METHOD FOR REINFORCING A 3D-PRINTED SAND CORE FOR PILLING AN INTEGRATED MULTI-WAY VALVE AND SAND CORE OF AN INTEGRATED HYDRAULIC MULTI-WAY VALVE

Abstract

Method for reinforcing a 3D-printed sand core for casting an integral hydraulic multi-way valve, comprising: Generating a sand core model of a sand core for an integral multi-way valve to be 3D printed in three-dimensional software, and then analyzing parts of the sand core model to determine a weak part of the sand core; wherein the weak part of the sand core includes a sand core part of a main valve orifice, an elongated sand core part, or a cantilevered sand core part for a hole. Constructing a pore channel with a pore diameter and length relative to the weak part of the sand core in the sand core model according to a ratio L / D of a length to a diameter of the weak part of the sand core, and forming a core reinforcement rod according to the pore channel with the pore diameter and length; and 3D printing of the sand core according to the sand core model, placement of the core reinforcement rod in the pore channel of the sand core and achieving a tight connection between the core reinforcement rod and the sand core in the process of hardening or solidifying the sand core, so that the overall strength of the sand core of the integral hydraulic multi-way valve is improved.

Description

Reference to related applications

[0001] The present application is based on and claims priority of Chinese patent application No. 202010126901.0, filed on February 28, 2020, entitled “PROCESS OF STRENGTHENING 3D PRINTED SAND CORE FOR THE CASTING OF INTEGRAL MULTI-WAY VALVE”, the disclosure of which is incorporated herein by reference in its entirety. Area

[0002] The present disclosure belongs to the technical field of 3D printing equipment and relates in particular to a method for reinforcing a 3D-printed sand core for casting an integral hydraulic multi-way valve and a sand core of an integral hydraulic multi-way valve. background

[0003] Currently, the methods for manufacturing a sand core for an integral hydraulic multi-way valve mainly include the conventional sand injection method and the 3D sand core printing method. The conventional sand injection method requires the creation of molds, resulting in a long manufacturing cycle and high costs for the integral hydraulic multi-way valve. However, since the 3D sand core printing method, known for its short cycle and low costs, uses both selective laser sintering and binder jetting to create a powder-based structure, the loose properties of the printed powder layer mean that the compactness and strength of the printed sand core are lower than those of a sand core produced by the current sand injection method.

[0004] DE 32 27 315 ​​C2 discloses a ceramic mold core and a method for casting components with channel-like recesses.

[0005] DE 43 23 002 A1 shows a core for pre-casting bores in castings and its manufacture.

[0006] To date, a printed sand core can only meet the casting requirements for a sand core of a simple part, such as an engine cylinder block and cylinder cover, a hydraulic torque converter housing, and a plate-type valve. In the case of an integral hydraulic multi-way valve with complex internal oil paths, a 3D-printed sand core exhibits a large number of cantilevered and elongated sand core sections. Such sand core sections are very easily deformed and even break under the influence of prolonged firing, a molten iron coating, the buoyancy of the molten iron, and their own thermal stress, ultimately leading to a casting failure.

[0007] In the process that led to the present disclosure, the inventors realized the following: 1. When the conventional mold-making process is used to produce a sand core for an integral multi-way valve, it is necessary to consider the draft angle and manufacture metal molds. This process significantly extends the development cycle and increases the cost of new products. Furthermore, the internal flow paths of multi-way valves are usually quite complex, and often the sand core components of these flow paths must be designed separately. This leads to numerous subsequent assembly processes for the sand core and poor fit, ultimately impacting the quality of the castings. 2. When the 3D-printed sand core, or more precisely, the sand core components, are constructed using current methods, both the compactness and the strength of the 3D-printed sand core are lower than those produced using the conventional sand injection method. This is because the apparent density of the pre-coated sand powder used for 3D printing is lower than the density of the sand grains. Furthermore, a sand core constructed using 3D printing is a solid, integrated sand core, and the uneven cross-sectional dimensions of different parts of the core inevitably lead to uneven strength. Elongated and cantilevered sections of the sand core are weak points, but these are not reinforced using current methods.Therefore, the weak parts of the 3D-printed sand core cannot withstand the effects of the prolonged burning of the molten iron, the buoyancy of the molten iron, and their own thermal stresses, leading to a warped and even broken sand core in the casting process, and ultimately to a casting failure. Brief description of the invention

