adjacent ceramic rollers.

[0077] This improves the compatibility with the furnace body and facilitates the adoption of steel rollers in existing roller hearth furnaces.

[0078] Furthermore, considering that the coefficient of thermal expansion of ceramics is smaller than that of steel, the expansion deformation of ceramic rollers after heating is usually less than that of steel rollers. Therefore, steel rollers are designed with allowance for expansion along their length. The difference in radial expansion between ceramic and steel rollers has almost no impact on the conveying of the material.

[0079] Specifically, one end of the steel roller 70 is the driving end, which is equipped with the aforementioned sprocket; the other end is the non-driving end, which is not equipped with the aforementioned sprocket.

[0080] Specifically, a double-row rolling bearing is provided in the eddy current cooling bearing housing of the roller head supporting the driving end of the steel roller 70 to position the steel roller 70 in the axial direction; a single-row rolling bearing is provided in the eddy current cooling bearing housing of the roller head supporting the non-driving end of the steel roller 70 to allow the deformation generated when the steel roller 70 rotates at high temperature to be transmitted to the roller head and the possible swing angle.

[0081] like Figure 1 As shown, in some embodiments, the roller hearth furnace is equipped with an upper heater 40A and a lower heater 40B, which are respectively arranged above and below the roller conveyor. Specifically, the upper heater 40A and the lower heater 40B are equipped with resistance wire heating tubes to achieve a preset temperature inside the furnace, such as 900°C or 950°C.

[0082] Therefore, the temperature of the furnace is usually as high as 950℃, and the steel roller is a good conductor of heat, so the temperature of the roller body is as high as 950℃, and the temperature of the roller head at both ends of the roller body is usually as high as 100-200℃, and the heat is continuously transferred to the bearing and the bearing seat. Therefore, cooling measures need to be taken for the bearing supporting the steel roller to achieve long-term stable operation of the bearing.

[0083] As shown in Figure 3 、 Figure 4 , the vortex refrigeration bearing seat 30 comprises:

[0084] a shell 31, which is provided with a cold gas passage, the cold gas passage is provided with a first end and a last end;

[0085] a vortex refrigeration structure 34, which is provided with a compressed gas inlet 34A and a cold gas outlet, the cold gas outlet is in communication with the first end;

[0086] The shell 31 is provided with a bearing mounting hole 32, at least one bearing 35 is mounted in the bearing mounting hole 32, the roller head is connected with the bearing, such as interference fit with the inner ring of the bearing, and a cavity is formed between the roller head and the surface of the bearing mounting hole 32; after the compressed gas is sent into the compressed gas inlet 34A, the cold gas is output through the cold gas outlet, the cold gas is transmitted through the cold gas passage, and the cold gas is discharged into the cavity at the last end.

[0087] In this way, the cold gas is sprayed to the inner roller head 70A to directly cool the inner roller head, avoiding the temperature rise of the bearing section 70C and avoiding the heat transfer to the bearing through this part of the shaft section. By cooling the working environment of the bearing, the working temperature of the bearing is kept at a lower temperature, which is conducive to the long-term stable work of the bearing.

[0088] In this way, compared with directly spraying cold gas into the bearing, the evaporation or air drying of the bearing grease can be avoided.

[0089] Specifically, the vortex refrigeration structure 34 can be arranged outside or inside the vortex refrigeration bearing seat. The vortex refrigeration structure uses the vortex refrigeration principle of compressed gas to obtain cold gas as low as-40℃, and the cold gas is sprayed to the roller head of the steel roller through the fine tubes arranged in the bearing seat shell, such as the cold gas passage described above. For example, the fine tubes can be uniformly arranged along the circumference of the bearing mounting hole, or can be uniformly arranged along the axis of the bearing mounting hole, so as to spray the cold gas to the roller head of the steel roller in multiple radial directions of the bearing mounting hole, and to strongly cool the roller head and reduce the temperature of the end of the steel roller, thereby reducing the working temperature of the bearing from the source, which is conducive to the long-term stable work of the bearing, thereby improving the stability and reliability of the equipment.

[0090] Generally, the compressed gas has a pressure greater than 5 Bar; the cold gas has a temperature at least 30℃ lower than the temperature of the compressed gas; and the hot gas has a temperature of at least 100℃.

[0091] Thus, the vortex refrigeration structure can stably obtain -40℃ cold gas or 100℃ hot gas by using the vortex refrigeration principle of the compressed gas.

