Low-pressure casting mold and casting method for steering mechanism of six-axis industrial robot

Abstract

The invention relates to the technical field of molds, in particular to a low-pressure casting mold and method for a steering mechanism of a six-axis industrial robot. The mold comprises an upper mold, a lower mold and a side mold which are made of metal materials, and an inner mold made of molding sand materials, an upper cavity is formed in the bottom of the upper mold; a lower cavity is formed in the top of the lower mold; a side cavity is formed in the first side of the side mold; the upper mold is detachably mounted on the lower mold, and the upper mold and the lower mold jointly form a parting surface arranged in the vertical direction; the first side of the side mold is detachably installed on the parting surface, and the bottom of the inner mold is in lap joint with the top of the lower mold and located in the lower cavity, so that a complete cavity matched with a steering mechanism casting in shape is formed among the inner mold, the upper cavity, the lower cavity and the side cavity; in this way, the metal mold provides high rigidity to resist micro-deformation in low-pressure casting, and it is guaranteed that the size of a casting body is stable; the molding sand inner mold is used for forming a complex inner cavity so as to improve the precision of a steering mechanism casting.

Description

Technical Field

[0001] This invention relates to the field of mold technology, and in particular to a low-pressure casting mold and casting method for a six-axis industrial robot steering mechanism. Background Technology

[0002] A six-axis industrial robot is an industrial robot that mimics the structure of a human arm and has six rotary joint axes. Due to its high degree of freedom, it can achieve complex spatial trajectories and multi-angle operations, and is widely used in automation fields such as welding, handling, assembly, and painting. As a key component of the second axis of a six-axis robot, the steering mechanism directly determines the overall motion accuracy and load capacity of the six-axis industrial robot. Therefore, this part has extremely high dimensional accuracy, excellent internal compactness, and a complex internal cavity structure.

[0003] The aforementioned steering mechanism is a high-precision, integrated housing casting, such as... Figures 1 to 5 As shown, it mainly includes a gear housing connected to the first shaft, a transmission housing connected to the transmission mechanism, and a connecting housing connected to the robotic arm. Currently, the castings of this steering mechanism are mainly produced using a low-pressure casting process combined with sand molds and sand cores. This is because sand molds and sand cores can create the sand molds and complex internal cavity structures required for the steering mechanism castings through an outer mold and a combined core box, such as irregularly shaped oil passages, asymmetrical assembly cavities, and multi-angle connection channels; at the same time, the sand mold and sand core material has good collapsibility, making it easy to remove after the casting solidifies; and the production cost of sand molds and sand cores is low. However, the strength and hardness of sand molds and sand cores are limited, and micro-deformation may occur under the continuous pressure during the low-pressure casting process, leading to a reduction in the accuracy of the steering mechanism castings. Summary of the Invention

[0004] In view of this, it is necessary to provide a low-pressure casting mold and casting method for a six-axis industrial robot steering mechanism. The aim is to design a matching metal mold based on the structural characteristics of the steering mechanism casting to improve the strength and hardness of the mold, thereby reducing the dimensional deviation of the steering mechanism casting caused by the micro-deformation of the mold during the low-pressure casting process, and thus improving the accuracy of the steering mechanism casting.

[0005] In a first aspect, the present invention provides a low-pressure casting mold for a six-axis industrial robot steering mechanism, comprising an upper mold, a lower mold, a side mold, and an inner mold. The upper mold, lower mold, and side mold are made of metal, and the inner mold is made of molding sand. The bottom of the upper mold is provided with an upper cavity adapted to the upper part of the steering mechanism casting. The top of the lower mold is provided with a lower cavity adapted to the lower part of the steering mechanism casting. The first side of the side mold is provided with a side cavity adapted to the side part of the steering mechanism casting. The bottom surface of the upper mold is detachably mounted on the top surface of the lower mold, and the same side of the upper mold and the lower mold together constitute a parting surface arranged in a vertical direction. The first side of the side mold is detachably mounted on the parting surface. The bottom of the inner mold overlaps the top of the lower mold and is located in the lower cavity, so that the inner mold, upper cavity, lower cavity, and side cavity form a complete cavity that matches the shape of the steering mechanism casting.

