阅读说明：本技术 一种往复移动式高温微波加热炉 (Reciprocating high-temperature microwave heating furnace ) 是由 程寓 王子祥 殷增斌 于 2021-07-14 设计创作，主要内容包括：本发明公开一种往复移动式高温微波加热炉。包括矩形谐振腔,波导,加热保温移动装置,电气控制系统和温度测量装置；试样批量放置在加热保温移动装置上,电气控制系统包括用于驱动加热保温移动装置往复移动的动力机构,动力机构通过PP推拉杆将动力传输给加热保温移动装置,PP推拉杆和矩形谐振腔之间设有微波抑制管；温度测量装置用于测量试样的温度,电气控制系统根据温度测量装置测量的温度控制加热保温移动装置的往复移动,使得加热试样处于不断变化的位置、不断扰动腔内电场,实现微波均匀加热。本发明的微波炉结构简单合理、安装方便,可以很好地改善试样微波加热均匀性,极大地提高了生产效率。(The invention discloses a reciprocating high-temperature microwave heating furnace. The device comprises a rectangular resonant cavity, a waveguide, a heating and heat-preserving mobile device, an electrical control system and a temperature measuring device; the electric control system comprises a power mechanism for driving the heating and heat-preserving moving device to reciprocate, the power mechanism transmits power to the heating and heat-preserving moving device through a PP push-pull rod, and a microwave suppression pipe is arranged between the PP push-pull rod and the rectangular resonant cavity; the temperature measuring device is used for measuring the temperature of the sample, and the electric control system controls the reciprocating movement of the heating and heat-preserving moving device according to the temperature measured by the temperature measuring device, so that the heating sample is in a constantly changing position and constantly disturbs an electric field in the cavity, and uniform microwave heating is realized. The microwave oven has simple and reasonable structure and convenient installation, can well improve the microwave heating uniformity of the sample, and greatly improves the production efficiency.)

1. A reciprocating high-temperature microwave heating furnace is characterized by comprising a rectangular resonant cavity (2), a waveguide (1) arranged on the rectangular resonant cavity (2), a heating and heat-preserving mobile device, an electrical control system and a temperature measuring device;

the electric control system comprises a power mechanism for driving the heating and heat-preserving moving device to reciprocate, the power mechanism transmits power to the heating and heat-preserving moving device through a PP push-pull rod (13), and a microwave suppression pipe (14) is arranged between the PP push-pull rod (13) and the rectangular resonant cavity (2); the temperature measuring device is used for measuring the temperature of the sample, and the electric control system controls the reciprocating movement of the heating and heat-preserving mobile device according to the temperature measured by the temperature measuring device, so that the heating sample is in a constantly changing position and constantly disturbs an electric field in the cavity, and finally microwave uniform heating is realized.

2. A microwave heating oven according to claim 1, wherein the waveguides are four rectangular waveguides, adjacent rectangular waveguides being arranged at 90 ° orthogonal to each other.

3. The microwave heating furnace according to claim 2, wherein the heating and heat-preserving moving device comprises a stainless steel bearing plate (7), an alumina asbestos (6), a ceramic heat-preserving plate (3) and a base plate (5) for placing heating samples, which are arranged from bottom to top in sequence, wherein the samples are placed on the upper part of the base plate (5) in batch;

the bottom of stainless steel bearing plate (7) is equipped with a plurality of gyro wheels (8), and the inside bottom surface of rectangle resonant cavity (2) is equipped with guide rail (9), heating heat preservation mobile device passes through gyro wheel (8) and moves realization reciprocating motion on guide rail (9).

4. A microwave oven according to claim 3, characterized in that the electrical control system comprises an electric motor (11), a ball screw mechanism (12) and a bearing housing (10);

the ball screw mechanism (12) is installed on the bearing seat (10), the PP push-pull rod (13) is connected with the ball screw mechanism (12) through a connecting rod in threaded fit with the screw, the rotary motion of the screw is converted into the linear motion of the heating and heat-preserving moving device through the bearing, the motor (11) is connected with the ball screw mechanism (12), and the motion of the whole heating and heat-preserving moving device is driven by the motor (11).

