Ceramic coating spraying process for machine tool guide rail

Abstract

The invention relates to the field of machine tool guide rail machining, and particularly discloses a ceramic coating spraying process for a machine tool guide rail. The guide rail is pretreated, residual grease on the surface of the guide rail is prevented from influencing the binding force of a ceramic coating, meanwhile, the surface roughness of the guide rail is improved, the binding strength of the guide rail and a coating material is improved, the temperature difference stress during coating spraying is reduced by preheating the guide rail, and the coating sprayed on the guide rail is effectively prevented from cracking; meanwhile, the thermal expansion coefficient difference between the guide rail and the ceramic coating is relieved by spraying the transition layer, and the falling risk of the ceramic coating is further reduced; a plurality of thin ceramic coatings are continuously sprayed by adopting a continuous spraying process, a thick ceramic coating is finally formed, and the plurality of thin ceramic coatings are mutually contacted and connected when being not completely cured, so that the interlayer binding force inside the ceramic coatings is enhanced, the ceramic coatings can be prevented from thermal accumulation cracking, and the service life of the ceramic coatings is prolonged. And the sprayed ceramic coating is subjected to heat treatment, and the residual stress of the ceramic coating is eliminated.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of machine tool guide rail processing, and particularly relates to a ceramic coating spraying process for machine tool guide rails. BACKGROUND

[0002] As a moving structure of the operating part of a machine tool, a machine tool guide rail is one of the structural parts that affect the accuracy of the machine tool. In long-term use, the machine tool guide rail may appear phenomena such as micro-welding tearing caused by adhesive wear, surface scratches caused by abrasive wear, thermal deformation caused by friction heat, and crawling caused by lubrication failure, etc., which may cause the accuracy of the machine tool to be lost. Among them, surface scratches may cause the roughness of the guide rail to deteriorate by more than 30%, and a temperature rise of 80 DEG C of the guide rail component may cause a 0.01 mm / m accuracy drift. These factors together cause the accuracy life of the guide rail to be far lower than the designed life. In order to enhance the life of the guide rail, a process of spraying a ceramic coating on the guide rail has appeared.

[0003] The ceramic coating spraying process mainly changes the material of the guide rail surface, thereby improving the hardness of the guide rail surface, reducing the thermal expansion coefficient of the guide rail surface material, inhibiting the deformation of the guide rail, and also reducing the friction coefficient of the guide rail surface, and comprehensively improving the accuracy life of the guide rail. However, the existing ceramic coating spraying process has obvious application defects. Since there is a material difference between the guide rail and the coating, the difference in the thermal expansion coefficients of the two causes interface stress, which may cause the ceramic coating to crack, and the guide rail and the ceramic coating cannot be tightly combined due to the material difference. These factors all cause the ceramic coating to be unable to be stably attached to the guide rail for long-term effect, and the ceramic coating spraying process needs to be improved. SUMMARY

[0004] In order to overcome the deficiencies of the prior art, the purpose of the present application is to provide a ceramic coating spraying process for machine tool guide rails, so as to solve the problem that the ceramic coating formed by the existing ceramic spraying process cannot be stably combined with the guide rail.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0006] A ceramic coating spraying process for machine tool guide rails, comprising:

[0007] The guide rail is pretreated including oil removal and degreasing and sand blasting roughening, the guide rail is preheated to 150 DEG C after covering the precision matching surface of the guide rail, and the guide rail is kept warm for 30-60 min;

[0008] A transition layer is sprayed on the surface of the guide rail;

[0009] A plurality of layers of ceramic coating are continuously sprayed on the guide rail using a ceramic spraying material, the thickness of each spraying is 20-30 mu m, the guide rail is stopped for 1 min after spraying three layers, and a ceramic coating with a total thickness of 0.2-0.4 mm is formed on the guide rail;

[0010] Raising the temperature of the coated guide rail and maintaining for 2-4 hours, using oil-resistant sealant to cure the ceramic coating micro-pores, and grinding the ceramic coating with diamond grinding wheel until the ceramic coating surface roughness Ra≤0.4μm;

[0011] Quality detection and processing.

[0012] Preferably, the oil removal and degreasing process comprises:

[0013] Using alkaline cleaning agent or organic solvent to remove the oil and cutting fluid residue on the surface of the guide rail;

[0014] Ultrasonic cleaning the guide rail with 5% sodium carbonate solution and water as solvent at 80℃ for 15-20 minutes;

[0015] Rinsing the guide rail with deionized water and drying at 60℃ for 30 minutes.

