Forging forming die and forming method of eccentric crank part

Abstract

The present application relates to the field of plastic processing, and discloses a forging forming die and method for eccentric crank parts of operating mechanism. The qualified forgings meeting the processing requirements are obtained by adopting conventional free forging hammer and die forging hammer and through reasonable design of blanking die film and circular insert final forging die. The blanking die film is composed of a male die, a female die, a cushion block and a cylindrical pin. The working surface of the male die is designed with a slope of 3-7 degrees to force the metal to flow to one side and avoid longitudinal burrs between the male die and the female die, thus meeting the requirements of die forging forming. The metal flow lines are along the longitudinal axis of the crank parts, the longitudinal mechanical properties are good, the production efficiency and quality stability are improved, and the raw material consumption is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of forging forming technology in the field of plastic processing, and particularly relates to a forging forming die and forming method for an eccentric crank part. BACKGROUND

[0002] The crank part is widely used in the operating mechanism in the mechanical industry and is composed of a shaft rod part, an irregular flange part and a boss part. The linear reciprocating motion of the flange part is converted into the rotating motion of the shaft rod part, and the force received by the local part is converted into the torque of the shaft rod part to drive the connecting piece to move. The working condition of the part under stress is complex. If the crank part for the operating mechanism fails, it will lead to disastrous consequences. Therefore, the quality stability and reliability of the crank part are required to be high. Generally, the forging blank is milled and turned into a crank part. Zang Dechang et al. (CN 102989956 A) disclosed a forming method for eccentric crank forgings. The heated bar stock is modified to be a cuboid forging, and the long tail handle cylinder is put into the mold after being pulled out. Although the material utilization rate is improved compared with the hexahedral forging containing the outer contour of the crank part, the material consumption is still large. Moreover, the blank making is difficult, the production efficiency is low, and the quality stability is limited. The crank part has a certain structural similarity with the steering knuckle part in the automobile industry. Zhang Yunjun et al. (Research and application of small flash precision forging technology for automobile steering knuckle. Forging Technology, 2018, 43(8): 1-7.) reported a new scheme of semi-closed small flash preforming and semi-closed small flash final forming. The material utilization rate of the new scheme is 88%. However, the material of the steering knuckle forging is 42CrMo steel, which has small deformation resistance at high temperature and is easy to fill the cavity. Moreover, the bar stock is placed horizontally during preforming, and the shaft rod part is extruded during die forging, which changes the metal flow direction. Moreover, this method is generally only suitable for the forging of the rod part with a relatively thick diameter and a relatively short length.

[0003] When the eccentric crank part is formed by forging, it is necessary to ensure that the flow direction is along the longitudinal direction of the rod part to improve the quality of the forging, and to reduce the material consumption to improve the production efficiency and batch stability. SUMMARY

[0004] To solve the above problems, the application discloses a forging forming die and forming method for an eccentric crank part, which can complete the manufacture of the crank forging with the help of conventional free forging hammer and die forging hammer equipment.

[0005] The specific technical scheme is as follows:

[0006] The application discloses a forging forming die for eccentric crank parts, which is characterized by the following structure: a female die is provided, the female die is shaped like a block, a through hole is arranged in the female die, a rectangular notch is arranged at the upper end of the female die, a pad is arranged at the lower end of the female die, a waist hole is arranged on the pad, a cylindrical pin is arranged in the female die and the waist hole, a male die is arranged in the rectangular notch of the female die and is shaped according to the shape of the rectangular notch, the lower working surface of the male die is arranged as an inclined surface, the angle between the inclined surface and the horizontal line is in the range of 3-7 degrees, and the intersection between the through hole and the rectangular notch is arranged with a rounded corner.

[0007] The application discloses a final forging forming die, which is characterized by the following structure: a lower die is provided, an upper die is arranged above the lower die, a final forging forming cavity of a blank is formed at the center of the upper die and the lower die, and a collecting cavity is further arranged outside the forming cavity and is formed by the gap between the upper die and the lower die.

[0008] The application discloses a forging forming method using the forging forming die for eccentric crank parts, which is characterized by the following steps: a forging product is designed according to the requirement of die forging forming, the sum of the volume of a flange and a boss of the crank is calculated, the diameter and height of a blank rod are designed, the outer contour of the blank is designed as a semicircle on one side and a rectangle on the other side, the diameter of the blank rod is taken as the diameter of a blanking section, the length of the blanking section is calculated according to the principle that the total volume of the forging is equal to the volume of the blanking, the blanking section is placed in a blanking die to forge the blank, the blank is cleaned and heated, and then is placed in a final forging forming die to perform die forging, the blank is trimmed and cleaned after the die forging, and finally the forging product is obtained.