5. A microwave oven according to claim 4, characterized by further comprising a magnetron mounted on the rectangular waveguide (1), the rectangular waveguide (1) being mounted above the rectangular resonant cavity (2), the magnetron being adapted to emit microwaves into the resonant cavity (2).

Technical Field

The invention belongs to the field of high-temperature microwave heating, and particularly relates to a reciprocating high-temperature microwave heating furnace.

Background

The high-temperature heating of ceramics, metal compounds, non-metal compounds and organic matters is performed by a traditional heating mode (such as a resistance heating furnace or a combustion heating furnace) and an electromagnetic heating mode (such as a microwave heating furnace). The biggest defect of the traditional heating mode is that the heat is heated from outside to inside through a positive temperature gradient by heat conduction, the temperature of the atmosphere in the furnace is required to be higher than the expected temperature of the heated material, so the heating is slow, the heating process is long, and great energy waste is caused. Microwave heating is one of electromagnetic heating modes, is an efficient heating mode which utilizes material dielectric loss to generate heat to enable materials to be self-heated from inside to outside, and can even realize simultaneous heating inside and outside under the condition of reasonable material volume, thereby greatly shortening the heating time. Research shows that the zirconia sintered by the microwave heating furnace can be sintered within 90 minutes, while the traditional heating mode needs 27 hours to complete the sintering. However, microwave heating still has a fatal disadvantage that the heating is not uniform. Non-uniformity of microwave heating generally results from non-uniformity of electric field distribution. Generally, there will always be regions of stronger and weaker electric fields in the microwave cavity. When a part of the object to be heated is located in a region where the electric field is strong and another part is located in a region where the electric field is weak, the amount of heat generated in each part is different, and finally heating unevenness and even thermal runaway are caused. This non-uniformity is more pronounced when multiple samples or large volumes of samples are heated. It is this disadvantage that greatly limits the further development and application of microwave heating technology. Therefore, how to improve the temperature distribution uniformity of the microwave heating sample becomes a problem of close attention of researchers at home and abroad.

Aiming at the problem, scholars at home and abroad develop a great deal of research work and provide a plurality of novel technical schemes. The following two aspects can be broadly summarized: first, microwave heating equipment is designed specifically, aiming at making the electric field distribution in the resonant cavity uniform. Such as the university of Sichuan Yangfeng Ming, Zhu Sha for the others has designed a four and has presented mouthful microwave heating furnace, adopts four microwave to present mouthful cooperation sweep frequency heating mode and has reduced the energy intercoupling between the port, has improved microwave heating homogeneity. (a four-port microwave cavity structure design for improving heating uniformity and efficiency), Yanfengming, vacuum electronic technology, fifth stage, pages 66-69, 2019); such as by introducing multiple microwave source feeds in combination with a microwave mode stirrer, which stirs the electric field as the microwaves are fed into the cavity, causing the electric field distribution to change continuously, thereby improving microwave heating uniformity (CN 201585163U); a plurality of auxiliary microwave sources are matched with a plurality of variable frequency microwave sources and are uniformly arranged on the outer side of the furnace body, and the heating uniformity is improved in a variable frequency heating mode (CN 104869679B). Secondly, a rotary turntable or a conveyor belt and the like are introduced to realize dynamic heating, and the aim is to ensure that the energy absorbed by each part of the material is uniform. For example, patent (CN 102062422 a) improves the uniformity of microwave heating by mounting a rotary turntable at the bottom of the microwave oven so that the object can be heated by rotating in the oven cavity. The patent (CN 204388587U) adopts the transmission mode that the material is continuously sent out by the trolley, solves the problem of microwave heating movement heating, and improves the uniformity of microwave heating. In addition, a microwave heating multi-cavity with a movable metal wall is designed, such as the leaf cyanine of Sichuan university, and the like, and in the heating process, the electric field distribution in the cavity is continuously changed by moving the metal wall in a single direction, so that the purpose of improving the microwave heating uniformity is achieved (research on the influence of the metal boundary movement of the microwave multi-cavity on heating, leaf cyanine, Sichuan university press (Nature science edition), volume 55, phase 1, pages 81-88 and 2018).

