Self-lubricating die guide plate and preparation method thereof

Abstract

The application belongs to the technical field of industrial product processing and preparation, and particularly relates to a self-lubricating mold guide plate and a preparation method thereof. The preparation method of the self-lubricating mold guide plate is as follows: flake graphite is subjected to microwave treatment for 5-15 minutes at 20-30 KW to open the pi bond of the flake graphite, the flake graphite after microwave treatment is placed in a nickel plating solution to obtain nickel-plated flake graphite; the nickel-plated flake graphite and metal powder are mixed and stirred for 5-10 hours to obtain mixed powder, and the mixed powder is placed in a mold for hot-pressing sintering, and a new self-lubricating mold guide plate is obtained after cooling and demolding. The application improves the degree of diffusion of metal atoms into graphite crystals through microwave treatment, enhances the affinity of graphite and metal, ensures the interface bonding strength of the material, and prevents the peeling of graphite phase when the self-lubricating mold guide plate is subjected to a large load.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of industrial product processing and preparation, and particularly relates to a self-lubricating mold guide plate and a preparation method thereof. BACKGROUND

[0002] The guide plate in the mold plays a key guiding and positioning role and is a core element in mold manufacturing. In the automobile mold industry, especially in the field of large and medium-sized stamping molds, the guide parts are often made of copper alloys such as tin bronze, lead bronze and aluminum bronze, or are processed in combination with low-carbon steel with excellent performance to produce advanced copper-steel bimetallic composite materials through powder metallurgy technology. However, due to the huge demand for guide plates in the production of automobile coverings, the weight of copper alloy consumed by an average set of molds is between 20 and 30 kilograms. During use, the guide plate is often subjected to wear and impact, resulting in irreparable damage and ultimately becoming waste, causing resource waste. The mold guide plate produced by using copper-based graphite self-lubricating material effectively solves these challenges and significantly improves the actual service life of the material and reduces waste.

[0003] In the prior art, the copper-based graphite self-lubricating mold guide plate is directly prepared by powder metallurgy. Although this method can obtain good performance and initially solves the problem of incompatibility of the graphite and copper interface, it is found that when a large load is applied, the graphite phase peels off, resulting in a large number of pits on the surface of the self-lubricating mold guide plate, increasing the surface roughness and increasing the product scrap rate. SUMMARY

[0004] To solve the above technical problems, the present application provides a self-lubricating mold guide plate and a preparation method, which can effectively prevent the peeling of the graphite phase of the self-lubricating mold guide plate under a large load.

[0005] To achieve the above purpose, the technical scheme of the present application is as follows.

[0006] The present application provides a preparation method of a self-lubricating mold guide plate, comprising the following steps:

[0007] The flaky graphite is subjected to microwave treatment for 5 to 15 minutes at 20 to 30 KW to open the π bond of the flaky graphite. The flaky graphite after microwave treatment is placed in a plating solution for nickel plating treatment to obtain nickel-plated flaky graphite.

[0008] The nickel-plated flaky graphite and metal powder are mixed to obtain a mixed powder. The mixed powder is placed in a mold for hot-pressing sintering. After cooling and demolding, a new self-lubricating mold guide plate is obtained.

[0009] The application can open the pi bond of flake graphite, increase the spacing between layers, make metal atoms easily diffuse into graphite crystals, improve the affinity of flake graphite and metal, ensure the interface bonding strength of the material, and further improve the lubricating performance of flake graphite, reduce the friction between flake and metal powder, and further prevent the shedding of graphite phase, thereby improving the service life of the product and reducing the scrap rate.

[0010] More importantly, if the microwave treatment power is lower than 20KW-30KW or the time is shorter than 5min-15min, the pi bond of flake graphite cannot be opened, and it is difficult for metal atoms to diffuse into graphite crystals; and if the microwave treatment power is higher than 20KW-30KW or the treatment time is longer than 5min-15min, excessive pores will be generated, intracrystalline pore defects will be formed, the internal defects of flake graphite will be increased, and the strength will be decreased.

