A process for the integral casting of a draw pin
By using core box preparation of sand cores and three-box molding process, the integral casting of traction pins was achieved, solving the safety and high cost problems caused by assembly method, and ensuring casting quality and production efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CRRC DALIAN CO LTD
- Filing Date
- 2023-11-20
- Publication Date
- 2026-06-19
AI Technical Summary
In existing technologies, traction pins are assembled using an assembly method, which can easily lead to angular deviations that cause safety issues. Furthermore, the process involves a large amount of machining, high costs, and a lack of integrated casting technology.
The process of preparing sand cores using a core box and a three-box molding process is used to achieve the integral casting of the upper traction body and the center pin. This includes preparing sand cores, making molds, and performing bottom pouring to ensure that the casting quality is up to standard.
The integral casting of the traction pin was achieved, the casting quality was qualified, it met the flaw detection requirements, and the production cost was reduced.
Smart Images
Figure CN117680644B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of traction pin casting technology, and more particularly to an integral casting process for traction pins. Background Technology
[0002] Currently, the upper traction body is assembled by combining the upper traction body and the center pin. The upper traction body is made of C-grade steel and produced by casting, while the center pin is made of 42CrMo and produced by forging. Due to the high product size, a reasonable integral casting process has not yet been designed. In actual use, this structure is prone to misalignment of the anti-loosening line. This is caused by angular deviation between the traction pin and the lower traction body, resulting in improper installation of the pressure plate and loosening of the bolts. This can cause significant safety problems during locomotive operation. In addition, the traction pin forging requires full-body machining. In the current technology, the traction pin is produced by free forging, resulting in a large machining volume and high production cost. There is an urgent need to study an integral structure production process for the upper traction structure that is easy to machine. Summary of the Invention
[0003] In view of the technical problems existing in the prior art, a casting process for integral traction pins is provided, which can realize the integral casting of traction body and center pin for subway use, while ensuring the quality of castings and meeting the requirements of magnetic particle testing, ultrasonic testing and processing acceptance.
[0004] The technical means employed in this invention are as follows:
[0005] A process for integral casting of a traction pin, wherein the traction pin includes an upper traction body, a central pin, and a lateral shock absorber seat; specifically including the following steps:
[0006] S1. A sand core for casting the inner cavity of the upper traction body is prepared using a core box.
[0007] The core box has a three-section structure, including an upper movable block, a middle movable block, and a lower movable block. The cavity in the middle of the core box conforms to the shape of the inner cavity of the upper traction body. The sand-pounding port of the core box is located in the upper movable block. The lower movable block has a split structure, and the two parts are connected by nuts.
[0008] When preparing the sand core, the lower layer block is first pounded with sand. Then, several conformal chills are placed at intervals along the bottom rounded corners of the lower layer block. The middle layer block is installed on the lower layer block. The middle layer block is then pounded with sand, and a lifting wire ring for core lifting is embedded in the sand. Finally, the upper layer block is installed, the pounded sand surface is smoothed, and after the sand core has hardened completely, the upper layer block, the middle layer block, and the lower layer block are removed, and the prepared sand core is lifted out.
[0009] S2. Make a traction pin mold according to the structure of the traction pin, including an upper traction body part, a central pin part and a transverse shock absorber seat part;
[0010] Sand molds, including lower, middle, and upper molds, are prepared using a lower sand box, a middle sand box, and an upper sand box.
[0011] The inner wall of the medium sand box is an inclined surface; the upper and lower edges of the outer side of the medium sand box are provided with positioning grooves for positioning with the upper sand box and the lower sand box; the upper and lower edges of the inner side of the medium sand box are provided with inner cavity reverse edges;
[0012] The stop ring and the positioning core head are shaped in the lower sand box;
[0013] The exposed riser of the casting is shaped in the upper sand box;
[0014] S2-1, Lower mold preparation: Place the lower sand box on the bottom plate, place the prepared direct pouring ceramic pipe at the pre-set inner water inlet positioning position, and place refractory brick pieces at the corresponding position of the direct pouring inlet;
[0015] S2-2, Medium-sized preparation: Place the medium sand box on the upper traction body part of the traction pin mold, place the sprue ceramic pipe according to the pre-set positioning, lay chromite sand at the connection rounded corner position of the cone wall of the upper traction body part of the traction pin mold near the bottom plate, and lay a chilled iron plate at the bottom of the side plate of the upper traction body part of the traction pin mold. Then place the sand mortar box. When the sand reaches the side position of the upper traction body part of the traction pin mold, place the L-shaped heat-insulating riser and place the air venting rod according to the pre-set positioning. After smoothing the mortar surface, the height of the medium-sized mold is flush with the top of the center pin part of the traction pin mold. After the molding sand has established initial strength, remove the center pin part of the traction pin mold and the air venting rod. After the sand mold has completely hardened, flip the sand box and remove the upper traction body part of the traction pin mold. Then place the transverse shock absorber seat and the sand core of the center pin part above the upper traction body part of the traction pin mold.