Above scheme, if through unidirectional movement metal wall, realize that the intracavity electric field constantly changes and improve the homogeneity, it is more loaded down with trivial details while the degree of difficulty is also great to realize. Other schemes such as multi-feed-port matched sweep frequency heating, additional mode stirrer, rotary turntable and the like are only used for microwave uniform heating of small-volume samples, and microwave uniform heating of batch samples or large-volume samples cannot be achieved.

Disclosure of Invention

The invention aims to provide a reciprocating high-temperature microwave heating furnace; the microwave oven can realize uniform heating of batch samples or large-volume samples, and improves heating efficiency and heating quality.

The technical solution for realizing the purpose of the invention is as follows: a reciprocating high-temperature microwave heating furnace comprises a rectangular resonant cavity, a waveguide arranged on the rectangular resonant cavity, a heating and heat-preserving mobile device, an electrical control system and a temperature measuring device;

the electric control system comprises a power mechanism for driving the heating and heat-preserving moving device to reciprocate, the power mechanism transmits power to the heating and heat-preserving moving device through a PP push-pull rod, and a microwave suppression pipe is arranged between the PP push-pull rod and the rectangular resonant cavity; the temperature measuring device is used for measuring the temperature of the sample, and the electric control system controls the reciprocating movement of the heating and heat-preserving mobile device according to the temperature measured by the temperature measuring device, so that the heating sample is in a constantly changing position and constantly disturbs an electric field in the cavity, and finally microwave uniform heating is realized.

Further, the waveguide is four rectangular waveguides, and adjacent rectangular waveguides are orthogonally arranged at 90 degrees.

Furthermore, the heating and heat-preserving moving device comprises a stainless steel bearing plate, alumina asbestos, a ceramic heat-preserving plate and a substrate which are sequentially arranged from bottom to top, and samples are placed on the upper part of the substrate in batches;

the bottom of stainless steel bearing plate is equipped with a plurality of gyro wheels, and the inside bottom surface of rectangular cavity is equipped with the guide rail, heating heat preservation mobile device passes through the gyro wheel and moves realization reciprocating motion on the guide rail.

Further, the electric control system comprises a motor, a ball screw mechanism and a bearing seat;

the ball screw mechanism is arranged on the bearing seat, the PP push-pull rod is connected with the ball screw mechanism through a connecting rod in threaded fit with the screw, the rotary motion of the screw is converted into linear motion of the heating and heat-preserving moving device through the bearing, the motor is connected with the ball screw mechanism, and the motion of the whole heating and heat-preserving moving device is driven by the motor.

Furthermore, the microwave oven also comprises a magnetron, wherein the magnetron is arranged on a rectangular waveguide, the rectangular waveguide is arranged above the rectangular resonant cavity, and the magnetron is used for emitting microwaves into the resonant cavity.

Compared with the prior art, the invention has the remarkable advantages that:

(1) the invention provides a design scheme of a reciprocating high-temperature microwave heating furnace. The method is characterized in that the influence rule of the number of feed ports of a microwave resonant cavity, the feed port layout and the resonant cavity size on an electric field in the cavity is researched by using a numerical simulation means, the microwave heating uniformity is represented by a temperature rise characteristic and a temperature non-uniformity coefficient, and finally, a layout design mode that four feed ports of the resonant cavity are mutually orthogonal at 90 degrees is determined, so that the microwave energy coupling among the feed ports and the electric field uniformly distributed in the resonant cavity are eliminated.

(2) The invention can well improve the microwave heating uniformity of batch samples or large-volume samples. Due to the propagation characteristics of the microwave electromagnetic field, when the microwave resonant cavity is determined, a region with a strong electric field and a region with a weak electric field always exist in the cavity. When a part of the object to be heated is located in a region where the electric field is strong and another part is located in a region where the electric field is weak, the amount of heat generated in each part is different, and finally heating unevenness and even thermal runaway are caused. The invention designs the heat preservation mobile device, the device comprises a heat preservation part and a mobile part, and the heat preservation part adopts alumina asbestos with low heat conductivity and ceramic heat preservation bricks, so that the heat loss can be well reduced; the moving part drives the heating sample to continuously do reciprocating movement in the cavity, so that the heating sample is in a continuously changing position and an electric field in the cavity is continuously disturbed, and finally different parts of the heating sample have the same loss power, so that the aim of uniform heating is fulfilled.