[0006] Preferably, the bottom surface of the upper mold has three first positioning holes, and the top surface of the lower mold has three second positioning holes, with each first positioning hole and each second positioning hole facing each other, so that the upper mold and the lower mold can be detachably connected by inserting positioning pins corresponding to the first positioning holes and the second positioning holes; the parting surface has four third positioning holes, of which two third positioning holes are located in the upper mold and two third positioning holes are located in the lower mold; the first side of the side mold has four fourth positioning holes, with each third positioning hole and the fourth positioning hole facing each other, so that the side mold and the parting surface can be detachably connected by inserting positioning pins corresponding to the third positioning holes and the fourth positioning holes.

[0007] Preferably, the top of the upper cavity is provided with an overflow riser; the top surface of the upper mold is provided with two rectangular air-cooling cavities, which are respectively located at the hot joints corresponding to the steering mechanism casting, and their bottoms are kept at a predetermined distance from the upper cavity; the top surface of the upper mold has at least two exhaust plugs communicating with the upper cavity.

[0008] Preferably, the low-pressure casting mold for the six-axis industrial robot steering mechanism further includes a split part, which is fixedly installed at the bottom of the upper mold, and its forming surface forms part of the upper cavity for forming the connecting shell part of the steering mechanism casting.

[0009] Preferably, the bottom surface of the lower mold has a gate, and a gate sleeve is provided on the gate; a main runner is provided inside the lower mold from the gate sleeve upward; the top of the main runner is branched into at least two branch runners, and each branch runner is connected to the lower cavity.

[0010] Preferably, the top of the lower mold is provided with at least two overlapping protrusions and overlapping blocks. One side of the overlapping block is close to the parting surface, and the other side has a positioning groove. The bottom of the inner mold is provided with a positioning core head that matches the overlapping protrusions and positioning groove, so that the bottom of the inner mold can overlap the top of the lower mold.

[0011] Preferably, the first side of the side mold has a transverse runner along the circumference of the gear housing of the steering mechanism casting, and at least two ingates are provided between the transverse runner and the gear housing of the steering mechanism casting, so that the molten metal fills the side cavity along the circumference of the gear housing; the transverse runner is also connected to a branch runner so that the molten metal from the self-gating runner can be introduced into each ingate in the future.

[0012] Preferably, the cross section of the horizontal gating is trapezoidal, and the end near the parting surface is a long base, so as to guide the molten metal to flow smoothly along the parting surface direction; the cross section of each ingate is trapezoidal, and the end near the horizontal gating is a long base, so as to buffer the molten metal flowing from the horizontal gating into the ingate.

[0013] Preferably, the top of the parting surface has at least two rectangular venting grooves along the vertical direction, the bottom of each venting groove is connected to the complete cavity, and the top is connected to the outside.

[0014] In a second aspect, the present invention provides a low-pressure casting method based on the low-pressure casting mold for the steering mechanism of a six-axis industrial robot as described in the first aspect, comprising the following steps:

[0015] S1. Pour the molten aluminum that meets the requirements into the low-pressure holding furnace and maintain the temperature of the molten aluminum at 705~715℃.

[0016] S2, perform a mold closing operation on the preheated upper mold, lower mold, side mold and inner mold to form a complete cavity;

[0017] S3, apply a first predetermined pressure to the low-pressure holding furnace so that the molten aluminum is smoothly filled into the complete cavity through the sprue sleeve, main runner, branch runner, horizontal runner and ingate;

[0018] S4, apply a second predetermined pressure to the low-pressure holding furnace and maintain it for a first predetermined time, so that the molten aluminum solidifies under the pressure;

[0019] S5, depressurize and allow the low-pressure casting mold of the steering mechanism to cool for a second predetermined time, so that the unsolidified aluminum liquid flows back to the holding furnace;

[0020] S6, open the low-pressure casting mold of the steering mechanism, remove the steering mechanism casting, and separate the inner mold from the steering mechanism casting.