[0011] In another preferred embodiment, the specific process of the nickel plating treatment is as follows:

[0012] The flake graphite treated by microwave is placed in plating liquid A, plating liquid B is added, and then the mixture is reacted at 55℃-80℃ for 20min-40min, washed, filtered, and dried to obtain nickel-plated flake graphite;

[0013] In the plating liquid A, the mass ratio of NiSO4, Na3C6H5O7, NaH2PO2 and water is 3.5-4:2.5-3.5:2.5-3.5:100;

[0014] In the plating liquid B, the mass ratio of NaOH, NH4Cl and water is 0.2-0.5:10-15:100.

[0015] In another preferred embodiment, the mass-volume ratio of flake graphite, plating liquid A and plating liquid B is 1kg:5L-6L:5L-6L.

[0016] In another preferred embodiment, the particle size of flake graphite is 200-325 mesh.

[0017] In another preferred embodiment, the metal powder is obtained by mixing copper powder, nickel powder and titanium powder in a mass ratio of 80-85:8-10:2-5.

[0018] In another preferred embodiment, the specific process of hot-pressing sintering is as follows:

[0019] The mixed powder is heated to 800℃-900℃ at a temperature rising rate of 50℃ / min-100℃ / min under vacuum conditions at 20MPa-30MPa, and kept for 0.5h-1h.

[0020] In another preferred embodiment, the stirring speed of the mixing is 30 rpm / min to 100 rpm / min, and the time is 5 h to 10 h.

[0021] The second aspect of the application provides the self-lubricating die guide plate.

[0022] Compared with the prior art, the application has at least the following beneficial effects:

[0023] (1) The application controls the time and power of microwave treatment to open the pi bond of flake graphite. If the microwave treatment power is too small or the time is too short, the degree of opening of the pi bond of graphite is small, the spacing between layers cannot be effectively opened, and it is difficult for metal atoms to diffuse into the graphite crystal. If the microwave treatment power is too large or the time is too long, the degree of opening of the pi bond of graphite is too large, the spacing between layers is excessively opened, intracrystalline pore defects are formed, the internal defects of graphite increase, and the strength decreases. Therefore, the microwave treatment power needs to be controlled in the range of 20 KW to 30 KW, and the time needs to be controlled in the range of 5 min to 15 min, so as to improve the degree of diffusion of metal atoms into the graphite crystal, enhance the affinity of graphite and metal, ensure the interface bonding strength of the material, and further prevent the peeling of graphite phase when the self-lubricating die guide plate is subjected to a large load. In addition, in cooperation with the nickel plating treatment, the friction between graphite and metal powder can be further reduced, and the peeling of graphite phase is further prevented.

[0024] (2) The application optimizes the composition of metal powder and introduces Ni and Ti elements. Compared with the existing metal composition of Cu, Ni or Cu, Sn, the application introduces Ni and Ti on the basis of Cu, can form Ni3Ti at the interface, further improves the interface bonding strength and mechanical properties, ensures the service performance and service life of the die guide plate, and meets the performance requirements of the guide plate for future high-precision dies. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 FIG. 1 is an organizational morphology and element analysis diagram of the self-lubricating die guide plate in Example 1 of the application; wherein a is a scanning electron microscope organizational morphology, b is EDS energy spectrum area scanning of Cu element, c is EDS energy spectrum area scanning of Ni element, and d is EDS energy spectrum area scanning of Ti element.

[0026] Figure 2 FIG. 2 is a result diagram of the self-lubricating die guide plate after impact in Example 1 of the application. DETAILED DESCRIPTION

[0027] The technical solutions in the present application will be described clearly and completely below in connection with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative efforts belong to the scope of the present application.

[0028] The methods described in the embodiments of the present application are all conventional methods unless otherwise specified. The materials, reagents, etc. used are all available from commercial channels unless otherwise specified.

[0029] In the existing public data, copper-based graphite self-lubricating materials are prepared by powder metallurgy directly. Although this method can obtain good material performance and preliminarily solve the problems of non-wetting, non-reaction and incompatibility of the interface between graphite and copper, the existing technology still cannot meet the performance requirements of the guide plate of the future high-precision mold, especially when the material is subjected to a large load. When the graphite phase peels off, a large number of pits appear on the guide plate of the mold, causing the surface roughness of the product to increase and the product scrap rate to rise.