(3) The invention has simple structure and convenient installation, and can greatly improve the production efficiency.

Drawings

FIG. 1 is a schematic view of the overall structure of a reciprocating high-temperature microwave oven according to the present invention.

FIG. 2 is a three-dimensional schematic view of a microwave oven chamber according to the present invention.

Figure 3 is a side view of a microwave oven cavity designed according to the present invention.

Fig. 4 is a three-dimensional schematic view of the heat preservation mobile device designed by the invention.

FIG. 5 is a cloud of the static microwave heating temperature profile of a batch of samples.

FIG. 6 is a cloud of static microwave heating electric field profiles of batch samples at different times.

FIG. 7 is a cloud of the reciprocating microwave heating temperature profile of a batch of samples.

FIG. 8 is a cloud of the distribution of the microwave heating electric field for the batch samples moving back and forth at different times.

Fig. 9 is a cloud of the static microwave heating temperature profile of a bulk sample.

FIG. 10 is a cloud diagram of the reciprocating microwave heating temperature distribution of a large-volume sample.

Description of reference numerals:

1-waveguide, 2-rectangular resonant cavity, 3-ceramic heat insulation board, 4-sample, 5-substrate, 6-alumina asbestos, 7-stainless steel bearing plate, 8-roller, 9-guide rail, 10-bearing seat, 11-motor, 12-ball screw mechanism, 13-PP push-pull rod, 14-microwave suppression tube and 15-furnace door.

Detailed Description

In order to make the technical solutions of the present invention better understood, those skilled in the art will now make further detailed descriptions of the present invention with reference to the accompanying drawings.

Referring to fig. 1, a reciprocating high temperature microwave oven. The microwave oven can realize uniform heating of batch samples or large-volume samples, and improves heating efficiency and heating quality.

The microwave oven is matched with the reciprocating movement of the heat preservation moving device through the specially designed multi-feed-port multimode microwave resonant cavity, so that a heating sample is in a constantly changing position and constantly disturbs an electric field in the cavity, and finally, uniform microwave heating is realized. The microwave oven comprises a rectangular resonant cavity 2, four rectangular waveguides 1, a heat preservation moving device, a PP push-pull rod 13, a microwave suppression pipe 14, a ball screw mechanism 12 and a motor 11. Four microwave input ports are arranged above the rectangular resonant cavity 2 and used for feeding microwave energy; the four rectangular waveguides 1 are orthogonally arranged above the rectangular resonant cavity 2 at an angle of 90 degrees; the heat preservation moving device is arranged in the cavity, so that reciprocating moving heating of the heating sample in the resonant cavity can be realized, heat loss of the heating sample can be reduced, and the temperature of the sample can be homogenized; one end of the PP push-pull rod 13 is connected with the heat preservation moving device through a microwave inhibition pipe 14, and the other end of the PP push-pull rod is connected with the ball screw mechanism 12, so that the power transmission function is achieved; the microwave inhibition tube 14 absorbs and reflects microwaves to dissipate the microwaves entering the inhibition tube, so that electromagnetic pollution is reduced; the ball screw mechanism 12 is mounted on a bearing and aims to convert the rotary motion of a screw into the linear motion of a heat-preservation moving device; the motor 11 is connected to a ball screw mechanism 12, and the movement of the entire temperature keeping moving device is driven by the motor.

In the microwave oven, the four rectangular waveguides 1 are orthogonally arranged at 90 degrees, a microwave inhibiting pipe 14 is arranged on the left side surface of the microwave oven, and the microwave inhibiting pipe 14 is used for connecting a PP push-pull rod 13 with a heat preservation moving device inside and outside a cavity and a ball screw mechanism 12.

The heat preservation part of the heat preservation moving device consists of alumina asbestos on the outer layer and ceramic material on the inner layer, and the heating sample is positioned on the substrate 5.

The heat preservation moving device is moved in a mode that the rotation motion of the ball screw is converted into linear motion to drive the PP push-pull rod, and finally the roller 8 on the heat preservation moving device reciprocates on the guide rail 9, so that the sample reciprocates and is heated by microwaves.

