Production process for centrifugally casting lubrication-free solid wear-resistant pin shaft

Abstract

The invention discloses a production process for a centrifugal casting lubrication-free solid wear-resistant pin shaft, and relates to the technical field of metal material preparation, in particular to the production process for the centrifugal casting lubrication-free solid wear-resistant pin shaft. A steel mold is used for casting, molten iron is rapidly cooled after being poured, a large amount of small spherical graphite is separated out from an internal structure, the functions of oil storage and self-lubrication are achieved, and the function that a lubricating agent does not need to be additionally added in the using process is achieved; a compact organization structure is obtained through the centrifugal casting process, the wear resistance of the pin shaft is remarkably improved, the service life of the pin shaft is prolonged, the maintenance and replacement frequency of equipment is reduced, and the production efficiency is improved; by means of the centrifugal casting die design of one die, multiple layers and one layer and multiple cavities, blanks can be rapidly produced in batches, the follow-up machining procedures are conducted, the production period is short, the requirement for large-scale production can be met, and the production efficiency and market competitiveness of enterprises are improved.

Description

Technical Field

[0001] The present invention relates to the field of mechanical parts manufacturing, and in particular to a production process of a centrifugally cast lubrication-free solid wear-resistant pin shaft. Background Art

[0002] In mechanical transmission systems, bearing pins are key connecting components, and their performance directly impacts the equipment's operational stability and service life. Construction machinery, such as excavators, operates in wet and muddy conditions for extended periods. Due to frequent and intense friction between bearing pins and connected components, they require a continuous supply of lubricant to reduce wear, minimize usage frequency, extend service life, and improve efficiency. However, conventional lubricants can erode with the materials in the operating environment, losing their lubricating effectiveness and damaging the bearing pins and bushings. This impacts the continuous operation of the construction machinery and increases maintenance and operating costs.

[0003] At the same time, existing pin manufacturing processes have shortcomings in terms of material and product quality stability. Conventional methods using low-carbon steel, machined and then heat-treated, only provide wear resistance on a thin surface layer, resulting in a short service life. Therefore, developing a lubrication-free, highly wear-resistant, and long-lasting solid pin manufacturing technology is of great practical significance. Summary of the Invention

[0004] The purpose of the present invention is to address the deficiencies of the prior art and provide a centrifugal casting process for producing a lubrication-free solid wear-resistant pin, so as to improve the performance and quality of the pin.

[0005] The present invention provides a centrifugally cast, lubrication-free, solid, wear-resistant pin production process, which is characterized by comprising the following steps: The first step is to melt the selected raw materials in a medium frequency induction furnace to make the alloy composition fully homogenized; silicon carbide is added to the furnace to increase carbon, the CE range is adjusted to 4.5%, and the furnace is opened at 1420°; the second step is to introduce the molten iron into the spheroidizing bag and spheroidize it using the wire feeding spheroidizing process; The third step is to introduce the molten iron into the spheroidizing bag and adopt the wire feeding spheroidizing process for spheroidization. After slag removal, it reaches the casting platform of the vertical centrifuge; The third step is to quickly pour the molten iron into each layer of the casting mold rotating on the vertical centrifuge through multiple pouring pipes set on the pouring platform. The molten iron enters the pouring port through the radial pouring channel and flows into the pin mold under the action of centrifugal force; Step 4: After pouring, the centrifugal casting mold is cooled; the centrifuge stops rotating; Step 5: Machining the removed blank into a pin according to the dimensions of the drawing; Step 6: Perform overall heat treatment on the pin shaft.

[0006] Furthermore, it is characterized in that the heat treatment method is water-air alternating quenching + air furnace isothermal treatment; the pin is placed in a material basket and placed upright, first entering the air quenching furnace to heat up for 1 hour, keeping warm at 880°C for 1 hour, and then taken out by forklift lift. It is immersed in water within 15 seconds to cool for 15 seconds, then raised above the water surface, and stayed in the air for 15 seconds to slightly uniformize the temperature of the pin, and then immersed in water for cooling for 10 seconds for the second time, and raised above the water surface for the second time. The pin temperature is about 280°, and enters a 280° tempering furnace to keep warm for 1.5 hours, and air-cooled; the water temperature before quenching is 32°, and the water temperature after quenching is 36°. During the quenching process, high-pressure air is sprayed from the bottom of the pool for stirring, and the propeller rotates and stirs from one side. The outdoor cooling tower provides circulating heat dissipation for the quenching pool, and continuous heat treatment is performed. The quenching water pool is kept below 40° to maintain the quenching intensity.

[0007] Furthermore, the rotation speed of the vertical centrifuge is selected to be 100 rpm.

