Manufacturing method of rocker arm type forge piece

Abstract

The invention belongs to the technical field of forging, and relates to a manufacturing method of rocker arm type forgings. The manufacturing method of the rocker arm type forge piece comprises the following steps: blanking; first-fire forging; the specific process of primary heating forging comprises the steps that firstly, an original blank and a bending die are subjected to lubricating treatment and preheating, then the original blank is subjected to primary heating and heat preservation, then the original blank is placed in the bending die to be bent through a press machine, a bent blank is formed, and the bent blank is ground; secondary heating forging; the specific process of secondary heating forging comprises the steps that firstly, the bent blank and the die forging die are lubricated and preheated, then the bent blank is heated and subjected to heat preservation for the second time, then the bent blank is placed in the die forging die to be pre-forged through a press machine, and ash cooling is conducted after forging. According to the process method, the original blank is subjected to die forging to ensure that the appearance quality of rocker arm type forgings is kept consistent, and the internal quality of the forgings is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of forging and relates to a method for manufacturing a rocker arm forging. Background Art

[0002] Rocker arm forgings are active force-bearing parts with complex structures and difficult-to-control forming processes. Usually, such forgings have high internal quality requirements, large quantities, and some parts of the final product are non-machined surfaces, so the consistency requirements for the appearance quality of the forgings are also very high. If the process method is unreasonable, it will affect the quality and performance of the product.

[0003] Therefore, there is an urgent need for a process method to improve quality and production efficiency and maintain the consistency of internal quality and appearance shape between each product. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and to provide a method for manufacturing a rocker arm forging.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for manufacturing a rocker arm forging comprises the following steps:

[0007] Step 1: Cutting materials;

[0008] Step 2: one-fire forging; the specific process of the one-fire forging is: firstly, the original blank and the bending die are preheated and lubricated in sequence, then the original blank is heated and kept warm for the first time, and then the original blank is placed in the bending die and bent by a press to form a bent blank, and the bent blank is polished;

[0009] Step 3: two-fire forging; the specific process of the two-fire forging is: firstly, the bending blank and the die forging die are preheated and lubricated in sequence, then the bending blank is heated and kept warm for a second time, and then the bending blank is placed in the die forging die and pre-forged by a press, and then cooled after forging to form a prototype of a rocker arm forging;

[0010] Step 4: primary laser trimming; after the primary laser trimming, gray cooling is performed, followed by sand blasting and grinding;

[0011] Step 5: Three-fire forging; firstly, the prototype of the rocker arm forging and the die forging die are preheated and lubricated in sequence, then the prototype of the rocker arm forging is heated and kept warm for the third time, and then the bent blank is placed in the die forging die and final forged by a press, and then cooled after forging to form a rocker arm forging;

[0012] Step 6: secondary laser trimming, followed by ash cooling;

[0013] Step 7: Annealing;

[0014] Step eight: heat treatment; the heat treatment includes quenching heat treatment and tempering heat treatment.

[0015] Furthermore, the preheating temperature of the original billet, the bent billet, and the rocker arm forging prototype is 100°C to 150°C, and the preheating time is 1.8h to 2.2h; the preheating temperature of the bending die and the die forging die is 150°C to 300°C, and the preheating time is 6h to 8h.

[0016] Furthermore, during the first heating and heat preservation, the second heating and heat preservation, and the third heating and heat preservation, the furnace temperature is raised to 1085° C. to 1115° C. and then heat preservation is performed, and the heat preservation time is: 25 min to 60 min.

[0017] ] Further, the bending angle in the step 2 is 73° to 77°.

[0018] Furthermore, the bending mold in step two includes an upper bending mold and a lower bending mold, the upper part of the lower bending mold is provided with an arc-shaped groove, and the lower part of the upper bending mold is provided with an arc-shaped protrusion, and the arc-shaped groove and the arc-shaped protrusion cooperate with each other; the upper bending mold is connected to the upper mold base of the press, and the lower bending mold is connected to the lower mold base of the press, and the original blank is pressed downward by the press to form an arc consistent with the arc-shaped groove and the arc-shaped protrusion.