[0030] The present application greatly improves the affinity of graphite and metal through microwave treatment and graphite nickel plating treatment, which is beneficial to ensure the interface bonding strength of the material, and further effectively prevents the occurrence of graphite phase peeling when the self-lubricating mold guide plate is subjected to a large load. Furthermore, the metal powder composition is optimized by introducing Ni and Ti elements, which are different from the existing metal composition of Cu, Ni or Cu, Sn. The present application introduces Ni and Ti on the basis of Cu, which can form Ni3Ti at the interface, further improving the interface bonding strength and mechanical properties, ensuring the service performance and service life of the mold guide plate, and meeting the performance requirements of the guide plate of the future high-precision mold.

[0031] A self-lubricating mold guide plate and a preparation method thereof will be described below. The purity of the pure copper powder, pure nickel powder and pure titanium powder in the following embodiments is 99.9%.

[0032] Embodiment 1

[0033] A preparation method of a self-lubricating mold guide plate, comprising the following steps:

[0034] S1, 200 mesh flake graphite is treated by microwave for 15 min under 20 KW to obtain microwave-treated flake graphite.

[0035] S2, the flaky graphite after microwave treatment is placed in plating solution A and stirred uniformly, then poured into plating solution B and stirred uniformly, and reacted at 55℃ for 20 min, then washed, filtered and dried to obtain nickel-plated flaky graphite; wherein the mass-volume ratio of flaky graphite, plating solution A and plating solution B is 1kg:5L:5L;

[0036] In plating solution A, the mass ratio of NiSO4, Na3C6H5O7, NaH2PO2 and water is 3:3.5:3.5:100;

[0037] In plating solution B, the mass ratio of NaOH, NH4Cl and water is 0.2:10:100.

[0038] S3, pure copper powder, pure nickel powder and pure titanium powder are mixed according to a mass ratio of 85:10:5 to obtain metal powder; the nickel-plated flaky graphite and the metal powder are mixed according to a mass ratio of 0.2:9.8 and stirred at 30rpm / min for 5h to obtain mixed powder; the particle size of the pure copper powder, the pure nickel powder and the pure titanium powder is 200 mesh.

[0039] S4, the mixed powder is hot-pressed and sintered, the sintering furnace is pumped to vacuum, the hot-pressing temperature is 800℃, the heating speed is 50℃ / min, the holding time is 0.5h, the pressure is 20MPa, and the self-lubricating mold guide plate is obtained after the furnace is cooled and demolded.

[0040] The organization morphology of the self-lubricating mold guide plate is determined, and the results are shown in Figure 1 It can be seen from Figure 1 that the organization of the self-lubricating mold guide plate is uniform and the interface is well combined.

[0041] Example 2

[0042] A preparation method of a self-lubricating mold guide plate, comprising the following steps:

[0043] S1, the flaky graphite of 275 mesh is treated by microwave for 10 min at 25KW to obtain flaky graphite after microwave treatment.

[0044] S2, the flaky graphite after microwave treatment is placed in plating solution A and stirred uniformly, then poured into plating solution B and stirred uniformly, and reacted at 70℃ for 30 min, then washed, filtered and dried to obtain nickel-plated flaky graphite; wherein the mass-volume ratio of flaky graphite, plating solution A and plating solution B is 1kg:6L:6L;

[0045] In plating solution A, the mass ratio of NiSO4, Na3C6H5O7, NaH2PO2 and water is 4:3.5:2.5:100;

[0046] The mass ratio of NaOH, NH4Cl and water in the plating solution B is 0.4:12:100 per liter of plating solution B.

[0047] S3, mixing pure copper powder, pure nickel powder and pure titanium powder according to a mass ratio of 85:10:5 to obtain metal powder; mixing the nickel-plated flake graphite and the metal powder according to a mass ratio of 0.6:9.4 and stirring at 50 rpm / min for 8 h to obtain mixed powder; the particle size of the pure copper powder, the pure nickel powder and the pure titanium powder is 275 mesh.

