阅读说明：本技术 一种用于球形燃料元件燃料区的预成型装置及其预成型方法 (Preforming device and preforming method for spherical fuel element fuel area ) 是由 刘兵 张�杰 卢振明 周湘文 史小龙 刘世福 唐亚平 王磊 李江华 于 2019-11-21 设计创作，主要内容包括：本发明涉一种用于球形燃料元件燃料区的预成型装置及其成型方法,包括上梁、工作台和多个加压工位,每个加压工位的电缸固定设置在上梁的底部,上压头通过压力传感器与电缸底部伸出的电缸活塞杆连接,模具钢套通过钢套拉杆与上压头连接,下压头固定设置在工作台上,模具放置在下压头上。该装置采用多个加压工位的设计,一次可以预成型多个球形燃料元件燃料区,大大提高产品的生产效率。采用电缸作为加压系统,可有效防止因采用液压系统产生的漏油和噪音问题,简化设备结构,节省空间；电缸的电缸活塞杆直线移动通过上压头对球形燃料元件燃料区施压,移动的距离和施加的压力可以精确控制,因此可以精确控制球形燃料元件燃料区的压制尺寸和压制压力。(The invention relates to a preforming device for a spherical fuel element fuel area and a forming method thereof. The device adopts the design of a plurality of pressurization stations, once can a plurality of spherical fuel element fuel areas of preforming, improves the production efficiency of product greatly. The electric cylinder is used as a pressurizing system, so that the problems of oil leakage and noise caused by the adoption of a hydraulic system can be effectively solved, the equipment structure is simplified, and the space is saved; the piston rod of the electric cylinder moves linearly to press the spherical fuel element fuel area through the upper pressure head, and the moving distance and the applied pressure can be accurately controlled, so that the pressing size and the pressing pressure of the spherical fuel element fuel area can be accurately controlled.)

1. The preforming device for the spherical fuel element fuel area is characterized by comprising an upper beam (1), a workbench (9) and a plurality of pressurizing stations, wherein each pressurizing station comprises an electric cylinder (2), a pressure sensor (4), an upper pressure head (5), a mold steel sleeve (6), a steel sleeve pull rod (12), a lower pressure head (7) and a mold (8), the electric cylinder (2) is fixedly arranged at the bottom of the upper beam (1), the upper pressure head (5) is connected with an electric cylinder piston rod extending out of the bottom of the electric cylinder (2) through the pressure sensor (4), the mold steel sleeve (6) is connected with the upper pressure head (5) through the steel sleeve pull rod (12), the lower pressure head (7) is fixedly arranged on the workbench (9), and the mold (8) is placed on the lower pressure head (7).

2. Preforming device for a spherical fuel element fuel area according to claim 1, characterized in that a threaded connection is used between the pressure sensor (4) and the electric cylinder piston rod, and a flanged connection is used between the pressure sensor (4) and the upper ram (5).

3. Preforming device for a spherical fuel element fuel zone according to claim 1, characterized in that the steel jacket tie-rod (12) is sheathed with a spring.

4. Preforming device for a spherical fuel element fuel area according to claim 1, characterized in that the preforming device further comprises a frame (10), the upper beam (1) and the working table (9) are respectively fixedly arranged on the frame (10), and the bottom of the frame (10) is fixedly provided with a foot plate (11).

5. Preforming device for the fuel area of spherical fuel elements according to claim 4, characterized in that a column (3) is vertically fixed between the upper beam (1) and the table (9).

6. The preforming device for a spherical fuel element fuel zone according to claim 1, wherein the plurality of pressing stations are independently operated or simultaneously operated.