[0021] The aforementioned low-pressure casting mold for the steering mechanism of a six-axis industrial robot includes an upper mold, a lower mold, a side mold, and an inner mold. The upper mold, lower mold, and side mold are made of metal, while the inner mold is made of molding sand. The bottom of the upper mold has an upper cavity that corresponds to the upper part of the steering mechanism casting. The top of the lower mold has a lower cavity that corresponds to the lower part of the steering mechanism casting. The first side of the side mold has a side cavity that corresponds to the side part of the steering mechanism casting. The bottom surface of the upper mold is detachably mounted on the top surface of the lower mold, and the same side of the upper and lower molds together form a parting surface arranged vertically. The first side of the side mold is detachably mounted on the parting surface. The bottom of the inner mold overlaps the top of the lower mold and is located within the lower cavity, so that the inner mold, upper cavity, lower cavity, and side cavity form a complete cavity that matches the shape of the steering mechanism casting. The upper, lower, and side molds made of metal are used to construct the forming cavity of the main body of the steering mechanism casting. Compared with molding sand molds, metal molds have higher strength and hardness, and can effectively resist micro-deformation under continuous pressure during low-pressure casting, thereby ensuring the dimensional stability of the main body structure of the casting formed by the upper, lower, and side cavities. At the same time, an inner mold made of molding sand is used to form the complex internal cavity structure required for the steering mechanism casting, taking advantage of its good formability. The complete cavity formed by the upper, lower, side, and inner molds ensures that the complex internal cavity structure of the steering mechanism casting can be formed smoothly, while the high-rigidity metal mold body bears the pressure and shapes it, thereby reducing the dimensional deviation of the steering mechanism casting caused by micro-deformation of the mold during low-pressure casting, and thus improving the accuracy of the steering mechanism casting. Attached Figure Description

[0022] Figure 1 This is a perspective view of the steering mechanism of this application.

[0023] Figure 2 This is a perspective view of the steering mechanism of this application from another angle.

[0024] Figure 3 This is a front view of the steering mechanism of this application.

[0025] Figure 4 This is a top view of the steering mechanism of this application.

[0026] Figure 5 This is a bottom view of the steering mechanism of this application.

[0027] Figure 6 This is a perspective view of the low-pressure casting mold for the steering mechanism of the six-axis industrial robot of this application.

[0028] Figure 7 This is an exploded top view of the low-pressure casting mold for the steering mechanism of the six-axis industrial robot of this application.

[0029] Figure 8 This is an exploded top view of the low-pressure casting mold of the six-axis industrial robot steering mechanism of this application from another direction.

[0030] Figure 9 This is an exploded view from an upward angle of the low-pressure casting mold for the steering mechanism of the six-axis industrial robot of this application.

[0031] Figure 10 This is a top view of the low-pressure casting mold for the six-axis industrial robot steering mechanism of this application.

[0032] Figure 11 yes Figure 10 A cross-sectional view of plane AA.

[0033] Figure 12 yes Figure 10 A cross-sectional view of the C-plane.

[0034] Figure 13 This is a side view of the low-pressure casting mold for the six-axis industrial robot steering mechanism of this application.

[0035] Figure 14 yes Figure 13 A cross-sectional view of the BB plane.

[0036] Figure 15 This is a perspective view of the low-pressure casting mold of the six-axis industrial robot steering mechanism of this application when the side mold is not installed.

[0037] Figure 16 This is a perspective view of the upper mold of this application.

[0038] Figure 17 This is a perspective view of the upper mold of this application from another angle.

[0039] Figure 18 This is a perspective view of the lower mold of this application.

[0040] Figure 19 This is a perspective view of the lower mold of this application from another angle.

[0041] Figure 20 This is a top view of the lower mold of this application.

[0042] Figure 21 This is a perspective view of the inner mold of this application.

[0043] Figure 22 This is a perspective view of the inner mold of this application from another angle.

[0044] Figure 23 This is a perspective view of the side mold of this application.

[0045] Figure 24 This is a front view of the side mold of this application.

[0046] Figure 25 This is a flowchart of the low-pressure casting method of this application.

[0047] In the diagram: a six-axis industrial robot steering mechanism low-pressure casting mold 10, upper mold 20, upper cavity 21, first positioning hole 22, overflow riser 23, air-cooling cavity 24, vent plug 25, lower mold 30, lower cavity 31, second positioning hole 32, gate 33, gate sleeve 34, main runner 35, branch runner 36, overlapping protrusion 37, overlapping block 38, positioning groove 39, side mold 40, side cavity 41, fourth positioning hole 42, horizontal runner 43, inner runner 44, inner mold 50, positioning core head 51, parting surface 60, third positioning hole 62, vent groove 63, and split body 70. Detailed Implementation