[0048] S4, hot-pressing sintering the mixed powder, evacuating the sintering furnace to vacuum, hot-pressing at a temperature of 850 DEG C, a temperature rising speed of 80 DEG C / min, holding for 1 h, a pressure of 25 MPa, and obtaining the self-lubricating mold guide plate by demolding after cooling with the furnace.

[0049] Example 3

[0050] A preparation method of a self-lubricating mold guide plate, comprising the following steps:

[0051] S1, microwave treating 325 mesh flake graphite at 30 KW for 5 min to obtain microwave-treated flake graphite.

[0052] S2, stirring the microwave-treated flake graphite in plating solution A until uniform, then stirring in plating solution B until uniform, and reacting at 80 DEG C for 40 min, and then washing, filtering and drying to obtain nickel-plated flake graphite; wherein the mass-volume ratio of the flake graphite, the plating solution A and the plating solution B is 1 kg:6 L:5 L.

[0053] In the plating solution A, the mass ratio of NiSO4, Na3C6H5O7, NaH2PO2 and water is 4:3:3:100.

[0054] In the plating solution B, the mass ratio of NaOH, NH4Cl and water is 0.5:15:100.

[0055] S3, mixing pure copper powder, pure nickel powder and pure titanium powder according to a mass ratio of 85:10:5 to obtain metal powder; mixing the nickel-plated flake graphite and the metal powder according to a mass ratio of 0.8:10 and stirring at 100 rpm / min for 10 h; the particle size of the pure copper powder, the pure nickel powder and the pure titanium powder is 325 mesh.

[0056] S4, hot-pressing sintering the mixed powder, evacuating the sintering furnace to vacuum, hot-pressing at a temperature of 900 DEG C, a temperature rising speed of 100 DEG C / min, holding for 1 h, a pressure of 30 MPa, and obtaining the self-lubricating mold guide plate by demolding after cooling with the furnace.

[0057] Comparative Example 1

[0058] A preparation method of a self-lubricating mold guide plate, comprising the following steps:

[0059] S1, 200 mesh flake graphite is subjected to microwave treatment at 20 KW for 15 min to obtain microwave-treated flake graphite.

[0060] S2, the microwave-treated flake graphite is stirred uniformly in plating solution A, then poured into plating solution B and stirred uniformly, and reacted at 55℃ for 20 min, then washed, filtered and dried to obtain nickel-plated flake graphite; wherein the mass-volume ratio of flake graphite, plating solution A and plating solution B is 1 kg: 5 L: 5 L;

[0061] In plating solution A, the mass ratio of NiSO4, Na3C6H5O7, NaH2PO2 and water is 3:3.5:3.5:100;

[0062] In plating solution B, the mass ratio of NaOH, NH4Cl and water is 0.2:10:100.

[0063] S3, the nickel-plated flake graphite and pure copper powder are mixed at a mass ratio of 0.2:9.8, and stirred at 30 rpm for 5 h to obtain a mixed powder; the particle size of the pure copper powder is 200 mesh.

[0064] S4, the mixed powder is subjected to hot-pressing sintering, the sintering furnace is pumped to vacuum, the hot-pressing temperature is 800℃, the heating rate is 50℃ / min, the holding time is 0.5 h, the pressure is 20 MPa, and after the mold is demolded after cooling in the furnace, a self-lubricating mold guide plate is obtained.

[0065] Comparative Example 2

[0066] A preparation method of a self-lubricating mold guide plate, comprising the following steps:

[0067] S1, 200 mesh flake graphite is subjected to microwave treatment at 20 KW for 15 min to obtain microwave-treated flake graphite.

[0068] In plating solution A, the mass ratio of NiSO4, Na3C6H5O7, NaH2PO2 and water is 3:3.5:3.5:100;

[0069] In plating solution B, the mass ratio of NaOH, NH4Cl and water is 0.2:10:100.

[0070] S2, pure copper powder, pure nickel powder, pure titanium powder are mixed according to the mass ratio of 85:10:5 to obtain metal powder; the nickel-plated flaky graphite and the metal powder are mixed according to the mass ratio of 0.2:9.8, and mixed and stirred at 30 rpm / min for 5h to obtain mixed powder; the particle size of the pure copper powder, the pure nickel powder and the pure titanium powder is 200 mesh.