7. Preforming method using a preforming device for a spherical fuel element fuel zone according to any of the claims 1-6, characterized in that the preforming method comprises the steps of:

step one, filling a mold (8) with a volume ratio of 4: 1-5: 1, placing the matrix graphite powder and dressing particles in a lower pressing head (7) on a workbench (9);

step two, starting the electric cylinder (2), moving a piston rod of the electric cylinder downwards, driving a mold steel sleeve (6) to downwards move by an upper pressure head (5), sleeving the mold (8) by the mold steel sleeve (6) and positioning, continuously moving the upper pressure head (5) downwards to pressurize the mold (8) to a set pressure, and maintaining the pressure for a set time;

after pressure maintaining is finished, moving the piston rod of the electric cylinder upwards, driving a die steel sleeve (6) to move upwards by an upper pressure head (5), and performing pressure relief according to set pressure relief time and pressure relief rate;

and fourthly, after pressure relief is finished, the piston rod of the electric cylinder continues to move upwards, the upper pressure head (5) drives the die steel sleeve (6) to move upwards to be separated from the die (8), the die (8) is moved out of the lower pressure head (7), and preforming of the fuel area of the spherical fuel element is finished.

8. The preforming method for the preforming device for the spherical fuel element fuel region according to claim 7, wherein in the second step, the pressurization rate is 1mm/s to 20mm/s, the forming pressure is 0.3MPa to 2.2MPa, and the pressure holding time is not more than 10 s;

in the third step, the pressure relief rate is 0.1-15 mm/s, and the pressure relief time is not more than 20 s.

9. The method of claim 7, wherein said pressure relief comprises a slow pressure relief and a fast pressure relief, said slow pressure relief time not exceeding 10s, and said fast pressure relief time not exceeding 5 s.

10. The preforming method for the preforming device for the spherical fuel element fuel region according to claim 7, wherein the total time of the pressurization, the pressure holding, and the pressure relief is 25s to 40 s.

Technical Field

The invention relates to the technical field of nuclear fuel preparation, in particular to a preforming device and a preforming method for a spherical fuel element fuel area.

Background

The pebble-bed high-temperature gas cooled reactor is one of the most advanced nuclear reactors recognized by the world and having proprietary intellectual property rights in China, and adopts spherical fuel elements with the fuel diameter of about 60mm and a certain amount of coating particles uniformly distributed in the fuel elements, wherein the part containing fuel in the center of a sphere is a fuel area, and the area without fuel at the periphery of the fuel area is called a fuel-free area. The forming process comprises the following steps: firstly, the coating particles and matrix graphite powder are mixed and then pressed under a certain pressure to form core spheres with a certain strength, then the core spheres and the graphite powder without a fuel area are pressed and formed under a high pressure condition, and the fuel area of the spherical fuel element is formed after low-temperature and high-temperature heat treatment. At present, a pressing system adopted for fuel area preforming is an oil pressure system, and the preforming process comprises the following steps: pressurizing, pressure maintaining and pressure relieving, wherein the whole period is not less than 45 s; the phenomenon of pressure uprush exists in the pressurizing process, and the pressure maintaining time cannot be adjusted; the pressure relief time is long and cannot be set; the ram and ram ascent/return speed cannot be adjusted; the equipment capacity can not meet the requirement of scale production of spherical fuel elements, the risk of oil leakage exists, the noise is high, a cooling system and a compressed air system need to be configured, and the maintenance is difficult.

Therefore, it is desirable to provide a preforming device and a preforming method for a spherical fuel element fuel area, in order to improve the production efficiency of equipment and the forming quality of products, achieve controllable preforming process parameters and optimized multi-station process parameters of the fuel area, simplify the structure of the equipment, reduce the noise and energy consumption of the equipment, eliminate the oil leakage problem of hydraulic equipment, facilitate the maintenance and repair of the equipment, and create a better workshop production environment, so as to meet the requirements of large-scale production of spherical fuel elements and popularization and application of high-temperature gas cooled reactors.

Disclosure of Invention

In view of the above, an object of the present invention is to provide a preforming apparatus for a spherical fuel element fuel region and a preforming method thereof, in which an electric cylinder piston rod of an electric cylinder is driven by electric energy to press a workpiece, instead of a hydraulic system and a hydraulic control system of an oil pressure device, a cooling system, a hydraulic actuator, a hydraulic control element and a hydraulic auxiliary element of the hydraulic system are not required, the device has a simple structure, the problem of oil leakage is solved, noise is greatly reduced, and an installation space of the device is saved.

