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CN-121988714-A - Process for producing drawing die by using U-shaped steel bar as internal chill

CN121988714ACN 121988714 ACN121988714 ACN 121988714ACN-121988714-A

Abstract

The invention relates to the technical field of full mold casting, and provides a process for producing a drawing die by using U-shaped steel bars as inner chill, wherein the solidification speed of a hot joint area is precisely controlled by the inner chill of the U-shaped steel bars, so that casting defects such as shrinkage cavity, shrinkage porosity and the like are effectively avoided; the size matching of the channel and the chill ensures the tight combination of the chill and the casting, enhances the feeding effect, adopts standardized U-shaped deformed steel to replace the custom-made conformal chill, omits the procedures of manufacturing and matching the chill foam model, greatly reduces the material and labor cost, does not need to manufacture the chill model alone, avoids the rework delay caused by the chill problem, accurate installation and paint protection of the chill, reduces the defect rate of the casting, avoids the rib plate structure by drilling, avoids the waste caused by destroying the strength of the model, completely embeds the chill into the model, does not directly contact with the molded surface, avoids the 'fleshing' defect caused by the infiltration of molten metal into the gap, obviously reduces the risk of machining the striker, and keeps the integrity of the molded surface.

Inventors

  • YU LEI
  • XU DAYI
  • FENG DASHUN
  • BAI MINGXUE
  • WANG ZONGHU
  • HU SIYANG
  • WANG WAN
  • CHEN KE

Assignees

  • 芜湖泓鹄材料技术有限公司

Dates

Publication Date
20260508
Application Date
20260113

Claims (9)

  1. 1. A process for producing a drawing die by using U-shaped steel bars as internal cooling irons is characterized by comprising the following steps of: Step one, model pretreatment, namely opening a channel in a hot joint area of an inner chiller to be arranged in the model, independently processing and forming the channel part, and drilling a through hole in the channel at intervals of 200 mm; Preparing an inner chiller, namely adopting standard U-shaped deformed steel bars as the inner chiller, and performing shot blasting rust removal on the inner chiller; Determining the specification and the number of the required internal chill according to the number and the positions of the openings in the groove, clearly marking on a model and a process box arrangement diagram, then completely blocking the notch on the surface of the model and the through holes in the lightening holes on the bottom surface of the die by using a cloth-based adhesive tape to prevent the paint from penetrating in the subsequent curtain coating, and adhering the box arrangement and the internal gate gasket after the blocking is finished; Coating and drying, namely coating the model integrally with water-based coating for two times, and drying; Step five, mounting the modeling and chill, namely placing the dried model on a modeling platform, removing a notch and a cloth-based adhesive tape at a lightening hole, inserting an inner chill into a corresponding through hole in a groove from the lightening hole at the bottom of the model, then trimming the foam thickness of the notch area, repairing the foam thickness back to the original designed profile contour, ensuring smooth transition with the peripheral profile; Smelting and pouring, namely smelting and spheroidizing molten iron, and then pouring and forming; Step seven, cooling and post-treatment, namely opening the box after the casting is insulated and cooled in the sand box, hanging the casting out, performing shot blasting to remove a pouring system, and then performing stress relief annealing; And step eight, cleaning and checking, namely comprehensively cleaning and polishing the castings to cut off the U-shaped steel bars exposed in the lightening holes along the roots, polishing and smoothening the steel bars, ensuring that the surfaces are smooth and have no residues, and checking and warehousing after cleaning.
  2. 2. The process for producing a drawing die by using a U-shaped steel bar as an internal chill according to claim 1, wherein the depth of the channel in the step one is the machining allowance of the molded surface +10mm+the diameter of the internal chill.
  3. 3. The process for producing a drawing die using a U-shaped steel bar as an internal chill according to claim 2, wherein in the step one, the channel width is 40 mm, the depth is 40 mm, and the diameter of the through hole is 20 mm.
  4. 4. A process for producing a drawing die using a U-bar as an internal chill according to claim 3, wherein the diameter of the internal chill in the second step is 20 mm.
  5. 5. The process for producing a drawing die by using a U-shaped steel bar as an internal chill according to claim 2, wherein the step one is to avoid the bottom rib plate structure during drilling.
  6. 6. The process for producing a drawing die by using a U-shaped steel bar as an internal chill according to claim 1, wherein the Baume of the paint in the fourth step is 55-60, the paint is coated and dried for the first time, then the paint is coated for the second time, the temperature of a drying room is set at 55-60 ℃, the drying time of the two times is not less than 12 hours, and the thickness of the coating after the coating is dried completely is not less than 1.5 mm.
  7. 7. The process for producing the drawing die by using the U-shaped steel bar as the internal chill according to claim 6, wherein the fourth step is to reinforce the die after the die is dried, and a foam plate with the thickness of about 40mm is used for reinforcing and supporting the bottom surface of the die to lighten the hole, so that the die is prevented from being deformed by pressing when sand is buried.
  8. 8. A process for producing a drawing die using a U-bar as an internal chill as set forth in claim 1, wherein said step six casting temperature is 1360±10 ℃.
  9. 9. The process for producing the drawing die by using the U-shaped steel bar as the internal chill, which is disclosed in claim 1, is characterized in that the seventh casting is opened after being cooled to 300 ℃ in a sand box, is heated to 540-560 ℃ at 60 ℃ per hour for stress relief annealing, is kept for 4 hours, and is discharged after being cooled to 260 ℃ along with a furnace.