[0016] S2-3. Upper mold preparation: Place the casting riser mold and sprue ceramic pipe according to the pre-set positioning, add sand and pound it to compact it. After it is completely hardened, take out the casting riser mold.
[0017] S3. The sand core is hoisted into place according to the positioning core head. The middle sand box and the lower sand box are positioned and joined together. Then the upper sand box and the middle sand box are positioned and joined together, so that the sprue tubes of the upper mold, the middle mold and the lower mold are connected. Then, the alignment of the sprue tubes of the upper mold, the middle mold and the lower mold is finely adjusted. The box clamps are fastened and the casting is prepared.
[0018] S4. Use bottom pouring method for casting. When pouring, the pouring spout should be 150mm away from the sprue. After filling, pause briefly, then pour more into the open riser. Cover the open riser with heat-insulating covering agent. After pouring, wait 12 hours to open the mold and clean the sand to obtain the integrally cast traction pin casting.
[0019] Furthermore, the bottom plate of the upper traction body portion of the traction pin mold is provided with a heat-insulating and heating riser with an easy-cut disc at the drilling position.
[0020] Furthermore, the bottom plate of the upper traction body part of the traction pin mold is staggered and laid flat with chills, and the gaps between the chills are filled and compacted with chromite sand.
[0021] Furthermore, an external chill is placed on the outer side of the transverse shock absorber seat portion of the traction pin mold.
[0022] Furthermore, the medium sand box is provided with several vertical triangular reinforcing ribs.
[0023] Furthermore, the middle sand box is positioned relative to the upper sand box and the lower sand box by bolts installed in the positioning groove.
[0024] Furthermore, a handle is installed on the outer frame structure of the medium sand box, and the upper part of the frame structure is cut off and a transition rounded corner is formed.
[0025] Furthermore, the upper traction body portion of the traction pin mold is provided with several anti-crack ribs at intervals corresponding to the bottom rounded corner.
[0026] Furthermore, during the medium-sized preparation, the sprue ceramic pipe placed in the medium sand box is a two-section type.
[0027] Furthermore, the core box includes the upper movable block, the middle movable block, and the lower movable block connected to each other by positioning pins.
[0028] Compared with the prior art, the present invention has the following advantages:
[0029] The integral casting process for traction pins provided by this invention enables the integral casting of the upper traction body and the center pin. The castings have undergone inspections such as magnetic particle testing, ultrasonic testing, density analysis, and machining verification, and no quality problems were found, meeting the quality target requirements. At the same time, it fills the technical gap in integral casting of locomotive traction pins.
[0030] Based on the above reasons, this invention can be widely promoted in the field of traction pin casting. Attached Figure Description
[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0032] Figure 1 This is a schematic diagram of the integral casting process of the traction pin described in this invention.
[0033] Figure 2 This is a schematic diagram of the sand box structure described in this invention.
[0034] Figure 3 This is a schematic diagram of the cross-sectional structure of the sand box described in this invention.
[0035] Figure 4 This is a schematic diagram of the cross-sectional structure of the core box described in this invention.
[0036] In the diagram: 1. Upper traction body; 2. Center pin; 3. Lateral shock absorber seat; 4. Medium sand box; 41. Reinforcing rib; 42. Inner cavity reverse edge; 43. Positioning groove; 44. Box handle; 45. Frame structure; 46. Transition rounded corner; 5. Core box; 51. Sand pounding port; 52. Bottom rounded corner; 6. L-shaped heat-generating riser; 7. Air vent; 8. External chill; 9. Bottom plate. Detailed Implementation
[0037] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.
[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0039] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.
[0040] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values of the components and steps described in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.
[0041] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.