[0019] Further, the upper surface of the arc-shaped groove is provided with a first arc-shaped fixing groove, and the lower surface of the arc-shaped protrusion is provided with a second arc-shaped fixing groove;

[0020] A third arc-shaped fixing groove is arranged on the upper surface of the lower bending die, the third arc-shaped fixing groove is located on both sides of the first arc-shaped fixing groove, and the third arc-shaped fixing groove is communicated with the first arc-shaped fixing groove.

[0021] Furthermore, the die forging die is divided into an upper die and a lower die, and after the upper die and the lower die are closed, a die cavity of a rocker arm forging is formed inside.

[0022] Furthermore, during the bending process in step 2, an underpressure of 3 mm to 5 mm needs to be reserved; during the pre-forging process in step 3, an underpressure of 1 mm to 2 mm needs to be reserved.

[0023] Furthermore, the heating temperature of the annealing in step six is ​​680° C. to 700° C., and the holding time of the annealing is 5.8 h to 6.2 h.

[0024] Furthermore, the quenching heat treatment in step eight is to heat the temperature of the rocker arm forgings to 1040°C to 1060°C and then keep it warm for 0.45h to 0.55h; the tempering heat treatment is to heat the temperature of the rocker arm forgings to 645°C to 655°C and then keep it warm for 0.9h to 1.1h.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The present invention adopts a bending + die forging process, firstly bending the original blank, and then die forging the bent blank, to ensure that the metal streamline of the original blank is complete, thereby improving the service life of the rocker arm forgings, ensuring that the appearance quality of the rocker arm forgings remains consistent, and improving the internal quality of the forgings.

[0027] 2. The present invention has simple operation steps. The internal metal streamline of the rocker arm forging is ensured by bending the die, and the overall appearance size is formed by the die forging die, thereby achieving stable quality during mass production and meeting the requirement of basically unified appearance size.

[0028] 3. The rocker arm forgings obtained by the present invention have a small machining allowance, which is close to the net size of the parts, thereby effectively saving material costs and improving machining efficiency.

[0029] 4. The present invention controls the appearance size through the mold and has less dependence on the operator. As long as the operator is familiar with the equipment operation, qualified products that meet the requirements can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings are incorporated in and constitute a part of this specification and, together with the description, serve to explain the principles of the present invention.

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0032] Figure 1 is a flow chart of the manufacturing method of the present invention;

[0033] Figure 2 It is a structural schematic diagram of the bending mold in the present invention;

[0034] Figure 3 It is a schematic diagram of the structure of the original blank in the present invention;

[0035] Figure 4 It is a schematic diagram of the placement position of the original blank and the bending mold in the present invention;

[0036] Figure 5 A schematic diagram of the process of bending the original blank using a bending die in the present invention;

[0037] Figure 6 It is a schematic diagram of the bending blank in the present invention;

[0038] Figure 7 It is a schematic diagram of the die forging die in the present invention;

[0039] Figure 8 It is a schematic diagram of the placement positions of the die forging die and the bending blank before die forging in the present invention;

[0040] Fig. 9 It is a schematic diagram of forming a die-forged rear rocker arm forging in the present invention;

[0041] Fig.10 It is a schematic diagram of the structure of the rocker arm forging produced in the present invention.

[0042] Among them: 1 is the original blank; 2 is the bending die; 2-1 is the upper bending die; 2-2 is the lower bending die; 2-11 is the arc-shaped protrusion; 2-21 is the arc-shaped groove; 2-23 is the first arc-shaped fixed groove; 2-24 is the second arc-shaped fixed groove; 2-25 is the third arc-shaped fixed groove; 3 is the die forging die; 3-1 is the upper die; 3-2 is the lower die; 4 is the bending blank; 5 is the prototype of the rocker arm forging; 6 is the rocker arm forging. DETAILED DESCRIPTION

[0043] Here, exemplary embodiments will be described in detail, and the embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are only examples consistent with some aspects of the present invention described in detail in the appended claims.

[0044] A method for manufacturing a rocker arm forging, such as Figure 1 As shown, the specific steps include:

[0045] Step 1: Cutting: The blank with a size of φ35×225mm is used, and the material of the blank is: 1Cr12Ni3MoVN.

