Full mold casting process for improving shrinkage porosity of groove of side wall drawing female die
By making grooves in the side fence stretching mold model and using other waist -shaped wedge to fix the cold iron, the problem of shrinkage of the groove area is solved, and the surface quality and accuracy of the casting is improved.
Patent Information
- Application Number
- CN202411610616.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-12
- Publication Date
- 2025-01-28
AI Technical Summary
In the die castings of automobile side circumference stamping molds, the thermal joints and processing allowance at the bottom of the groove lead to a high chance of shrinkage, and the prior art is difficult to effectively solve this problem.
By making grooves in the side of the sideways pull -up concave model, and pasted lumbar -shaped wedge blocks such as cold iron models, the cold iron is closely matched with the model, and the cold iron floats and the gap. Essence
Effectively avoid the shrinking defects in the groove area, improve the surface quality and accuracy of the casting, and reduce the processing costs of the mold plant and the risk of project delay.
Abstract
Description
Technical Field
[0001] The invention relates to the field of full-mold casting, and in particular to a full-mold casting process for improving the shrinkage of a side wall drawing die groove. Background Art
[0002] The side panel of a car is the most important outer contour surface of a car, and it is also the most demanding outer panel of each OEM. Therefore, each mold factory has the highest requirements for the stamping die casting of the side panel, and no shrinkage or micro-shrinkage on the surface is allowed. The concave die casting of the side panel stamping die is generally a sharp-angle groove from the A-pillar to the upper side beam. In order to ensure the force-bearing structure of the mold, the mold manufacturer generally adds support ribs at the lowest point of the groove, resulting in a heat node at the bottom of the groove, which greatly increases the probability of shrinkage in the entire groove area. The side panel drawing die adopts full-mold casting and is produced after the foam model is processed by CNC. Generally, the mold surface will leave a processing allowance of 10-12mm. The minimum size tool generally used when making the model is 10mm in diameter. When processing the A-pillar to the upper side beam area, the bottom of the groove cannot be completely processed, resulting in the processing allowance of the groove part being greater than the reserved processing amount, generally reaching 18-20mm. The increase in processing allowance further increases the probability of shrinkage cavities and shrinkage in this position of the final casting. In order to prevent shrinkage cavities and shrinkage in ductile iron castings, the mold surface is generally processed by the following method: Looseness. The general measure currently taken is to design and produce direct-formed chillers. When the chillers are matched with the model, the chiller model is generally polished to make it match the foam model without gaps. The interval between the chillers is 35-40mm. The interval between the chillers is to fill sand to fix the chillers in the molding sand. If the interval is cancelled, the chillers will float up when pouring molten iron, which is loose and causes a shortage of the mold casting surface. Because of the above-mentioned mold structure and processing allowance, shrinkage defects still occur during the processing of the A-pillar to the upper side beam area, especially at the interval between the chillers. The probability of shrinkage is greater. This area is the most important exposed surface. Once shrinkage defects occur, the mold manufacturers cannot accept overcutting and welding, and the casting will be scrapped. At the same time, the mold manufacturers will claim mold processing fees and project delay fines from the foundry, bringing huge losses to the foundry. Summary of the invention
[0003] In view of this, the purpose of the present invention is to propose a full-mold casting process for improving the shrinkage of the groove of the side wall drawing die, so as to solve the technical problem that the side wall drawing die is prone to shrinkage.
[0004] Based on the above purpose, the present invention provides a full mold casting process for improving the shrinkage of the side wall drawing die groove, comprising the following steps: Step 1: Make a model of the side wall drawing die, with a model surface margin of 12mm, and at the same time make a direct conformable chill model. The corresponding direct conformable chill model is made according to the negative surface margin of 12mm. The direct conformable chill from the A-pillar to the upper side beam area is cut into sections of 250-300mm, and no gap is left when each two sections are placed on the model. The thickness of the main part of the direct conformable chill model is not less than the wall thickness of the casting; Step 2: Matching the direct conformable chill model with the side panel drawing die model. After grinding the knife marks on the direct conformable chill model, match it with the side panel drawing die model to ensure that there is no gap at the edge. The position of the conformable chill on the model is covered with cloth-based tape, and two isosceles trapezoidal wedges are pasted on the back of each conformable chill from the A-pillar to the upper side beam area; Step 3: Use the side bottom injection system to paste the inner gate patch; Step 4: coating the side wall drawing die model and the direct conformable chill model with paint and drying them, and then shaping and casting the direct conformable chill model into direct conformable chill; Step 5: After placing the side wall drawing die model on the molding platform, tear off the cloth-based tape marking the position of the direct-formed chill on the side wall drawing die model, place the direct-formed chill with the corresponding number on the model, brush the alcohol-based paint on the junction between the direct-formed chill and the side wall drawing die model, connect the pouring system, wait for the alcohol-based paint brushed around the chill on the side wall drawing die model to dry, bury the sand, stack the sand box frame, turn the box over and continue to bury the sand until the molding is completed and transferred to the area to be poured; Step six, smelting the ductile iron material, and after smelting, pouring the side drawing die model to obtain the side drawing die casting.