In order to solve the technical problems, the invention adopts the following technical scheme:

the utility model provides a preforming device for spherical fuel element fuel district, the device includes upper beam, workstation and a plurality of pressurization station, and every pressurization station includes electric jar, pressure sensor, goes up pressure head, mould steel bushing, steel bushing pull rod, lower pressure head and mould, the fixed bottom that sets up at the upper beam of electric jar, it is connected with the electric jar piston rod that stretches out bottom the electric jar through pressure sensor to go up the pressure head, the mould steel bushing passes through the steel bushing pull rod and is connected with last pressure head, lower pressure head is fixed to be set up on the workstation, the mould is placed on lower pressure head. The position of the lower pressure head on the workbench is adjustable.

Preferably, the pressure sensor is in threaded connection with the electric cylinder piston rod, and the pressure sensor is in flange connection with the upper pressure head. The upper pressure head and pressure sensor function to pressurize the spherical fuel element fuel area and provide pressure signal feedback. The pressure sensor can control the molding pressure of the fuel area of the spherical fuel element through pressure, and the pressure control precision is 0.05 MPa. The pressure sensor can also be replaced by a grating ruler, the pressing size of the fuel area of the spherical fuel element is accurately controlled by measuring the moving distance of the piston rod of the electric cylinder, and the size deviation is controlled to be 0.02 mm.

Preferably, the steel sleeve pull rod is sleeved with a spring. And each mould steel sleeve is connected with the upper pressure head by two sets of steel sleeve pull rods, and the mould steel sleeves are used for positioning the mould and applying pressure to the fuel area of the spherical fuel element. The spring outside the steel sleeve pull rod can realize the relative movement between the die steel sleeve and the upper pressure head.

Preferably, the preforming device further comprises a frame, the upper beam and the workbench are respectively and fixedly arranged on the frame, and a ground foot plate is fixedly arranged at the bottom of the frame. The frame plays a supporting role, the frame comprises an upper beam frame, a workbench frame and side frames, the upper beam is fixedly arranged on the upper beam frame, the workbench is fixedly arranged on the workbench frame, and the upper beam frame and the workbench frame are fixedly connected through the two side frames.

Preferably, a vertical column is vertically and fixedly arranged between the upper beam and the workbench. The upright posts support the upper beam and the workbench.

Preferably, the plurality of pressing stations are respectively controlled to operate independently or synchronously. The operation periods of the plurality of pressurizing stations are basically consistent, the station with the longest operation time is different from the station with the shortest operation time, and the operation time difference is less than 2 s.

The preforming method using the preforming device for the fuel region of the spherical fuel element is characterized by comprising the following steps:

step one, filling a mold with a volume ratio of 4: 1-5: 1, placing the matrix graphite powder and dressing particles in a lower pressure head on a workbench;

step two, starting the electric cylinder, moving a piston rod of the electric cylinder downwards, driving a mold steel sleeve to move downwards by an upper pressure head, sleeving the mold by the mold steel sleeve and positioning, continuously moving the upper pressure head downwards to pressurize the mold to a set pressure, and maintaining the pressure for a set time;

after the pressure maintaining is finished, moving the piston rod of the electric cylinder upwards, driving the mould steel sleeve to upwards move by the upper pressure head, and performing pressure relief according to the set pressure relief time and pressure relief rate;

and fourthly, after the pressure relief is finished, the piston rod of the electric cylinder continues to move upwards, the upper pressure head drives the mold steel sleeve to move upwards to be separated from the mold, and the mold is moved out of the lower pressure head to complete the pre-molding of the fuel area of the spherical fuel element.

Preferably, in the second step, the pressurizing rate is 1mm/s-20mm/s, preferably 5mm/s-10mm/s, the forming pressure is 0.3MPa-2.2MPa, preferably 0.3MPa-2.0MPa, and the pressure maintaining time is not more than 10s, preferably not more than 5 s; in the third step, the pressure relief rate is 0.1mm/s-15mm/s, preferably 0.2mm/s-5mm/s, and the pressure relief time is not more than 20s, preferably not more than 15 s. The operation parameters of each station can be independently set, the forming pressure is continuously adjustable within 0MPa-2.2MPa, the pressure maintaining time is arbitrarily adjustable, and the pressure releasing time is continuously adjustable within 0s-45 s.