[0042] For ease of description, spatial relative terms such as "above," "over," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation besides the orientation of the device as described in the figures. For example, if the device in the figures is inverted, a device described as "above" or "above" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.
[0043] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.
[0044] Example 1
[0045] like Figure 1-4 As shown, this invention provides an integral casting process for a traction pin. The traction pin includes an upper traction body 1, a central pin 2, and a transverse shock absorber seat 3. The traction pin is approximately 700 mm high. The integral casting process for the traction pin employs ester-hardened water glass sand molding and core making. Considering the molding operation and ensuring casting quality, this invention adopts a three-box molding casting process. Specifically, it includes the following steps:
[0046] S1. A sand core for casting the inner cavity of the upper traction body 1 is prepared using a core box 5.
[0047] The core box 5 has a three-section structure, including an upper movable block, a middle movable block, and a lower movable block connected to each other by positioning pins. The cavity in the middle of the core box conforms to the shape of the inner cavity of the upper traction body 1. The sand pounding port 51 of the core box 5 is located in the upper movable block. The lower movable block has a split structure, and the two parts are connected by nuts. The structural design of the core box 5 of the present invention facilitates insertion during the core making process. Making the sand pounding port 51 a separate movable block structure facilitates the manufacturing of the rounded corners of the sand core.
[0048] When preparing the sand core, the lower layer block is first pounded with sand. Then, several conformal chills are placed at intervals along the bottom rounded corner 52 of the lower layer block. The middle layer block is installed on the lower layer block. The middle layer block is then pounded with sand, and a lifting wire ring for core lifting is embedded in the sand. Finally, the upper layer block is installed, the pounded sand surface is smoothed, and after the sand core has hardened completely, the upper layer block, the middle layer block, and the lower layer block are removed, and the prepared sand core is lifted out.
[0049] S2. Make a traction pin mold according to the structure of the traction pin, including an upper traction body part, a central pin part and a transverse shock absorber seat part;
[0050] Sand molds, including lower, middle, and upper molds, are prepared using a lower sand box, a middle sand box, and an upper sand box.
[0051] The traction pin casting is molded in the intermediate sand box 4; the height of the intermediate sand box is 680mm; the inner wall of the intermediate sand box 4 is an inclined surface at 2° with the vertical direction; the inner wall of the intermediate sand box 4 is provided with several vertical triangular reinforcing ribs 41 at intervals; the upper and lower edges of the outer side of the intermediate sand box 4 are provided with positioning grooves 43 for positioning with the upper sand box and the lower sand box; the upper and lower edges of the inner side of the intermediate sand box 4 are provided with inner cavity reverse edges 42; the inner side of the intermediate sand box 4 has no other box straps except for the reinforcing ribs 41. Such a structure makes it easy for the sand mold to come out during the box flipping process, but after the box flipping, it lacks the supporting force and adhesion of the box straps, which makes it very easy to cause the box to come out. Therefore, the intermediate sand box 4 of the present invention is provided with an inclined inner side and the inner cavity reverse edge 42; the frame structure 45 on the outer side of the intermediate sand box 4 is used to install the box handle 44, and the upper part of the frame structure 45 is cut off and a transition rounded corner 46 is formed; since the height of the sand box is too high when the box is closed, the upper part of the frame structure is removed to facilitate the box closure.
[0052] The stop ring and the positioning core are shaped in the lower sand box. In order to eliminate casting defects and misalignment with the middle sand box, the outer side of the stop ring is made of conformal chill, with a machining allowance of 10mm on both the inner and outer sides.
[0053] An external chill 8 is placed on the outer side of the transverse shock absorber seat of the traction pin; the external chill 8 is a chill rod structure, which can control the sequential solidification of the casting and prevent the generation of cracks and shrinkage defects.
[0054] The exposed riser of the casting is shaped in the upper sand box;
[0055] S2-1, Lower mold preparation: The lower sand box is placed on the bottom plate. Several cold iron plates are laid at intervals on the corresponding position of the bottom plate mold to offset the effect of high bottom pouring temperature. The gaps between the cold iron plates are filled and compacted with chromite sand. The prepared sprue ceramic pipe is placed at the pre-set inner water inlet positioning position, and refractory brick pieces are placed at the corresponding position of the sprue.
