Ram seat sand mold 3D printing modeling method

Abstract

The invention discloses a ram base sand mold 3D printing modeling method. The method comprises the following steps that A, a casting process scheme is designed; b, designing a corresponding hollow sand mold structure according to the geometrical shape, the casting performance and the process scheme of the casting; c, making a model; d, the molten iron contact surfaces of all the sand molds are subjected to coating brushing treatment; e, box distribution; and F, box assembling and pouring. According to the invention, modeling-free modeling is realized, the molding cost can be saved by 450,000 yuan, meanwhile, the production period is obviously shortened, and the production efficiency is greatly improved. The 3D printer is adopted to print the sand mold, the size precision is high and can reach 0.3 mm, the gap is small during core assembly, positioning is accurate, and the quality of the mold cavity is guaranteed. And the sand mold design adopts a shape following design, so that the sand consumption is reduced, and the sand mold strength is ensured. The weight of each sand mold is small, the weight of the sand molds is reduced, the material cost is saved, operation is convenient, large hoisting equipment is not needed, the requirement for the equipment capacity is low, and the molding labor intensity is small.

Description

Technical Field

[0001] The invention relates to the technical field of metal molding casting, and in particular to a 3D printing modeling method for a ram seat sand mold. Background Art

[0002] The sand mold digital model printing technology in 3D printing technology has the following printing operations: the printer's nozzle operates according to the two-dimensional data of the model section under the control of the software system, and selectively sprays special ink on the corresponding position of the sand surface. After each layer is bonded, the bottom plate of the working box drops a distance equal to the layer thickness, and the cycle continues until the bonding of the entire printed product is completed. 3D printed sand mold casting can be used for castings with small tonnage and complex structures, but there will be some problems when using 3D printed large sand molds: when the mold is removed after printing, the larger sand mold has no hand pick and lift, and the worker can only pick the bottom of the mold with his hand to remove the mold from the printing box. Fingers are easily crushed by the mold, and it is time-consuming and laborious.

[0003] The ram seat is one of the main components of the gantry machining center. The ram seat of DFP20040 weighs several tons and is made of gray cast iron 300. It has very high product quality requirements and is a casting with a relatively complex structure in a large gantry machining center. The traditional casting molding process has the following shortcomings: In addition to making two upper and lower molds, traditional molding also requires 14 sand molds, which are expensive and have a mold making cycle of more than one month, often consuming a lot of money and extending the casting production cycle. In addition, the traditional molding accuracy is not high, the positioning is not easy to control, the core gap is large, and deformation and other problems ultimately affect the size of the casting. In addition, the traditional molding sand mold is large in size and heavy in weight, which not only has a high labor intensity, but also often requires the use of large-scale box turning and lifting equipment, which has high requirements for workshop equipment. Summary of the invention

[0004] In order to solve the problem that wooden molds need to be developed when making small batches of products, which consumes a lot of money and has a long production cycle, the present invention provides a ram seat sand mold 3D printing modeling method which can significantly reduce casting costs, shorten production cycles, improve modeling accuracy, facilitate assembly, and reduce labor intensity.

[0005] The present invention adopts the following technical solution, a ram seat sand mold 3D printing modeling method, comprising the following steps: A. Casting process design; DFP20040 ram seat, the overall dimensions are: 220×160×115cm. When designing the ram seat: consider the size of the 3D printing equipment, and the principle of convenient coating and box matching; when designing the sand mold: the size of the sand mold must meet the requirements of the equipment and cannot exceed the size of the equipment; the requirements for core assembly: to facilitate core assembly; the requirements for coating: to facilitate coating on the surface in contact with molten iron; the design of the lifting: to facilitate the transportation of the printed sand mold; the weak parts should be designed to be strengthened; B. Design a corresponding hollow sand mold structure according to the geometric shape, casting performance and process plan of the casting, split the sand mold structure into multiple sand molds and sand cores that can be printed with the help of 3D printing equipment, specifically, the sand mold cavity of the ram seat is divided into 16 sand mold units, and positioning is made on each sand mold unit to ensure the subsequent assembly accuracy, and analyze and check each part of the sand mold structure to determine the fragile connection parts in each part of the sand mold, and design a three-dimensional model of each sand mold unit using mapping software corresponding to each of the sand mold units; The size of the DFP20040 ram seat exceeds the printing range of the 3D printer. The casting shape is divided into four shape sand mold units, namely the left lower mold sand mold, the right lower mold sand mold, the left upper mold sand mold, the right upper mold sand mold, and 12 intermediate sand cores. Each adjacent intermediate sand core is connected in sequence. A straight runner and the first horizontal runner are set in the middle of the upper part of the left upper mold sand mold. The top of the left upper mold sand mold and the right upper mold sand mold are designed with multiple exhaust holes. Sand molds weighing more than 30 kg or inconvenient to carry manually are hoisted. C. Making a model: importing the model files of each sand mold unit into a 3D printer, placing the designed sand molds piece by piece in a 3D printing sand box, and printing them into sand molds according to the model files; D. After printing is completed, each sand mold unit is lifted out for cleaning and transported to the molding workshop, and the molten iron contact surface of each sand mold is treated with paint; E. Box matching: After drying, use the positioning on the sand mold unit to assemble. First, assemble the left lower mold sand mold and the right lower mold sand mold, drop the 12 intermediate sand cores one by one, use the core support for those that cannot be fixed, and finally cover the left upper mold sand mold and the right upper mold sand mold to complete the box matching, and grind off the protruding lifting device, so that when covering the sand box, the size of the sand box can be reduced; the cavity formed inside after the box matching is the ram seat; F. Assembling boxes and pouring: Place a sand box outside the assembled sand mold, fill the hollow space between the sand box and the sand mold with resin sand, and put the boxes together for pouring after hardening. After pouring, clean the sand, cut the riser, and conduct a preliminary inspection of the casting. If it is qualified, proceed to the next step.

