Powder discharging structure used in annular pellet green pressing process

Abstract

The invention belongs to the technical field of nuclear fuel preparation, and particularly relates to a powder discharging structure used in the annular pellet green pressing process, which comprises an upper punch, a punch sleeve, an upper punch rod and a center rod. The base of the upper punch is used for being installed on the top of an upper punch rod. The punch sleeve is used for penetrating through the upper portion of the upper punch and is in threaded connection with the upper punch rod. A center hole and a powder discharging hole are formed in the upper punch. The powder discharging hole is formed in the side edge of the center hole. One end of the center rod is used for being installed at a center hole of an upper punch, and the other end of the center rod is used for being installed on rotary forming press equipment. The powder discharging hole is formed in the side edge of the center hole of the upper punch, so that the technical problem that the upper punch is prone to breakage due to the fact that powder discharging is not timely in the annular pellet green pressing process is solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of nuclear fuel preparation, and particularly relates to a powder discharging structure used in the green compact pressing process of a ring-shaped pellet. BACKGROUND

[0002] In the field of nuclear fuel preparation, a cold pressing forming technology is generally used to prepare a green pellet. The following steps are needed to make a green pellet from powder: mold loading, pressing, mold unloading, green pellet pushing away, and mold reloading. A certain weight or volume of uranium dioxide powder 4 is loaded into a mold cavity 2, a rotary forming press is rotated at a certain pressure, the powder is pressed by an upper punch 1 and a lower punch 3, the powder is clamped and engaged with each other under the action of an external force to form a green pellet with a certain size, shape, density, and strength, the pressure is removed, the green pellet is taken out of the mold cavity, and the desired product is obtained. See Figure 1 .

[0003] According to the force form classification during pressing of the green pellet, the pressing can be divided into unidirectional pressing and bidirectional pressing, and the industrialized and large-scale production generally adopts the bidirectional pressing mode to prepare the green pellet. The pressing process is shown in Figure 2 . The traditional green pellet is in a cylindrical shape, and in the filling process of the mold cavity, the powder can be quantitatively filled by relying on its own gravity, and the pores in the powder do not affect the filling quality of the mold cavity.

[0004] In the pressing process of the ring-shaped green pellet, the mold includes an upper punch, a lower punch, a female mold, and a center rod. The mold fitting diagram of the ring-shaped pellet is shown in Figure 3 , and the center rod is shown in Figure 4 .

[0005] In the early production process, with the use of the equipment, the top of the center rod accumulates powder that cannot be discharged and brings the accumulated powder into the upper punch. As the amount of residual powder in the upper punch accumulates more and more, the powder is compacted, the force on the inside of the upper punch becomes larger and larger, and the upper punch is broken, as shown in Figure 5 .

[0006] Therefore, how to solve the technical problem that the upper punch is prone to breaking due to untimely powder discharging in the pressing process of the ring-shaped green pellet. SUMMARY

[0007] Therefore, the application provides a powder discharging structure used in the pressing process of a ring-shaped green pellet, which solves the technical problem that the upper punch is prone to breaking due to untimely powder discharging in the pressing process of the ring-shaped green pellet by arranging a powder discharging hole on the side of the center hole of the upper punch.

[0008] The application provides a powder discharging structure used in a green compact pressing process of a ring-shaped core block, which comprises an upper punch, a punch sleeve, an upper punch rod and a center rod. A base of the upper punch is used for being mounted on the top of the upper punch rod. The punch sleeve is used for penetrating from the upper part of the upper punch and being threadedly connected with the upper punch rod. The upper punch is provided with a center hole and a powder discharging hole. The powder discharging hole is arranged at the side of the center hole. One end of the center rod is used for being mounted at the center hole of the upper punch, and the other end of the center rod is used for being mounted on a rotary forming press equipment.

[0009] In one specific embodiment of the application, the central axis of the powder discharging hole and the central axis of the center hole form an acute angle.

[0010] In one specific embodiment of the application, a side of the upper punch rod close to the upper punch is provided with a T-shaped hole. The T-shaped hole comprises a transverse hole and a longitudinal hole, and the longitudinal hole is coaxially designed with the center hole of the upper punch.

[0011] In one specific embodiment of the application, the diameter of the longitudinal hole is greater than the diameter of the center hole of the upper punch.

[0012] In one specific embodiment of the application, the diameter of the longitudinal hole is 3 mm.

[0013] In one specific embodiment of the application, the center rod is in a conical structure.

[0014] In one specific embodiment of the application, the center rod is divided into a bottom and a first cylindrical structure, a second cylindrical structure and a third cylindrical structure which are sequentially arranged at one side of the bottom. The diameters of the first cylindrical structure, the second cylindrical structure and the third cylindrical structure sequentially decrease.

[0015] In one specific embodiment of the application, the diameter of the first cylindrical structure is 3.1 mm. The diameter of the second cylindrical structure is 2.04 mm. The diameter of the third cylindrical structure is 2.01 mm.