[0009] The ratio of the length of the free upsetting part to the diameter of the blank during the blanking die forging is ensured to be less than 2.5-3.0, so that the blanking die is prevented from losing stability.

[0010] The parting surface of the blank is arranged at the center of the axial dimension of the flange.

[0011] Further, the application further discloses a method for placing a blanking section in a blanking die to forge a blank: first, the blanking section is placed in a female die, the bottom end of the blanking section contacts a pad, a male die is arranged at the top end of the blanking section, the male die is hammered, the hammering is stopped when the upper end of the male die is 15-20 mm away from the upper end of the female die, the female die is reversed, the pad is arranged at the upper end, and the blanking section is separated from the blanking die by hammering the pad.

[0012] The present application has the advantages that the present application provides a forging forming die and forming method of eccentric crank parts, which is used for manufacturing eccentric crank forgings, and compared with free forging manufacturing hexahedral containing body forgings or die forging forming eccentric crank, the production efficiency is improved, the quality consistency is good, the randomness of manual operation is reduced, the material consumption required for forming is reduced, only conventional free forging hammer and die forging hammer are required for forming, a circular insert die is used for die forging, the die cost is much lower than that of a whole die, and the designed blank making die structure is simple, the working surface of the male die is designed with a 3°-7° slope, which avoids generating longitudinal burrs between the male die and the female die, saves the polishing process, and ensures the final forging quality. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 Process route map for the forging forming method of crank parts;

[0014] Figure 2 Die forging drawing of eccentric crank forgings;

[0015] Figure 3 Rough blank drawing required for die forging forming;

[0016] Figure 4 A view of Figure 3 ;

[0017] Figure 5 Die forging final forming die drawing;

[0018] Figure 6 A view of Figure 5 ;

[0019] Figure 7 Blank die drawing used for blank forging;

[0020] Figure 8 A view of Figure 7 . DETAILED DESCRIPTION

[0021] 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, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application. EMBODIMENT

[0022] The eccentric crank part forging forming die sets a female die 2, the female die 2 is in the shape of a block, a round through hole 16 is arranged in the female die 2, a rectangular notch 17 is arranged at the upper end of the female die 2, a pad 4 is arranged at the lower end of the female die 2, a waist hole 6 is arranged on the pad 4, a cylindrical pin 3 is arranged in the female die 2 and the waist hole 6, a male die 1 is arranged in the rectangular notch 17 of the female die 2 and is conformally arranged with the shape of the rectangular notch 17, the lower working surface 8 of the male die 1 is arranged in the shape of an inclined surface, and the angle α between the lower working surface 8 and the horizontal line ranges from 3° to 7°; and the junction between the round through hole 16 and the rectangular notch 17 is arranged in the shape of a rounded corner.

[0023] The final forging forming die sets a lower die 10, an upper die 9 is correspondingly arranged above the lower die 10, the upper die 9 and the lower die 10 are combined at the center to form a blank final forging forming cavity 11, and a collecting cavity 12 is further arranged outside the forming cavity 11 and is formed by the gap between the upper die 9 and the lower die 10.

[0024] A forging forming method using the above-mentioned eccentric crank part forging forming die, the forging drawing of a certain crank part is designed, the material used is 17-4PH stainless steel, the shape is as shown in the figure, Figure 2 the diameter of the shaft rod part 13 is , the length of the shaft rod part 13 is , the thickness of the flange plate part 14 is , the horizontal projection distance from the shaft center is , the maximum width is 60.81mm, the diameter of the boss part 15 is , and the total height is , the blank is designed in the shape of a semicircle on one side and a rectangle on the other side, and the specific forging forming method of the embodiment is as follows:

[0025] 1) Cutting: cutting is performed by sawing, according to the diameter of the forging rod, the volume of the forging (including the burr), whether the free upsetting part of the blank is unstable is checked, the diameter of the material section is determined to be Φ42±0.3mm, the length is 178±0.5mm, the flat end face is rounded with a radius of R5.

[0026] 2) Heating: resistance furnace heating, heating temperature 1100℃~1130℃, warm charging, holding time 20min~65min.