[0008] Furthermore, the centrifugal casting mold shown includes a flange for installation on a vertical centrifugal casting machine, and the flange installation position corresponds to the rotation axis of the centrifugal casting machine; a runner assembly is installed at a position corresponding to the center axis of the flange, and the runner assembly is a shell, and the inner surface is lined with refractory sand and sprayed with paint; a plurality of detachable pin molds are radially evenly distributed on the side of the runner assembly, and the runner assembly is connected to the pin mold; air vents are evenly arranged on the side wall of the pin mold, and the air vents are sealed with refractory sand.

[0009] Furthermore, the coating is prepared by uniformly stirring silica powder as refractory powder, bentonite as suspending agent, water as carrier liquid, and water glass as binder, and can adhere to the surface of the metal mold to play a role in heat insulation protection.

[0010] Furthermore, the runner gate assembly includes a runner gate lower assembly fixedly mounted on the flange, a runner gate upper assembly mounted on the runner gate lower assembly, and an asbestos pad is arranged between the upper assembly and the lower assembly; a sinking platform is arranged on the upper part of the runner gate upper assembly, an upper cover is installed on the sinking platform, and a gate is arranged in the middle of the upper cover; a pressure ring is arranged around the upper cover, a first oblique wedge hole is arranged on the side wall of the sinking platform, the first oblique wedge cooperates with the first oblique wedge hole, and an upper cover pressure surface is arranged at the corresponding position of the first oblique wedge and the pressure ring.

[0011] Furthermore, a W-shaped positioning block is fixedly provided on the circumference of the flange, and a slot is formed between the W-shaped positioning block and the outer wall of the runner gate assembly. A flange edge is provided at the mating end of the pin shaft mold and the runner gate assembly, and the flange edge cooperates with the slot; the side surface of the flange edge on the upper part of the pin shaft mold is a pressure-bearing surface, and a mold pressure surface is provided at the end of the first bevel, and the mold pressure surface cooperates with the pressure-bearing surface.

[0012] Furthermore, a second oblique wedge hole is provided on the W-shaped positioning block, the second oblique wedge cooperates with the second oblique wedge hole, a runner gate assembly pressure surface is provided on the second oblique wedge, and the runner gate assembly pressure surface corresponds to the runner gate upper edge surface.

[0013] Furthermore, the pin mold includes an upper pin mold assembly and a lower pin mold assembly, an asbestos pad is arranged between the upper pin mold assembly and the lower pin mold assembly; a locking block is arranged on the lower pin mold assembly, and a locking hook is arranged at a corresponding position of the upper pin mold assembly, a third bevel is arranged between the locking block and the locking hook, and the third bevel locks the lower pin mold assembly and the upper pin mold assembly; the thickness of the third bevel is greater than the depth of the flange groove of the inner cavity of the pin mold; and paint is sprayed inside the pin mold.

[0014] The present invention provides a centrifugal casting process for producing lubrication-free solid wear-resistant pins. Compared with ordinary sand casting, the process has a fast cooling speed, and a large number of small spherical graphite are precipitated in the internal structure, which has the functions of oil storage and self-lubrication, and does not require external lubricant during use; the centrifugal casting process obtains a dense organizational structure, significantly improves the wear resistance of the pin, extends the service life of the pin, reduces the maintenance and replacement frequency of equipment, and improves production efficiency; the centrifugal casting mold design with one mold and multiple layers, and one layer and multiple cavities, realizes the rapid batch production of blanks, and after subsequent processing steps, the production cycle is short, which can meet the needs of large-scale production and improve the production efficiency and market competitiveness of the enterprise. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a process flow chart of the present invention; Figure 2 It is a structural schematic diagram of the centrifugal casting mold of the present invention; Figure 3 is a top view of the centrifugal casting mold of the present invention; Figure 4 It is a structural schematic diagram of the flange of the present invention; Figure 5 It is a structural schematic diagram of the runner gate assembly of the present invention; Figure 6 It is a structural schematic diagram of the pin mold of the present invention; Figure 7 It is a structural schematic diagram of the outer end of the pin mold of the present invention; Figure 8 It is a cross-sectional view of the first oblique wedge of the centrifugal casting mold of the present invention. DETAILED DESCRIPTION