[0016] In one specific embodiment of the application, the lengths of the first cylindrical structure, the second cylindrical structure and the third cylindrical structure sequentially decrease.

[0017] The application has the advantages that: the powder discharging hole is arranged at the side of the center hole of the upper punch, so that the powder in the upper punch with the center rod can be timely discharged, the accumulation of the residual powder in the upper punch is reduced or even avoided, the fracture of the upper punch is avoided, the industrial production of the ring-shaped core block is realized, the replacement of the mold after the damage of the punch is avoided, the labor intensity of the personnel is reduced, the direct contact between the personnel and the material is avoided, and the material loss caused by the damage of the punch in the pressing process is avoided. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1The diagram shows a schematic of the cold pressing process of a rotary forming press.

[0019] Figure 2 The diagram shown illustrates the bidirectional compression process.

[0020] Figure 3 The diagram shows the assembly of the annular core block mold.

[0021] Figure 4 The image shown is a physical diagram of the center rod.

[0022] Figure 5 The image shown is a photograph of a broken upper punch.

[0023] Figure 6 The diagram shown is a schematic diagram of a powder discharge structure used in the pressing process of a ring-shaped core block according to an embodiment of this application.

[0024] Figure 7 The diagram shown is a schematic diagram of a powder discharge structure for the pressing process of a ring-shaped core block green body, provided by another embodiment of this application.

[0025] Figure 8 The diagram shown is a schematic representation of the position and size of the powder discharge hole added to the upper punch according to an embodiment of this application.

[0026] Figure 9 The figure shown is a cone-shaped design of a central rod according to an embodiment of this application.

[0027] Figure 10 The image shown is a T-hole diagram of an upper punch rod according to an embodiment of this application.

[0028] Figure 11 The image shown is a physical schematic diagram of an upper punch, punch sleeve, and upper punch rod in a powder discharge structure used in the pressing process of a ring-shaped core block according to an embodiment of this application.

[0029] Figure 12 As shown Figure 11 The image shows the actual product after the upper punch, punch sleeve, and upper punch rod are installed.

[0030] Figure 13 The image shown is a physical diagram of an upper punch provided in one embodiment of this application.

[0031] Figure 14 As shown Figure 13 A photograph of the upper punch at another angle.

[0032] Figure 15 The image shown is a final installation effect diagram of a powder discharge structure used in the pressing process of a ring-shaped core block according to an embodiment of this application. Detailed Implementation

[0033] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0034] At least one embodiment of this application provides a powder discharge structure for the pressing process of annular pellets. This powder discharge structure is suitable for the design and application of powder discharge structures in all annular pellet pressing processes in the field of nuclear fuel preparation technology, and is especially suitable for pressing green pellets of powders with small average particle size and poor flowability.

[0035] refer to Figure 6 and Figure 8 The powder removal structure used in the pressing process of ring-shaped core preforms includes an upper punch, a punch sleeve, an upper punch rod, and a center rod. The base of the upper punch is used to mount the top of the upper punch rod. The punch sleeve passes through the upper part of the upper punch and is threadedly connected to the upper punch rod. The upper punch has a center hole and a powder removal hole. The powder removal hole is located on the side of the center hole. One end of the center rod is used to mount the center of the upper punch, and the other end is used to mount it on a rotary forming press.

[0036] It should be noted that the center rod can also be called the core rod. Figure 6 This is a design drawing for a general-purpose core block mold with a center hole. After the center rod is installed on a rotary forming press, it is fixed to the lower punch using a core rod seat, moving with the lower punch. This powder discharge structure for the ring-shaped core block green body pressing process may also include a female die. The female die is used for pressing the ring-shaped core block green body. After the center rod is installed at the center hole of the upper punch, the powder discharge hole is not blocked by the center hole.

[0037] According to the technical solution provided in the embodiments of this application, by setting a powder discharge hole on the side of the center hole of the upper punch, the powder brought into the upper punch by the center rod can be discharged in time through the powder discharge hole, reducing or even avoiding the upper punch breakage caused by the accumulation of residual powder in the upper punch. This realizes the industrial production of the ring core block, avoids the need to replace the mold after the punch is damaged, reduces the labor intensity of personnel, avoids direct contact between personnel and materials, and avoids material loss caused by the damage of the punch during the pressing process.

[0038] In at least one embodiment of this application, the central axis of the powder discharge hole forms an acute angle with the central axis of the central hole.

[0039] In at least one embodiment of this application, reference is made to Figure 7The upper punch rod has a T-hole on the side near the upper punch head. The T-hole includes a transverse hole and a longitudinal hole, with the longitudinal hole coaxial with the center hole of the upper punch head. In this way, by setting the T-hole on the side of the center rod near the upper punch head, the small amount of powder entering the upper punch head is prevented from being compacted and can be smoothly discharged through the powder discharge hole of the upper punch head, further ensuring that the powder brought into the upper punch head by the center rod can be discharged in a timely manner.

[0040] In at least one embodiment of this application, the diameter of the longitudinal hole is larger than the diameter of the central hole of the upper punch.

