Manufacturing Method of High-Pressure Pump Eccentric Wheel

Abstract

A manufacturing method for a high-pressure pump eccentric wheel. The blank is obtained by sawing the stock. After annealing and softening the blank, shot blasting to remove the oxide skin, and phosphating-saponifying treatment, a die set and a die are set on a crank-type cold forging press and corresponding working steps are carried out to prepare a high-pressure pump eccentric wheel comprising a hollow circular cylinder and a flange offset from the center of the hollow cylinder. The present invention adopts the advanced near-net-shape cold extrusion technology. Only four working steps are required to complete the manufacturing of the eccentric wheel with a single feeding. The material utilization rate is as high as over 95%. The product precision is IT8-11, the surface roughness Ra > 10μm, and the mechanical properties are excellent.

Description

Technical Field

[0001] The present invention relates to a technology in the field of cold forging, specifically a cold forging manufacturing method for the eccentric wheel of a high-pressure pump for a diesel engine. Background Art

[0002] Currently, the manufacturing methods for eccentric wheels all adopt machining of metal using special machine tools, which not only cuts off the metal streamline of the parts, deteriorates the mechanical properties of the materials, but also wastes a lot of materials. The prior art such as the precise forming method for an eccentric water-drop-shaped end cover forging recorded in the application number 202211176289.3. For the water-drop-shaped forging, the eccentric material is very little, the material distribution and flow are easy, and a hot forging process that is not environmentally friendly and is convenient for forming is adopted. The resulting forgings are large-headed and large-eared, and the amount of machining is very large. It is not comparable to the accuracy and quality of cold-forged products. Summary of the Invention

[0003] Aiming at the problem that the existing forging technology is only applicable to the forming of conventional products and cannot be applied to the manufacturing of eccentric wheels on high-pressure pumps, the present invention proposes a manufacturing method for the eccentric wheels of high-pressure pumps. By adopting the advanced cold forging technology with little or no cutting, the manufacturing of the eccentric wheel can be completed with only four working steps with one feeding of materials. The material utilization rate is over 95%, the product accuracy is IT8 - 11, the surface roughness is Ra0.2 - 1.6, and the mechanical properties are excellent.

[0004] The present invention is realized through the following technical solutions:

[0005] The present invention relates to a manufacturing method for the eccentric wheels of high-pressure pumps, including:

[0006] Step 1) Blanking and pre-treatment: Blanking with a sawing machine to obtain a blank, and the blank is annealed and softened, shot blasted to remove the oxide scale, and subjected to phosphating-saponifying lubrication treatment;

[0007] Step 2) Set up a die set and a die on a crank-type cold forging press and perform corresponding working steps, specifically including:

[0008] 2.1) Forward extrusion, specifically: The degree of deformation is 37% - 40%.

[0009] 2.2) Cold forging and pre-upsetting the flange, set the inclination angle of the lower plane of the preformed eccentric flange of the female die with respect to the horizontal plane to 0°, and set the inclination angle β of the end of the male die with respect to the horizontal plane in the range of 9° - 12°.

[0010] 2.3) Compound cold extrusion and finish forging the flange, specifically: Reverse extrude the inner hole of the upper cylinder corresponding to the first working step, leaving a web with a thickness of 3 - 5 mm in the middle, and the reverse extrusion deformation degree is 37% - 40% and shape the eccentric flange.

[0011] 2.4) Punching, specifically: punching off the web generated by compound cold extrusion to prepare a cold forging of a high-pressure pump eccentric wheel that includes a hollow cylinder and a flange offset from the center of the hollow cylinder.

[0012] Technical effects

[0013] The present invention can produce an eccentric wheel with a complete and smooth metal streamline and excellent performance through four working steps on a single press by cold forging method. At the same time, more than 50% of the material is saved, with 78.8 g of material saved per piece. Calculated based on an annual production of 2 million automobiles, 158 tons of steel can be saved annually. Description of the drawings

[0014] Figure 1 Schematic diagram of the high-pressure pump eccentric wheel part prepared by the present invention;

[0015] Figure 2 Schematic diagram of the cold die forging process of the eccentric wheel part;

[0016] In the figure: a is the blank, b, c, and d are the semi-finished parts obtained after three working steps in sequence, and e is the cold forging;

[0017] Figure 3 Schematic diagram of the mold assembly of the four working steps of the present invention;

[0018] In the figure: a) the first working step, b) the second working step, c) the third working step, d) the fourth working step;

[0019] Figure 4 and Figure 5 is Figure 3 Partial enlarged schematic diagram;