[0046] Step 2: one-fire forging; the specific process of the one-fire forging is: firstly, the original blank 1 and the bending die 2 are preheated and lubricated in sequence, then the original blank 1 is heated and kept warm for the first time, and then the original blank 1 is placed in the bending die 2 and bent by a press to form a bent blank 4, and the bent blank 4 is polished;

[0047] Step 3: two-fire forging; the specific process of the two-fire forging is: firstly, the bending blank 4 and the die forging die 3 are preheated and lubricated in sequence, then the bending blank 4 is heated and kept warm for a second time, and then the bending blank 4 is placed in the die forging die 3 and pre-forged by a press, and then cooled after forging to form a prototype 5 of a rocker arm forging;

[0048] Step 4: primary laser trimming; the primary laser trimming is followed by gray cooling, followed by sand blowing and grinding; the primary laser trimming requires a 3mm to 5mm burr to be left on one side to prevent the burrs left by the trimming from being drawn into the forging body and forming folding defects.

[0049] Step 5: three-fire forging; firstly, the rocker arm forging prototype 5 and the die forging die 3 are preheated and lubricated in sequence, then the rocker arm forging prototype 5 is heated and kept warm for the third time, and then the bent blank is placed in the die forging die 3 and final forged by a press, and then cooled after forging to form a rocker arm forging 6;

[0050] Step 6: Secondary laser trimming, followed by gray cooling; the secondary laser trimming needs to leave a 2mm to 3mm burr on one side to prevent the heat affected zone caused by laser trimming from appearing on the forging body.

[0051] Step 7: Annealing; the annealing step includes: raising the charging temperature to 350-550°C, then heating to 675-705°C and keeping it warm for 45-75 minutes; after the insulation is completed, cooling the furnace temperature to ≤350°C and taking it out of the furnace, and cooling it at room temperature;

[0052] During the die forging process, residual stress will be generated in the forging due to plastic deformation. Annealing is used to eliminate the residual stress inside the forging to prevent the residual stress from causing deformation, cracking and other problems in the subsequent processing or use of the forging.

[0053] Step 8: Heat treatment;

[0054] The heat treatment steps include:

[0055] Heating: After heating for 55 to 65 minutes, raise the temperature to 1035 to 1065°C;

[0056] Insulation: Insulation at 1035-1065℃ for 25-35min;

[0057] Air cooling: 350~400℃;

[0058] Furnace charging: 350~400℃;

[0059] Heating: After heating for 60 minutes, raise the temperature to 635-665°C;

[0060] Insulation: Insulation at 635-665℃ for 60min;

[0061] The furnace is cooled to ≤350℃ and then air-cooled at room temperature.

[0062] The heat treatment includes quenching heat treatment and tempering heat treatment. Quenching improves the hardness and strength of the material so that it can withstand greater loads. Tempering eliminates the thermal stress and structural stress generated inside the workpiece during the quenching process, so that the forgings have good comprehensive properties and more stable dimensions.

[0063] Specifically, the present invention adopts a bending + die forging process scheme, firstly bends the original blank 1 to ensure that the metal streamline of the original blank 1 is complete, and then the bent blank is die forged to ensure that the appearance quality of the rocker arm forging 6 remains consistent, thereby improving the internal quality of the forging. The present invention has simple operating steps, and the internal metal streamline of the rocker arm forging 6 is ensured by the bending die 2, and then the overall appearance size is formed by the die forging die 3, thereby achieving the requirements of stable quality and basically uniform appearance size during mass production.

[0064] like Figure 3 As shown, the original blank 1 used to make the rocker arm forging 6 is made of stainless steel, which is generally made of round steel that meets standard requirements.