[0016] Preferably, the oil removal and degreasing process further comprises using steel wire wheel to brush mechanically and using 10% hydrochloric acid solution to acid clean, rinsing with deionized water after rust removal, and drying after the rinsing wastewater is neutral.

[0017] Preferably, the sand blasting roughening process comprises:

[0018] Selecting 80#-120# emery, and controlling the compressed air pressure to be 0.5-0.7MPa;

[0019] The surface roughness of the guide rail after sand blasting roughening is Ra2.5-3.0μm, and the surface presents uniform matte;

[0020] Blowing off the dust on the surface of the guide rail with dry and oil-free compressed air.

[0021] Preferably, the transition layer comprises a metal layer and an alloy layer, the metal layer comprises a nickel metal layer and a chromium metal layer, the alloy layer comprises a zinc-chromium alloy layer, the spraying gas atmosphere of the transition layer spraying equipment is 60-75SLPM argon and 20-25SLPM hydrogen, the current control is 600-700A, the voltage control is 80-120V, the moving speed of the spray gun is 10-12m / min, the reciprocating spraying is uniform, the single spraying distance is 120-150mm, the interlayer temperature control is less than 120℃, and the total thickness of the formed transition layer is 20-25μm.

[0022] Preferably, the ceramic spraying material comprises AI2O3, TiO2, ZrO2, Cr2O3, SiO2, MgO, BeO, Y2O3, SiC, WC, BC, TiC, Si3N4, TiN, BN, AIN, TiB, ZrB2.

[0023] Preferably, the spraying gas atmosphere of the ceramic coating spraying device is 80-120 SLPM argon and 40-55 SLPM hydrogen, the current control is 500-650 A, the voltage control is 70-100 V, the uniform reciprocating spraying is performed, the continuous spraying is performed when the bottom layer is not completely solidified, each layer is sprayed and then cooled to below 80℃ before the next layer is sprayed, the single spraying distance is 100-150 mm, the single spraying thickness is 20-30 μm, and each spraying of 3 layers is stopped for 1 minute until the ceramic coating is completely formed.

[0024] Preferably, the temperature of the guide rail after the coating spraying is increased to the range of 250-350℃.

[0025] Preferably, the oil resistance sealing agent comprises epoxy resin and silicon resin.

[0026] Compared with the prior art, the beneficial effects of the present application are:

[0027] The present application avoids the influence of the residual oil on the guide rail surface on the ceramic coating adhesion by the pretreatment of the guide rail, improves the guide rail surface roughness, improves the bonding strength of the guide rail and the coating material, reduces the temperature difference stress during the coating spraying by the preheating of the guide rail, effectively avoids the cracking of the coating sprayed on the guide rail, relieves the difference of the thermal expansion coefficient between the guide rail and the ceramic coating by the spraying of the transition layer, further reduces the risk of the ceramic coating falling off, continuously sprays multiple thin ceramic coatings by the continuous spraying process, and finally forms a thick ceramic coating. The multiple thin ceramic coatings are connected to each other when not completely solidified, enhances the interlayer adhesion of the ceramic coating, prevents the thermal accumulation cracking of the ceramic coating, and eliminates the residual stress of the ceramic coating by the heat treatment of the sprayed ceramic coating, improves the crystallinity, promotes the close combination of the ceramic coating and the guide rail, and improves the performance of the coating. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The flowchart of the ceramic coating spraying process for the machine tool guide rail disclosed in the present application is shown in the figure. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0030] Embodiment one:

[0031] Please refer to Figure 1 The ceramic coating spraying process for the machine tool guide rail shown in the figure comprises:

[0032] The guide rail is pretreated including degreasing and sand blasting, the precision fitting surface of the guide rail is covered, and the guide rail is preheated to 150 DEG C, the preheating can use an infrared heating furnace or a hot air gun, and the preheating is kept for 30-60 min, so that the whole temperature of the guide rail is uniform;

[0033] A transition layer is sprayed on the surface of the guide rail;

[0034] A plurality of ceramic coating layers are continuously sprayed on the guide rail by using a ceramic spraying material, the thickness of each spraying is 20-30 mu m, three layers are sprayed and stopped for 1 min, and the ceramic coating layer with a total thickness of 0.2-0.4 mm is formed on the guide rail;

[0035] The temperature of the guide rail after the spraying of the coating layer is increased, and the temperature is kept for 2-4 hours, an oil-resistant sealing agent is used to solidify and fill the micropores of the ceramic coating layer, and the ceramic coating layer is precisely ground by using a diamond grinding wheel until the surface roughness Ra of the ceramic coating layer is less than or equal to 0.4 mu m;

[0036] Quality detection and treatment.