[0048] The technical solutions and effects of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0049] Please refer to Figures 6 to 18In a first aspect, the present invention provides a low-pressure casting mold 10 for a six-axis industrial robot steering mechanism, comprising an upper mold 20, a lower mold 30, a side mold 40, and an inner mold 50. The upper mold 20, lower mold 30, and side mold 40 are made of metal, and the inner mold 50 is made of molding sand. The bottom of the upper mold 20 is provided with an upper cavity 21 adapted to the upper part of the steering mechanism casting; the top of the lower mold 30 is provided with a lower cavity 31 adapted to the lower part of the steering mechanism casting; the side mold 40... The first side is provided with a side cavity 41 adapted to the side part of the steering mechanism casting; the bottom surface of the upper mold 20 is detachably mounted on the top surface of the lower mold 30, and the same side of the upper mold 20 and the lower mold 30 together form a parting surface 60 arranged in the vertical direction; the first side of the side mold 40 is detachably mounted on the parting surface 60, and the bottom of the inner mold 50 overlaps the top of the lower mold 30 and is located in the lower cavity 31, so that the inner mold 50, the upper cavity 21, the lower cavity 31 and the side cavity 41 are arranged in the same way. A complete cavity matching the shape of the steering mechanism casting is formed between the upper mold 20, lower mold 30, and side mold 40 made of metal. Thus, the forming cavity of the main body of the steering mechanism casting is constructed. Compared with molding sand mold, metal mold has higher strength and hardness, and can effectively resist micro-deformation under continuous pressure during low-pressure casting, thereby ensuring the dimensional stability of the main body structure of the casting formed by the upper cavity 21, lower cavity 31, and side cavity 41. At the same time, the inner mold 50 made of molding sand is used to form the complex internal cavity structure required by the steering mechanism casting by utilizing its good formability. The complete cavity formed by the upper mold 20, lower mold 30, side mold 40, and inner mold 50 ensures that the complex internal cavity structure of the steering mechanism casting can be formed smoothly. The high-rigidity metal mold body bears pressure and shapes the casting, thereby reducing the dimensional deviation of the steering mechanism casting caused by micro-deformation of the mold during low-pressure casting, and thus improving the accuracy of the steering mechanism casting.

[0050] In this embodiment, the parting surface 60 is set on multiple outer contour planes of the steering mechanism casting, and the planes are connected by inclined planes or arc surfaces. This design makes the contact surface between the side mold 40 and the parting surface 60 mainly a plane or a gently curved surface, which greatly reduces the resistance and wear of opening and closing the mold and facilitates the opening and closing operation of the mold. On the other hand, setting the parting surface 60 mainly on the plane or near-plane area of ​​the casting itself can make the division of the mold cavity more reasonable, effectively reducing defects such as flash and misalignment that may be caused by the parting surface 60 passing through complex curved surfaces or key mating surfaces. This ensures that the main contour dimensions of the steering mechanism casting formed in the low-pressure casting mold 10 of the six-axis industrial robot steering mechanism are stably within the design tolerance range, thereby ensuring the accuracy of the steering mechanism casting.

[0051] In this embodiment, the upper mold 20, lower mold 30, and side mold 40 are made of ductile iron 450, with a coefficient of thermal expansion of 12×10⁻⁶. -6 / ℃, according to the above parameters, calculate the dimensions of the upper cavity 21, lower cavity 31 and side cavity 41, which can improve the product's precision.

[0052] Please refer to Figures 15 to 18 Furthermore, the bottom surface of the upper mold 20 has three first positioning holes 22, and the top surface of the lower mold 30 has three second positioning holes 32. Each first positioning hole 22 and each second positioning hole 32 is aligned with the other, allowing for a detachable connection between the upper mold 20 and the lower mold 30 by inserting positioning pins corresponding to the first and second positioning holes 22 and 32. The parting surface 60 has four third positioning holes 62, with two third positioning holes 62 located in the upper mold 20 and two in the lower mold 30. The first side of the side mold 40 has four fourth positioning holes 62. Positioning holes 42, and third positioning holes 62 and fourth positioning holes 42 are arranged opposite each other, so that the side mold 40 and the parting surface 60 can be detachably connected by inserting positioning pins corresponding to the third positioning holes 62 and the fourth positioning holes 42; specifically, by setting the first positioning hole 22, the second positioning hole 32, the third positioning hole 62 and the fourth positioning hole 42, the upper mold 20, the lower mold 30 and the side mold 40 can be quickly and accurately closed, reducing the difficulty of the mold closing operation, shortening the mold closing time, and ensuring that the position of each cavity is consistent after each mold closing.