[0020] In the figure: 101-104 are the punches used in the four working steps, 201-203 are the lower ejector rods used in the first to third working steps, 304 is the punching die used in the fourth working step, 301-303 are the cold forging dies for the 1st to 3rd working steps; 3-5 are the 3-layer interference sleeves, 2-layer interference sleeves, and the die in sequence; 304 is the punching die; 6, 7, and 8 are the semi-finished parts obtained after 3 working steps respectively; 9 is the cold forging after punching;

[0021] Figure 6 Schematic diagram of the folding defect formed in the compound extrusion working step;

[0022] In the figure: a) the displacement of the material from the horizontal surface of the mold, b) the annular corrugations on the blank, c) the appearance of the folding defect;

[0023] Figure 7 is Schematic diagram of the shrinkage cavity (blank with the first type of geometric dimensions) occurring when >6°;

[0024] In the figure: a) the material flow velocity vector, b) the shrinkage cavity, c) the formation of folding;

[0025] Figure 8 For the schematic diagram of folding (blank with the second type of geometric dimensions) occurring under the condition of >0°;

[0026] Figure 9 For the schematic diagram of folding occurring in compound extrusion;

[0027] In the figure: a) The start of deformation; b) Scrap on the horizontal plane of the die; c) The folding that appears;

[0028] Figure 10 For the schematic diagram of eliminating defects in compound extrusion;

[0029] In the figure: a) The start of deformation; b) The material is transferred out from the horizontal plane of the eccentric flange; c) No folding is formed.

[0030] Figure 11 For the measured process force of each working step in the embodiment;

[0031] In the figure: a), b), and c) respectively correspond to the first working step, the second working step, and the third working step in sequence. Specific implementation mode

[0032] As Figure 2 shown, this embodiment relates to a manufacturing method of a high-pressure pump eccentric wheel, including:

[0033] Step 1) Blanking and blank pre-treatment: As Figure 2 shown in a), saw the Φ24mm No. 10 cold-rolled round steel into Φ24×22.2 blanks on a sawing machine, anneal and soften the blanks, then sandblast to remove the oxide scale, and perform phosphating-saponifying lubrication treatment, and dry naturally.

[0034] Step 2) Cold die forging treatment: As Figure 2 shown in b~e and Figures 3 - 5 shown, set up a die set and dies on a 4MN crank-type cold forging press (J87-400) and perform corresponding working steps, specifically including:

[0035] 2.1) Set up a combined concave die 3, 4, 5 with three-layer interference fit, a first convex die 101, a first concave die 301, and a first lower ejector rod 201, and perform forward extrusion on the blank as Figure 2 shown in a). The first convex die 101 is used to pre-upset and flatten the end face of the blank and push the blank downward for forward extrusion. The extrusion depth satisfies that the upper plane of the first lower ejector rod 201 and the lower plane of the eccentric flange are on the same horizontal plane, and obtain the semi-finished product as Figure 2 shown in b) for the second working step to upset the flange with the undeformed material.

[0036] For the said forward extrusion, the deformation degree ε = 39.1%;

[0037] Among the combined female dies 3, 4, and 5 described above, the mating conical surfaces of each layer sleeve and the outer conical surface of the female die have a vertical inclination angle of 1°30′. The mating conical surfaces of each layer sleeve are ground on the same grinding machine, and the interference amount is 7 - 8‰ of the inner hole diameter of this layer. The pressing-in sequence of the combined female die adopts the room-temperature pressing-in method. In addition to ensuring the interference amount, it is also required that the surface finish of the mating surface is not lower than R = 0.4μm, and it is ensured that the contact area should not be less than 75% of the mating area.

[0038] In order to avoid the prestressed ring from cracking due to excessive prestress, first press the middle prestressed ring into the outer ring, and finally press the female die. The disassembly sequence is opposite, first press out the female die, and then press out the middle ring.

[0039] 2.2) Set the combined female dies 3, 4, 5 with three-layer interference fit, the second punch 102, the second female die 302, and the second lower ejector rod 202, and Figure 2 pre-forge the flange of the semi-finished part 6 shown in b to obtain the semi-finished part 7.

[0040] The material of the outer sleeve 3 in the combined female die described above is 40Cr, and it is heat-treated to 42 - 46HRC; the material of the middle sleeve 4 is spring steel 60Si2Mn, and it is heat-treated to 46 - 50HRC.

[0041] As shown in Table 1 and Table 2, they are the inclination angle values of the lower plane and the upper plane of the flange and the defects found in the die forging process in the pre-forging flange process step. Through similar analysis, satisfactory cold forgings will only appear when only the upper inclination angle changes and the lower inclination angle is equal to zero, as shown in Table 3.

