Novel high-performance ring groove reinforced steel piston and preparation method thereof

Abstract

The invention aims to provide a novel high-performance ring groove reinforced steel piston, and solves the problems of difficulty in uniform heating and difficulty in uniform hardening in a surface hardening process of a first ring groove part of the steel piston. The diameter of the steel piston ranges from 60 mm to 300 mm. According to the preparation method, sulfur and phosphorus element limits are strictly required, copper, vanadium, titanium, nitrogen and other elements are added, isothermal treatment is carried out after forging, a coarse flaky pearlitic structure is formed, and the high-frequency quenching performance and the cutting performance of the material are remarkably improved under the condition that the strength is not changed; the metallographic structure of the piston is a coarse sheet pearlite and ferritic structure; the hardness is 250-310 HBW, the tensile strength is greater than or equal to 850 Mpa, and the ductility is greater than 10%. The production and processing cost of the steel piston is reduced; and on the other hand, the inner side face of the first ring groove is subjected to targeted and uniform quenching and hardening treatment, so that the problems of excessive blow-by amount, engine oil burning and the like caused by high-temperature abrasion of the first ring groove are solved.

Description

Technical Field

[0001] The invention relates to the processing of a steel piston, and in particular to a novel high-performance ring groove reinforced steel piston and a preparation method thereof. Background Art

[0002] As a key core component of the engine, the piston is used to withstand the gas pressure and drive the crankshaft to rotate through the piston-connecting rod mechanism to provide power. The piston is subjected to alternating mechanical and thermal loads when working, and is exposed to high temperature, high pressure, high speed, and poor lubrication for a long time, resulting in harsh working conditions.

[0003] According to the main material classification, there are three main types of pistons on the market: aluminum pistons, steel pistons, and cast iron pistons. With the upgrading of engines, the explosion pressure and power per liter of the engine are constantly increasing. For example, when the explosion pressure of the engine is greater than 200 bar and the power per liter reaches 32-40 kW / L, aluminum pistons can no longer meet the technical requirements due to the limitation of their material strength; therefore, steel pistons are gradually favored by OEMs.

[0004] During the actual installation and use of steel pistons, problems such as excessive blowby and oil burning caused by high-temperature wear of the first ring groove often occur. Enhancing the wear resistance and strength of the first ring groove of the piston can effectively deal with problems such as excessive blowby and oil burning caused by high-temperature wear. However, since the first ring groove is a slit structure, its conventional surface hardening method is limited by process and equipment and is difficult to achieve ideal technical effects. Quenching hardening is a low-cost and widely used hardening process, but it is difficult to effectively heat the inner surface of the slit during quenching hardening of the first ring groove. A more common method is to use high-precision laser scanning for heating, but the above method has high requirements for equipment, and the surface is gradually scanned for heating and quenching, and the surface hardening treatment is unevenly distributed and the effect is not ideal. High-frequency heating can achieve uniform and rapid heating of the surface of the first ring groove, but the traditional high-frequency heating head cannot extend into the first ring groove to achieve complete heating of its surface, and thus cannot achieve the effect of uniform hardening. Summary of the invention

[0005] In view of the above problems, the purpose of the present invention is to propose a new type of high-performance ring groove reinforced steel piston to solve the problem of difficulty in uniform heating and hardening in the surface hardening process of the first ring groove portion of the steel piston.

[0006] The technical solution is that its diameter ranges from 60 to 300 mm; its chemical composition, in terms of weight percentage, is: C0.3-0.45%, Si1.1-1.5%, P0-0.025%, S0.02-0.05%, Mn2.1-3.0%, Cr0.5-1.0%, Cu1.1-2.0%, V0.05-0.2%, Ti0.05-0.08%, Nb0.01-0.05%, and the balance is Fe; and the piston matrix structure is coarse lamellar pearlite + ferrite structure, with a hardness of 250-310 HBW, a tensile strength of ≥850 MPa, and an elongation of greater than 10%; the first ring groove is a trapezoidal ring, the ring groove bottom width is 1-5 mm, the ring groove top width is 3-8 mm, and the ring groove depth is 5-10 mm.

[0007] In the above or some embodiments, the surface hardness of the first ring groove is obtained by high-frequency heating quenching.

