Casting granulator pressing wheel with gradient structure

Abstract

The utility model aims to provide a casting granulator pinch roller with a gradient structure, which is mainly used for solving the technical problem of prolonging the service life of the pinch roller. A casting granulator pressing wheel with a gradient structure comprises a pressing wheel body, and the pressing wheel body comprises a wear-resisting part, a transition part and a tough core part from outside to inside; a pinch roller shaft mounting hole is formed in the center of the pinch roller body; rolling grooves are formed in the outer side of the wear-resisting part in the circumferential direction at intervals, and the cross section contours of the rolling grooves are of a composite curve structure. The technical scheme has the following advantages: through the gradient structure design of hard outside and tough inside, the contradiction that the hardness and the toughness of the traditional homogenizing pinch roller cannot be obtained at the same time is perfectly solved. The wear-resistant part provides extremely high wear resistance, and the internal tough core part ensures the overall strength and impact resistance, so that the comprehensive performance of the pinch roller is optimal.

Description

Technical Field

[0001] This utility model relates to the field of pellet mill pressure roller technology, specifically a cast pellet mill pressure roller with a gradient structure. Background Technology

[0002] Pellet mills are widely used in industries such as feed, fertilizer, and biomass energy. Their working principle involves the relative rolling of the pressure roller and the ring die, which forces powdery materials through the die holes in the ring die to form cylindrical pellets. The pressure roller, as a key wear component directly involved in the extrusion molding process, operates in extremely harsh environments, needing to withstand intense extrusion stress, severe material friction, and periodic impact loads.

[0003] Currently, traditional pressure rollers are mostly made of a single material, cast steel or alloy steel, and their surface hardness is achieved through heat treatment processes such as integral quenching. This homogeneous structure of pressure rollers has inherent drawbacks: to resist wear, the roller surface requires extremely high hardness, but high hardness inevitably leads to a decrease in material toughness. This makes the roller prone to developing micro-cracks on the surface or subsurface when subjected to impact and contact fatigue, which can then propagate into spalling, chipping, or even breakage, resulting in a short service life. Conversely, if surface hardness is reduced to ensure toughness, the roller is highly susceptible to wear failure. This contradiction between hardness and toughness severely restricts the performance and lifespan of pressure rollers.

[0004] Therefore, there is an urgent need for a new type of pressure roller that can simultaneously take into account the characteristics of high surface hardness and high wear resistance as well as high internal toughness and high strength, so as to comprehensively improve its overall performance and service life. Utility Model Content

[0005] The purpose of this invention is to provide a casting pellet mill pressure roller with a gradient structure, mainly to solve the technical problem of improving the service life of the pressure roller.

[0006] The technical solution adopted by this utility model to solve its technical problem is:

[0007] A casting pellet mill pressure roller with a gradient structure includes a pressure roller body, which from the outside to the inside includes a wear-resistant part, a transition part and a tough core; the pressure roller body has a pressure roller shaft mounting hole at its center.

[0008] The outer circumferential surface of the wear-resistant part is provided with rolling grooves at intervals, and the cross-sectional profile of the rolling groove adopts a compound curve structure.

[0009] Preferably, the compaction groove extends from the bottom of the groove to both sides of the groove wall and includes, in sequence, a central arc-shaped section, a transition oblique section, and an outer reinforcing section; the central arc-shaped section is located at the center of the bottom of the groove, the transition oblique section is symmetrically connected to both ends of the central arc-shaped section, and the outer reinforcing section is symmetrically connected to the outer end of the transition oblique section.

[0010] Preferably, the outer reinforcing segment has an arc or sawtooth structure.

[0011] Preferably, the arc radius R1 of the central arc segment and the arc radius R2 of the outer reinforcing segment satisfy the relationship: R1 > 3R2.

[0012] Preferably, the surface of the rolling groove is provided with a wear-resistant coating.

[0013] Preferably, the transition portion is fitted between the tough core and the wear-resistant portion and is connected by a key structure.

[0014] Preferably, the inner cavity surface of the wear-resistant part is interference-fitted with the outer peripheral surface of the transition part, and the inner cavity surface of the transition part is interference-fitted with the outer peripheral surface of the tough core part.

[0015] Preferredly, the wear-resistant part and the transition part, as well as the transition part and the tough core, are connected by wedge keys.

[0016] Preferably, the wedge-shaped keyways on the outer circumference of the transition section and the wedge-shaped keyways on the inner cavity surface of the transition section are staggered in the circumferential direction.