[0042] Table 1 Defects Appearing in the Second Process Step When Using the Geometric Dimensions of the First-Type Blank

[0043]

[0044] Table 2 Defects Appearing in the Second Process Step When Using the Geometric Dimensions of the Second-Type Blank

[0045]

[0046] Table 3 Under the Condition of Using the Geometric Dimensions of the Blank in the Second Process Step and = 0°

[0047]

[0048] The processing results show that there are several obvious defects in the proposed die. When forging the blank with the geometric dimensions of the first type in the second process step, almost a gap is formed along the entire eccentric over-profile line as Figure 6 a, Figure 6 b shows, and shrinkage cavities appear at the end of die forging, as Figure 6As shown in c. When forming the flange, if >6°, there will be severe metal flow in the radial direction as Figure 7 shown in a, resulting in the formation of shrinkage cavities as Figure 7 shown in b, and forming folds in the third working step as Figure 7 shown in c.

[0049] For similar problems, observe the second working step of die forging according to the geometric dimensions of the second type of blank and under the condition of >0°, folds are formed as Figure 8 shown. Observe the compound extrusion of the semi-finished product shown in c2 in Figure 2 , transfer the material on the horizontal surface of the eccentric flange after the second working step to the flange forming place to extrude and fill the missing material, and further form folds as Figure 9 shown in a and Figure 9 b, as Figure 9 shown in c.

[0050] It can be concluded that the accumulation of materials for the larger flange must be achieved by increasing the inclination angle of the upper plane of the flange , and the lower plane angle should be equal to zero. Preferably, in this embodiment, the parameter α is set to 0° and the parameter β is set to 9° - 12°, so as to avoid different defects existing at other angles. As shown in Table 3 and Figure 10 , when the upper inclination angle ≥9°, almost no waste and defects are formed on the die surface material, as Figure 10 shown.

[0051] In summary, in this embodiment, the inclination angle β of the end of the second punch 102 with the horizontal plane is 9°, so as to pre-place some materials on the eccentric flange to ensure that the flange in the next working step is filled without defects.

[0052] In this embodiment, the preformed eccentric flange lower plane of the second die 302 has an inclination angle with the horizontal plane =0°.

[0053] 2.3) Set the combined dies 3, 4, 5 with three-layer interference fit, the third punch 103, the third die 303 and the third lower ejector rod 203 to perform backward extrusion of the cylindrical inner hole and shape the flange part.

[0054] The cross-sectional area of the third punch 103 is as Figure 1 shown.

[0055] For the backward extrusion mentioned above, the deformation degree ε = 39%; the flange part is shaped.

[0056] As Figure 3 , Figure 4As shown, the top of the first lower ejector rod 201 is provided with a working belt with h1 = 3 mm for direct extrusion of the inner hole. Correspondingly, the bottom of the third punch 103 is provided with a working belt of the same structure for reverse extrusion of an inner hole of the same size at the corresponding position of the semi-finished part 7. The diameter of the working belt is 0.2 mm larger than the rod body connected thereto, that is, Z = 0.1 mm, so as to reduce the friction force of metal flow. The end plane of the punch and the working belt are transitioned with a small arc and should be carefully polished.

[0057] 2.4) Set two layers of combined matrix dies 3, 10, the fourth punch 104 and the fourth matrix die 304 to Figure 2 perform punching on the semi-finished part drawing (9) shown in d, punch off the web formed by compound extrusion, and obtain the cold forging finished product as Figure 1 .

[0058] Since the punching force in this working step is small, only two layers of combined matrix dies are required.

[0059] The materials of the combined matrix dies are all cold die steel Cr12MoV, the hot forging deformation reaches a forging ratio of 5, and the heat treatment hardness is 58 - 62 HRC.

[0060] The fourth punch 104 is of a cylindrical integral structure and is suitable for cold punching of smaller forgings. This kind of punch is convenient to fasten and is directly fastened to the punch holder through a nut. The positioning is accurate and the punching precision is high.

[0061] The fourth matrix die 304 adopts a circular punching matrix die structure, and the clearance δ between the punch and the matrix die is 0.15 - 0.2 mm. This punching matrix die generally only plays a supporting role, and the die rib plays a positioning role. The die cavity is designed according to the Figure 1 forged part shown. For the convenience of taking and placing the forged part, a clearance Δ is left between the cold forging and the punching matrix die, and its value is Δ = e / 2 + (0.3 - 0.5) mm, where e is the positive tolerance of the forged part at this place.