Preferably, the pressure relief comprises slow pressure relief and fast pressure relief, the slow pressure relief time is not more than 10s, and the fast pressure relief time is not more than 5 s.

Preferably, the total time of said pressurizing, holding pressure and depressurizing is 25s to 40s, preferably 28s to 33 s.

A preforming method for a preforming device for a fuel region of a spherical fuel element using the above device, the preforming method comprising the steps of:

the invention has the following beneficial effects:

due to the adoption of the technical scheme, the preforming device for the spherical fuel element fuel area and the preforming method thereof adopt the design of a plurality of pressurizing stations, a plurality of spherical fuel element fuel areas can be preformed at one time, and the production efficiency of products is greatly improved. The electric cylinder is used as a pressurizing system, so that the problems of oil leakage caused by the adoption of a hydraulic system and noise caused by a motor can be effectively solved, a complex condensing system is omitted, the structure of equipment is greatly simplified, and a large amount of space is saved; the piston rod of the electric cylinder moves linearly to press the spherical fuel element fuel area through the upper pressure head, and the moving distance and the applied pressure can be accurately controlled, so that the pressing size and the pressing pressure of the spherical fuel element fuel area can be accurately controlled.

The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical means of the present invention more clearly understood and to make the technical means implementable in accordance with the contents of the description, and to make the above and other objects, technical features, and advantages of the present invention more comprehensible, one or more preferred embodiments are described below in detail with reference to the accompanying drawings.

Drawings

One or more embodiments are illustrated by way of example in the accompanying drawings, which correspond to the figures in which like reference numerals refer to similar elements and which are not to scale unless otherwise specified.

FIG. 1 shows a front view schematic of a preforming device for a spherical fuel element fuel section according to the invention.

FIG. 2 shows a side view schematic of a preform apparatus for a spherical fuel element fuel zone of the present invention.

Description of the main reference numerals:

1-upper beam, 2-electric cylinder, 3-upright column, 4-pressure sensor, 5-upper pressure head, 6-die steel sleeve, 7-lower pressure head, 8-die, 9-workbench, 10-frame, 11-ground foot disc and 12-steel sleeve pull rod.

Detailed Description

The following detailed description of the present invention is provided in conjunction with the accompanying drawings, but it should be understood that the scope of the present invention is not limited to the specific embodiments.

Throughout the specification and claims, unless explicitly stated otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element or component but not the exclusion of any other element or component.

Spatially relative terms, such as "below," "lower," "upper," "above," "upper," and the like, may be used herein for ease of description to describe one element or feature's relationship to another element or feature in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the object in use or operation in addition to the orientation depicted in the figures. For example, if the items in the figures are turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the elements or features. Thus, the exemplary term "below" can encompass both an orientation of below and above. The article may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative terms used herein should be interpreted accordingly.

As shown in fig. 1 and 2, a preforming apparatus for a fuel region of a spherical fuel element includes a frame 10, an upper beam 1, a table 9, and a plurality of pressing stations. The upper beam 1 and the workbench 9 are respectively fixedly arranged on a frame 10, and a ground foot plate 11 is fixedly arranged at the bottom of the frame 10. The frame 10 plays a supporting role, the frame 10 comprises an upper beam frame, a workbench frame and side frames, the upper beam 1 is fixedly arranged on the upper beam frame, the workbench 9 is fixedly arranged on the workbench frame, and the upper beam frame and the workbench frame are fixedly connected through the two side frames. And a vertical column 3 is vertically and fixedly arranged between the upper beam 1 and the workbench 9. The column 3 supports the upper beam 1 and the table 9.