[0071] S3, the mixed powder is subjected to hot-pressing sintering, the sintering furnace is pumped to vacuum, the hot-pressing temperature is 800 DEG C, the temperature rising speed is 50 DEG C / min, the temperature holding time is 0.5h, the pressure is 20MPa, and the self-lubricating mold guide plate is obtained after the mold is demolded after being cooled with the furnace.

[0072] Comparative Example 3

[0073] A preparation method of a self-lubricating mold guide plate comprises the following steps:

[0074] S1, the 200 mesh flaky graphite is subjected to microwave treatment at 20KW for 3min to obtain microwave-treated flaky graphite.

[0075] S2, the microwave-treated flaky graphite is stirred uniformly in plating solution A, then poured into plating solution B and stirred uniformly, and reacted at 55 DEG C for 20min, and then washed, filtered and dried to obtain nickel-plated flaky graphite; wherein the mass-volume ratio of the flaky graphite, the plating solution A and the plating solution B is 1kg:5L:5L;

[0076] In the plating solution A, the mass ratio of NiSO4, Na3C6H5O7, NaH2PO2 and water is 3:3.5:3.5:100;

[0077] In the plating solution B, the mass ratio of NaOH, NH4Cl and water is 0.2:10:100.

[0078] S3, pure copper powder, pure nickel powder, pure titanium powder are mixed according to the mass ratio of 85:10:5 to obtain metal powder; the nickel-plated flaky graphite and the metal powder are mixed according to the mass ratio of 0.2:9.8, and mixed and stirred at 30 rpm / min for 5h to obtain mixed powder; the particle size of the pure copper powder, the pure nickel powder and the pure titanium powder is 200 mesh.

[0079] S4, the mixed powder is subjected to hot-pressing sintering, the sintering furnace is pumped to vacuum, the hot-pressing temperature is 800 DEG C, the temperature rising speed is 50 DEG C / min, the temperature holding time is 0.5h, the pressure is 20MPa, and the self-lubricating mold guide plate is obtained after the mold is demolded after being cooled with the furnace.

[0080] Comparative Example 4

[0081] A preparation method of a self-lubricating mold guide plate comprises the following steps:

[0082] S1, 200 mesh scale graphite is treated by microwave for 20 min under 20 KW to obtain microwave treated scale graphite.

[0083] S2, the microwave treated scale graphite is stirred in plating solution A, then is poured into plating solution B and stirred, and is reacted at 55 DEG C for 20 min, and then is washed, filtered and dried to obtain nickel plated scale graphite; wherein the mass ratio of scale graphite, plating solution A and plating solution B is 1 kg: 5 L: 5 L.

[0084] In plating solution A, the mass ratio of NiSO4, Na3C6H5O7, NaH2PO2 and water is 3:3.5:3.5:100.

[0085] In plating solution B, the mass ratio of NaOH, NH4Cl and water is 0.2:10:100.

[0086] S3, pure copper powder, pure nickel powder and pure titanium powder are mixed according to a mass ratio of 85:10:5 to obtain metal powder; the nickel plated scale graphite and the metal powder are mixed according to a mass ratio of 0.2:9.8, and are stirred at 30 rpm / min for 5 h to obtain mixed powder; the particle size of the pure copper powder, the pure nickel powder and the pure titanium powder is all 200 mesh.

[0087] S4, the mixed powder is subjected to hot-pressing sintering, the sintering furnace is pumped to vacuum, the hot-pressing temperature is 800 DEG C, the temperature rising speed is 50 DEG C / min, the temperature maintaining time is 0.5 h, the pressure is 20 MPa, and after the self-lubricating mold guide plate is cooled and demolded in the furnace, the self-lubricating mold guide plate is obtained.

[0088] In order to further illustrate the performance of the self-lubricating mold guide plate in the application, the following experiment is conducted.

[0089] The self-lubricating mold guide plates prepared in Example 1 to Example 3 and Comparative Example 1 to Comparative Example 4 are respectively subjected to 100 times of 20 MPa load impact, and the roughness results are shown in Table 1, and the graphite phase peeling of the self-lubricating mold guide plate in Example 1 is subjected to laser scanning, and the results are shown in Figure 2 .