[0008] The present invention also proposes a novel high-performance ring groove reinforced steel piston processing method to solve the problem of difficulty in uniform heating and uniform hardening encountered in the surface hardening process of the first ring groove portion of the steel piston.

[0009] The processing method is:

[0010] STEP1. Melting of head and skirt bar blanks: accurately weigh each raw material, weigh each component according to the proportion, and use a medium frequency induction furnace for melting at a melting temperature of 1550-1650℃; let the molten iron stand for 15 minutes; then use a copper mold for water cooling, and then hot rolling, air cooling and finishing to form head and skirt bar blanks;

[0011] STEP2. After the head and skirt bars are sawn off, they are subjected to medium frequency induction heating at a temperature of 1200-1240°C. After reaching the temperature, they are forged with a forging ratio greater than 1:10. After forging, they are isothermally treated, cooled, and shot blasted three times;

[0012] STEP3. After the piston head and skirt forgings are roughly machined, they are friction welded using nitrogen protection friction welding technology. The welding surface roughness is Rz25-90, and the edge of the welding surface is chamfered with an arc of R2.5-5.0mm. The dimensional tolerance of the welding surface can be within 0.05mm;

[0013] STEP4. After welding, stress relief annealing treatment is performed, and the semi-finished piston is finely processed to form a semi-finished product with a pin hole and outer circle with special profiles;

[0014] STEP5. The semi-finished product after fine processing is subjected to high-frequency quenching treatment on the first ring groove area by using an EFD high-frequency quenching machine, the equipment power is 10-200KW, the equipment frequency is 75-150KHZ, and the actual power is 50%; the high-frequency quenching machine includes a high-frequency quenching coil, the high-frequency quenching coil includes an induction part surrounded by a single-turn spiral and matching the size of the first ring groove, and the induction part includes an intervention part intervened in the first ring groove;

[0015] STEP6. After high-frequency quenching, the semi-finished product is subjected to stress relief treatment at 185±5℃;

[0016] STEP 7. After annealing, the semi-finished product is phosphated and coated with a new type of nano-coating to form the new type of high-performance ring groove reinforced steel piston finished product.

[0017] In the above or some embodiments, in the step STEP2, the piston head and the skirt are forged, the starting forging temperature is 1200-1350°C, the final forging temperature is 980-1150°C, and after forging, they are transferred to a tunnel-type holding furnace for an isothermal treatment, the isothermal temperature is 600°C±10°C, the isothermal time is 120±10 minutes, and air cooling is performed after the isothermal treatment;

[0018] In the above or some embodiments, the high-frequency quenching treatment is performed on the first ring groove area of ​​the semi-finished product after fine machining in step STEP5, including the following steps:

[0019] The semi-finished piston is placed on a fixture that is positioned by a stopper and an auxiliary stopper for clamping;

[0020] The piston rotates at a speed of 300±10r / min;

[0021] The induction coil is lowered, and the intervention part is inserted into the first annular groove, and the gap between the intervention part and the annular groove wall is 0.1 mm;

[0022] During the rotation of the piston, the magnetic flux lines are cut to form an induced current, which heats the ring groove wall to 800-1000°C; in the fifth step, the spray device starts to spray the quenching liquid to perform quenching cooling. After cooling, the piston stops rotating, the coil rises, and the workpiece is removed;

[0023] Clean the quenching liquid remaining on the piston surface and dry it.

[0024] In the above or some embodiments, in the first ring groove area after high-frequency quenching in step STEP5, the quenching layer thickness is ≥0.2 mm, the microhardness is ≥500 HV1, and the ring groove size deformation is <0.03 mm.

[0025] In the above or some embodiments, the quenching liquid model of step STEP5 is Houghton quenching liquid, the quenching liquid concentration is 20-25, and the spraying time is 1-5 seconds.

[0026] This patent strictly requires the limits of sulfur and phosphorus elements, and adds copper, vanadium, titanium, nitrogen and other elements. Through isothermal treatment after forging, a coarse lamellar pearlite structure is formed. Without changing the strength, the high-frequency quenching performance and cutting performance of the material are significantly improved, and the production and processing cost of steel pistons is reduced. On the other hand, the inner side of the first ring groove is subjected to targeted and uniform quenching and hardening treatment to avoid problems such as excessive blowby and oil burning caused by high-temperature wear of the first ring groove.