[0065] like Figure 4 , Figure 5 As shown in the figure, when performing the bending operation, first align the centers of the upper and lower bending dies and fix them on the upper and lower die bases of the press respectively. Then heat the original blank 1 to the specified temperature and time. After the heating and heat preservation is completed, take the original blank 1 out of the heating device, as shown in the figure. Figure 4 As shown, the upper bending die 2-1 is placed at the center of the lower bending die 2-2, and the right end of the original blank 1 is aligned with the inner groove of the right end of the lower bending die 2-2. Then, the upper bending die 2-1 moves downward under the pressure of the press to bend the original blank 1 (as shown in FIG. Figure 5 As shown). After the original blank 1 is bent, the Figure 6 After the blank is cooled to room temperature, the wrinkles of the curved part of the blank 1 are polished to avoid breakage in the subsequent die forging process.

[0066] In addition, in step 1, a blank with a size of φ35mm×225mm is selected for cutting; the original blank 1, the bent blank 4, and the rocker arm forging prototype 5 are preheated at 100℃~150℃ for 2 hours and then lubricant is sprayed on the surface of the blank piece by piece (lubrication treatment); the lubrication of the bending die 2 and the die forging die 3 is mainly to lubricate the die cavity by spraying graphite emulsion.

[0067] In the step 1, the bending blank 4 is ground mainly by using an angle grinder, which can completely remove the oxide scale on the surface of the forging, and can completely remove forging defects such as cracks, folds, pits, etc. on the surface of the forging.

[0068] Furthermore, the preheating temperature of the original blank 1, the bent blank 4, and the rocker arm forging prototype 5 is 100°C to 150°C, and the preheating time is 1.8 to 2.2 hours; the preheating temperature of the bending die 2 and the die forging die 3 is 150°C to 300°C, and the preheating time is: the preheating time is: 6h to 8h.

[0069] Furthermore, during the first heating and heat preservation, the second heating and heat preservation, and the third heating and heat preservation, the furnace temperature is raised to 1085° C. to 1115° C. and then heat preservation is performed, and the heat preservation time is: 25 min to 60 min.

[0070] Furthermore, the bending angle in step 2 is 73° to 77°.

[0071] Furthermore, if Figure 2 As shown, the bending mold 2 in the step 2 includes an upper bending mold 2-1 and a lower bending mold 2-2, the upper portion of the lower bending mold 2-2 is provided with an arc-shaped groove 2-21, and the lower portion of the upper bending mold 2-2 is provided with an arc-shaped protrusion 2-11, and the arc-shaped groove 2-21 and the arc-shaped protrusion 2-11 cooperate with each other; the upper bending mold is connected to the upper mold base of the press, and the lower bending mold 2-2 is connected to the lower mold base of the press, and the original blank 1 is pressed downward by the press to form an arc consistent with the arc-shaped groove 2-21 and the arc-shaped protrusion 2-11.

[0072] Further, the upper surface of the arc-shaped groove 2-21 is provided with a first arc-shaped fixing groove 2-23, and the lower surface of the arc-shaped protrusion 2-11 is provided with a second arc-shaped fixing groove 2-24;

[0073] The upper surface of the lower bending mold 2-2 is provided with a third arc-shaped fixing groove 2-25, and the third arc-shaped fixing groove 2-25 is located on both sides of the first arc-shaped fixing groove 2-23, and the third arc-shaped fixing groove 2-25 is connected to the first arc-shaped fixing groove 2-23.

[0074] Specifically, the bending die is composed of an upper bending die 2-1 and a lower bending die 2-2, and the upper and lower bending dies are generally made of die steel. The pressure used by the press is 50% to 60% of the 1600t electric screw press.

[0075] Furthermore, the die forging die 3 is divided into an upper die 3 - 1 and a lower die 3 - 2 , and after the upper die 3 - 1 and the lower die 3 - 2 are closed, a die cavity of the rocker arm forging 6 is formed inside.

[0076] Specifically, Figure 7 As shown, the die forging die 3 is composed of an upper die 3-1 and a lower die 3-2, and the die is generally made of die steel. The upper and lower die forging dies are respectively fixed on the upper and lower die bases of the press for use.