[0053] Please refer to Figure 12 , Figure 16 and Figure 17 Furthermore, the top of the upper cavity 21 is provided with an overflow riser 23; the top surface of the upper mold 20 is provided with two rectangular air-cooling chambers 24, which are respectively located at the hot spots corresponding to the steering mechanism casting, and their bottoms are kept at a predetermined distance from the upper cavity 21; the top surface of the upper mold 20 has at least two vent plugs 25 communicating with the upper cavity 21; specifically, the overflow riser 23 can effectively collect the oxide slag generated by the oxidation of the molten metal during the filling process and exclude it from the steering mechanism casting, thereby improving the purity of the steering mechanism casting; the air-cooling chamber 24 located above the hot spot cools the area by introducing room temperature compressed air, changing the solidification sequence at the hot spot so that it solidifies before the surrounding thin-walled areas, thereby reducing the risk of shrinkage porosity and shrinkage defects caused by the molten metal at the hot spot solidifying last and insufficient feeding; the vent plugs 25 can allow the gas in the complete cavity to be smoothly discharged during the filling process, thereby reducing the generation of porosity defects inside the steering mechanism casting.

[0054] In this embodiment, the predetermined distance is ≥10mm.

[0055] In this embodiment, the hot spot refers to the area in the steering mechanism casting with a large wall thickness, poor heat dissipation conditions, and where the molten metal is the last to solidify. It is the position on the transmission shell of the steering mechanism casting corresponding to the air-cooled cavity 24.

[0056] Please refer to Figure 17 Furthermore, the low-pressure casting mold 10 for the six-axis industrial robot steering mechanism also includes a split part 70. The split part 70 is fixedly installed at the bottom of the upper mold 20, and its forming surface constitutes part of the upper cavity 21 for forming the connecting shell part of the steering mechanism casting. Specifically, the top of the upper mold 20 has two connecting holes communicating with the outside, and the split part 70 has two corresponding mounting holes. The split part 70 is fastened to the designated position of the upper cavity 21 at the bottom of the upper mold 20 by screwing bolts through the mounting holes into the connecting holes. The reason for adopting a split design for this part is mainly based on two considerations: firstly, this part is a hollow structure in the casting, and if it is integrated with the upper mold 20... The cavity is formed by molding, but during the filling of molten metal, gas is easily trapped at the top of the cavity. If this gas cannot be discharged smoothly, it may be drawn into the molten metal, causing porosity defects in the steering mechanism casting. However, by using a separate 70 part for independent installation, a small gap will naturally form between the assembly surface of the separate 70 and the upper mold 20. This gap can serve as an effective venting channel, allowing the trapped gas to escape, thereby improving the internal quality of the casting. Secondly, this part has a special structure. If it is machined as an integral part with the upper mold 20, the overhang length of the machining tool will be too long, which is prone to vibration during cutting. This will lead to increased surface roughness of the cavity and difficulty in ensuring dimensional accuracy, and may even affect tool life. With the separate 70 structure, it can be machined separately, effectively avoiding the process problems caused by the excessive overhang length of the machining tool and ensuring the machining quality of the formed surface.

[0057] Please refer to Figure 14 and Figures 18 to 20 Furthermore, the bottom surface of the lower mold 30 has a gate 33, and a gate sleeve 34 is provided on the gate 33; a main runner 35 is provided inside the lower mold 30 from the gate sleeve 34 upwards; the top of the main runner 35 branches into at least two branch runners 36, and each branch runner 36 is connected to the lower cavity 31; specifically, the main runner 35 is divided into multiple branch runners 36, so that the molten metal can fill the cavity synchronously and smoothly from multiple positions, avoiding turbulence, air entrapment and local overheating caused by the excessively fast filling speed of a single gate 33, making the temperature field distribution of the molten metal more uniform, thereby shortening the filling time and reducing oxide inclusions.

[0058] Please refer to Figures 18 to 20Furthermore, the top of the lower mold 30 is provided with at least two overlapping protrusions 37 and overlapping blocks 38. One side of the overlapping block 38 is close to the parting surface 60, and the other side has a positioning groove 39. The bottom of the inner mold 50 is provided with a positioning core head that matches the overlapping protrusions 37 and positioning groove 39, so that the bottom of the inner mold 50 can overlap the top of the lower mold 30. Specifically, through the cooperation of the protrusions, overlapping blocks 38 and core head, the inner mold 50 is provided with precise and stable positioning and support to prevent the inner mold 50 from shifting or floating during the mold closing process or under the impact of molten metal filling, thus ensuring the accuracy of the dimensions of the complex inner cavity formed by molding sand.