[0016] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0017] Use as Figure 2-3The centrifugal casting mold shown in the figure comprises a flange 1 for mounting on a vertical centrifugal casting machine, wherein the flange mounting position corresponds to the rotation axis of the centrifugal casting machine; a sprue assembly 2 is mounted at a position corresponding to the center axis of the flange; Figure 5 As shown, the gate assembly includes a gate lower part 21 fixedly mounted on the flange by welding, a positioning pin is provided on the top of the gate lower part, a positioning hole is provided at the bottom of the gate upper part 22, the positioning hole cooperates with the positioning pin, and the gate upper part is mounted on the gate lower part; a sinking platform is provided on the upper part of the gate upper part, an upper cover 24 is mounted on the sinking platform, a gate 25 is provided in the middle of the upper cover, and a pressure ring 26 is provided around the circumference; the flange, the gate lower part, the gate upper part, and the upper cover together form a shell; like Figure 4 As shown, a W-shaped positioning block 3 is fixedly welded on the circumference of the flange, a second oblique wedge hole 31 is provided on the W-shaped positioning block, a second oblique wedge 32 cooperates with the second oblique wedge hole, a runner gate assembly pressure surface is provided on the second oblique wedge, the runner gate assembly pressure surface cooperates with the upper edge surface of the runner gate upper assembly, and the runner gate upper assembly is pressed onto the runner gate lower assembly; The W-shaped positioning block and the outer wall of the runner assembly form a slot 33, such as Figure 6 As shown, a flange 41 is provided at the joint between the pin mold 4 and the runner assembly, an asbestos pad is placed between the flange and the runner assembly, and an oblique wedge is driven between the other side of the flange and the slot, so that the pin mold is tightly attached to the outer wall of the runner assembly; Figure 8 As shown, a first oblique wedge hole 27 is provided on the upper part of the side wall of the sinking platform assembled on the runner gate, and the first oblique wedge 28 cooperates with the first oblique wedge hole. An upper cover pressure surface 29 is provided at a position corresponding to the first oblique wedge and the pressure ring, and a mold pressure surface 20 is provided at a position corresponding to the pin mold. The upper cover pressure surface cooperates with the pressure ring, and the mold pressure surface cooperates with the pressure-bearing surface of the side of the flange edge of the upper part of the pin mold. The upper cover is pressed tightly onto the runner gate through the first oblique wedge, and the pin mold is pressed tightly onto the flange.

[0018] In this way, multiple pin molds are radially evenly distributed on the side of the runner gate assembly, and the runner gate assembly is connected to the pin mold through a connecting hole 5 set on the side of the runner gate assembly; it is worth noting that the joint between the upper part of the runner gate and the lower part of the runner gate is set at a position corresponding to the diameter of the connecting hole; the pin mold is also divided into two parts, the upper and lower parts, and the joint is also set at a position corresponding to the diameter of the connecting hole; this arrangement makes it convenient to disassemble the mold and the runner gate assembly after casting and take out the blank.

[0019] The lower part of the pin mold is fixed to the mounting flange by welding, such as Figure 7As shown, a locking block 42 is provided on the lower part of the pin shaft mold, a locking hook 43 is provided at the corresponding position of the upper part of the pin shaft mold, and a third oblique wedge 44 is provided between the locking block and the locking hook. The third oblique wedge locks the lower part of the pin shaft mold and the upper part of the pin shaft mold to increase the overall firmness of the pin shaft mold; obviously, the thickness of the third oblique wedge is greater than the depth of the flange groove 45 of the inner cavity of the pin shaft mold to facilitate the disassembly of the pin shaft mold; the pin shaft mold is evenly provided with vent holes on the side wall, and the vent holes are sealed with refractory sand to facilitate the discharge of gas during casting.

[0020] A production process for a centrifugally cast lubrication-free solid wear-resistant pin shaft comprises the following steps: The first step is to melt the selected raw materials in a medium frequency induction furnace to make the alloy composition fully homogenized; add silicon carbide to increase carbon in the furnace, adjust the CE range to 4.5%, and take it out of the furnace at 1420°; The second step is to introduce the molten iron into the spheroidizing bag and adopt the wire feeding spheroidizing process for spheroidization. It will reach the casting platform of the vertical centrifuge 90 seconds after the slag is removed. The third step is to quickly pour the molten iron into the gate of the casting mold rotating on the vertical centrifuge. The silicon-bismuth inoculant is added along with the flow. The molten iron flows into the pin mold under the action of centrifugal force. The rotation speed of the vertical centrifuge is selected to be 100 rpm, which can obtain a gravity coefficient of 5.4 times, and the pin casting is well filled. If the rotation speed is selected to be 200 rpm, the gravity coefficient increases to 22 times, and the possibility of molten iron leakage and splashing increases.

[0021] Step 4: After pouring is completed, the mold is cooled naturally for 20 minutes and the centrifuge stops rotating.