[0092] As shown in Figure 3 , Figure 4 The shell is also provided with a mounting stop 33 for arranging the vortex refrigeration bearing seat 30 in the through hole of the furnace body of the roller hearth furnace. Thus, the roller bar can be removed from the furnace by disassembling the bearing seat at both ends of the roller bar, and a new roller bar can be arranged in the furnace body through the through hole, improving the interchangeability of the roller bar and saving the maintenance time required for replacing the roller bar. Thus, the vortex refrigeration bearing seat is arranged at the driving end and the non-driving end of the steel roller bar, and the roller bar can be replaced without stopping the furnace under the condition of high-temperature operation of the furnace.

[0093] When the steel roller bar 70 is supported by the two vortex refrigeration bearing seats 30 arranged on the two sides of the furnace body, the cold gas discharged from the end into the corresponding chamber cools the inner sides of the two roller heads of the rotating steel roller bar, and the outer roller head 70B is located outside the furnace body.

[0094] As shown in Figure 1 In the front half of the heating furnace, the vortex refrigeration bearing seat 30 is used to generate -40℃ cold gas for cooling the inner roller head of the steel roller bar 70 by using the vortex refrigeration principle, avoiding the problem of serious heat conduction of the steel roller bar and affecting the service life of the bearing.

[0095] Thus, the vortex refrigeration structure is installed in the bearing seat shell, the compressed gas supply pipeline in the factory is connected, and the vortex refrigeration structure can continuously generate -40℃ cold gas. The cold gas continuously passes through the fine holes arranged in the axial or radial direction on the shell and is sprayed to the inner roller head, so that the roller head is uniformly cooled, the working temperature of the bearing is reduced from the source, and a longer service life of the bearing can be obtained.

[0096] For the roller hearth furnace with a protective atmosphere in the furnace, the protective atmosphere is connected as the compressed gas to the inlet of the vortex refrigeration structure, which can achieve the technical effects of the vortex refrigeration bearing seat as described above. At the same time, the protective atmosphere can be continuously delivered to the furnace through the fine holes, which is also beneficial to the uniformity of the atmosphere of the furnace door.

[0097] As shown in Figure 1 and Figure 2As shown, the roller-hearth heating furnace is equipped with an eddy current refrigeration gas source pipeline 50 for eddy current refrigeration. Specifically, dry air with low dew point at room temperature is sent to the eddy current refrigeration gas source pipeline. Generally, after the cold gas cools the inner roller head, it enters the furnace or freely dissipates outside the furnace, so generally no additional cold gas collection pipeline is provided.

[0098] In some embodiments, the roller-hearth heating furnace further comprises: a heat preservation pipeline;

[0099] The eddy current refrigeration structure further provides a hot gas outlet;

[0100] After the compressed gas is sent into the compressed gas inlet, hot gas is output through the hot gas outlet, and the hot gas is delivered to the furnace body through the heat preservation pipeline.

[0101] In this way, the waste heat gas (which can reach more than 100 degrees Celsius) discharged by the eddy current refrigeration structure is collected through the heat preservation pipeline, which can preheat the material sheet and realize the reuse of the waste heat gas output by the eddy current refrigeration structure.

[0102] Generally, the furnace body of the heating furnace is also connected to a protective gas source pipeline to fill a sufficient amount of protective gas into the furnace, which can prevent the surface of the material sheet from oxidizing, improve the heating quality, and achieve uniform heating of the material sheet without scale.

[0103] In some embodiments, if a protective atmosphere is used as compressed gas, the hot gas output by the heat preservation pipeline can be merged into the protective gas source pipeline or directly introduced into the furnace for use as a protective atmosphere. In this way, the waste heat gas discharged by the eddy current refrigeration structure can be fully utilized, saving the heat used to heat the protective atmosphere and saving energy.

[0104] As previously explained, ceramics are poor conductors of heat, which can avoid the temperature of the roller head at the bearing connection being too high. For example, Figure 1 As shown, the drive end and the non-drive end of the ceramic roller can be provided with conventional bearing seats, and the aforementioned eddy current refrigeration bearing seats are not necessary.

[0105] In this way, different materials are used for roller bars in different areas of the furnace. In the material sheet warming area in the first half of the furnace, steel roller bars made of heat-resistant steel material are used. In the second half of the furnace, ceramic roller bars are used to take advantage of their better high-temperature strength to meet the process requirements of rapid material discharge. In this way, the problem of roller bar damage caused by coating corrosion is avoided, and the long-term stability of the production capacity of the roller-hearth heating furnace and the high pass rate of the products are realized.