Description

Process for producing drawing die by using U-shaped steel bar as internal chill Technical Field The invention relates to the technical field of full mold casting, in particular to a process for producing a drawing die by using U-shaped steel bars as internal chill. Background When a full mold casting process is adopted to produce a large-sized and high-precision drawing mold for the automobile panel, in order to prevent casting defects such as shrinkage porosity, shrinkage cavity and the like generated by concentrated heat sections of a working molded surface in the solidification process, a direct conformal chill is usually arranged in a heat section area in the prior art. The chiller is arranged closely to the profile of the foam pattern and uses its high thermal conductivity to accelerate local cooling, thereby optimizing the solidification sequence. However, this method has the following significant drawbacks: 1. The cost is high, the period is long, the direct conformal chill is required to be designed independently according to a mould drawing, and a corresponding foam chill model is manufactured by a model manufacturer. The process comprises multiple working procedures of grinding and matching, marking and positioning, numbering, curtain coating, drying and the like, wherein the cost of a chill model and pouring of a single ton of products is not lower than 4000 yuan. At the same time, the whole process prolongs the production period by at least 1 day, and if the chiller is lost or formed poorly, the compensation will cause further delay. 2. The labor intensity is high, the efficiency is low, the weight of a single chill is about 15 kg after casting, adhesive tapes are manually torn off block by block during molding, the mold is carried and accurately placed in a corresponding area of the mold, the operation is complex, the physical consumption is high, and the operation efficiency is seriously affected. 3. And the poor fitting causes the machine addition risk that complete fitting is difficult to realize between the chill and the foam pattern, and high-temperature molten metal is easy to infiltrate into gaps during pouring, so that partial 'fleshing' (i.e. non-design thickening) of the casting is caused. The defect is extremely easy to cause tool collision in the subsequent machining process, so that not only is an expensive tool damaged, but also the whole casting can be scrapped. Therefore, a novel chiller application process capable of effectively controlling shrinkage porosity of hot spots and avoiding the problems is needed. Disclosure of Invention In view of the above, the invention aims to provide a process for producing a drawing die by using U-shaped steel bars as internal cooling irons, which solves the problems in the background technology. Based on the above purpose, the invention provides a process for producing a drawing die by using U-shaped steel bars as internal chill, which comprises the following steps: Step one, model pretreatment, namely opening a channel in a hot joint area of an inner chiller to be arranged in the model, independently processing and forming the channel part, and drilling a through hole in the channel at intervals of 200 mm; Preparing an inner chiller, namely adopting standard U-shaped deformed steel bars as the inner chiller, and performing shot blasting rust removal on the inner chiller; Determining the specification and the number of the required internal chill according to the number and the positions of the openings in the groove, clearly marking on a model and a process box arrangement diagram, then completely blocking the notch on the surface of the model and the through holes in the lightening holes on the bottom surface of the die by using a cloth-based adhesive tape to prevent the paint from penetrating in the subsequent curtain coating, and adhering the box arrangement and the internal gate gasket after the blocking is finished; Coating and drying, namely coating the model integrally with water-based coating for two times, and drying; Step five, mounting the modeling and chill, namely placing the dried model on a modeling platform, removing a notch and a cloth-based adhesive tape at a lightening hole, inserting an inner chill into a corresponding through hole in a groove from the lightening hole at the bottom of the model, then trimming the foam thickness of the notch area, repairing the foam thickness back to the original designed profile contour, ensuring smooth transition with the peripheral profile; Smelting and pouring, namely smelting and spheroidizing molten iron, and then pouring and forming; Step seven, cooling and post-treatment, namely opening the box after the casting is insulated and cooled in the sand box, hanging the casting out, performing shot blasting to remove a pouring system, and then performing stress relief annealing; And step eight, cleaning and checking, namely comprehensively cleaning and polishing the castings to cut off th