[0006] Preferably, the lifting device in step B is a lifting handle used on the outer shape sand mold unit, including the left lower mold sand mold, the right lower mold sand mold, the left upper mold sand mold and the right upper mold sand mold, which is directly lifted by a cloth belt; and a hook used on the intermediate sand core, the hook is an inverted T-shape, is inserted from the rectangular opening on the mouth, and is lifted after rotating 90°. The thickness of the sand mold below the rectangular opening ensures the lifting strength, and the inside is hollowed.

[0007] In order to prevent the outer shape sand mold from deforming after printing and to ensure the strength of the outer shape sand mold after lifting, reinforcing ribs are set at the weak positions of the local parts of the left upper mold sand mold, and the reinforcing ribs must be sawed off before the sand mold is assembled.

[0008] Beneficial effects: ① The present invention realizes moldless modeling and reduces costs. The cost is only 30% of the traditional casting method. At the same time, the production cycle is significantly shortened, and the working hours are only 40% of the traditional casting method, which greatly improves production efficiency.

[0009] ② The present invention uses a 3D printer to print sand molds, with high dimensional accuracy, up to -0.3--0.3mm; the sand used has a small mesh size of 50-100 mesh, the printed sand mold has high precision and a smooth surface, and the positioning and lifting devices designed on the sand mold are also integrated with the sand mold. The core assembly time gap is small, and the positioning is accurate to ensure the quality of the mold cavity. The DFP20040 ram seat casting has a smooth surface, clear contours, and improved inner cavity cleanliness.

[0010] ③ The sand mold design of the present invention adopts a mold-based design to reduce the amount of sand used while ensuring the strength of the sand mold. Each sand mold has a small weight, which reduces the weight of the sand mold, saves material costs, is easy to operate, does not require large-scale lifting equipment, has low equipment capacity requirements, and has low molding labor intensity. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a schematic diagram of the structure of the ram seat casting of the present invention.

[0012] Figure 2 It is a schematic diagram of the casting system of the ram seat casting of the present invention.

[0013] Figure 3 Schematic diagram of the core splitting structure of the sand mold unit of the ram seat casting of the present invention.

[0014] Figure 4 Schematic diagram of the interior of the sand mold unit box of the ram seat casting of the present invention.

[0015] Figure 5 Schematic diagram of the sand mold unit box assembly of the ram seat casting of the present invention.

[0016] In the figure: left lower mold sand mold 1, right lower mold sand mold 2, left upper mold sand mold 3, right upper mold sand mold 4, intermediate sand core 5, straight runner 6, first cross runner 7, exhaust hole 8, hanging handle 9, hanging hook 10, reinforcing rib 11. DETAILED DESCRIPTION