[0059] Please refer to Figures 23 to 24 Furthermore, the first side of the side mold 40 has a transverse sprue 43 circumferentially arranged along the gear housing of the steering mechanism casting, and at least two ingates 44 are provided between the transverse sprue 43 and the gear housing of the steering mechanism casting, so that the molten metal fills the side cavity 41 circumferentially along the gear housing; the transverse sprue 43 is also connected to a branch sprue 36, so that the molten metal from the self-gating sprue 35 can be introduced into each ingate 44 in the future; specifically, the annular transverse sprue 43 arranged around the gear housing, together with multiple ingates 44, achieves circumferentially balanced filling of the gear housing area; this design can evenly disperse the heat brought in by the molten metal, prevent overheating in local areas of the gear housing, and thus avoid shrinkage problems caused by slow cooling in that area; at the same time, the large annular transverse sprue 43 serves as a good feeding channel, which can continuously provide molten aluminum for feeding during the solidification of the gear housing, thereby preventing internal defects in the steering mechanism casting caused by insufficient feeding.

[0060] Please refer to Figures 23 to 24 Furthermore, the cross-section of the horizontal sprue 43 is trapezoidal, with a long base at the end near the parting surface 60 to guide the molten metal to flow smoothly along the parting surface 60. The cross-section of each ingate 44 is trapezoidal, with a long base at the end near the horizontal sprue 43 to buffer the molten metal flowing from the horizontal sprue 43 into the ingate 44. Specifically, the trapezoidal horizontal sprue 43 guides the molten metal flow to turn smoothly, reducing turbulence. The trapezoidal ingate 44 adopts a "wide inlet, narrow outlet" cross-sectional change, which buffers and rectifyes the molten metal from the horizontal sprue 43, allowing it to enter the gear housing cavity at a more stable speed, thereby reducing splashing, air entrapment, and oxidation of the molten metal during the filling process and improving the internal quality of the casting.

[0061] Please refer to Figure 11 and Figure 15Furthermore, at least two rectangular venting grooves 63 are vertically opened on the top of the parting surface 60. The bottom end of each venting groove 63 is connected to the complete cavity, and the top end is connected to the outside. Specifically, the venting grooves 63 and the venting plugs 25 of the upper mold together form a three-dimensional venting system. They are located at the highest point of the cavity and the area where gas is most likely to accumulate. They can efficiently discharge the gas deep in the cavity and at the top in the later stage of filling, thereby reducing the porosity defects at the top or dead corner of the casting.

[0062] Please refer to Figure 25 Secondly, the present invention provides a low-pressure casting method for a low-pressure casting mold 10 for a six-axis industrial robot steering mechanism based on the first aspect, comprising the following steps:

[0063] S1. Pour the molten aluminum that meets the requirements into the low-pressure holding furnace and maintain the temperature of the molten aluminum at 705~715℃.

[0064] S2, perform a mold closing operation on the preheated upper mold 20, lower mold 30, side mold 40 and inner mold 50 to form a complete cavity;

[0065] S3, apply a first predetermined pressure to the low-pressure holding furnace, so that the aluminum liquid is smoothly filled into the complete cavity through the sprue sleeve 34, main runner 35, branch runner 36, horizontal runner 43 and inner runner 44.

[0066] S4, apply a second predetermined pressure to the low-pressure holding furnace and maintain it for a first predetermined time to allow the molten aluminum to solidify under this pressure; the second predetermined pressure is 410 mbar and the first predetermined time is 400 s;

[0067] S5, depressurize and allow the low-pressure casting mold of the steering mechanism to cool for a second predetermined time, allowing the unsolidified aluminum liquid to flow back to the holding furnace; the second predetermined time is 100s;

[0068] S6, open the low-pressure casting mold of the steering mechanism, take out the steering mechanism casting, and separate the inner mold 50 from the steering mechanism casting.

[0069] In this embodiment, step S2 includes:

[0070] S201, install the upper mold 20, lower mold 30, and side mold 40 into their corresponding positions on the low-pressure casting equipment and fix them in place; subsequently,

[0071] S202, the upper mold 20, lower mold 30 and side mold 40 are preheated to 200~300℃ by the equipment heating system or external heating device;

[0072] S203, uniformly spray coating on the surfaces of the upper cavity 21, lower cavity 31 and side cavity 41, and control the coating thickness to be 0.15-0.3mm;

[0073] S204, heat the upper mold 20, lower mold 30 and side mold 40 to 300~400℃ to dry the coating;

[0074] S205, the inner mold 50 is aligned with the positioning core at its bottom and the positioning groove 39 on the overlapping protrusion 37 and overlapping block 38 on the top of the lower mold 30, and placed stably so that the inner mold 50 is stably overlapped at the predetermined position on the top of the lower mold 30.