[0008] The technical solution used in the present disclosure is: A method for reinforcing a 3D-printed sand core for casting an integral hydraulic multi-way valve, which includes: Creating a sand core model of a sand core for an integral multi-way valve to be 3D printed in three-dimensional software, and then analyzing parts of the sand core model to determine a weak part of the sand core; Constructing a pore channel with a pore diameter and length relative to the weak part of the sand core in the sand core model according to a ratio L / D of a length to a diameter of the weak part of the sand core, and forming a core reinforcement rod according to the pore channel with the pore diameter and length; and 3D printing of the sand core according to the sand core model, placement of the core reinforcement rod in the pore channel of the sand core and achieving a tight connection between the core reinforcement rod and the sand core in the process of hardening or solidifying the sand core, so that the overall strength of the sand core of the integral hydraulic multi-way valve is improved.

[0009] In some embodiments, the sand core model for the integral multi-way valve to be 3D printed is generated in three-dimensional software, and the parts of the sand core model are analyzed to determine the weak part of the sand core; the weak part of the sand core includes a sand core part of a valve main opening, an elongated sand core part, or a cantilevered sand core part for a hole.

[0010] In some embodiments, a method for reinforcing a 3D-printed sand core for casting an integral hydraulic multi-way valve further includes: measuring the cross-sectional diameter D and the length L of the weak part of the sand core in the sand core model and calculating the ratio L / D of the length to the diameter.

[0011] In some embodiments, constructing a pore channel with the pore diameter and length in the sand core model according to the ratio L / D of the length to the diameter of the weak part of the sand core involves: Creating a pore channel to place a core reinforcement rod in the sand core model, wherein the diameter of the pore channel is not less than 10% of the diameter of the weak part of the sand core and not greater than 15% of the diameter of the weak part of the sand core if the L / D value of the weak part of the sand core is greater than 6, to ensure that the strength of the sand core is increased while preventing breakage of the 3D-printed sand core in the post-processing procedure resulting from a low initial strength; at the same time, the pore channel extends up to 5-10 mm into the interior of a sand core main body so that the core reinforcement rod is supported and fixed by the sand core main body; and a pore channel corresponding to a cantilevered sand core does not completely penetrate a cantilevered end and penetrates over a distance of less than approximately 5 mm.

[0012] In some embodiments, forming the core reinforcement rod according to the pore channel with the pore diameter and length according to the constructed pore channel of the sand core involves placing a steel tube core rod for the sand core part of the valve main opening, wherein a plurality of air holes are drilled into the side wall of the steel tube core rod to aid uniform venting of a weak sand core part having a large diameter in the casting process, and for the weak part of the sand core that is not the sand core part of the valve main opening (an elongated sand core part for a hole, a cantilevered sand core part for a hole), a solid ceramic core rod is used.

[0013] In some embodiments, the 3D printing of the sand core according to the sand core model, the placement of the core reinforcement rod in the pore channel of the sand core, and the achievement of a tight connection between the core reinforcement rod and the sand core through the process of hardening or solidifying the sand core include: For a sand core printed using the binder formation process, the immediate removal of the sand core, cleaning of the outer surface of the sand core, and removal of loose sand adhering to the pore channel after completion of printing are required. then the penetration of a specially manufactured core reinforcement rod into the pore channel of the sand core and finally the achievement of a tight connection between the sand core and the core reinforcement rod after the sand core has hardened; or, for a sand core printed using the selective laser sintering process, placing the core reinforcement rod in the pore channel before heat-curing the sand core and then achieving a tight bond between the sand core and the core. of the core reinforcement rod in the process of hot hardening the sand core.