[0077] After the mold is installed, the surface of the bent blank 4 obtained after bending is sprayed with glass lubricant, and then the bent blank 4 is heated and kept warm again. After the bending blank 4 is heated and kept warm, it is taken out from the heating device, such as Figure 8 As shown, the bent blank 4 is quickly placed above the forging lower die 5. Then the upper die 3-1 moves downward under the pressure of the press to perform die forging on the bent blank 4. Fig. 9 As shown, after the bending blank 4 is die forged, the following Fig.10 The rocker arm forging 6 is shown.

[0078] The upper die 3-1 is pressed downward, and the lower die 3-2 is fixed on the die base of the press, and the pressure value is 60% to 70% of the pressure of the 1600t electric screw press.

[0079] Furthermore, during the bending process in step 2, an underpressure of 3 mm to 5 mm needs to be reserved; during the pre-forging process in step 3, an underpressure of 1 mm to 2 mm needs to be reserved.

[0080] Furthermore, the heating temperature of the annealing in step six is ​​680° C. to 700° C., and the annealing holding time is 6 hours.

[0081] Furthermore, the quenching heat treatment in step eight is to heat the temperature of the rocker arm forging 6 to 1040°C~1060°C and then keep it warm for 0.45h~0.55h; the tempering heat treatment is to heat the temperature of the rocker arm forging 6 to 645°C~655°C and then keep it warm for 0.9h~1.1h.

[0082] Furthermore, in the step 1, the pressure of the press is 8000 kN to 9600 kN; in the steps 2 and 3, the pressure of the press is 9600 kN to 11200 kN.

[0083] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0084] Example 1

[0085] A method for manufacturing a rocker arm forging comprises the following steps:

[0086] Step 1: Cutting: The blank is made of φ35×225mm material, and the material used is 1Cr12Ni3MoVN;

[0087] Step 2: one-fire forging; the specific process of the one-fire forging is: first preheating and lubricating the original blank 1 and the bending die 2 in turn, then heating and keeping the original blank 1 for the first time, and then placing the original blank 1 in the bending die 2 and bending it through a press to form a bent blank 4, and grinding the bent blank 4; wherein, the original blank is sprayed with lubricant for lubrication, and the bending die is lubricated with graphite emulsion, the preheating temperature of the original blank is 100°C, and the preheating time is 1.8 hours; the preheating temperature of the bending die is: 150°C, and the preheating time is 6h; during the first insulation heating, the furnace temperature is first raised to 1085°C, the insulation time is 60min, the bending angle is 73°, and a 3mm underpressure needs to be reserved during the bending process.

[0088] Step three: two-fire forging; the specific process of the two-fire forging is: first preheating and lubricating the bending blank 4 and the die forging die 3 in turn, then heating and keeping the bending blank 4 for a second time, and then placing the bending blank 4 in the die forging die 3 for pre-forging by a press, and cooling after forging to form a rocker arm forging prototype 5; wherein, the bending blank 4 is lubricated by spraying lubricant, and the die forging die 3 is lubricated with graphite emulsion, the preheating temperature of the preheating of the bending blank is 100°C, and the preheating time is 1.8h; the preheating temperature of the die forging die 3 is 150°C, and the preheating time is 6h; during the second insulation heating, the furnace temperature is first raised to 1085°C, and the insulation time is 60min. A 1mm underpressure needs to be reserved during the pre-forging process.

[0089] Step 4: primary laser trimming; after the primary laser trimming, gray cooling is performed, followed by sand blasting and grinding;

[0090] Step 5: three-fire forging; firstly, the rocker arm forging prototype 5 and the die forging die 3 are preheated and lubricated in sequence, then the rocker arm forging prototype 5 is heated and kept warm for the third time, and then the bent blank is placed in the die forging die 3 and is finally forged by a press, and then cooled after forging to form a rocker arm forging 6; wherein, the rocker arm forging prototype 5 is lubricated by spraying lubricant, and the die forging die 3 is lubricated by graphite emulsion, the preheating temperature of the rocker arm forging prototype 5 is 100°C, and the preheating time is 1.8 hours; the preheating temperature of the die forging die 3 is 150°C, and the preheating time is 6h; during the third heat preservation heating, the furnace temperature is first increased to 1085°C and then kept warm, and the holding time is: 60min.