[0027] 3) Die forging: die forging is performed by a 1-ton free forging hammer, the size of the die is designed as follows: the height of the male die 1 is 70mm, the width is 44.4mm, the slope α of the lower working surface is 5°; the total height of the female die 2 is 225mm, the cavity depth is 125mm, the cavity width is 45mm; and the height of the pad is 40mm.

[0028] Firstly, the female die 2 is placed on the lower anvil of the forging hammer, then the blank 5 is put into the female die 2, the bottom end of the blank 5 contacts the pad 4, the male die 1 is placed on the top end of the blank 5, the upper anvil of the forging hammer continuously strikes the male die 1, the male die 1 continuously moves downwards, when the upper end of the male die 1 is 15mm-20mm away from the upper end of the female die, the hammering is stopped, the rough blank is made, the rough blank includes a head 18 and a rod 19, when the rough blank is forged by the die, the metal flows into the α-side cavity formed by the lower working surface 8 of the male die, on the one hand, it is beneficial to force the metal of the blank 5 to flow to one side eccentrically, on the other hand, the deformed metal generates a reaction force on the male die 1, the horizontal component of the reaction force guides the movement of the male die 1, reduces the gap size between the male die 1 and the female die 2, and reduces or even eliminates the longitudinal burr when the rough blank is made.

[0029] The female die 2 is turned upside down, the pad 4 is at the upper end, a certain force is applied to the pad 4 by the upper anvil of the forging hammer, the male die 1 and the forged piece are ejected. The cylindrical pin 3 passes through the through hole of the pad 4 and is fixed in the female die 2, the pad 4 will not slide out of the cavity, the female die 2 is turned upside down again, the pad 4 is returned to the original position, and is ready to prepare the second rough blank.

[0030] 4) Cleaning: polish the sharp edge and surface defects of the rough blank, all pits, cracks, folds and sheet oxides should be removed, and the polished part should be smooth. Sandblasting is used to clean the surface oxide.

[0031] 5) Heating: resistance furnace heating, heating temperature 1100℃-1130℃, warm loading furnace, holding time 25min-90min.

[0032] 6) Die forging: using 2-ton die forging hammer equipment for die forging, baking iron or heater preheats the mold to 200℃-300℃, high-pressure spray gun sprays water-based graphite to lubricate the mold cavity of the upper die 9 and the lower die 10 of the final forging forming mold, clamps the rough blank and puts the rod part into the lower die 10, ensures that the horizontal projection of the rough blank falls completely into the cavity, the upper die 9 moves downward, the first hammer light strikes (strike energy 2%-5%), the second hammer heavy strikes (strike energy 50%-70%), the forged piece is taken out, the high-pressure spray gun sprays water-based graphite to cool and lubricate the cavity of the upper die 9 and the lower die 10, the forged piece is put back, the third hammer and the fourth hammer heavy strikes (strike energy 50%-70%), when the burr bridge thickness is 2mm-3mm, the die forging process is completed.

[0033] 7) Edge cutting: immediately after forging, edge cutting is performed on the 2500KN punch equipment, ensuring that the temperature is not lower than 950℃, allowing the heating temperature for return to the furnace (1000±10)℃, holding for 5min-15min.

[0034] 8) Cleaning: polish and remove burrs and surface defects, all pits, cracks, folds and sheet oxides should be removed. The polished part should be smooth, and the processing surface should be left with not less than one-third of the nominal machining allowance, sandblasting is used to clean the surface oxide.

[0035] 9) Inspection: Check the thickness of the flange and the overall height of the crank using a vernier caliper. If qualified, transfer to the warehouse.

[0036] Example Two:

[0037] A forging drawing is designed for a crank part, the material used is TC4 titanium alloy, the shape is as shown in Figure 2 the diameter of the shaft of the forging is , the length of the shaft 13 is , the thickness of the flange 14 is , the horizontal projection distance from the shaft center is , the maximum width is 60.81mm, the diameter of the boss 15 is , and the total height is . The specific forging forming process of this embodiment is as follows:

[0038] 1) Cutting: Cutting by sawing, according to the diameter of the shaft of the forging, the volume of the forging (including burr), check whether the free upsetting part of the blank is unstable. Determine the diameter of the material section Φ42±0.3mm, the length 178±0.5mm, the flat end face and the round corner R5.

[0039] 2) Heating: Heating in a resistance furnace, heating temperature 930℃~960℃, loading into the furnace, holding time 45min~85min.