[0014] According to a second aspect of the present disclosure, a sand core for an integral hydraulic multi-way valve is specified, which was formed by a method mentioned above for reinforcing a 3D-printed sand core for casting an integral hydraulic multi-way valve. Brief description of the drawings Fig. Figure 1 is a schematic sketch of a sand core of an integral hydraulic multi-way valve according to an embodiment of the present disclosure; Fig. 2 is a schematic sketch of a sand core part of a valve main opening in Fig. 1; Fig. Figure 3 is a schematic sketch of an elongated sand core section for a hole in Fig. 1; Fig. Figure 4 is a schematic sketch of a self-supporting sand core section for a hole in Fig. 1; Fig. Figure 5 is a schematic sketch of a steel tube core rod for a sand core of an integral hydraulic multi-way valve according to an embodiment of the present disclosure; Fig. Figure 6 is a schematic sketch of a ceramic core rod for a sand core of an integral hydraulic multi-way valve according to an embodiment of the present disclosure. Detailed description of the embodiments

[0015] The technical solutions in the embodiments of the present disclosure are clearly and completely described below in conjunction with the accompanying drawings. It should be clarified that the described embodiments represent only a subset of the embodiments of the present disclosure and not all embodiments. The following description of at least one embodiment serves only for illustrative purposes and is in no way intended to limit the present disclosure or its applications. All other embodiments that can be obtained by those skilled in the art from the embodiments of the present disclosure without inventive effort are within the scope of protection of the present invention.

[0016] Unless expressly stated otherwise, the relative arrangement of components and steps, numerical expressions, and numerical values ​​listed in these embodiments do not constitute a limitation of the scope of this disclosure. It should also be clarified that, for the sake of simplicity, the size of various parts shown in the drawings is not drawn to scale. The technologies, methods, and equipment known to those skilled in the art in the relevant field may not be discussed in detail, but where applicable, they should be considered part of the stated specification. In all examples shown and discussed herein, each specific value should be understood as an example only, and not as a limitation. Therefore, other examples of the embodiment may have different values.It should be noted that in the following drawings similar reference numbers and letters denote similar elements, so that an element defined in one drawing does not need to be discussed further in subsequent drawings.

[0017] The embodiment of the present disclosure specifies a method for reinforcing a 3D-printed sand core for casting an integral hydraulic multi-way valve, comprising the following steps: Step 1, a sand core model of a sand core to be 3D printed for an integral hydraulic multi-way valve is created in three-dimensional software, as described in Fig. 1 shown, then parts of the sand core model are analyzed to determine a weak part of the sand core, such as a sand core part 1 of a valve main opening, an elongated sand core part 2 for a hole, or a cantilevered sand core part 3 for a hole; Fig. 2 is a schematic sketch of a sand core part of a valve main opening in Fig. 1; Fig. Figure 3 is a schematic sketch of an elongated sand core section for a hole in Fig. 1; Fig. Figure 4 is a schematic sketch of a self-supporting sand core section in Fig. 1. In step 2, a cross-sectional diameter D and a length L of the weak part of the sand core, including the sand core part 1 of the main valve opening, the elongated sand core part 2 for a hole or the cantilevered sand core part 3 for a hole, as determined in step 1, are measured and the ratios L / D of the length to the diameter are calculated. In step 3, if the L / D value is greater than 6, a pore channel is created in the sand core model for the weak part of the sand core, based on the result calculated in step 2. This channel allows for the placement of a core reinforcement rod. The diameter of the pore channel is no less than 10% and no greater than 15% of the diameter of the weak part of the sand core to ensure that the strength of the sand core is increased while preventing the 3D-printed sand core model from breaking during the post-processing due to its initial strength. Simultaneously, the pore channel extends 5-10 mm into the main body of the sand core, allowing the core reinforcement rod to be supported and fixed within the core. Specifically, the pore channel corresponding to the cantilevered part of the sand core does not fully penetrate the cantilevered end and extends a distance of less than approximately 5 mm. In step 4, according to the pore channel of the sand core determined in step 3, a steel tube core rod should preferably be used for the sand core part of a valve main opening or another large diameter sand core part, wherein a plurality of air holes are drilled into the side wall of the steel tube core rod to assist uniform venting of the large diameter sand core part in the casting process, and wherein a solid ceramic core rod is used for the other sand core (an elongated sand core part 2 for a hole or a cantilevered sand core part 3 for a hole). Fig. Figure 5 is a schematic sketch of a steel tube core rod for a sand core of an integral hydraulic multi-way valve according to one embodiment; Fig.Figure 6 is a schematic sketch of a ceramic core rod for a sand core of an integral hydraulic multi-way valve according to one embodiment; and internal holes of the core reinforcement rod and the pore channel of the sand core together play a role in the uniform venting of the sand core. Step 5: For a sand core printed using the binder formation process, it is necessary to remove the sand core immediately after printing is complete, clean the outer surface of the sand core, and remove any loose sand adhering to the pore channel. Then, a specially made core reinforcement rod penetrates the pore channel of the sand core, and finally, a tight bond between the sand core and the core reinforcement rod is achieved after the sand core has cured. For a sand core printed using the selective laser sintering process, a core reinforcement rod is placed in the pore channel before the sand core is heat-cured, and then a tight bond between the sand core and the core reinforcement rod is achieved during the heat-curing process.