[0017] Preferably, the mounting hole of the pressure roller shaft is provided with multiple flat keyways in the circumferential direction, and the multiple flat keyways in the circumferential direction are arranged in a "star" pattern.

[0018] The effects provided in the utility model description are merely those of the embodiments, and not all the effects of the utility model. The above technical solution has the following advantages or beneficial effects:

[0019] 1. Through a gradient structure design of "hard on the outside and tough on the inside," the contradiction between hardness and toughness in traditional homogeneous pressure rollers is perfectly resolved. The wear-resistant part provides extremely high wear resistance, while the tough inner core ensures overall strength and impact resistance, thus optimizing the overall performance of the pressure roller.

[0020] 2. By eliminating the obvious bonding interface between hard and tough materials, the stress concentration phenomenon is fundamentally improved, which greatly reduces the risk of the pressure roller falling off, peeling off, or even breaking under heavy load and impact conditions, making the equipment operation safer and more reliable.

[0021] 3. The unique composite curve structure of the compaction trough, especially the outer reinforced section, can more effectively "grab" and "guide" materials, increasing the amount of material entering the extrusion zone, thereby significantly improving the output efficiency of the pellet mill.

[0022] 4. The arc-shaped section at the center of the compaction trough provides a stable pre-compaction zone, the transitional oblique section achieves a smooth pressure transition, and the outer reinforcing section forms concentrated pressure in key areas. This gradient pressure design makes the material more evenly compressed, resulting in better molding quality and lower pulverization rate. At the same time, it avoids local stress concentration and extends the service life of the pressure roller and ring die. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the end face of Embodiment 1 of this utility model;

[0024] Figure 2 for Figure 1 Enlarged view of a portion of point A in the middle;

[0025] Figure 3 This is a schematic diagram of the end face of Embodiment 2 of this utility model;

[0026] In the figure: 1. Pressure roller shaft mounting hole; 2. Flat keyway; 3. Wear-resistant part; 4. Transition part; 5. Tough core; 6. Compaction groove; 61. Central arc section; 62. Transition oblique section; 63. Outer reinforcing section; 7. Wedge-shaped keyway. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0029] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. In the description of the invention, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as merely or implying relative importance.

[0030] In the description of this invention, unless otherwise explicitly specified and limited, the terms "set up," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0031] like Figure 1-3As shown, a pressure roller for a casting pellet mill with a gradient structure includes a disc-shaped pressure roller body. A pressure roller shaft mounting hole 1 is machined at the center of the pressure roller body. Multiple flat keyways 2 are provided circumferentially around the pressure roller shaft mounting hole 1, arranged in a "X" pattern for mounting the roller onto the pellet mill via the pressure roller shaft.

[0032] Example 1

[0033] The pressure roller body is integrally formed by centrifugal composite casting process and includes a three-layer structure from the outside to the inside, namely wear-resistant part 3, transition part 4, and tough core part 5. The wear-resistant part 3 is located on the outermost side of the pressure roller body, and the transition part 4 is located between the wear-resistant part 3 and the tough core part 5.

[0034] The wear-resistant part 3 can be made of high-chromium cast iron (such as Cr15, Cr20, etc.), and its hardness after casting can reach HRC 62 or above. Its thickness is 15% to 20% of the total wall thickness (radial dimension) of the pressure roller body. This layer is mainly responsible for bearing the wear during operation. Multiple rolling grooves 6 are provided at intervals on the outer circumferential direction of the wear-resistant part 3.

[0035] The cross-sectional profile of the compaction trough 6 is a composite curve structure, extending from the bottom of the trough to the two side walls, and includes a central arc-shaped section 61, a transitional oblique section 62, and an outer reinforcing section 63 in sequence. The central arc-shaped section 61 is located at the center of the trough bottom and is an arc, used to initially gather material and form a stable pressure base. The transitional oblique section 62 is symmetrically connected to both ends of the central arc-shaped section 61 and is a straight section forming an acute angle (15° to 45°) with the radial direction of the pressure roller body, used to gently guide the material towards the extrusion zone. The outer reinforcing section 63 is symmetrically connected to the outer end of the transitional oblique section 62 and is an arc or sawtooth structure (teeth are triangular, trapezoidal, or wavy), used to form local high pressure at the entrance of the extrusion zone, enhancing the "biting" ability and friction of the material. The arc radius R1 of the central arc-shaped section 61 and the arc radius R2 of the outer reinforcing section 63 satisfy the relationship: R1 > 3R2. The surface of the compaction trough 6 is coated with a wear-resistant coating, such as a tungsten carbide coating.