[0037] As can be seen from the above, the guide rail is pretreated, the residual oil on the surface of the guide rail is avoided to affect the bonding force of the ceramic coating layer, the surface roughness of the guide rail is improved, the bonding strength of the guide rail and the coating material is improved, the temperature difference stress during the spraying of the coating layer is reduced by preheating the guide rail, and the cracking of the coating layer sprayed on the guide rail is effectively avoided; meanwhile, the transition layer is sprayed to relieve the difference between the guide rail and the ceramic coating layer in the thermal expansion coefficient, and the risk of the ceramic coating layer falling off is further reduced; the continuous spraying process is adopted to continuously spray a plurality of thin ceramic coating layers, and finally a thick ceramic coating layer is formed, the plurality of thin ceramic coating layers are connected to each other when the plurality of thin ceramic coating layers are not completely solidified, the interlayer bonding force of the ceramic coating layer is enhanced, the ceramic coating layer is prevented from cracking due to heat accumulation, the ceramic coating layer after the spraying is treated, the residual stress of the ceramic coating layer is eliminated, the crystallinity is improved, the ceramic coating layer is closely combined with the guide rail, and the use performance of the coating layer is improved.

[0038] Example two:

[0039] Please refer to Figure 1 Fig. 1 shows a ceramic coating spraying process for a machine tool guide rail, which comprises:

[0040] The guide rail is pretreated including degreasing and sand blasting, the precision fitting surface of the guide rail is covered, and the guide rail is preheated to 150 DEG C, the preheating can use an infrared heating furnace or a hot air gun, and the preheating is kept for 30-60 min, so that the whole temperature of the guide rail is uniform;

[0041] A transition layer is sprayed on the surface of the guide rail;

[0042] The ceramic spray material is used to continuously spray multiple layers of coating on the guide rail, the single spraying thickness is 20-30 mu m, three layers are sprayed and stopped for 1 minute, and the ceramic coating with a total thickness of 0.2-0.4 mm is formed on the guide rail;

[0043] The temperature of the guide rail after coating spraying is raised, and maintained for 2-4 hours, the oil resistance sealing agent is used to cure and fill the micropores of the ceramic coating, the diamond grinding wheel is used to precisely grind the ceramic coating until the surface roughness Ra of the ceramic coating is less than or equal to 0.4 mu m;

[0044] Quality detection and processing.

[0045] As can be seen from the above, the guide rail is pretreated, so that the influence of residual oil on the surface of the guide rail on the bonding force of the ceramic coating is avoided, and the surface roughness of the guide rail is improved, the bonding strength of the guide rail and the coating material is improved, the temperature difference stress during coating spraying is reduced by preheating the guide rail, and the cracking of the coating sprayed on the guide rail is effectively avoided; meanwhile, the transition layer is sprayed to relieve the difference between the guide rail and the ceramic coating in the thermal expansion coefficient, and the risk of ceramic coating falling off is further reduced; the continuous spraying process is used to continuously spray multiple thin ceramic coatings, and finally a thick ceramic coating is formed, the multiple thin ceramic coatings are connected to each other when they are not completely cured, the interlayer bonding force of the ceramic coating is enhanced, and the use performance of the ceramic coating is improved.

[0046] The oil removal and degreasing process comprises removing oil and cutting fluid residues on the surface of the guide rail by using an alkaline cleaning agent or an organic solvent, the alkaline cleaning agent comprises a sodium hydroxide solution, and the organic solvent comprises acetone and ethanol; the guide rail is ultrasonically cleaned in a 5% sodium carbonate solution and water at 80 DEG C for 15-20 minutes, so that deep oil stains on the guide rail are removed, and dirt residues in the gap are ensured; the guide rail is washed with deionized water, and dried at 60 DEG C for 30 minutes, so that the residual moisture on the surface of the guide rail does not produce pores during spraying.

[0047] The oil removal and degreasing process further comprises mechanical derusting by using a steel wire wheel and acid pickling derusting by using a 10% hydrochloric acid solution, when the guide rail material is cast iron, an inhibitor needs to be added to the hydrochloric acid solution to prevent corrosion of the base material, and the guide rail is washed with deionized water after derusting, and dried after the washing wastewater is neutralized.