[0018] The method for reinforcing a 3D-printed sand core for casting an integral hydraulic multi-way valve, as disclosed in the present disclosure, has at least one of the following beneficial effects: In the method for reinforcing a 3D-printed sand core for casting an integral hydraulic multi-way valve, as described in the present disclosure, the pore channel with pore diameter and length in the sand core model is constructed with respect to the weak part of the sand core, such as the cantilevered sand core part, the elongated sand core part for a hole, and the sand core part of the main valve opening, after the three-dimensional model of the sand core to be printed for the integral hydraulic valve has been created, and after completion of the 3D printing of the sand core, the core reinforcement rod is formed according to the pore channel with pore diameter and length and pre-arranged in the pore channel of the sand core, so that the overall strength of the sand core of the integral hydraulic multi-way valve is improved to achieve the sand core strength required for casting the integral hydraulic multi-way valve.and to improve the success rate of rapid casting of the integral hydraulic multi-way valve using the 3D-printed sand core.

[0019] The following benefits are provided: 1. Reinforced Sand Core. The apparent density of pre-coated sand powder for 3D printing is lower than the density of the sand grain body, and the compactness and strength of the printed sand core cannot withstand the effects of prolonged firing of the molten iron, the buoyancy of the molten iron, and its own thermal stresses. This often results in the casting process producing a warped and fractured sand core. In the present disclosure, a high-strength core rod is pre-arranged for the 3D-printed sand core to reinforce the weak part of the sand core. This not only reduces the risk of fracture in intermediate stages, such as sand core transfer and flow painting, but also improves the sand core's resistance to high temperatures in the casting process. 2. Uniform venting. The pre-formed pore channel for the sand core of the integral hydraulic multi-way valve not only plays a role in the placement of the core reinforcement rod, but also facilitates the uniform venting of the sand core during the casting process. 3. High casting success rate of the integral hydraulic multi-way valve. A high-strength core rod is pre-arranged at the weakest point of the sand core of the integral hydraulic multi-way valve, effectively improving the overall strength of the sand core. During the casting process, the buoyancy of the molten iron and the thermal stress of the sand core are primarily transferred to the core reinforcement rod and ultimately to the main body of the sand core. This reduces the risk of breakage for the sand core and ultimately increases the casting success rate for the integral hydraulic multi-way valve.