[0106] With the foregoing description, the roller is driven by the motor and rotates in situ. Once the power is accidentally cut off, the roller stops rotating, and the furnace body is still in a high-temperature environment. The steel roller has poor thermal stability at high temperature. Due to the dead weight and thermal deformation, the sag of the local roller body of the steel roller is too large. After power-on, the roller will seriously scratch the two sides of the furnace wall or collide with the adjacent roller during rotation, so that the motor cannot drive the roller to rotate.

[0107] To this end, in some embodiments, the roller bottom heating furnace further comprises: a ceramic bracket arranged directly below the steel roller for supporting the steel roller after radial deformation.

[0108] For example, the ceramic bracket has a V-shaped cross section. When the sag of the local roller body of the steel roller near the middle part is large enough due to the dead weight and thermal deformation, the steel roller is supported by the V-shaped cross section, which can prevent the sag of the local roller body of the steel roller from continuing to increase. During normal rotation of the steel roller, the height between the V-shaped cross section and the lowest point of the steel roller in the vertical direction can be 6-15 mm.

[0109] For example, the ceramic bracket has a horizontal contact surface. When the sag of the local roller body of the steel roller near the middle part is large enough due to the dead weight and thermal deformation, the steel roller is supported by the horizontal contact surface, which can prevent the sag of the local roller body of the steel roller from continuing to increase. During normal rotation of the steel roller, the height between the horizontal contact surface and the lowest point of the steel roller in the vertical direction can be 6-15 mm.

[0110] Therefore, the ceramic bracket arranged below the steel roller prevents the steel roller from deforming in a large size when the roller stops rotating for a long time due to accidental power failure or the like, which is beneficial to the long-term stable operation of the roller bottom heating furnace.

[0111] As shown in Figure 3 , Figure 4 The end includes at least two first blind holes 31A extending in the radial direction of the bearing mounting hole, the open end of the first blind hole 31A is located on the surface of the bearing mounting hole, and the blind end of the first blind hole 31A is located in the shell; the head includes at least one second blind hole 31B extending in the radial direction of the bearing mounting hole and / or at least two third blind holes 31C extending in the axial direction of the bearing mounting hole.

[0112] Therefore, by guiding the cold air output by the eddy current refrigeration structure 34 to at least two first blind holes 31A extending in the radial direction of the bearing mounting hole or in the axial direction, a cold air passage can be efficiently and conveniently arranged inside the shell, the machinability is good, and the pressure loss of the air path is small.

[0113] Specifically, when the cold air output by the eddy current refrigeration structure 34 is guided to at least two first blind holes 31A extending along the radial direction of the bearing mounting hole in the axial direction through the third blind holes 31C, the eddy current refrigeration structure 34 can be arranged on the end surface of the bearing seat or inside the bearing seat.

[0114] As shown in Figure 3 , Figure 4 , at least one second blind hole 31B extending along the radial direction of the bearing mounting hole is arranged at the front end,

[0115] The cold air channel further comprises a transition part connecting the front end and the rear end, and the transition part comprises at least two third blind holes 31C extending along the axial direction of the bearing mounting hole.

[0116] Specifically, when the cold air output by the eddy current refrigeration structure 34 is guided to at least two first blind holes 31A extending along the radial direction of the bearing mounting hole in the axial direction, the eddy current refrigeration structure 34 can be arranged on the side surface of the bearing seat, as shown in Figure 3 Thus, it is beneficial for the installation of the bearing seat, and the steel roller can be conveniently replaced, and the interchangeability is better as a whole.

[0117] Specifically, the bearing seat 30 is cast, and various processes are performed after the casting is completed. The inner hole extending along the radial direction or extending along the axial direction can be coarsely processed by casting, and then drilled. It can also be directly drilled. Generally, the cold air channel comprises at least two inner holes having a communication relationship, and the inner holes are blind holes, one end of which is a through end and the other end is a blind end. For example, an auxiliary process hole can be first punched, and after the processing is completed, the auxiliary process hole is plugged with a plugging plug 36 to form a blind end.