[0005] Preferably, in the step of drawing the concave die on one side, a groove with a cross-section of 20*20 mm is cut at the bottom of the groove in the area from the A-pillar to the upper side beam.
[0006] Preferably, the size of the wedge block in step 2 is 40 mm for the upper base, 80 mm for the lower base, 70 mm for the height, and the distance between the two wedge blocks is 150 mm.
[0007] Preferably, the coating thickness after drying in step 4 is not less than 1.5 mm.
[0008] Preferably, in step 4, the conformable chill needs to be molded and cast into an iron chill in advance. After the chill is sanded, cooled and shot blasted, an alcohol-based coating is applied on the chill surface to ensure that the coating has a thickness of 1.5-2 mm after drying.
[0009] Preferably, in step five, after the material is transferred to the area to be poured, the iron is pressed on the upper sand box, the weight of the pressed iron is about 7 times the weight of the pouring, and it covers the entire length direction of the sand box.
[0010] Preferably, the pouring temperature in step six is 1360±10°C.
[0011] Preferably, the step 7 is also included, wherein the side wall drawing die casting is cooled and then unpacked, and then the side wall drawing die casting is shot blasted, and then the gating system is removed, and the side wall drawing die casting is polished, and finally the qualified side wall drawing die casting is inspected. The beneficial effects of the present invention are as follows: the present invention leaves no gaps between the conformable chills, and two isosceles trapezoidal wedges are pasted on the back of the conformable chill model, and the conformable chill is fixed in the molding sand by the wedges on the back, thereby preventing the conformable chill from floating and causing machining deficiencies on the casting surface, while also avoiding shrinkage between the chill gaps; when making the model, the groove positions that are difficult to machine into place are overcut to form grooves for the model deficiencies, and the grooves are covered by the conformable chill during molding, and the shape of the groove positions is formed by the covered conformable chill, thereby avoiding shrinkage at these positions due to excessive actual machining allowances. DETAILED DESCRIPTION
[0012] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments.
[0013] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.
[0014] This embodiment provides a full mold casting process for improving the shrinkage of the side wall drawing die groove, including the following steps: Step 1. Make a model of the side wall drawing die according to the drawing. The bottom of the groove in the area from the A-pillar to the upper side beam is overcut into a groove with a cross-section of 20*20mm. The model surface allowance is 12mm. At the same time, a direct conformable chill model is designed and made. The corresponding direct conformable chill model is made with a negative surface allowance of 12mm. The chill in the area from the A-pillar to the upper side beam is divided into sections of 250-300mm. There is no gap between each two sections when placed on the model. The thickness of the main part of the conformable chill is not less than the wall thickness of the casting and is not less than 60mm. When making the model, overcut downward at the groove position that is not easy to process in place to form a groove of the model shortage. The groove is covered by the conformable chill during modeling. The shape of the groove position is formed by the covered conformable chill to avoid shrinkage at this position due to large actual processing allowance.
[0015] Step 2: directly match the conformable chill model with the side panel drawing die model, grind the knife marks on the chill model and match it with the side panel model to ensure that there is no gap on the edge. The position of the conformable chill on the side panel drawing die model is covered with cloth-based tape, and two isosceles trapezoidal wedges are pasted on the back of each conformable chill from the A-pillar to the upper side beam area. The wedge size is 40mm on the upper bottom, 80mm on the lower bottom, and 70mm in height. The distance between the two wedges is 150mm, and they are arranged in the center. During molding, there is no molding sand to fix the chills, which may cause the chills to float and drift, resulting in a shortage of the casting surface. Through the two wedges on the back of the chills, the chills can be fixed in the molding sand to prevent the chills from floating and causing abnormal casting surfaces. By leaving no gaps between the conformable chills, two isosceles trapezoidal wedges are pasted on the back of the conformable chill model, and the conformable chill is fixed in the molding sand through the wedges on the back, which prevents the conformable chill from floating and causing a shortage of the casting surface, and also avoids shrinkage between the chill gaps. Step 3: Design the pouring system according to the product weight, use the side bottom pouring system, and paste the inner gate patch; Step 4: Coat the product and the chill model with coating and dry them to ensure that the coating thickness is not less than 1.5mm after drying. The direct-shaped chill model should be molded and cast into an iron chill in advance. After the chill is sanded, cooled and shot blasted, an alcohol-based coating is applied on the chill surface to ensure that the coating thickness is 1.5-2mm after drying. Step 5: After placing the side wall drawing die model on the molding platform, tear off the cloth-based tape marking the position of the conformable cold iron on the side wall drawing die model, and place the conformable cold iron of the corresponding number on the side wall drawing die model. Brush the alcohol-based paint on the junction of the cold iron and the side wall drawing die model, and connect the pouring system according to the process requirements. After the alcohol-based paint brushed on the periphery of the cold iron on the side wall drawing die model is completely dry, you can start sand burying molding, stack the sand box frame, turn the box over and continue to bury the sand until the molding is completed and transport it to the area to be poured, press the iron on the upper sand box, the weight of the iron is about 7 times the pouring weight, and it covers the entire length direction of the sand box; Step 6: Melt the ductile iron material, and then pour the side drawing die model at a pouring temperature of 1360±10°C to obtain the side drawing die casting. Step seven, unpack the side wall drawing die casting after cooling, then shot blast the side wall drawing die casting, remove the pouring system, grind the side wall drawing die casting, and finally inspect to obtain qualified side wall drawing die casting.