[0056] S2-2, Medium-sized preparation: Place the medium sand box 4 on the upper traction body part of the traction pin mold, and place the sprue ceramic pipe according to the pre-set positioning. Set an insulated and heating riser with an easy-cut disc at the drilled position of the bottom platen 9 of the upper traction body part of the traction pin mold. Lay chromite sand at the connecting rounded corner of the conical wall of the upper traction body part of the traction pin mold near the bottom platen 9, and lay a chilled iron plate at the bottom of the side plate of the upper traction body part of the traction pin mold. Then place the sand mortar box. When the sand volume reaches the traction... When the upper traction body part of the traction pin mold is positioned on the side, place an L-shaped heat-insulating riser 6 and place an air vent 7 according to the pre-set position. After scraping and smoothing the sand surface, the height of the medium mold is flush with the top of the center pin part of the traction pin mold. After the molding sand has built up initial strength, remove the center pin part of the traction pin mold and the air vent 7. After the sand mold has fully hardened, flip the sand box and remove the upper traction body part of the traction pin mold. Then place the transverse shock absorber seat and the sand core of the center pin part above the upper traction body part of the traction pin mold.
[0057] S2-3. Upper mold preparation: Place the casting riser mold and sprue ceramic pipe according to the pre-set positioning, add sand and pound it to compact it. After it is completely hardened, take out the casting riser mold.
[0058] S3. The sand core is hoisted into place according to the positioning core head. The middle sand box 4 and the lower sand box are positioned and joined together. Then the upper sand box and the middle sand box 4 are positioned and joined together, so that the sprue tubes of the upper mold, the middle mold and the lower mold are connected. Then, the alignment of the sprue tubes of the upper mold, the middle mold and the lower mold is finely adjusted. The box clamps are fastened and the casting is prepared.
[0059] S4. Use bottom pouring method for casting. When pouring, the pouring spout should be about 150mm away from the sprue. After filling, pause briefly, then pour more into the open riser. Cover the open riser with heat-insulating covering agent. After pouring, wait 12 hours to open the mold and clean the sand to obtain the integrally cast traction pin casting.
[0060] Furthermore, step S4 also includes grinding the areas requiring flaw detection after heat treatment, shot blasting, and cleaning of the obtained casting, performing magnetic particle testing and ultrasonic testing procedures, and applying anti-rust paint after the casting is finished.
[0061] Furthermore, in step 4, a low-return pouring method is adopted, and molten steel enters from the drilled position of the bottom plate 9 of the upper traction body part of the traction pin mold.
[0062] Furthermore, due to the large size of the traction pin body and the proximity of the sprue position to the wall of the medium sand box, the reinforcing rib 41 is not provided at the sprue position inside the medium sand box 4 corresponding to the upper traction body part of the traction pin mold.
[0063] Furthermore, the middle sand box 4 is positioned with the upper sand box and the lower sand box by bolts installed in the positioning groove 43, making the positioning between the three sand boxes more accurate and eliminating the need for the use of the upper pressure iron.
[0064] Furthermore, the box handle 44 is eccentrically upward by 50mm to facilitate the box-flipping operation when closing the box.
[0065] Furthermore, the upper traction body portion of the traction pin mold is provided with several 8mm anti-crack ribs at intervals corresponding to the bottom rounded corner 52.
[0066] Furthermore, during the medium-sized preparation, the direct casting ceramic tube placed in the medium sand box 4 is a two-section type, and the positioning of the two sections of ceramic tube adopts a small gap high positioning.
[0067] This embodiment applies the integral casting process of the traction pin described in this invention to the production of traction pins for Xi'an Metro Line 8. After heat treatment, shot blasting, and cleaning, the areas requiring flaw detection are ground, and magnetic particle testing and ultrasonic testing are performed. After the casting is finished, anti-rust paint is applied and the machining process begins. The casting passes flaw detection inspection and machining verification to prove that its quality is qualified.