[0027] Instruction Manual

[0028] Figure 1 It is a process flow chart of the steel piston of the present invention.

[0029] Figure 2 This is the metallographic structure diagram of the semi-finished steel piston head skirt.

[0030] Figure 3 This is the distribution diagram of the high-frequency quenching hardened layer of the first ring groove of the present invention.

[0031] Figure 4 It is the thickness of the hardened layer of the steel piston after high-frequency quenching.

[0032] Figure 5 The cross section of the ring groove of the steel piston after high-frequency quenching

[0033] Figure 6 This is a 50-fold metallographic structure diagram of the high-frequency quenching hardened layer of the first ring groove of the present invention.

[0034] Figure 7 This is a 500-fold metallographic structure diagram of the high-frequency quenching hardened layer of the first ring groove of the present invention.

[0035] Figure 8 50x image of the metallographic structure of the steel piston after high-frequency quenching.

[0036] Fig. 9 500 times magnification of the metallographic structure of the steel piston after high-frequency quenching. DETAILED DESCRIPTION

[0037] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0038] In the description of the present invention, “plurality” means two or more than two, unless otherwise clearly and specifically defined.

[0039] The steel piston has a diameter range of 60-300 mm; its chemical composition, in terms of weight percentage, is: C0.3-0.45%, Si1.1-1.5%, P0-0.025%, S0.02-0.05%, Mn2.1-3.0%, Cr0.5-1.0%, Cu1.1-2.0%, V0.05-0.2%, Ti0.05-0.08%, Nb0.01-0.05%, and the balance is Fe; and the piston matrix structure is coarse lamellar pearlite + ferrite structure, with a hardness of 250-310 HBW, a tensile strength of ≥850 MPa, and an elongation of more than 10%; the first ring groove is a trapezoidal ring, the ring groove bottom width is 1-5 mm, the ring groove top width is 3-8 mm, and the ring groove depth is 5-10 mm.

[0040] The steel piston is subjected to isothermal treatment after forging by adding elements such as manganese, nitrogen, vanadium, and titanium to form a coarse lamellar pearlite + solid solution strengthened ferrite structure, thereby significantly improving the cutting performance of the material; by increasing the silicon and chromium content, the thermal conductivity of the material is reduced; by adding copper elements, a copper-rich ferrite structure is formed to improve the mechanical properties of the material; and during the actual operation of the piston, the copper-rich ferrite continuously precipitates nano-scale particles, thereby improving the wear resistance of the piston and reducing the risk of cylinder pulling. The method for preparing the steel piston also comprises the following steps: the ingredients are prepared according to the above components, and the nitrogen element is added A nitrogen-containing alloy is added and smelted in a medium-frequency induction furnace. The smelted steel liquid is deoxidized and dehydrogenated, and then hot-rolled and air-cooled to form piston head and skirt bars. After the bars are sawed, medium-frequency induction heating is performed again to forge the piston head and skirt blanks. The forged head and skirt blanks are subjected to an isothermal treatment process to form a forged blank with a matrix structure of coarse lamellar pearlite + ferrite. After the blanks are rough-machined, friction-welded, and fine-machined, the first ring groove area is subjected to high-frequency quenching treatment, and finally surface treatment and skirt nano-coating printing are performed to obtain the finished piston.

[0041] Embodiment 1:

[0042] A new type of high-performance ring groove reinforced steel piston and its production process; its chemical composition is: C0.35%, Si1.1%, P0.02%, S0.025%, Mn2.1%, Cr0.6%, Cu1.1%, V0.06%, Ti0.08%, Nb0.015%, and the balance is Fe. The piston matrix structure is coarse lamellar pearlite + ferrite structure, hardness 280HBW, tensile strength 880Mpa, elongation 12%;

[0043] The preparation process of a novel high-performance ring groove reinforced steel piston is characterized by comprising the following steps:

[0044] (1) Melting of the head and skirt bar blanks: accurately weigh each raw material, weigh each component according to the proportion, and use a medium frequency induction furnace for melting at a melting temperature of 1550-1650°C; the molten iron is allowed to stand for 15 minutes; then it is water-cooled in a copper mold, and then hot-rolled, air-cooled and finished to form the head and skirt bar blanks;

[0045] (2) After the head and skirt bars are sawn off, they are subjected to medium frequency induction heating at a temperature of 1200-1240°C. After reaching the temperature, they are forged with a forging ratio greater than 1:10. After forging, they are subjected to isothermal treatment, cooled after isothermal treatment, shot blasted three times after cooling, and subjected to magnetic particle inspection.

