In recent years, with the rapid development of manufacturing technology, the demand for efficient, flexible, and innovative manufacturing methods in the industrial field has been increasing. In this context, the application of robots is becoming increasingly widespread and gradually becoming an important component of automated production lines and customized manufacturing. However, traditional casting methods are still very cumbersome and limited in some aspects, with long mold making time and long production cycles becoming limiting factors that restrict the development cycle of robots. To address this issue, an innovative method for 3D printing and rapid casting of robotic arms without molds has been proposed. This method combines casting with 3D printing moldless mold manufacturing technology, aiming to improve the efficiency, flexibility, and innovation of the casting process. It abandons the traditional mold making process, transforms design inspiration into entities, and achieves casting in a short period of time, thus meeting the urgent need of modern manufacturing to quickly respond to market demand.
Printing technology, also known as additive manufacturing or rapid prototyping, is an advanced manufacturing technique that creates objects by stacking materials layer by layer. Unlike traditional subtractive manufacturing methods such as milling and turning, printing adds materials layer by layer, allowing designers to more flexibly create complex geometric shapes and structures. This technology covers a variety of different processes and materials, including plastics, metals, ceramics, etc. The basic working principle of printing is to divide the digital model into thin layers and then construct entities layer by layer. The process mainly involves: firstly, creating a digital 3D model using computer-aided design software; Then, the model is divided into thin layers to generate a series of 2D layers, providing a path for the printer to build; Finally, the printer adds materials layer by layer according to the path of each slice, forming the final three-dimensional object. Printing technology is widely used in various fields, for example, in manufacturing, it is used for producing prototypes, customized parts, and small batch production; In the medical field, it is used for bioprinting, manufacturing medical devices, and personalized medical products; In the aerospace industry, it is used to manufacture lightweight components and complex structures; In the construction industry, it is used to manufacture building prototypes, models, and special structures.
Printing technology has undergone more than 30 years of development and has achieved certain achievements in both technological accumulation and production practice. In the field of casting, printing technology has also been maturely applied, mainly in the manufacturing of sand molds and direct printing of metal products. In addition, printing technology can repair defects that occur during the casting process of products, so the application of this technology in the casting field is deep and extensive. Selective laser sintering technology uses a laser beam to scan and sinter sand materials layer by layer, constructing sand molds layer by layer. This process is similar to laser sintering metal printing technology, but is usually applied to sand mold manufacturing. After laser sintering, the sand mold forms a solid structure. 3D jet printing technology uses nozzles to spray adhesive onto sand powder, gradually constructing the contour of the sand mold layer by layer. In this process, the area where the sand powder is coated with adhesive forms a solid structure, while other areas remain loose. This technology is fast and suitable for large-scale production. Stereoscopic photopolymerization technology uses ultraviolet light sources to irradiate liquid photosensitive resin and solidify it layer by layer into a shape. This technology usually has
High resolution, suitable for manufacturing models with fine structures. The 3D printing head sprays adhesive according to the interface contour information using a dual nozzle, while simultaneously spraying the adhesive and catalyst. Through the cross-linking of the two, it is manufactured
The sand mold can be poured after being coated with paint. The forearm of a robot is a key component responsible for connecting the robot body to end effectors (such as grippers and tools), while also achieving load bearing and transmission, as well as motion control functions. The design and application of robotic arms are constantly evolving to meet the demand for automation and intelligence in different fields. They play an important role in improving production efficiency, reducing manual labor, and performing dangerous tasks. (1) Establishment of 3D model for castings. Before starting modeling, it is necessary to clarify the design parameters of the casting, including size, shape, material, etc; Select CAD software suitable for modeling, divide, trim, and combine the basic geometry, and add details and features on the basis of the basic geometry to improve the design of the casting; Optimize the design, adjust the size, shape, and features to meet the design requirements, manufacturing requirements, and material process performance; Check the model to ensure geometric correctness, accurate dimensions, and avoid potential manufacturing issues; After completing the 3D model of the casting, export it to a common file format for subsequent analysis, simulation, or manufacturing. (2) Mold design and 3D printing. Obtain a 3D model of the parts that need to be cast, use CAD software to design sand molds, design sand cores for parts that require internal cavities, assemble the designed sand molds and cores into a complete casting mold system, and use 3D printing technology suitable for sand mold manufacturing to print the sand molds layer by layer
And sand cores. (3) Casting castings. Take out the molten metal from the furnace and pour it into the prepared sand mold through the sprue. The pouring process needs to be careful to avoid the entry of gases and inclusions, while ensuring that the metal can fill the entire cavity. Once the metal fills the mold, let the mold cool and solidify. After the metal is fully cooled, separate the shell and core box, and take out the completed casting. This process may require some additional processing (such as removing gates, trimming surfaces, etc.) as well as some post-processing techniques (such as sandblasting, heat treatment, surface coating, etc.) to meet the final requirements of the part.
Design the mechanical arm casting process based on the structural characteristics of the casting. The most important aspects of casting process design are the gating system and riser design. The design of the pouring system needs to consider factors such as metal fluidity, cooling uniformity, and gas removal. A reasonable pouring system design can ensure that the entire mold is uniformly filled, reducing the occurrence of pores and defects. The design of the riser should ensure that it can effectively eliminate gas while not introducing too many impurities. A well-designed riser can help improve the quality of castings. After designing the pouring system and riser, forming simulation can be carried out to simulate the filling, solidification, cooling and other processes of metal. Through simulation, possible defects (such as pores and warping) can be predicted and optimized for design. During the simulation process, the gating system and riser parameters can be adjusted, such as sprue size, shape, riser position, etc., to find the optimal design. The robotic arm is the main supporting component of the robot’s motion mechanism, with a relatively complex structure and high precision requirements. In order to produce high-quality and short cycle castings, taking into account the characteristics of the arm casting structure and volume, the parting surface is set on the part water On the maximum plane of flat projection. Through simulation analysis and previous single mold application, in order to improve efficiency and save runner materials, the arm adopts two pieces of the first mock examination, each piece is equipped with two ingates and five risers, and the ingate adopts Flat and thin structure, with a riser (function) set at the end of the metal liquid filling to improve the filling speed and shrinkage capacity of the metal liquid. Mold design includes sand mold design and sand core design. After determining the casting process, a wrapped mold model is generated based on the three-dimensional model size of the casting, which is a rectangular prism with external dimensions of 700cm × 700cm × 310cm. By performing operations such as copying extended surfaces and differentiating entities, the mold model is segmented into parts with composite shapes Sand molds and cores with positioning structure and matching gaps. The sand core assembly installs the arm axial support sand core and wire channel sand core that have been cleaned and coated onto the mold, ensuring that they are accurately positioned and fixed to form the final hollow structure or channel. Check that all sand cores are assembled properly. After installing all the sand for the two parts, clean up the scattered sand that fell into the inner cavity during assembly. Assemble the upper and lower mold sand molds and pour them together to ensure that the aluminum alloy fully fills the space between the sand mold and sand core, forming the overall shape of the robot arm. Wait for the aluminum alloy to cool and solidify in the mold to ensure that the casting can maintain its shape and structure. After the solidification of the casting is completed, remove the sand core. Take out the sand core from the casting and conduct the final casting inspection to ensure that the casting meets the design requirements.