[0062] Through specific actual experiments, from the perspective of the influence of the inclination angle changing from 9° to 12° on the die forging force and the characteristics of material flow, the proposed process can be completed on a 4 MN cold forging press, as Figure 11 shown, which is the force diagram of the die forging process. The metal streamline of the prepared eccentric wheel extruded part is complete and smooth, and the performance is excellent. In addition to the significant improvement of the mechanical properties of the parts, more than 50% of the metal is saved for each part. Each part saves 78.8 g of materials. Calculated based on an annual output of 2 million vehicles, the annual savings of steel is 158 tons.

[0063] The above specific implementation can be locally adjusted in different ways by those skilled in the art without departing from the principles and purposes of the present invention. The protection scope of the present invention is subject to the claims and is not limited by the above specific implementation, and all implementation solutions within its scope are subject to the constraints of the present invention.

Claims

1. A manufacturing method of a high-pressure pump eccentric wheel, characterized in that, Including: Step 1) Blanking and pre-treatment; Step 2) Set up a die set and a die on a crank type cold forging press and perform corresponding process steps, specifically including: 2.1) Forward extrusion, specifically: Set up a combined die with three layers of interference fit, a first punch, a first die, and a first lower ejector rod. The inner hole is forward extruded through the working belt provided at the top of the first lower ejector rod. Among them: The first punch is used to pre-upset and flatten the end face of the blank and push the blank downward for forward extrusion. The extrusion depth satisfies that the upper plane of the first lower ejector rod and the lower plane of the eccentric flange are on the same horizontal plane to obtain a semi-finished product; For the said forward extrusion, the deformation degree is 37%-40%; 2.2) Cold forging, pre-upsetting the flange, specifically: Set up a combined die with three layers of interference fit, a second punch, a second die, and a second lower ejector rod to pre-upset the flange of the semi-finished part to obtain a semi-finished part; The lower plane of the preformed eccentric flange in the second die has a horizontal inclination angle of 0°; The inclination angle β of the end of the second punch with the horizontal plane ranges from 9° to 12°; 2.3) Compound cold extrusion final forging of the flange, specifically: Set up a combined die with three layers of interference fit, a third punch, a third die, and a third lower ejector rod to reverse extrude the inner hole of the upper cylinder corresponding to the first process step, leaving a web with a thickness of 3-5 mm in the middle. The reverse extrusion deformation degree is 37%-40% and the eccentric flange is shaped; 2.4) Punching, specifically: Set up a two-layer combined die, a fourth punch, and a fourth die to punch off the web generated by compound cold extrusion to prepare a cold forging of a high-pressure pump eccentric wheel including a hollow cylinder and a flange offset from the center of the hollow cylinder.

2. The manufacturing method of the high-pressure pump eccentric wheel according to claim 1, characterized in that, The said Step 1 is specifically: Saw the Φ24mm No. 10 cold-rolled round steel into Φ24×22.2 blanks on a sawing machine. After annealing and softening the blank, sandblast to remove the oxide scale, and perform phosphating-saponifying lubrication treatment and natural drying.

3. The manufacturing method of the high-pressure pump eccentric wheel according to claim 1, characterized in that, In the combined die described in Step 2.1), the mating conical surface of each layer sleeve and the outer conical surface of the die have a vertical inclination angle of 1°30′. The mating conical surfaces of each layer sleeve are ground on the same grinding machine, and the interference amount is 7-8‰ of the inner hole diameter of this layer; For the pressing-in order of the combined die, the room temperature pressing-in method is adopted. In order to avoid cracking the prestress ring due to excessive prestress, first press the middle prestress ring into the outer ring, and finally press the die into it.

4. The manufacturing method of the high-pressure pump eccentric wheel according to claim 1, characterized in that, The inclination angle β of the end of the second punch with the horizontal plane is β = 9°; 5. The manufacturing method of the high-pressure pump eccentric wheel according to claim 1, characterized in that, The fourth punch is of a cylindrical integral structure, suitable for cold punching of smaller forgings; The fourth die adopts a circular punching die structure; 6. The manufacturing method of the high-pressure pump eccentric wheel according to claim 5, characterized in that The gap δ between the fourth punch and the fourth die is δ = 0.15-0.2 mm; 7. The manufacturing method of the high-pressure pump eccentric wheel according to claim 6, characterized in that A gap Δ is left between the cold forging and the fourth die, and its value is Δ = e / 2+(0.3-0.5) mm, where e is the positive tolerance of the forging at this place.

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