[0046] (3) After rough machining, the piston head and skirt forgings are friction welded using the nitrogen protection friction welding technology independently developed by our company. The welding surface roughness is Rz25-90, and the edge of the welding surface is chamfered with an arc of R2.5-5.0mm. The dimensional tolerance of the welding surface can be within 0.05mm;

[0047] (4) After welding, stress relief annealing treatment is performed, and the semi-finished piston product is finely processed to form a semi-finished product with a pin hole and an outer circle having a special profile;

[0048] (5) The semi-finished product after fine processing is subjected to high-frequency quenching treatment of the first ring groove by using an EFD high-frequency quenching machine tool, with an equipment power of 10-200KW, an equipment frequency of 75-150KHZ, and an actual power of 50%;

[0049] (6) The semi-finished product after high-frequency quenching is subjected to stress relief treatment at 185±5℃;

[0050] (7) The semi-finished product after annealing is phosphated and coated with a new type of nano-coating to form the new high-performance ring groove reinforced steel piston finished product.

[0051] The steel piston was tested for its tensile strength of 980MPa and thermal conductivity of 24W / mk (the thermal conductivity of the current steel piston material is 38W / mk). No rust was found in the formic acid simulation corrosion test (corrosion liquid preparation: pour 100mI formic acid into 500ml water, add 2.5g sodium chloride to dissolve and dilute to 1000ml, shake well).

[0052] Embodiment 2:

[0053] A new type of high-performance ring groove reinforced steel piston and its preparation method, the chemical composition of which is, by weight percentage, C0.4%, Si1.3%, P0.02%, S0.02%, Mn2.3%, Cr0.8%, Cu1.5%, V0.2%, Ti0.08%, Nb0.03%, and the balance is Fe. The piston matrix structure is coarse lamellar pearlite + ferrite structure, with a hardness of 308 HBW, a tensile strength of 950 MPa, and an elongation greater than 11%. The preparation process of the new type of high-performance ring groove reinforced steel piston is characterized by comprising the following steps:

[0054] (1) Melting of the head and skirt bar blanks: accurately weigh each raw material, weigh each component according to the proportion, and use a medium frequency induction furnace for melting at a melting temperature of 1550-1650°C; the molten iron is allowed to stand for 15 minutes; then it is water-cooled in a copper mold, and then hot-rolled, air-cooled and finished to form the head and skirt bar blanks;

[0055] (2) After the head and skirt bars are sawn off, they are subjected to medium frequency induction heating at a temperature of 1200-1240°C. After reaching the temperature, they are forged with a forging ratio greater than 1:10. After forging, they are subjected to isothermal treatment, cooled after isothermal treatment, shot blasted three times after cooling, and subjected to magnetic particle inspection.

[0056] (3) After rough machining, the piston head and skirt forgings are friction welded using the nitrogen protection friction welding technology independently developed by our company. The welding surface roughness is Rz25-90, and the edge of the welding surface is chamfered with an arc of R2.5-5.0mm. The dimensional tolerance of the welding surface can be within 0.05mm;

[0057] (4) After welding, stress relief annealing treatment is performed, and the semi-finished piston product is finely processed to form a semi-finished product with a pin hole and an outer circle having a special profile;

[0058] (5) The semi-finished product after fine processing is subjected to high-frequency quenching treatment of the first ring groove by using an EFD high-frequency quenching machine tool, with an equipment power of 10-200KW, an equipment frequency of 75-150KHZ, and an actual power of 50%;

[0059] (6) The semi-finished product after high-frequency quenching is subjected to stress relief treatment at 185±5℃;

[0060] (7) The semi-finished product after annealing is phosphated and coated with a new type of nano-coating to form the new high-performance ring groove reinforced steel piston finished product.