[0020] The above description includes only preferred embodiments of the present disclosure. It should be noted that the various improvements and modifications can also be carried out by the person skilled in the art without departing from the fundamentals of the present invention, and these improvements and modifications should also be considered to be within the scope of protection of the present disclosure.

Claims

[1] Method for reinforcing a 3D-printed sand core for casting an integral hydraulic multi-way valve, comprising: Generating a sand core model of a sand core for an integral multi-way valve to be 3D printed in three-dimensional software, and then analyzing parts of the sand core model to determine a weak part of the sand core; wherein the weak part of the sand core includes a sand core part of a main valve orifice, an elongated sand core part, or a cantilevered sand core part for a hole. Constructing a pore channel with a pore diameter and length relative to the weak part of the sand core in the sand core model according to a ratio L / D of a length to a diameter of the weak part of the sand core, and forming a core reinforcement rod according to the pore channel with the pore diameter and length; and 3D printing of the sand core according to the sand core model, placement of the core reinforcement rod in the pore channel of the sand core and achieving a tight connection between the core reinforcement rod and the sand core in the process of hardening or solidifying the sand core, so that the overall strength of the sand core of the integral hydraulic multi-way valve is improved. [2] Method for reinforcing a 3D-printed sand core for casting an integral hydraulic multi-way valve according to claim 1, further comprising: measuring the cross-sectional diameter D and the length L of the weak part of the sand core in the sand core model and calculating the ratio L / D of the length to the diameter. [3] Method for reinforcing a 3D-printed sand core for casting an integral hydraulic multi-way valve according to claim 2, comprising constructing the pore channel with the pore diameter and length in the sand core model according to the ratio L / D of the length to the diameter of the weak part of the sand core: Creating a pore channel for placing a core reinforcement rod in the sand core model when the L / D value of the weak part of the sand core is greater than 6, wherein the diameter of the pore channel is not less than 10% and not greater than 15% of the diameter of the weak part of the sand core to ensure that the strength of the sand core is increased while preventing breakage of the 3D-printed sand core resulting from low initial strength during the post-processing procedure; simultaneously, the pore channel extends 5-10 mm into a sand core main body so that the core reinforcement rod is supported and fixed by the sand core main body; and a pore channel that forms a cantilevered sand core This corresponds to a cantilevered end that does not penetrate completely and penetrates over a distance of less than approximately 5 mm. [4] Method for reinforcing a 3D-printed sand core for casting an integral hydraulic multi-way valve according to claim 1, wherein forming the core reinforcement rod according to the pore channel with the pore diameter and length according to the constructed pore channel of the sand core comprises: placing a steel tube core rod in a sand core part for a valve main opening, wherein a plurality of air holes are drilled into the side wall of the steel tube core rod to assist uniform venting of a weak sand core part having a large diameter in the casting process, and using a solid ceramic core rod for the weak part of the sand core that is not the sand core part of the valve main opening. [5] Method for reinforcing a 3D-printed sand core for casting an integral hydraulic multi-way valve according to claim 1, wherein 3D printing the sand core according to the sand core model comprises placing the core reinforcement rod in the pore channel of the sand core and achieving a tight connection between the core reinforcement rod and the sand core by hardening or solidifying the sand core: In the case of a sand core printed using the binder formation process, the sand core is removed after printing is complete, the outer surface of the sand core is cleaned, and any loose sand adhering to the pore channel is removed. Then, a specially made core reinforcement rod is inserted into the pore channel of the sand core, and finally, a tight seal is achieved between the sand core and the core reinforcement rod after the sand core has cured. In the case of a sand core printed using the selective laser sintering process, a core reinforcement rod is placed in the pore channel before heat-curing the sand core, and then a tight connection between the sand core and the core reinforcement rod is achieved in the heat-curing process of the sand core. [6] Sand core for an integral hydraulic multi-way valve formed by the method of reinforcing a 3D-printed sand core for casting an integral hydraulic multi-way valve according to one of claims 1-5.

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