Every pressurization station includes electric jar 2, pressure sensor 4, goes up pressure head 5, mould steel bushing 6, steel bushing pull rod 12, lower pressure head 7 and mould 8, electric jar 2 is fixed to be set up in the bottom of upper beam 1, it is connected with the electric jar piston rod that 2 bottoms of electric jar stretch out through pressure sensor 4 to go up pressure head 5, mould steel bushing 6 passes through steel bushing pull rod 12 and is connected with last pressure head 5, lower pressure head 7 is fixed to be set up on workstation 9, mould 8 is placed on lower pressure head 7. The position of the lower pressure head 7 on the workbench 9 can be adjusted. The preforming device adopts the design of a plurality of pressurizing stations, and can press a plurality of spherical fuel element fuel area products at one time under the same process condition. In order to ensure the stress consistency of the mold 8 of each pressurizing station, each pressurizing station independently uses one electric cylinder 2, the technological parameters and the operation state of each pressurizing station can be independently set and controlled and can also be synchronously operated, and the operation time difference of each station in synchronous operation is less than 2 s.

The pressure sensor 4 is in threaded connection with the electric cylinder piston rod, and the pressure sensor 4 is in flange connection with the upper pressure head 5. The upper ram 5 and pressure sensor 4 function to pressurize the spherical fuel element fuel area and provide pressure signal feedback. The pressure sensor 4 can control the molding pressure of the fuel area of the spherical fuel element through pressure, and the pressure control precision is 0.05 MPa. The pressure sensor 4 can also be replaced by a grating ruler, and the pressing size of the fuel area of the spherical fuel element is accurately controlled by measuring the moving distance of the piston rod of the electric cylinder, and the size deviation is controlled to be 0.02 mm.

A spring is sleeved outside the steel sleeve pull rod 12. Each mould steel sleeve 6 is connected with the upper pressure head 5 by two sets of steel sleeve pull rods 12, and the mould steel sleeve 6 is used for positioning the mould and pressing a fuel area of the spherical fuel element. The spring outside the steel sleeve pull rod 12 can realize the relative movement between the die steel sleeve 6 and the upper pressure head 5.

The plurality of pressurizing stations are respectively controlled to operate independently or synchronously. The operation periods of the plurality of pressurizing stations are basically consistent, the station with the longest operation time is different from the station with the shortest operation time, and the operation time difference is less than 2 s.

The preforming method using the preforming device for the fuel region of the spherical fuel element is characterized by comprising the following steps:

step one, filling a mold 8 with a volume ratio of 4: 1-5: 1, placing the matrix graphite powder and dressing particles in a lower pressing head 7 on a workbench 9;

step two, starting the electric cylinder 2, moving a piston rod of the electric cylinder downwards, driving the die steel sleeve 6 to move downwards by the upper pressure head 5, sleeving the die 8 by the die steel sleeve 6 and positioning, continuously moving the upper pressure head 5 downwards to pressurize the die 8 to a set pressure, and maintaining the pressure for a set time; the pressurizing rate is 1mm/s-20mm/s, preferably 5mm/s-10mm/s, the forming pressure is 0.3MPa-2.2MPa, preferably 0.3MPa-2.0MPa, and the pressure maintaining time is not more than 10s, preferably not more than 5 s;

after the pressure maintaining is finished, moving the piston rod of the electric cylinder upwards, driving the mould steel sleeve 6 to move upwards by the upper pressure head 5, and performing pressure relief according to the set pressure relief time and pressure relief rate; the pressure release rate is 0.1mm/s-15mm/s, preferably 0.2mm/s-5mm/s, and the pressure release time is not more than 20s, preferably not more than 15 s. The operation parameters of each station can be independently set, the forming pressure is continuously adjustable within 0MPa-2.2MPa, the pressure maintaining time is arbitrarily adjustable, and the pressure releasing time is continuously adjustable within 0s-45 s.

And step four, after the pressure relief is finished, the piston rod of the electric cylinder continues to move upwards, the upper pressure head 5 drives the die steel sleeve 6 to move upwards to be separated from the die 8, the die 8 is moved out of the lower pressure head 7, and the preforming of the fuel area of the spherical fuel element is finished.

The pressure relief can be a one-stage pressure relief, also can be multistage formula pressure relief, and the preferred two-stage type pressure relief of multistage formula pressure relief, two-stage formula pressure relief include slow pressure relief and quick pressure relief, slow pressure relief time is no longer than 10s, quick pressure relief time is no longer than 5 s.

The total time of the pressurization, the pressure holding and the depressurization is 25s to 40s, preferably 28s to 33 s.