[0061] The tensile strength of the steel piston was tested to be 1000MPa, the thermal conductivity was 26W / mk (the thermal conductivity of the current material of the steel piston is 38W / mk), and no rust was found in the formic acid simulation corrosion experiment (corrosion liquid preparation: 100mI formic acid was poured into 500ml of water, 2.5g of sodium chloride was added to dissolve and then diluted to 1000ml, and shaken well).

[0062] Embodiment 3:

[0063] A new type of high-strength ring groove reinforced steel piston and its preparation method, the chemical composition of which is, by weight percentage: C0.35%, Si1.0%, P0.025%, S0.03%, Mn1.5%, Cr0.3%, Cu1.0%, V0.15%, Ti0.08%, Nb0.05%, and the balance is Fe. The piston matrix structure is coarse lamellar pearlite + ferrite structure, with a hardness of 270 HBW, a tensile strength of 900 MPa, and an elongation greater than 11.5%;

[0064] The preparation process of a novel high-performance small-bore directional friction welded steel piston is characterized by comprising the following steps:

[0065] (1) Melting of the head and skirt bar blanks: accurately weigh each raw material, weigh each component according to the proportion, and use a medium frequency induction furnace for melting at a melting temperature of 1550-1650°C; the molten iron is allowed to stand for 15 minutes; then it is water-cooled in a copper mold, and then hot-rolled, air-cooled and finished to form the head and skirt bar blanks;

[0066] (2) After the head and skirt bars are sawn off, they are subjected to medium frequency induction heating at a temperature of 1200-1240°C. After reaching the temperature, they are forged with a forging ratio greater than 1:10. After forging, they are subjected to isothermal treatment, cooled after isothermal treatment, shot blasted three times after cooling, and subjected to magnetic particle inspection.

[0067] (3) After rough machining, the piston head and skirt forgings are friction welded using the nitrogen protection friction welding technology independently developed by our company. The welding surface roughness is Rz25-90, and the edge of the welding surface is chamfered with an arc of R2.5-5.0mm. The dimensional tolerance of the welding surface can be within 0.05mm;

[0068] (4) After welding, stress relief annealing treatment is performed, and the semi-finished piston product is finely processed to form a semi-finished product with a pin hole and an outer circle having a special profile;

[0069] (5) The semi-finished product after fine processing is subjected to high-frequency quenching treatment of the first ring groove by using an EFD high-frequency quenching machine tool, with an equipment power of 10-200KW, an equipment frequency of 75-150KHZ, and an actual power of 50%;

[0070] (6) The semi-finished product after high-frequency quenching is subjected to stress relief treatment at 185±5℃;

[0071] (7) The semi-finished product after annealing is phosphated and coated with a new type of nano-coating to form the new high-performance ring groove reinforced steel piston finished product.

[0072] The tensile strength of the steel piston was tested to be 1100MPa, the thermal conductivity was 28W / mk (the thermal conductivity of the current material of the steel piston is 38W / mk), and no rust was found in the formic acid simulation corrosion experiment (corrosion liquid preparation: pour 100mI formic acid into 500ml of water, add 2.5g of sodium chloride to dissolve and dilute to 1000ml, and shake well).

[0073] In the above or some embodiments, the high frequency quenching machine includes a high frequency quenching coil, the high frequency quenching coil includes an induction portion surrounded by a single spiral turn and matching the size of the first annular groove, and the induction portion includes an intervention portion intervened in the first annular groove.

[0074] This patent strictly requires the limits of sulfur and phosphorus elements, and adds copper, vanadium, titanium, nitrogen and other elements. Through isothermal treatment after forging, a coarse lamellar pearlite structure is formed. Without changing the strength, the high-frequency quenching performance and cutting performance of the material are significantly improved, and the production and processing cost of steel pistons is reduced. On the other hand, the inner side of the first ring groove is subjected to targeted and uniform quenching and hardening treatment to avoid problems such as excessive blowby and oil burning caused by high-temperature wear of the first ring groove.

Claims

1. A new type of high-performance ring groove reinforced steel piston with a diameter range of 60-300mm; its chemical composition, in terms of weight percentage, is: C0.3-0.45%, Si1.1-1.5%, P0-0.025%, S0.02-0.05%, Mn2.1-3.0%, Cr0.5-1.0%, Cu1.1-2.0%, V0.05-0.2%, Ti0.05-0.08%, Nb0.01-0.05%, and the balance is Fe; and the piston matrix structure is coarse lamellar pearlite + ferrite structure, with a hardness of 250-310 HBW, a tensile strength of ≥850Mpa, and an elongation of more than 10%; the first ring groove is a trapezoidal ring, with a ring groove bottom width of 1-5mm, a ring groove top width of 3-8mm, and a ring groove depth of 5-10mm.