[0048] The grit blasting roughening process includes: selecting 80#-120# diamond sand, controlling the compressed air pressure to be 0.5-0.7 MPa; the grit blasting roughening guide rail surface roughness is Ra2.5-3.0 μm, and a uniform pitted surface is presented, and it is necessary to pay attention to not missing or over-spraying the guide rail surface, and over-spraying will cause the guide rail substrate surface to be loose, and too high roughness will reduce the bonding strength of the ceramic coating and the guide rail; dry and oil-free compressed air is used to blow clean the guide rail surface dust.

[0049] The transition layer includes a metal layer and an alloy layer, the metal layer includes a nickel metal layer and a chromium metal layer, the alloy layer includes a zinc-chromium alloy layer, the spraying gas atmosphere of the transition layer spraying equipment is 60-75 SLPM argon and 20-25 SLPM hydrogen, the argon is used to maintain the stability of the plasma arc, and the hydrogen is used to improve the heat content and enhance the melting effect, the current control is 600-700 A, which is used to control the energy input, the voltage control is 80-120 V, which is used to adjust the arc length, the spraying gun moving speed is 10-12 m / min, and the uniform speed reciprocating spraying is used, the single spraying distance is 120-150 mm, so as to balance the ion temperature and speed, the interlayer temperature control is less than 120℃, so as to avoid the guide rail substrate from being overheated and deformed, and the total thickness of the formed transition layer is 20-25 μm, and the too thick transition layer will crack, and the too thin transition layer has poor effect.

[0050] The ceramic spraying material includes AI2O3, TiO2, ZrO2, Cr2O3, SiO2, MgO, BeO, Y2O3, SiC, WC, BC, TiC, Si3N4, TiN, BN, AlN, TiB and ZrB2, and a user can select the ceramic layer spraying material according to the requirement, and can also mix a plurality of materials to form a composite spraying material according to the use requirement, so as to adjust the wear resistance and toughness of the ceramic coating on the guide rail surface.

[0051] The spraying gas atmosphere of the ceramic coating spraying equipment is 80-120 SLPM argon and 40-55 SLPM hydrogen, the current control is 500-650 A, the voltage control is 70-100 V, the uniform speed reciprocating spraying is used, the continuous spraying is used when the bottom layer is not completely solidified, each layer is sprayed, and then cooled to below 80℃ before the next layer is sprayed, so as to enhance the interlayer bonding, the single spraying distance is 100-150 mm, the single spraying thickness is 20-30 μm, each layer is sprayed, and then cooled to 80℃ before the next layer is sprayed, so as to prevent the heat accumulation from cracking, the spraying gun angle is always perpendicular to the guide rail surface, and the deviation is less than 5° as far as possible, so as to avoid the shadow effect to cause the pore, each 3 layers are stopped for 1 minute, and then naturally cooled to release the structure stress, until the ceramic coating is completely formed.

[0052] The guide rail temperature after the elevated coating spraying is completed ranges from 250℃ to 350℃, and the ceramic layer crystallinity is improved.

[0053] The oil resistance sealing agent comprises epoxy resin and silicon resin, different resin types can be selected according to different processing temperatures, the sealing agent can fill the micropores on the ceramic layer, and the porosity can be reduced to below 2%.

[0054] When the ceramic coating is precisely ground by the diamond grinding wheel, the feed amount of the diamond grinding wheel is less than 0.01 mm / time, and the ceramic coating can be effectively prevented from cracking.

[0055] Quality detection includes bonding strength, hardness, thickness uniformity and porosity, the strength detection method is ASTM C633 tensile method, the detection standard is greater than 50 MPa, the unqualified product is returned to work and sand blasted, the hardness of the ceramic coating is measured by using a microhardness tester, the unqualified product in hardness is treated by adjusting the spraying power or the powder particle size, the thickness uniformity of the ceramic coating is detected by using an eddy current thickness gauge, the thickness uniformity of the ceramic coating can be adjusted by optimizing the moving mode of the spray gun, the porosity of the ceramic coating can be measured by using metallographic sectioning and image analysis method, and the sealing process or re-spraying is added to the unqualified product in porosity.