[0091] Step 6: secondary laser trimming, followed by ash cooling;

[0092] Step seven: annealing; the heating temperature of annealing is 680° C., and the annealing holding time is 5.8 h.

[0093] Step 8: Heat treatment: The heat treatment includes quenching heat treatment and tempering heat treatment. The quenching heat treatment heats the rocker arm forging 6 to 1040°C and then keeps the temperature for 0.45h; the tempering heat treatment heats the rocker arm forging 6 to 645°C and then keeps the temperature for 0.9h.

[0094] Example 2

[0095] A method for manufacturing a rocker arm forging comprises the following steps:

[0096] Step 1: Cutting: Cutting uses a blank with a size of φ35×225mm, and the material used for the blank is: 1Cr12Ni3MoVN;

[0097] Step 2: one-fire forging; the specific process of the one-fire forging is: first preheating and lubricating the original blank 1 and the bending die 2 in turn, then heating and keeping the original blank 1 for the first time, and then placing the original blank 1 in the bending die 2 and bending it through a press to form a bent blank 4, and grinding the bent blank 4; wherein, the original blank is sprayed with lubricant for lubrication, and the bending die is lubricated with graphite emulsion, the preheating temperature of the original blank is 125°C, and the preheating time is 2h; the preheating temperature of the bending die 2 is 225°C, and the preheating time is 7h; during the first insulation heating, the furnace temperature is first raised to 1100°C, the insulation time is 42.5min, the bending angle is 75°, and a 4mm underpressure needs to be reserved during the bending process.

[0098] Step three: two-fire forging; the specific process of the two-fire forging is: first preheating and lubricating the bent blank 4 and the die forging die 3 in turn, then heating and keeping the bent blank 4 for a second time, and then placing the bent blank 4 in the die forging die 3 for pre-forging by a press, and cooling after forging to form a rocker arm forging prototype 5; wherein, the bent blank 4 is lubricated by spraying lubricant, and the die forging die 3 is lubricated with graphite emulsion, the preheating temperature of the original blank is 125°C, and the preheating time is 2h; the preheating temperature of the die forging die 3 is 225°C, and the preheating time is 7h; during the second insulation heating, the furnace temperature is first raised to 1100°C, and the insulation time is 42.5min. A 1.5mm underpressure needs to be reserved during the pre-forging process.

[0099] Step 4: primary laser trimming; after the primary laser trimming, gray cooling is performed, followed by sand blasting and grinding;

[0100] Step 5: three-fire forging; firstly, the rocker arm forging prototype 5 and the die forging die 3 are preheated and lubricated in sequence, and then the rocker arm forging prototype 5 is heated and kept warm for the third time, and then the bent blank is placed in the die forging die 3 and final forged by a press, and then cooled after forging to form a rocker arm forging 6; wherein, the rocker arm forging prototype 5 is lubricated by spraying lubricant, and the die forging die 3 is lubricated by graphite emulsion, and the preheating temperature of the rocker arm forging prototype 5 is 125°C, and the preheating time is 2h; the preheating temperature of the die forging die 3 is 225°C, and the preheating time is 7h; during the third heat preservation heating, the furnace temperature is first increased to 1100°C, and the heat preservation time is 42.5min.

[0101] Step 6: secondary laser trimming, followed by ash cooling;

[0102] Step seven: annealing; the heating temperature of annealing is 690° C., and the annealing holding time is 6 hours.

[0103] Step 8: Heat treatment: The heat treatment includes quenching heat treatment and tempering heat treatment. The quenching heat treatment heats the rocker arm forging 6 to 1050°C and then keeps the temperature for 0.5h; the tempering heat treatment heats the rocker arm forging 6 to 650°C and then keeps the temperature for 1h.