[0118] Thus, the composite roller type roller bottom heating furnace of the embodiment of the present application is equipped with a steel roller and a ceramic roller, meets the heating demand of the coated plate, and overcomes the problem of corrosion of the roller. At the same time, for the high thermal conductivity problem of the steel roller, the vortex refrigeration bearing seat is used in a matched manner to realize strong cooling and realize long-term use of the bearing. Finally, the composite roller type roller bottom heating furnace can meet the requirements of long-term stable operation of automobile parts enterprises and reduce the operation cost.

[0119] Note that the above is only a preferred embodiment of the present application and the technical principle applied. Those skilled in the art will understand that the present application is not limited to the specific embodiments described herein, and those skilled in the art can make various obvious changes, readjustments and substitutions without departing from the scope of the present application. Therefore, although the present application has been described in more detail through the above embodiments, the present application is not limited to the above embodiments, and can include more other equivalent embodiments without departing from the concept of the present application, and all belong to the protection scope of the present application.

Claims

1. A composite roller-bar type roller hearth heating furnace, comprising a furnace body, characterized in that, Comprise: a plurality of steel roller bars, a plurality of ceramic roller bars, a plurality of eddy current refrigeration bearing seats; the plurality of steel roller bars are arranged side by side in the sheet heating area in the furnace body; the plurality of ceramic roller bars are arranged side by side in the rapid discharge area in the furnace body; the plurality of steel roller bars are respectively supported by the plurality of eddy current refrigeration bearing seats; after the sheet enters the furnace body, it is conveyed by the plurality of steel roller bars, and after passing through the sheet heating area, it is conveyed by the plurality of ceramic roller bars, and passes through the rapid discharge area; the steel roller bar is a hollow structure, which comprises two roller heads at both ends and a roller body between the two roller heads; the roller body is used to hold the sheet and convey it; the two roller heads are respectively supported by the two eddy current refrigeration bearing seats; the eddy current refrigeration bearing seat comprises: a shell provided with a cold gas channel, the cold gas channel is provided with a first end and a last end; an eddy current refrigeration structure is provided with a compressed gas inlet and a cold gas outlet, the cold gas outlet is communicated with the first end; the shell is provided with a bearing mounting hole, at least one bearing is mounted in the bearing mounting hole, the roller head is connected with the bearing, and a cavity is formed between the roller head and the surface of the bearing mounting hole; after the compressed gas is sent into the compressed gas inlet, cold gas is output through the cold gas outlet, and the cold gas is transmitted through the cold gas channel and discharged into the cavity at the last end.

2. The furnace as claimed in claim 1, wherein Further comprising: a first roller bar driving device; the plurality of steel roller bars are driven by the first roller bar driving device to rotate at a first rotating speed, so that the sheet is conveyed at a first linear velocity.

3. The furnace as claimed in claim 2, wherein Further comprising: a second roller bar driving device; the plurality of ceramic roller bars are driven by the second roller bar driving device to rotate at a second rotating speed switched from the first rotating speed, so that the sheet is conveyed at a second linear velocity switched from the first linear velocity; wherein the second linear velocity is a positive integer multiple of the first linear velocity.

4. The heating furnace of claim 1, wherein when the steel roller bar rotates supported by the two eddy current refrigeration bearing seats oppositely arranged on both sides of the furnace body, the cold gas discharged into the corresponding cavity through the last end cools the inner side of the two roller heads of the rotating steel roller bar respectively.

5. The furnace of claim 4 wherein, the last end comprises at least two first type blind holes extending along the radial direction of the bearing mounting hole, and the through end of the first type blind hole is located on the surface of the bearing mounting hole; the first end comprises at least one second type blind hole extending along the radial direction of the bearing mounting hole, and / or at least two third type blind holes extending along the axial direction of the bearing mounting hole.

6. The furnace of claim 5 wherein, when the first end comprises at least one second type blind hole extending along the radial direction of the bearing mounting hole, the cold gas channel further comprises a transition part, the first end and the last end are connected through the transition part, and the transition part comprises at least two third type blind holes extending along the axial direction of the bearing mounting hole.

7. The furnace as claimed in claim 1, wherein Further comprising: a heat preservation pipeline; the eddy current refrigeration structure further comprises a hot gas outlet; after the compressed gas is sent into the compressed gas inlet, hot gas is output through the hot gas outlet, and the hot gas is conveyed to the furnace body through the heat preservation pipeline.

8. The furnace as claimed in claim 3, wherein, Further comprising: a ceramic bracket arranged directly below the steel roller bar, used to hold the steel roller bar after radial deformation.

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