[0022] Step 5: Remove the mold and install another set of molds on the centrifuge; Step 6. Repeat steps 2 to 5 for the newly installed mold to achieve continuous operation; disassemble the removed mold and take out the pin.

[0023] Step 7: Heat treat the pin casting as a whole; place the pin in a basket and place it upright. Use blocks to separate the pins to ensure smooth flow of cooling water during quenching. Isothermal quenching is done by alternating water and air quenching + isothermal treatment in an air furnace. Figure 7 As shown, it first enters the air quenching furnace for heating for 1 hour, keeps warm at 880°C for 1 hour, is taken out by forklift lift, and enters water for cooling within 15 seconds for 15 seconds, then rises above the water surface and stays in the air for 15 seconds to slightly uniformize the temperature of the pin shaft, enters water for cooling for 10 seconds for the second time, rises above the water surface for the second time, the pin shaft temperature is about 280°, enters the 280° tempering furnace for keeping warm for 1.5 hours, and air cools; the water temperature before quenching is 32°, and the water temperature after quenching is 36°. During the quenching process, high-pressure air is sprayed from the bottom of the pool for stirring, and the propeller rotates and stirs from one side. The outdoor cooling tower provides circulating heat dissipation for the quenching pool, and continuous heat treatment is carried out. The quenching pool water temperature is kept below 40° to maintain the quenching intensity.

[0024] Step 8. Machine the pin casting into a pin according to the dimensions on the drawing.

[0025] The present invention provides a centrifugal casting process for producing lubrication-free solid wear-resistant pins. Compared with ordinary sand casting, the process greatly reduces the use of casting sand and binders, reduces chemical pollution, the generation of solid waste and dust pollution, and is more environmentally friendly; it can meet the needs of large-scale production; it has a fast cooling speed, and a large number of small spherical graphite are precipitated in the internal structure, which has the functions of oil storage and self-lubrication, and no external lubricant is required during use; the centrifugal casting process obtains a dense organizational structure, significantly improves the wear resistance of the pin, extends the service life of the pin, reduces the maintenance and replacement frequency of equipment, and improves production efficiency; the one-mold multi-cavity centrifugal casting mold design realizes the rapid batch production of blanks, and after subsequent processing steps, the production cycle is short, which can meet the needs of large-scale production and improve the production efficiency and market competitiveness of the enterprise.

[0026] In order to further improve production efficiency, a centrifugal casting mold with multiple layers in one mold and multiple cavities in one layer can be designed to achieve rapid batch production of blanks. After subsequent processing steps, the production cycle is short, which can meet the needs of large-scale production and improve the company's production efficiency and market competitiveness.

[0027] The above embodiments are provided for persons familiar with the art to implement or use the technical solutions of the present application. The temperature and time mentioned in the solutions are reference standards. There is no need to pursue absolute precision in actual production. Personnel familiar with the art can make various modifications or changes to the above embodiments without departing from the idea of ​​the technical solutions of the present application. Therefore, the scope of protection of the present application is not limited to the above embodiments, but should be the maximum scope of the innovative features mentioned in the claims.

Claims

1. A centrifugal casting process for producing a lubrication-free solid wear-resistant pin, characterized in that: It includes the following steps: The first step is to melt the selected raw materials in a medium frequency induction furnace to make the alloy composition fully homogenized; silicon carbide is added to the furnace to increase carbon, the CE range is adjusted to 4.5%, and the furnace is opened at 1420°; the second step is to introduce the molten iron into the spheroidizing bag and spheroidize it using the wire feeding spheroidizing process; The second step is to introduce the molten iron into the spheroidizing bag and adopt the wire feeding spheroidizing process for spheroidization. After slag removal, it reaches the casting platform of the vertical centrifuge; The third step is to quickly pour the molten iron into each layer of the casting mold rotating on the vertical centrifuge through multiple pouring pipes set on the pouring platform. The molten iron enters the pouring port through the radial pouring channel and flows into the pin mold under the action of centrifugal force; Step 4: After pouring, the centrifugal casting mold is cooled; the centrifuge stops rotating; Step 5: Remove the mold and install another set of molds on the centrifuge; Step 6: Repeat steps 2 to 5 for the newly installed mold to achieve continuous operation; disassemble the removed mold and take out the pin casting; Step 7: Heat treat the pin casting as a whole; Step 8. Machine the pin casting into a pin according to the dimensions on the drawing.