[0017] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0018] Embodiment 1: A 3D printing method for a ram seat sand mold, comprising the following steps: A. Casting process design; DFP20040 ram seat, the overall dimensions are: 220×160×115cm. When designing the ram seat, the size of the 3D printing equipment is considered, and the principle of convenient coating and box matching is adopted. When designing the sand mold: the size of the sand mold must meet the requirements of the equipment and cannot exceed the size of the equipment; the requirements for core assembly must be convenient for core assembly; the requirements for coating must be convenient for coating on the surface in contact with molten iron; the design of the lifting is convenient for the transportation of the printed sand mold; the weak parts must be designed to be strengthened; B. Design a corresponding hollow sand mold structure according to the geometric shape, casting performance and process plan of the casting, split the sand mold structure into multiple sand molds and sand cores that can be printed with the help of 3D printing equipment, specifically, divide the sand mold cavity of the ram seat into 16 sand mold units, and analyze and check each part of the sand mold structure to determine the weak connection parts in each part of the sand mold, and design a three-dimensional model of each sand mold unit using mapping software corresponding to each of the sand mold units; The size of the DFP20040 ram seat exceeds the printing range of the 3D printer. The casting shape is divided into four shape sand mold units, namely the left lower mold sand mold 1, the right lower mold sand mold 2, the left upper mold sand mold 3, the right upper mold sand mold 4, and 12 intermediate sand cores 5. Each adjacent intermediate sand core 5 is connected in sequence. A straight runner 6 and a first cross runner 7 are arranged in the middle of the upper part of the left upper mold sand mold 3. A plurality of exhaust holes 8 are designed on the top of the left upper mold sand mold 3 and the right upper mold sand mold 4. The lifting handles 9 on the left lower mold sand mold 1, the right lower mold sand mold 2, the left upper mold sand mold 3 and the right upper mold sand mold 4 are directly lifted by cloth belts; and the hook 10 used on the intermediate sand core 5 is an inverted T-shaped hook, which is put in from the rectangular mouth on the mouth and lifted after rotating 90°. The thickness of the sand mold under the rectangular mouth is guaranteed to ensure the lifting strength, and the inside is hollowed. A reinforcing rib 11 is provided at a local weak position of the upper mold sand mold 3 on the left side, and the reinforcing rib should be sawed off before the sand mold is assembled; C. Making a model: importing the model files of each sand mold unit into a 3D printer, placing the designed sand molds piece by piece in a 3D printing sand box, and printing them into sand molds according to the model files; D. The molten iron contact surface of each sand mold is treated with paint; E. Packing: First assemble the left lower mold sand mold 1 and the right lower mold sand mold 2, drop the 12 intermediate sand cores 5 in, use core supports if they cannot be fixed, and finally cover the left upper mold sand mold 3 and the right upper mold sand mold 4 to complete the packing. The cavity formed inside after packing is the ram seat; F. Assembling boxes and pouring: Place a sand box outside the assembled sand mold, fill the hollow space between the sand box and the sand mold with resin sand, and put the boxes together for pouring after hardening. After pouring, clean the sand, cut the riser, and conduct a preliminary inspection of the casting. If it is qualified, proceed to the next step.

Claims

1. A 3D printing method for a ram seat sand mold, characterized in that , including the following steps: A. Casting process design; DFP20040 ram seat, the overall dimensions are: 220×160×115cm. When designing the ram seat: consider the size of the 3D printing equipment, and the principle of convenient coating and box matching; when designing the sand mold: the size of the sand mold must meet the requirements of the equipment and cannot exceed the size of the equipment; the requirements for core assembly: to facilitate core assembly; Requirements for coating: coating on the surface in contact with molten iron; design of lifting: convenient for the transportation of printed sand molds; Weak parts should be designed to be strengthened; B. Design a corresponding hollow sand mold structure according to the geometric shape, casting performance and process plan of the casting, split the sand mold structure into multiple sand molds and sand cores that can be printed with the help of 3D printing equipment, specifically, the sand mold cavity of the ram seat is divided into 16 sand mold units, and positioning is made on each sand mold unit, and each part of the sand mold structure is analyzed and checked to determine the weak connection parts in each part of the sand mold, and corresponding to each of the sand mold units, a three-dimensional model of each sand mold unit is designed using mapping software; The size of the DFP20040 ram seat exceeds the printing range of the 3D printer. The casting shape is divided into four shape sand mold units, namely the left lower mold sand mold, the right lower mold sand mold, the left upper mold sand mold, the right upper mold sand mold, and 12 intermediate sand cores. Each adjacent intermediate sand core is connected in sequence. A straight runner and the first horizontal runner are set in the middle of the upper part of the left upper mold sand mold. The top of the left upper mold sand mold and the right upper mold sand mold are designed with multiple exhaust holes. Sand molds weighing more than 30 kg or inconvenient to carry manually are hoisted. C. Making a model: importing the model files of each sand mold unit into a 3D printer, placing the designed sand molds piece by piece in a 3D printing sand box, and printing them into sand molds according to the model files; D. After printing is completed, each sand mold unit is lifted out for cleaning and transported to the molding workshop, and the molten iron contact surface of each sand mold is treated with paint; E. Packing: After drying, use the positioning on the sand mold unit to assemble. First, assemble the left lower mold sand mold and the right lower mold sand mold, drop the 12 intermediate sand cores one by one, and use core supports for those that cannot be fixed. Finally, cover the left upper mold sand mold and the right upper mold sand mold to complete the packing. The cavity formed inside after packing is the ram seat; F. Assembling boxes and pouring: Place a sand box outside the assembled sand mold, fill the hollow space between the sand box and the sand mold with resin sand, and put the boxes together for pouring after hardening. After pouring, clean the sand, cut the riser, and conduct a preliminary inspection of the casting. If it is qualified, proceed to the next step.

2. A ram seat sand mold 3D printing modeling method according to claim 1, characterized in that: The lifting device of step B is used on the outer shape sand mold unit, including the lifting handles on the left lower mold sand mold, the right lower mold sand mold, the left upper mold sand mold and the right upper mold sand mold, which are directly lifted by cloth belts; and the hook used on the intermediate sand core, which is an inverted T-shaped hook, is inserted from the rectangular opening on the mouth, rotated 90° and then lifted. The thickness of the sand mold under the rectangular opening is guaranteed to ensure the lifting strength, and the inside is hollowed.

3. A ram seat sand mold 3D printing modeling method according to claim 1 or 2, characterized in that: Reinforcing ribs are set at the local weak position of the left upper sand mold.

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