[0036] The tough core 5 is made of 42CrMo or high-strength ductile iron (QT600-3), with a hardness of approximately HRC 35 after tempering. Its thickness is approximately 55% to 70% of the total wall thickness (radial dimension) of the pressure roller body, exhibiting high strength and toughness. This layer serves as the load-bearing skeleton of the pressure roller body. The transition section 4 is located between the wear-resistant section 3 and the tough core 5, and is made of a mixture of materials from both. For example, during the casting process, the two alloy liquids (high-chromium cast iron and high-strength ductile iron in a 1:2 ratio) of the wear-resistant section 3 and the tough core 5 are mixed, causing the outer wear-resistant section 3 and the tough core 5 to melt and diffuse at the interface, forming a transition region with a continuous and smooth change in chemical composition, metallographic structure, and mechanical properties. The thickness of this transition section 4 is typically controlled to be 10% to 30% of the total wall thickness (radial dimension) of the pressure roller, and its hardness smoothly transitions from HRC 62 in the outer layer to HRC 35 in the inner layer.

[0037] Example 2

[0038] The wear-resistant part 3, transition part 4, and toughening core 5 can be manufactured separately. During installation, the transition part 4 is fitted between the toughening core 5 and the wear-resistant part 3. The inner cavity surface of the wear-resistant part 3 is press-fitted with the outer peripheral surface of the transition part 4, and the inner cavity surface of the transition part 4 is press-fitted with the outer peripheral surface of the toughening core 5. Preferably, the wear-resistant part 3 and the transition part 4, as well as the transition part 4 and the toughening core 5, are connected by wedge keys. The inner cavity surface of the wear-resistant part 3, the outer peripheral surface and the inner cavity surface of the transition part 4, and the outer peripheral surface of the toughening core 5 are all provided with wedge keyways 7. The wedge keyways 7 on the outer peripheral surface of the transition part 4 and the wedge keyways 7 on its inner cavity surface are staggered in the circumferential direction.

[0039] Except for the technical features described in the specification, all other technologies are known to those skilled in the art.

[0040] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A cast granulator pellet wheel having a gradient structure comprising a pellet wheel body, characterized in that, The pressure roller body comprises a wear-resistant part, a transition part, and a tough core from the outside to the inside; the pressure roller body has a pressure roller shaft mounting hole at its center. The outer circumferential surface of the wear-resistant part is provided with rolling grooves at intervals, and the cross-sectional profile of the rolling groove adopts a compound curve structure.

2. A cast granulator wheel having a gradient structure according to claim 1, characterized in that The compaction groove extends from the bottom of the groove to both sides of the groove wall and includes a central arc-shaped section, a transition oblique section, and an outer reinforcing section in sequence. The central arc-shaped section is located at the center of the groove bottom, the transition oblique section is symmetrically connected to both ends of the central arc-shaped section, and the outer reinforcing section is symmetrically connected to the outer end of the transition oblique section.

3. A granulator casting wheel having a gradient structure according to claim 2, characterized in that, The outer reinforcing section has an arc or sawtooth structure.

4. A granulator casting wheel having a gradient structure according to claim 2, characterized in that, The arc radius R1 of the central arc segment and the arc radius R2 of the outer reinforcing segment satisfy the relationship: R1 > 3R2.

5. A casting pellet mill pressure roller with a gradient structure according to claim 1, characterized in that, The surface of the rolling groove is coated with a wear-resistant coating.

6. A casting pellet mill pressure roller with a gradient structure according to claim 1, characterized in that, The transition section is fitted between the tough core and the wear-resistant section and is connected by a key structure.

7. A cast granulator pressure wheel having a gradient structure according to claim 1, characterised in that, The inner cavity surface of the wear-resistant part is interference-fitted with the outer peripheral surface of the transition part, and the inner cavity surface of the transition part is interference-fitted with the outer peripheral surface of the tough core part.

8. A cast granulator pressure wheel having a gradient structure according to claim 1, characterised in that, The wear-resistant part and the transition part, as well as the transition part and the tough core, are connected by wedge keys.

9. A cast granulator pressure wheel having a gradient structure according to claim 8, characterised in that, The wedge-shaped keyways on the outer circumference of the transition section and the wedge-shaped keyways on the inner cavity surface of the transition section are staggered in the circumferential direction.

10. A casting pellet mill pressure roller with a gradient structure according to any one of claims 1-9, characterized in that, The mounting hole of the pressure roller shaft is provided with multiple flat keyways in the circumferential direction, and the multiple flat keyways in the circumferential direction are arranged in a "star" pattern.

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