2. The process for producing a centrifugally cast lubrication-free solid wear-resistant pin according to claim 1, characterized in that: The heat treatment method is water-air alternating quenching + isothermal treatment in an air furnace; the pin is placed in a material basket and placed upright, first entering the air quenching furnace to heat up for 1 hour, keeping warm at 880°C for 1 hour, and then taken out by a forklift lift. It is immersed in water within 15 seconds to cool for 15 seconds, then raised above the water surface and retained in the air for 15 seconds to slightly uniformize the temperature of the pin, and then immersed in water for 10 seconds and raised above the water surface for the second time. The pin temperature is about 280°, and it is placed in a 280° tempering furnace for 1.5 hours and air-cooled; the water temperature before quenching is 32°, and the water temperature after quenching is 36°. During the quenching process, high-pressure air is sprayed from the bottom of the pool for stirring, and the propeller rotates and stirs from one side. The outdoor cooling tower provides circulating heat dissipation for the quenching pool, and continuous heat treatment is performed. The quenching water pool is kept below 40° to maintain the quenching intensity.

3. The manufacturing process of a lubrication-free solid wear-resistant pin according to claim 1, characterized in that: The rotation speed of the vertical centrifuge is selected to be 100 rpm.

4. The production process of a centrifugal casting lubrication-free solid wear-resistant pin according to claim 1, characterized in that: The centrifugal casting mold includes a flange for installation on a vertical centrifugal casting machine, and the flange installation position corresponds to the rotation axis of the centrifugal casting machine; a runner gate assembly is installed at a position corresponding to the center axis of the flange, and the runner gate assembly is a shell, the inner surface of which is lined with refractory sand and sprayed with paint; a plurality of detachable pin shaft molds are radially evenly distributed on the side of the runner gate assembly, and the runner gate assembly is connected to the pin shaft mold; ventilation holes are evenly arranged on the side wall of the pin shaft mold, and the ventilation holes are sealed with refractory sand.

5. The centrifugal casting mold for a lubrication-free solid wear-resistant pin according to claim 4, characterized in that: The coating is prepared by uniformly stirring and mixing silica powder as refractory powder, bentonite as suspending agent, water as carrier liquid and water glass as binder. The coating can adhere to the surface of the metal mold and play a role of heat insulation protection.

6. The centrifugal casting mold for a lubrication-free solid wear-resistant pin according to claim 4, characterized in that: The runner gate assembly includes a runner gate lower assembly fixedly mounted on a flange, a runner gate upper assembly mounted on the runner gate lower assembly, and an asbestos pad is arranged between the upper assembly and the lower assembly; a sinking platform is arranged on the upper part of the runner gate upper assembly, an upper cover is installed on the sinking platform, and a gate is arranged in the middle of the upper cover; a pressure ring is arranged around the upper cover, a first oblique wedge hole is arranged on the side wall of the sinking platform, the first oblique wedge cooperates with the first oblique wedge hole, and an upper cover pressure surface is arranged at the corresponding position of the first oblique wedge and the pressure ring.

7. The centrifugal casting mold for a lubrication-free solid wear-resistant pin according to claim 4, characterized in that: A W-shaped positioning block is fixedly provided on the circumference of the flange, and a slot is formed between the W-shaped positioning block and the outer wall of the runner gate assembly. A flange edge is provided at the mating end of the pin shaft mold and the runner gate assembly, and the flange edge is mated with the slot. An asbestos pad is provided between the flange edge and the runner gate assembly, and an inclined wedge is driven between the other side of the flange edge and the slot, so that the pin shaft mold is tightly attached to the outer wall of the runner gate assembly; the side surface of the flange edge on the upper part of the pin shaft mold is a pressure-bearing surface, and a mold pressure surface is provided at the end of the first inclined wedge, and the mold pressure surface is mated with the pressure-bearing surface.

8. The centrifugal casting mold for a lubrication-free solid wear-resistant pin according to claim 7, characterized in that: The W-shaped positioning block is provided with a second oblique wedge hole, the second oblique wedge cooperates with the second oblique wedge hole, the second oblique wedge is provided with a runner gate component pressure surface, and the runner gate component pressure surface corresponds to the runner gate upper edge surface.

9. The process for producing a centrifugally cast lubrication-free solid wear-resistant pin according to claim 4, characterized in that: The pin mold includes an upper pin mold assembly and a lower pin mold assembly, an asbestos pad is arranged between the upper mold assembly and the lower pin mold assembly; a locking block is arranged on the lower pin mold assembly, a locking hook is arranged at a corresponding position of the upper pin mold assembly, a third oblique wedge is arranged between the locking block and the locking hook, and the third oblique wedge locks the lower pin mold assembly and the upper pin mold assembly; the thickness of the third oblique wedge is greater than the depth of the flange groove in the inner cavity of the pin mold; and paint is sprayed inside the pin mold.

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