[0016] In this embodiment, when making the model, the groove position which is difficult to be machined into place is overcut downward, and no space is left between the conformable chills. The back of the conformable chill is made into two wedge blocks, and the conformable chill is fixed in the molding sand by the wedge blocks on the back. This can avoid shrinkage and greatly improve product quality.
[0017] It should be understood by those skilled in the art that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the present invention is limited to these examples; under the concept of the present invention, the technical features in the above embodiments or different embodiments may also be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity. Any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.
Claims
1. A full mold casting process for improving the shrinkage of the side drawing die groove, characterized in that: The following steps are included: Step 1: Make a model of the side wall drawing die, with a model surface margin of 12mm, and at the same time make a direct conformable chill model. The corresponding direct conformable chill model is made according to the negative surface margin of 12mm. The direct conformable chill from the A-pillar to the upper side beam area is cut into sections of 250-300mm, and no gap is left when each two sections are placed on the model. The thickness of the main part of the direct conformable chill model is not less than the wall thickness of the casting; Step 2: Matching the direct conformable chill model with the side panel drawing die model. After grinding the knife marks on the direct conformable chill model, match it with the side panel drawing die model to ensure that there is no gap at the edge. The position of the conformable chill on the model is covered with cloth-based tape, and two isosceles trapezoidal wedges are pasted on the back of each conformable chill from the A-pillar to the upper side beam area; Step 3: Use the side bottom injection system to paste the inner gate patch; Step 4: coating the side wall drawing die model and the direct conformable chill model with paint and drying them, and then shaping and casting the direct conformable chill model into direct conformable chill; Step 5: After placing the side wall drawing die model on the molding platform, tear off the cloth-based tape marking the position of the direct-formed chill on the side wall drawing die model, place the direct-formed chill with the corresponding number on the model, brush the alcohol-based paint on the junction between the direct-formed chill and the side wall drawing die model, connect the pouring system, wait for the alcohol-based paint brushed around the chill on the side wall drawing die model to dry, bury the sand, stack the sand box frame, turn the box over and continue to bury the sand until the molding is completed and transferred to the area to be poured; Step six, smelting the ductile iron material, and after smelting, pouring the side drawing die model to obtain the side drawing die casting.
2. The full mold casting process for improving the shrinkage of the side wall drawing die groove according to claim 1, characterized in that: In the step, when the one side surrounding drawing die is used, a groove with a cross-section of 20*20mm is cut at the bottom of the groove in the area from the A-pillar to the upper side beam.
3. The full mold casting process for improving the shrinkage of the side wall drawing die groove according to claim 1 is characterized in that: The dimensions of the wedge block in step 2 are 40 mm for the upper base, 80 mm for the lower base, 70 mm for the height, and 150 mm for the distance between the two wedge blocks.
4. The full mold casting process for improving the shrinkage of the side wall drawing die groove according to claim 1, characterized in that: After drying in step 4, the coating thickness is not less than 1.5 mm.
5. The full mold casting process for improving the shrinkage of the side wall drawing die groove according to claim 4 is characterized in that: In the fourth step, the cold iron needs to be molded and cast into an iron cold iron in advance. After the cold iron is sanded, cooled and shot blasted, an alcohol-based coating is applied on the cold iron surface to ensure that the coating has a thickness of 1.5-2 mm after drying.
6. The full mold casting process for improving the shrinkage of the side wall drawing die groove according to claim 1, characterized in that: In the step 5, after the material is transferred to the area to be poured, the iron is pressed on the upper sand box. The weight of the iron is about 7 times the weight of the pouring, and it covers the entire length direction of the sand box.
7. The full mold casting process for improving the shrinkage of the side wall drawing die groove according to claim 1, characterized in that: The pouring temperature in step six is 1360±10°C.
8. The full mold casting process for improving the shrinkage of the side wall drawing die groove according to claim 1, characterized in that: The method also includes step seven, cooling the side wall drawing die casting and then unpacking the side wall drawing die casting, then shot blasting the side wall drawing die casting, removing the pouring system, grinding the side wall drawing die casting, and finally inspecting to obtain qualified side wall drawing die casting.