[0104] Example 3

[0105] A method for manufacturing a rocker arm forging comprises the following steps:

[0106] Step 1: Cutting: The blank is made of φ35mm×225mm blank, and the material of the blank is 1Cr12Ni3MoVN;

[0107] Step 2: one-fire forging; the specific process of the one-fire forging is: first preheating and lubricating the original blank 1 and the bending die 2 in turn, then heating and keeping the original blank 1 for the first time, then placing the original blank 1 in the bending die 2 and bending it through a press to form a bent blank 4, and grinding the bent blank 4; wherein, the original blank is sprayed with lubricant for lubrication, the bending die is lubricated with graphite emulsion, the preheating temperature of the original blank is 150°C, and the preheating time is 2.2 hours; the preheating temperature of the bending die 2 is 300°C, and the preheating time is 8h; during the first insulation heating, the furnace temperature is first raised to 1115°C, the insulation time is 25min, the bending angle is 77°, and a 5mm underpressure needs to be reserved during the bending process.

[0108] Step three: two-fire forging; the specific process of the two-fire forging is: first preheating and lubricating the bent blank 4 and the die forging die 3 in turn, then heating and keeping the bent blank 4 for a second time, and then placing the bent blank 4 in the die forging die 3 for pre-forging by a press, and cooling after forging to form a rocker arm forging prototype 5; wherein, the bent blank 4 is lubricated by spraying lubricant, and the die forging die 3 is lubricated with graphite emulsion, the preheating temperature of the original blank is 150°C, and the preheating time is 2.2 hours; the preheating temperature of the die forging die 3 is 300°C, and the preheating time is 8h; during the second insulation heating, the furnace temperature is first raised to 1115°C, and the insulation time is 25min. A 2mm underpressure needs to be reserved during the pre-forging process.

[0109] Step 4: primary laser trimming; after the primary laser trimming, gray cooling is performed, followed by sand blasting and grinding;

[0110] Step 5: three-fire forging; firstly, the rocker arm forging prototype 5 and the die forging die 3 are preheated and lubricated in sequence, and then the rocker arm forging prototype 5 is heated and kept warm for the third time, and then the bent blank is placed in the die forging die 3 and final forging is performed by a press, and then the rocker arm forging 6 is formed by gray cooling after forging; wherein, the rocker arm forging prototype 5 is lubricated by spraying lubricant, and the die forging die 3 is lubricated by graphite emulsion, and the preheating temperature of the rocker arm forging prototype 5 is 150°C, and the preheating time is 2.2 hours; the preheating temperature of the die forging die 3 is 300°C, and the preheating time is 8h; during the third heat preservation heating, the furnace temperature is first increased to 1115°C, and the heat preservation time is 25min.

[0111] Step 6: secondary laser trimming, followed by ash cooling;

[0112] Step seven: annealing; the heating temperature of annealing is 700° C., and the annealing holding time is 6.2 h.

[0113] Step 8: Heat treatment: The heat treatment includes quenching heat treatment and tempering heat treatment. The quenching heat treatment heats the rocker arm forging 6 to 1060°C and then keeps the temperature for 0.55h; the tempering heat treatment heats the rocker arm forging 6 to 655°C and then keeps the temperature for 1.1h.

[0114] Table 1 Performance statistics of the L longitudinal direction in Examples 1 to 3

[0115]

[0116] It can be seen that in Examples 1 to 3, the tensile strength range is: 930 to 1130 MPa, the extension strength range is ≥760 MPa, the elongation after fracture is ≥14%, the Izod impact is ≥61 J, and the hardness (HB) range is: 286 to 331. It can be seen that the tensile performance, extension strength, elongation after fracture, cross-sectional shrinkage, Izod impact, hardness and other properties of the present invention are excellent.

[0117] The above description is only a specific embodiment of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention.