[0090] Table 1 roughness of different lubricating mold guide plates

[0091] Group Roughness Comparative Example 1 1.52 μm Comparative Example 2 5.58 μm Comparative Example 3 1.21 μm Comparative Example 4 0.95 μm Example 1 0.72 μm Example 2 0.58 μm Example 3 0.41 μm

[0092] As can be seen from the results in Table 1, the roughness of Examples 1 to 3 is significantly lower than that of Control Groups 1 to 4. The results of Control Groups 1 to 4 show that microwave treatment has the greatest impact on the roughness of the self-lubricating mold guide plate. Both excessively long and short microwave treatment times affect the roughness of the self-lubricating mold guide plate, thereby increasing its roughness and affecting the interfacial strength between the graphite phase and the metal, leading to graphite phase detachment. Furthermore, the roughness of Comparative Example 1 shows that the present invention, by introducing nickel and titanium powder into the metal powder, can further reduce the roughness. This is because the simultaneous introduction of nickel and titanium powder onto the copper powder base can form Ni3Ti at the interface, further improving the interfacial bonding strength and mechanical properties, ensuring the service performance and lifespan of the mold guide plate, and meeting the performance requirements of future high-precision molds.

[0093] from Figure 2 It can be seen that after 100 impacts under a load of 20MPa, the self-lubricating mold guide plate in Embodiment 1 of the present invention has low surface roughness and no peeling defects. This indicates that the method in the present invention can effectively improve the interfacial strength between the graphite phase and the metal powder, effectively prevent the graphite phase from falling off under large loads, ensure the service performance and service life of the self-lubricating mold guide plate, and meet the performance requirements of future high-precision molds for guide plates.

[0094] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for preparing a self-lubricating mold guide plate, characterized in that, Includes the following steps: Flake graphite is microwaved at 20KW~30KW for 5min~15min to open the π bonds in the flake graphite. The microwave-treated flake graphite is then nickel-plated to obtain nickel-plated flake graphite. Nickel-plated flake graphite and metal powder are mixed in a mass ratio of 0.2~0.8:8~10 to obtain a mixed powder. The mixed powder is hot-pressed and sintered, then cooled to obtain a self-lubricating mold guide plate. The metal powder is obtained by mixing copper powder, nickel powder and titanium powder in a mass ratio of 80~85:8~10:2~5.

2. The method for preparing a self-lubricating mold guide plate according to claim 1, characterized in that, The specific process of the nickel plating treatment is as follows: Microwave-treated flake graphite is placed in plating solution A, then plating solution B is added, and the reaction is carried out at 55℃~80℃ for 20min~40min. After washing, filtration, and drying, nickel-plated flake graphite is obtained. In the plating solution A, the mass ratio of NiSO4, Na3C6H5O7, NaH2PO2 and water is 3.5~4:2.5~3.5:2.5~3.5:100; In the plating solution B, the mass ratio of NaOH, NH4Cl and water is 0.2~0.5:10~15:

100.

3. The method for preparing the self-lubricating mold guide plate according to claim 2, characterized in that, The mass-to-volume ratio of the flake graphite, plating solution A, and plating solution B is 1 kg: 5 L~6 L: 5 L~6 L.

4. The method for preparing a self-lubricating mold guide plate according to claim 1, characterized in that, The particle size of flake graphite is 200 mesh to 325 mesh.

5. The method for preparing a self-lubricating mold guide plate according to claim 1, characterized in that, The specific process of hot pressing and sintering is as follows: The mixed powder was heated to 800℃~900℃ under vacuum conditions of 20MPa~30MPa at a heating rate of 50℃ / min~100℃ / min and held at that temperature for 0.5h~1h.

6. The method for preparing a self-lubricating mold guide plate according to claim 1, characterized in that, The mixing speed is 30 rpm to 100 rpm, and the time is 5 h to 10 h.

7. A self-lubricating mold guide plate prepared by the preparation method according to any one of claims 1 to 6.

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