[0075] S206, the upper mold 20 is driven downward by the low-pressure casting equipment to align its bottom surface with the top surface of the lower mold 30. Then, positioning pins are inserted into the corresponding first positioning hole 22 and second positioning hole 32 to complete the precise closure of the upper mold 20 and the lower mold 30, forming the main mold.

[0076] S207, the first side of the side mold 40 is aligned with the parting surface 60 by the low-pressure casting equipment, and the positioning pin is inserted into the corresponding third positioning hole 62 and fourth positioning hole 42 to complete the closure of the side mold 40 and the main mold.

[0077] Specifically, the coating is a water-based refractory coating, which provides heat insulation, lubrication, prevents direct contact between molten metal and mold cavity, and improves the surface quality of castings.

[0078] In this embodiment, step S3 includes:

[0079] S301, Dry gas is introduced into the heat preservation furnace;

[0080] S302, pressurize the holding furnace to 190mbar and hold for 19 seconds to allow the molten aluminum to rise steadily and begin filling the cavity;

[0081] S303, pressurize the holding furnace to 290mbar and hold for 12 seconds to accelerate the filling of the main cavity of the aluminum liquid;

[0082] S304, pressurize the holding furnace to 350mbar and hold for 2 seconds to completely fill the cavity with molten aluminum and begin to build up crystallization pressure;

[0083] S305, pressurize the holding furnace to 410 mbar and hold for 10 seconds to allow the molten aluminum to fill the mold under high pressure and prepare for the subsequent pressure holding and solidification stage.

[0084] Example 1: Assembly process of low-pressure casting mold 10 for the steering mechanism of a six-axis industrial robot

[0085] 1. Preheat the upper mold 20, lower mold 30 and side mold 40 to 200~300℃;

[0086] 2. Apply water-based refractory coating evenly to the surface of the upper cavity 21, the surface of the lower cavity 31, and the surface of the side cavity 41, and control the coating thickness to be 0.15-0.3mm;

[0087] 3. Heat the upper mold 20, lower mold 30 and side mold 40 after spraying to 300~400℃ to dry the paint;

[0088] 4. After placing the lower mold 30, align the positioning core at the bottom of the inner mold 50 with the positioning groove 39 on the overlapping protrusion 37 and overlapping block 38 at the top of the lower mold 30, and place the inner mold 50 stably so that the inner mold 50 is securely overlapped at the predetermined position on the top of the lower mold 30.

[0089] 5. Align the bottom surface of the upper mold 20 with the top surface of the lower mold 30, so that the three first positioning holes 22 on the bottom surface of the upper mold 20 are aligned with the three second positioning holes 32 on the top surface of the lower mold 30. Insert the positioning pins into the corresponding first positioning holes 22 and second positioning holes 32 to complete the closure of the upper mold 20 and the lower mold 30. At this time, the same side of the upper mold 20 and the lower mold 30 together form the parting surface 60 set in the vertical direction.

[0090] 6. Align the first side of the side mold 40 with the parting surface 60, so that the four fourth positioning holes 42 on the first side of the side mold 40 are aligned with the four third positioning holes 62 on the parting surface 60. Insert the positioning pins into the corresponding third positioning holes 62 and fourth positioning holes 42 to complete the closure of the side mold 40 and the parting surface 60.

[0091] At this time, the inner mold 50, the upper cavity 21 of the upper mold 20, the lower cavity 31 of the lower mold 30, and the side cavity 41 of the side mold 40 together form a complete cavity that matches the shape of the steering mechanism casting.

[0092] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A low-pressure casting mold for a six-axis industrial robot steering mechanism, characterized in that, The system includes an upper mold, a lower mold, a side mold, and an inner mold. The upper mold, lower mold, and side mold are made of metal, while the inner mold is made of molding sand. The bottom of the upper mold has an upper cavity that adapts to the upper part of the steering mechanism casting. The top of the lower mold has a lower cavity that adapts to the lower part of the steering mechanism casting. The first side of the side mold has a side cavity that adapts to the side part of the steering mechanism casting. The bottom surface of the upper mold is detachably mounted on the top surface of the lower mold, and the same side of the upper and lower molds together form a parting surface arranged in the vertical direction. The first side of the side mold is detachably mounted on the parting surface. The bottom of the inner mold overlaps the top of the lower mold and is located in the lower cavity, so that the inner mold, upper cavity, lower cavity, and side cavity form a complete cavity that matches the shape of the steering mechanism casting.