[0040] 3) Die forging: Die forging blank by 1 ton free forging hammer, the designed die size: male die 1 height 70mm, width 44.4mm, the lower end working surface slope α is 3°; female die 2 total height 225mm, cavity depth 125mm, cavity width 45mm; pad height 40mm.

[0041] First, place the female die 2 on the lower anvil of the forging hammer, then put the material section 5 into the female die 2, the bottom end of the material section 5 contacts the pad 4, and the male die 1 is placed on the top end of the material section 5. The upper anvil of the forging hammer continuously hammers the male die 1, and the male die 1 continuously moves downward, and stops hammering when the upper end of the male die 1 is 15mm~20mm away from the upper end of the female die.

[0042] Turn over the female die 2, with the pad 4 at the upper end, apply a certain force to the pad 4 through the upper anvil of the forging hammer to eject the male die 1 and the forging, the cylindrical pin 3 is fixed in the female die 2 through the through hole of the pad 4, and the pad 4 will not slide out of the cavity. Turn over the female die 2 again, and the pad 4 returns to its original position, ready to prepare the second blank.

[0043] 4) Cleaning: Grind the sharp edges and surface defects of the blank, such as pits, cracks, folds, and sheet oxide skin, etc. should be completely removed, and the polished part should be smooth and connected, and the surface oxide skin should be cleaned by sandblasting.

[0044] 5) Heating: resistance furnace heating, heating temperature 930-960℃, to warm furnace, holding time 45-85min.

[0045] 6) Die forging: using 2 tons die forging hammer equipment for die forging final forming, baking iron or heater preheating mold 200-300℃, high pressure spray gun spraying water-based graphite lubricating upper die 9 and lower die 10 die cavity. Clamping blank put the rod into the lower die 10, the blank gathering part is offset from the axis of the crank flange cavity, ensuring that the horizontal projection of the blank falls completely into the cavity. The upper die 9 moves downward, the first hammer light blow (blow energy 2-5%), the second hammer heavy blow (blow energy 50-70%), take out the forging, high pressure spray gun spraying water-based graphite cooling and lubricating the cavity of upper die 9 and lower die 10, put back the forging, third hammer and fourth hammer heavy blow (blow energy 50-70%), when the burr bridge thickness is 2-3mm, the die forging process is completed.

[0046] 7) Edge cutting: immediately after forging on 2500KN punch equipment for edge cutting, ensuring that the temperature is not lower than 800℃, allowing the heating temperature of return to furnace (900±10)℃, holding time 5-15min.

[0047] 8) Cleaning: polishing to remove burrs and surface defects, pits, cracks, folds, sheet oxide skin and so on should be completely removed, polishing place smooth transition, ensuring that the processing surface leaves not less than one-third of the nominal processing allowance, sandblasting to clean the surface oxide skin.

[0048] 9) Inspection: using vernier caliper to check the thickness of the flange and the overall height of the crank, after passing the inspection, it is put into the warehouse.