The invention provides a microwave heating furnace, which comprises a microwave furnace body, a heat preservation moving device, a microwave heating device, an electric control system, a temperature measuring device and the like. The temperature measuring device is used for measuring the temperature of the heating sample, and the electric control system provides electric energy for each device and uniformly controls the working program of each device. The heat preservation mobile device can reduce the heat loss of the heating sample and homogenize the temperature of the sample, and can also drive the whole heat preservation part to do reciprocating motion in the cavity, and the specific implementation measures can be as follows: the motor rotates to drive a lead screw in the ball screw mechanism to rotate so as to drive the PP push-pull rod to move linearly, and the PP push-pull rod pulls the roller below the heat preservation moving device so that the roller can move on the guide rail in a reciprocating mode. The microwave heating device comprises a microwave source, a magnetron, a rectangular waveguide and the like. The substrate is arranged on the upper surface of the heat insulation plate in the heat insulation moving device, the magnetron is arranged on the rectangular waveguide which is arranged above the resonant cavity, and the magnetron is used for emitting microwaves into the cavity. The number and the installation position of the substrate and the rectangular waveguide are determined according to the specific size and the shape of the resonant cavity, and the invention is not particularly limited.

In the microwave heating process of the sample, an operator firstly places the sample on the upper surface of the substrate according to a certain layout. The moving distance, the moving period and relevant microwave heating process parameters are set through an electric control system. Then the microwave source provides energy to release microwaves, and the sample positioned above the substrate is heated to raise the temperature. The sample is heated by the sample heat-insulating moving device, and the sample moves back and forth along the guide rail in the sintering process, and the sample continuously traverses different positions in the resonant cavity, so that the energy obtained by different parts of the sample tends to be the same, and the sample continuously reciprocates until reaching the specified temperature.

As can be seen from the above description, in the reciprocating high temperature microwave heating oven of the present invention, the electric field in the cavity is agitated by reciprocating the sample in the resonant cavity, so that each part of the sample obtains the same energy to achieve uniform heating.

The improvement of the reciprocating high-temperature microwave heating furnace on the heating uniformity of the samples is illustrated by batch samples and large-volume sample simulated cloud pictures. FIG. 5 is a graph showing a microwave sintering temperature cloud for a batch sample at rest. It can be seen from the figure that the temperature distribution of the sample at the middle part of the substrate is relatively uniform, and the temperature range is approximately 1230-1300 ℃, while the temperature of the sample at the upper left corner and the lower right corner of the substrate is relatively high, but only reaches 1380 ℃ at most. The temperature difference of the entire sample was 150 ℃. FIG. 6 shows an electric field cloud of a batch of samples at different times of rest. It can be seen that the temperature of the sample is higher in the region with higher electric field strength, while the electric field of the sample itself does not change with time in the stationary state, which results in a faster temperature rise in the region with higher electric field of the sample and a slower temperature rise in the region with lower electric field of the sample. Finally, the temperature of the batch of samples is greatly different, and the uniformity is poor. Fig. 7 shows a temperature cloud of a reciprocating microwave heating sample, and it can be seen from the figure that the temperature of the sample at the middle part of the substrate is relatively low, while the temperature of the sample at the two sides of the substrate is relatively high, but the temperature difference of the whole sample is only 100 ℃, and the temperature uniformity is improved by 35% compared with the temperature uniformity in a static state. This is mainly because the electric field of the sample is constantly changing during the reciprocating movement. As shown in fig. 8, the electric field of the sample is constantly switched between the high electric field and the low electric field, the power loss of the sample is correspondingly reduced when the sample is in the low electric field area, and the power loss of the sample is correspondingly increased when the sample is in the high electric field area, which is beneficial to the conduction of the heat of the sample from the high temperature area to the low temperature area in time; in addition, the high and low electric field regions at this time may be switched with each other in the next time period, and finally, the whole sample has better temperature uniformity. Similarly, fig. 9 shows a temperature cloud of a large volume sample heated by microwaves in a quiescent state. It can be seen from the graph that the temperature difference of the entire sample was 290 ℃. Fig. 10 shows a reciprocating microwave heating temperature cloud chart, and it can be seen that the temperature difference of the whole sample is 180 ℃, and the temperature uniformity is improved by 36% compared with the static heating mode. Therefore, the reciprocating microwave heating can improve the heating uniformity of the sample to a certain extent.