[0056] Compared with the performance of a traditional steel guide rail and a steel guide rail sprayed with the ceramic coating by using the process, the following table can be obtained:

[0057]

[0058] As shown in the above table, after the existing guide rail is plated with the ceramic film by using the process, the service life and precision stability of the guide rail are improved, the energy consumption and maintenance frequency are reduced, and the thermal error is effectively controlled.

[0059] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms is not necessarily directed to the same embodiment or example. In addition, the skilled in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples without contradiction.

Claims

1. A ceramic coating spray process for machine tool guideways, characterized by, The method comprises the following steps: Pre-treatment of the guide rail, including degreasing and sand blasting, preheating the guide rail to 150℃ for 30-60 minutes after covering the precision fitting surface of the guide rail; Spraying a transition layer on the surface of the guide rail; Spraying a plurality of layers of ceramic spray material on the guide rail, with a single spraying thickness of 20-30 μm, stopping for 1 minute after spraying three layers, to form a ceramic coating with a total thickness of 0.2-0.4 mm on the guide rail; Raising the temperature of the guide rail after the spraying of the coating is completed, and maintaining for 2-4 hours, using an oil-resistant sealing agent to solidify and fill the pores of the ceramic coating, and precisely grinding the ceramic coating by using a diamond grinding wheel until the surface roughness Ra of the ceramic coating is less than or equal to 0.4 μm; Quality detection and treatment.

2. A process for ceramic coating of machine tool guideways as claimed in claim 1, wherein: The degreasing process comprises the following steps: Using an alkaline cleaning agent or an organic solvent to remove oil and cutting fluid residues on the surface of the guide rail; Ultrasonic cleaning of the guide rail in a 5% sodium carbonate solution and water as solvents at 80℃ for 15-20 minutes; Rinsing the guide rail with deionized water and drying at 60℃ for 30 minutes.

3. A process for ceramic coating of machine tool guideways as claimed in claim 2, wherein: The degreasing process further comprises mechanical rust removal by using a steel wire wheel and acid pickling with a 10% hydrochloric acid solution, rinsing with deionized water after rust removal, drying after the rinsing wastewater is neutralized.

4. A process for ceramic coating of machine tool guideways as claimed in claim 1 wherein: The sand blasting process comprises the following steps: Selecting 80#-120# corundum and controlling the compressed air pressure to be 0.5-0.7 MPa; Spraying and grinding the surface of the guide rail to have a roughness of Ra 2.5-3.0 μm and a uniform matte appearance; Blowing off the dust on the surface of the guide rail by using dry and oil-free compressed air.

5. A process for ceramic coating of machine tool guideways as claimed in claim 1, wherein: The transition layer comprises a metal layer and an alloy layer, the metal layer comprises a nickel metal layer and a chromium metal layer, the alloy layer comprises a zinc-chromium alloy layer, the spraying gas atmosphere of the spraying equipment for the transition layer is 60-75 SLPM argon and 20-25 SLPM hydrogen, the current control is 600-700 A, the voltage control is 80-120 V, the spraying gun moving speed is 10-12 m / min, the spraying is uniformly reciprocated, the single spraying distance is 120-150 mm, the interlayer temperature control is less than 120℃, and the total thickness of the formed transition layer is 20-25 μm.

6. A process for ceramic coating of machine tool guideways as claimed in claim 1, wherein: The ceramic spray material comprises AI2O3, TiO2, ZrO2, Cr2O3, SiO2, MgO, BeO, Y2O3, SiC, WC, BC, TiC, Si3N4, TiN, BN, AlN, TiB and ZrB2.

7. A process for ceramic coating of machine tool guideways as claimed in claim 1 wherein: The spraying gas atmosphere of the ceramic coating spraying equipment is 80-120 SLPM argon and 40-55 SLPM hydrogen, the current control is 500-650 A, the voltage control is 70-100 V, the spraying is uniformly reciprocated, the spraying is continuously performed when the bottom layer is not completely solidified, the spraying of the next layer is performed after the cooling to below 80℃ after the spraying of each layer is completed, the single spraying distance is 100-150 mm, the single spraying thickness is 20-30 μm, stopping for 1 minute after spraying three layers, until the ceramic coating is completely formed.

8. A process for ceramic coating of machine tool guideways as claimed in claim 1 wherein: The temperature range of the guide rail after the spraying of the coating is completed is 250-350℃.

9. A process for ceramic coating of machine tool guideways as claimed in claim 1 wherein: The oil-resistant sealing agent comprises epoxy resin and silicone resin.

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