Claims

1. A forging forming method of a forging forming die using an eccentric crank member, characterized by: The device comprises a female die, the female die is shaped like a block, a round through hole is arranged in the female die, a rectangular notch is arranged at the upper end of the female die, a cushion block is arranged at the lower end of the female die, a waist hole is arranged on the cushion block, a cylindrical pin is arranged in the female die and the waist hole, a male die is arranged in the rectangular notch of the female die and is shaped according to the shape of the rectangular notch, the lower working surface of the male die is shaped like an inclined plane, and the angle between the lower working surface and the horizontal line is in the range of 3°-7°; and the intersection between the round through hole and the rectangular notch is arranged with a rounded corner; The final forging forming die is provided with a lower die, an upper die is correspondingly arranged above the lower die, the upper die and the lower die are combined at the center to form a blank final forging forming cavity, a collecting cavity is further arranged outside the forming cavity, the collecting cavity is formed by the gap between the upper die and the lower die, a forging product is designed according to the requirements of die forging forming, the sum of the volumes of a flange and a boss of a crank is calculated, the diameter and height of a blank rod are designed, the outer contour of the blank is designed as a semicircle on one side and a rectangle on the other side, the diameter of the blank rod is taken as the diameter of a blank section, the length of the blank section is calculated by the formula that the total volume of the forging is equal to the volume of the blank, the blank section is placed in a billet forming die to forge the blank, and then the blank is cleaned and heated, and finally the blank is placed in a final forging forming die to perform die forging, the blank is trimmed and cleaned after the die forging, and finally the forging product is obtained; The forging forming method of the eccentric crank part forging forming die comprises the following steps: 1) blanking: the blank is cut by sawing, the diameter and length of the blank section are determined according to the diameter of the rod of the forging and the volume of the forging, the flat end face is rounded, and the corner is rounded; 2) heating: the blank section is heated in a resistance furnace, the heating temperature is 1100-1130 DEG C, the blank section is loaded into the furnace when it is heated to the temperature, and the holding time is 20-65 min; 3) billet forging: the blank section is forged into a blank by a 1-ton free forging hammer, the female die is first placed on the lower anvil of the forging hammer, then the blank section is placed in the female die, the bottom end of the blank section contacts the cushion block, the male die is placed on the top end of the blank section, the upper anvil of the forging hammer continuously hammers the male die, the male die continuously moves downward, the hammering is stopped when the upper end of the male die is 15-20 mm away from the upper end of the female die, and finally the blank is obtained, the blank comprises a head and a rod, when the blank is forged by the billet forging, the alpha-side cavity flow of the deformed metal to the lower working surface of the male die, on the one hand, is beneficial to force the blank metal to flow to one side, and on the other hand, the horizontal component of the reaction force of the deformed metal to the male die guides the movement of the male die, reduces the gap size between the male die and the female die, and reduces the longitudinal burr when the blank is made; The female die is turned upside down, the cushion block is at the upper end, the male die and the forging are ejected by applying a certain force to the cushion block by the upper anvil of the forging hammer, the cylindrical pin passes through the through hole of the cushion block and is fixed in the female die, the cushion block cannot slide out of the cavity, the female die is turned upside down again, the cushion block is returned to the original position, and the second blank is prepared; 4) cleaning: the sharp edges and surface defects of the blank are polished, the concave pits, cracks, folds and flaky oxides are all removed, the polished part is smoothly connected, and the surface oxides are cleaned by sandblasting; 5) heating: the blank section is heated in a resistance furnace, the heating temperature is 1100-1130 DEG C, the blank section is loaded into the furnace when it is heated to the temperature, and the holding time is 25-90 min; 6) die forging: using 2 tons die forging hammer equipment for die forging forming, baking iron or heater preheating mold 200℃~300℃, high pressure spray gun spraying water-based graphite lubricating final forging forming mold cavity of upper and lower mold, clamping blank put the rod into the lower mold, ensure that the horizontal projection of the blank falls completely into the cavity, the upper mold moves downward, the first hammer light hits, the hitting energy is 2%~5%, the second hammer heavy hits, the hitting energy is 50%~70%, take out the forging, high pressure spray gun sprays water-based graphite to cool and lubricate the cavity of the upper and lower mold, put back the forging, carry out the third hammer and the fourth hammer heavy hit, the hitting energy is 50%~70%, the thickness of the burr bridge is 2mm~3mm, the die forging process is completed; 7) trimming: trimming immediately after forging on 2500KN punch equipment, ensuring that the temperature is not lower than 950℃, the allowed return to furnace heating temperature is 1000±10℃, and the holding time is 5min~15min; 8) cleaning: polishing to remove burrs and surface defects, pits, cracks, folds and sheet oxide should be completely removed, the polished part is smooth and connected, and the processing surface is left with not less than one-third of the nominal processing allowance, and the surface oxide is cleaned by sandblasting; 9) inspection: using vernier caliper to check the thickness size of flange plate and the total height size of crank, and after passing, it is transferred into warehouse.

2. The method of swage forming a swage forming die for an eccentric crank part according to claim 1, characterized by: The ratio of the length of the free upsetting part to the diameter of the blank during die forging is ensured to be not more than 2.5~3.0 to prevent instability during upsetting.

3. The method of swage forming a swage forming die for an eccentric crank part according to claim 1, characterized by: The parting surface of the blank is arranged at the center of the axial size of the flange plate.

4. The method of swage forming a swage forming die for an eccentric crank part according to claim 1, characterized by The method for placing the material segment in the blanking die to forge the blank: first, place the material segment in the female die, the bottom end of the material segment contacts the pad, the male die is placed at the top end of the material segment, and the male die is hammered, when the upper end of the male die is 15mm~20mm away from the upper end of the female die, stop hammering, reverse the female die, and place the pad at the upper end, hammer the pad to separate the material segment from the blanking die.

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