2. The new high-performance ring groove reinforced steel piston according to claim 1, It is characterized in that The surface hardness of the first ring groove is obtained by high-frequency heating quenching.

3. The new high-performance ring groove reinforced steel piston processing method according to claim 1, It is characterized in that STEP1. Melting of head and skirt bar blanks: accurately weigh each raw material, weigh each component according to the proportion, and use a medium frequency induction furnace for melting at a melting temperature of 1550-1650℃; let the molten iron stand for 15 minutes; then use a copper mold for water cooling, and then hot rolling, air cooling and finishing to form head and skirt bar blanks; STEP2. After the head and skirt bars are sawn off, they are subjected to medium frequency induction heating at a temperature of 1200-1240°C. After reaching the temperature, they are forged with a forging ratio greater than 1:

10. After forging, they are isothermally treated, cooled, and shot blasted three times; STEP3. After the piston head and skirt forgings are roughly machined, they are friction welded using nitrogen protection friction welding technology. The welding surface roughness is Rz25-90, and the edge of the welding surface is chamfered with an arc of R2.5-5.0mm. The dimensional tolerance of the welding surface can be within 0.05mm; STEP4. After welding, stress relief annealing treatment is performed, and the semi-finished piston is finely processed to form a semi-finished product with a pin hole and outer circle with special profiles; STEP5. The semi-finished product after fine processing is subjected to high-frequency quenching treatment on the first ring groove area by using an EFD high-frequency quenching machine, the equipment power is 10-200KW, the equipment frequency is 75-150KHZ, and the actual power is 50%; the high-frequency quenching machine includes a high-frequency quenching coil, the high-frequency quenching coil includes an induction part surrounded by a single-turn spiral and matching the size of the first ring groove, and the induction part includes an intervention part intervened in the first ring groove; STEP6. After high-frequency quenching, the semi-finished product is subjected to stress relief treatment at 185±5℃; STEP 7. After annealing, the semi-finished product is phosphated and coated with a new type of nano-coating to form the new type of high-performance ring groove reinforced steel piston finished product.

4. The new high-performance ring groove reinforced steel piston processing method according to claim 3, It is characterized in that In the step STEP2, the piston head and skirt are forged, the starting forging temperature is 1200-1350°C, the final forging temperature is 980-1150°C, and after forging, they are transferred into a tunnel-type holding furnace for an isothermal treatment, the isothermal temperature is 600°C±10°C, the isothermal time is 120±10 minutes, and air cooling is performed after the isothermal treatment is completed.

5. The new high-performance ring groove reinforced steel piston processing method according to claim 3 or 4, It is characterized in that The step STEP5 of high-frequency quenching the first ring groove area of ​​the semi-finished product after fine machining comprises the following steps: The semi-finished piston is placed on a fixture that is positioned by a stopper and an auxiliary stopper for clamping; The piston rotates at a speed of 300±10r / min; The induction coil is lowered, and the intervention part is inserted into the first annular groove, and the gap between the intervention part and the annular groove wall is 0.1 mm; During the rotation of the piston, the magnetic flux lines are cut to form an induced current, which heats the ring groove wall to 800-1000°C; in the fifth step, the spray device starts to spray the quenching liquid to perform quenching cooling. After cooling, the piston stops rotating, the coil rises, and the workpiece is removed; Clean the quenching liquid remaining on the piston surface and dry it.

6. The preparation process of the new high-performance ring groove reinforced steel piston according to claim 5, It is characterized in that In the step STEP5, after high-frequency quenching, the quenching layer thickness of the first ring groove area is ≥0.2 mm, the microhardness is ≥500 HV1, and the ring groove size deformation is <0.03 mm.

7. The preparation process of the new high-performance ring groove reinforced steel piston according to claim 6, It is characterized in that The quenching liquid model of step STEP5 is Houghton quenching liquid, the quenching liquid concentration is 20-25, and the spraying time is 1-5 seconds.

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