[0118] It should be understood that the present invention is not limited to what has been described above and that various modifications and changes may be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for manufacturing a rocker arm forging, characterized in that: The following steps are involved: Step 1: Cutting materials; Step 2: single-fire forging; the specific process of single-fire forging is: firstly, the original blank (1) and the bending die (2) are preheated and lubricated in sequence, then the original blank (1) is heated and kept warm for the first time, then the original blank (1) is placed in the bending die (2) and bent by a press to form a bent blank (4), and the bent blank (4) is polished; Step 3: two-fire forging; the specific process of the two-fire forging is: firstly, the bending blank (4) and the die forging die (3) are preheated and lubricated in sequence, then the bending blank (4) is heated and kept warm for a second time, and then the bending blank (4) is placed in the die forging die (3) and pre-forged by a press, and then cooled after forging to form a prototype of a rocker arm forging (5); Step 4: primary laser trimming; after the primary laser trimming, gray cooling is performed, followed by sand blasting and grinding; Step 5: three-fire forging; firstly, the rocker arm forging prototype (5) and the die forging die (3) are preheated and lubricated in sequence, then the rocker arm forging prototype (5) is heated and kept warm for the third time, and then the bent blank is placed in the die forging die (3) and final forged by a press, and then cooled after forging to form a rocker arm forging (6); Step 6: secondary laser trimming, followed by ash cooling; Step 7: Annealing; Step eight: heat treatment; the heat treatment includes quenching heat treatment and tempering heat treatment.

2. The method for manufacturing a rocker arm forging according to claim 1, characterized in that: The preheating temperature of the original blank (1), the bent blank (4), and the rocker arm forging prototype (5) is 100°C to 150°C, and the preheating time is 1.8h to 2.2h; the preheating temperature of the bending die (2) and the die forging die (3) is 150°C to 300°C, and the preheating time is 6h to 8h.

3. The method for manufacturing a rocker arm forging according to claim 1, characterized in that: During the first heating and heat preservation, the second heating and heat preservation, and the third heating and heat preservation, the furnace temperature is first increased to 1085° C. to 1115° C. and then heat preservation is performed, and the heat preservation time is: 25 min to 60 min.

4. The method for manufacturing a rocker arm forging according to claim 1, characterized in that: In the step 2, the bending angle is 73° to 77°.

5. The method for manufacturing a rocker arm forging according to claim 1, characterized in that: The bending die (2) in step 2 comprises an upper bending die (2-1) and a lower bending die (2-2); the upper portion of the lower bending die (2-2) is provided with an arc-shaped groove (2-21), and the lower portion of the upper bending die (2-1) is provided with an arc-shaped protrusion (2-11); the arc-shaped groove (2-21) and the arc-shaped protrusion (2-11) cooperate with each other; the upper bending die (2-1) is connected to an upper die seat of a press, and the lower bending die (2-2) is connected to a lower die seat of the press; the original blank (1) is pressed downward by the press to form an arc that is consistent with the arc-shaped groove (2-21) and the arc-shaped protrusion (2-11).

6. The method for manufacturing a rocker arm forging according to claim 5, characterized in that: The upper surface of the arc-shaped groove (2-21) is provided with a first arc-shaped fixing groove (2-23), and the lower surface of the arc-shaped protrusion (2-11) is provided with a second arc-shaped fixing groove (2-24); The upper surface of the lower bending die (2-2) is provided with a third arc-shaped fixing groove (2-25), the third arc-shaped fixing groove (2-25) is located on both sides of the first arc-shaped fixing groove (2-23), and the third arc-shaped fixing groove (2-25) is connected to the first arc-shaped fixing groove (2-23).

7. The method for manufacturing a rocker arm forging according to claim 1, characterized in that: The die forging die (3) is divided into an upper die (3-1) and a lower die (3-2); after the upper die (3-1) and the lower die (3-2) are closed, a die cavity of a rocker arm forging (6) is formed inside.

8. The method for manufacturing a rocker arm forging according to claim 1, characterized in that: During the bending process in step 2, an underpressure of 3 mm to 5 mm needs to be reserved; during the pre-forging process in step 3, an underpressure of 1 mm to 2 mm needs to be reserved.

9. The method for manufacturing a rocker arm forging according to claim 1, characterized in that: The heating temperature of the annealing in the step six is ​​680° C. to 700° C., and the holding time of the annealing is 5.8 h to 6.2 h.

10. The method for manufacturing a rocker arm forging according to claim 1, characterized in that: The quenching heat treatment in step eight is to heat the rocker arm forging (6) to a temperature of 1040° C. to 1060° C. and then keep it warm for 0.45 h to 0.55 h; the tempering heat treatment is to heat the rocker arm forging (6) to a temperature of 645° C. to 655° C. and then keep it warm for 0.9 h to 1.1 h.

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