2. The low-pressure casting mold for the steering mechanism of a six-axis industrial robot as described in claim 1, characterized in that, The upper mold has three first positioning holes on its bottom surface, and the lower mold has three second positioning holes on its top surface. The first and second positioning holes are aligned with each other, allowing for a detachable connection between the upper and lower molds by inserting positioning pins corresponding to the first and second positioning holes. The parting surface has four third positioning holes, two located in the upper mold and two in the lower mold. The first side of the side mold has four fourth positioning holes, with the third and fourth positioning holes aligned with each other, allowing for a detachable connection between the side mold and the parting surface by inserting positioning pins corresponding to the third and fourth positioning holes.

3. The low-pressure casting mold for the six-axis industrial robot steering mechanism as described in claim 1, characterized in that, The top of the upper cavity is provided with an overflow riser; the top surface of the upper mold is provided with two rectangular air-cooling cavities, which are respectively located at the hot joints corresponding to the steering mechanism casting, and their bottoms are kept at a predetermined distance from the upper cavity; the top surface of the upper mold has at least two exhaust plugs that communicate with the upper cavity.

4. The low-pressure casting mold for the six-axis industrial robot steering mechanism as described in claim 1, characterized in that, The low-pressure casting mold for the six-axis industrial robot steering mechanism also includes a split part, which is fixedly installed at the bottom of the upper mold. Its forming surface forms part of the upper cavity and is used to form the connecting shell part of the steering mechanism casting.

5. The low-pressure casting mold for the steering mechanism of a six-axis industrial robot as described in claim 1, characterized in that, The bottom surface of the lower mold has a gate, and a gate sleeve is provided on the gate; a main runner is provided inside the lower mold from the gate sleeve upward; the top of the main runner is branched into at least two branch runners, and each branch runner is connected to the lower cavity.

6. The low-pressure casting mold for the steering mechanism of a six-axis industrial robot as described in claim 1, characterized in that, The top of the lower mold is provided with at least two overlapping protrusions and overlapping blocks. One side of the overlapping block is close to the parting surface, and the other side has a positioning groove. The bottom of the inner mold is provided with a positioning core head that matches the overlapping protrusions and positioning groove, so that the bottom of the inner mold can overlap the top of the lower mold.

7. The low-pressure casting mold for the steering mechanism of a six-axis industrial robot as described in claim 1, characterized in that, The first side of the side mold has a horizontal runner along the circumference of the gear housing of the steering mechanism casting, and at least two ingates are provided between the horizontal runner and the gear housing of the steering mechanism casting, so that the molten metal fills the side cavity along the circumference of the gear housing; the horizontal runner is also connected to a branch runner so that the molten metal from the future self-gating channel can be introduced into each ingate.

8. The low-pressure casting mold for the steering mechanism of a six-axis industrial robot as described in claim 7, characterized in that, The cross-section of the horizontal gating is trapezoidal, and the end near the parting surface is a long base to guide the molten metal to flow smoothly along the parting surface direction; the cross-section of each ingate is trapezoidal, and the end near the horizontal gating is a long base to buffer the molten metal flowing from the horizontal gating into the ingate.

9. The low-pressure casting mold for the steering mechanism of a six-axis industrial robot as described in claim 1, characterized in that, The top of the parting surface has at least two rectangular venting grooves along the vertical direction. The bottom of each venting groove is connected to the complete cavity, and the top is connected to the outside.

10. A low-pressure casting method based on the low-pressure casting mold of the six-axis industrial robot steering mechanism according to any one of claims 1 to 9, characterized in that, Includes the following steps: S1. Pour the molten aluminum that meets the requirements into the low-pressure holding furnace and maintain the temperature of the molten aluminum at 705~715℃. S2, perform a mold closing operation on the preheated upper mold, lower mold, side mold and inner mold to form a complete cavity; S3, apply a first predetermined pressure to the low-pressure holding furnace so that the molten aluminum is smoothly filled into the complete cavity through the sprue sleeve, main runner, branch runner, horizontal runner and ingate; S4, apply a second predetermined pressure to the low-pressure holding furnace and maintain it for a first predetermined time, so that the molten aluminum solidifies under the pressure; S5, depressurize and allow the low-pressure casting mold of the steering mechanism to cool for a second predetermined time, so that the unsolidified aluminum liquid flows back to the holding furnace; S6, open the low-pressure casting mold of the steering mechanism, remove the steering mechanism casting, and separate the inner mold from the steering mechanism casting.

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