[0041] For example, the diameter of the center hole of the upper punch can be 2.04 mm, with an upper deviation of +0.011 and a lower deviation of +0.003.

[0042] In at least one embodiment of this application, the diameter of the longitudinal hole is 3 mm. (See reference...) Figure 10 In the cloud-line section, the diameter of the T-hole is φ3.

[0043] In at least one embodiment of this application, reference is made to Figure 9 The center rod has a tapered structure. This tapered design further reduces the amount of powder accumulating at the top of the center rod.

[0044] In at least one embodiment of this application, the central rod is divided into a bottom and a first cylindrical structure, a second cylindrical structure, and a third cylindrical structure located sequentially on one side of the bottom. The diameters of the first cylindrical structure, the second cylindrical structure, and the third cylindrical structure decrease sequentially.

[0045] In at least one embodiment of this application, the diameter of the first cylindrical structure is 3.1 mm. The diameter of the second cylindrical structure is 2.04 mm. The diameter of the third cylindrical structure is 2.01 mm.

[0046] It should be noted that the tapered structure of the central rod has changed from 2.04mm to 2.01mm, which is a small change in size.

[0047] In at least one embodiment of this application, the lengths of the first cylindrical structure, the second cylindrical structure, and the third cylindrical structure decrease sequentially.

[0048] The following is a detailed illustration of a method for using a powder discharge structure in the pressing process of a ring-shaped core block, based on actual physical images.

[0049] Figure 11 To machine the upper punch, install the upper punch base onto the top of the upper punch rod. Pass the punch sleeve through the top of the upper punch and connect it to the upper punch rod using threads. Then, install the entire assembly on the rotary forming press. See [link to relevant documentation]. Figure 12 .

[0050] according to Figure 12Machining center rods and mounting them on rotary forming press equipment.

[0051] according to Figure 13 and Figure 14 The upper punch was improved and installed on a rotary forming press. When combined, they form a new powder discharge structure.

[0052] The final installation effect of the rotational molding press equipment is shown in the figure. Figure 15 .

[0053] After installation following the above steps, materials were added for testing. Over 3000 kg of materials were produced without any breakage of the upper punch due to powder discharge issues.

[0054] It should be noted that the combination of the technical features in the embodiments of this application is not limited to the combination methods described in the embodiments of this application or the combination methods described in specific embodiments. All technical features described in this application can be freely combined or combined in any way, unless they contradict each other.

[0055] As indicated in this application and claims, unless the context clearly indicates otherwise, the words "a," "an," and / or "the" do not specifically refer to the singular and may also include the plural. Generally speaking, the term "comprising" only indicates that it includes the explicitly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0056] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications or equivalent substitutions made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A powder discharge structure for use in the pressing process of annular core blocks, characterized in that, It includes an upper punch, a punch sleeve, an upper punch rod, and a center rod. The base of the upper punch is used to mount on the top of the upper punch rod. The punch sleeve passes through the upper part of the upper punch and is threaded to the upper punch rod. The upper punch has a center hole and a powder discharge hole, with the powder discharge hole located on the side of the center hole. One end of the center rod is used to mount at the center hole of the upper punch, and the other end of the center rod is used to mount on a rotary forming press.

2. The powder discharge structure for the pressing process of annular core blocks according to claim 1, characterized in that, The central axis of the powder discharge hole forms an acute angle with the central axis of the central hole.

3. The powder discharge structure for the pressing process of annular core blocks according to claim 1, characterized in that, The upper punch rod has a T-hole on the side near the upper punch head. The T-hole includes a transverse hole and a longitudinal hole, and the longitudinal hole is designed to be coaxial with the center hole of the upper punch head.

4. A powder discharge structure for use in the pressing process of annular core blocks according to claim 3, characterized in that, The diameter of the longitudinal hole is larger than the diameter of the center hole of the upper punch.

5. A powder discharge structure for use in the pressing process of annular core blocks according to claim 3, characterized in that, The diameter of the longitudinal hole is 3mm.

6. A powder discharge structure for use in the pressing process of annular core blocks according to any one of claims 1 to 5, characterized in that, The central rod has a conical structure.

7. A powder discharge structure for use in the pressing process of annular core blocks according to claim 6, characterized in that, The central rod is divided into a bottom and a first cylindrical structure, a second cylindrical structure, and a third cylindrical structure located sequentially on one side of the bottom. The diameters of the first cylindrical structure, the second cylindrical structure, and the third cylindrical structure decrease sequentially.

8. A powder discharge structure for use in the pressing process of annular core blocks according to claim 7, characterized in that, The diameter of the first cylindrical structure is 3.1 mm, the diameter of the second cylindrical structure is 2.04 mm, and the diameter of the third cylindrical structure is 2.01 mm.

9. A powder discharge structure for use in the pressing process of annular core blocks according to claim 7, characterized in that, The lengths of the first cylindrical structure, the second cylindrical structure, and the third cylindrical structure decrease sequentially.

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