[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A process for integral casting of a traction pin, characterized in that, The traction pin includes an upper traction body, a center pin, and a lateral shock absorber seat; specifically, it includes the following steps: S1. A sand core for casting the inner cavity of the upper traction body is prepared using a core box. The core box has a three-section structure, including an upper movable block, a middle movable block, and a lower movable block. The cavity in the middle of the core box conforms to the shape of the inner cavity of the upper traction body. The sand-pounding port of the core box is located in the upper movable block. The lower movable block has a split structure, and the two parts are connected by nuts. When preparing the sand core, the lower layer block is first pounded with sand. Then, several conformal chills are placed at intervals along the bottom rounded corners of the middle layer block. The middle layer block is installed on the lower layer block. The middle layer block is then pounded with sand, and wire lifting rings for core lifting are embedded in the sand. Finally, the upper layer block is installed, the pounded sand surface is smoothed, and after the sand core has hardened completely, the upper layer block, the middle layer block, and the lower layer block are removed, and the prepared sand core is lifted out. S2. Make a traction pin mold according to the structure of the traction pin, including an upper traction body part, a central pin part and a transverse shock absorber seat part; Sand molds, including lower, middle, and upper molds, are prepared using a lower sand box, a middle sand box, and an upper sand box. The inner wall of the medium sand box is an inclined surface; the upper and lower edges of the outer side of the medium sand box are provided with positioning grooves for positioning with the upper sand box and the lower sand box; the upper and lower edges of the inner side of the medium sand box are provided with inner cavity reverse edges; The stop ring and the positioning core head are shaped in the lower sand box; The exposed riser of the casting is shaped in the upper sand box; S2-1, Lower mold preparation: Place the lower sand box on the bottom plate, place the prepared direct pouring ceramic pipe at the pre-set inner water inlet positioning position, and place refractory brick pieces at the corresponding position of the direct pouring inlet; S2-2, Medium-sized preparation: Place the medium sand box on the upper traction body part of the traction pin mold, place the sprue ceramic pipe according to the pre-set positioning, lay chromite sand at the connection rounded corner position of the cone wall of the upper traction body part of the traction pin mold near the bottom plate, and lay a chilled iron plate at the bottom of the side plate of the upper traction body part of the traction pin mold. Then place the sand mortar box. When the sand reaches the side position of the upper traction body part of the traction pin mold, place the L-shaped heat-insulating riser and place the air venting rod according to the pre-set positioning. After smoothing the mortar surface, the height of the medium-sized mold is flush with the top of the center pin part of the traction pin mold. After the molding sand has established initial strength, remove the center pin part of the traction pin mold and the air venting rod. After the sand mold has completely hardened, flip the sand box and remove the upper traction body part of the traction pin mold. Then place the transverse shock absorber seat and the sand core of the center pin part above the upper traction body part of the traction pin mold. S2-3. Upper mold preparation: Place the casting riser mold and sprue ceramic pipe according to the pre-set positioning, add sand and pound it to compact it. After it is completely hardened, take out the casting riser mold. S3. The sand core prepared in step S1 is hoisted into place according to the positioning core head. The middle sand box and the lower sand box are positioned and joined together. Then the upper sand box and the middle sand box are positioned and joined together, so that the sprue tubes of the upper mold, the middle mold and the lower mold are connected. Then, the alignment of the sprue tubes of the upper mold, the middle mold and the lower mold is finely adjusted. The box clamps are fastened and the casting is prepared. S4. Use bottom pouring method for casting. When pouring, the pouring spout should be 150mm away from the sprue. After filling, pause briefly, then pour more into the open riser. Cover the open riser with heat-insulating covering agent. After pouring, wait 12 hours to open the mold and clean the sand to obtain the integrally cast traction pin casting.
2. The trunnion integral casting process of claim 1 wherein, The bottom plate of the upper traction body part of the traction pin mold is equipped with a heat-insulating and heating riser with an easy-cut disc at the drilling position.
3. The trunnion integral casting process of claim 1 wherein, The upper traction body part of the traction pin mold has staggered bottom plates with cold iron plates laid flat, and the gaps between the cold iron plates are filled and compacted with chromite sand.
4. The trunnion integral casting process of claim 1 wherein, An external chill is placed on the outer side of the transverse shock absorber seat portion of the traction pin mold.
5. The trunnion integral casting process of claim 1 wherein, The medium sand box is equipped with several vertical triangular reinforcing ribs.
6. The integral casting process for the traction pin according to claim 1, characterized in that, The middle sand box is positioned relative to the upper sand box and the lower sand box by bolts installed in the positioning groove.
7. The trunnion integral casting process of claim 1 wherein, The outer side frame structure of the medium sand box is used to install the box handle, and the upper part of the frame structure is cut off and a transition rounded corner is formed.
8. The trunnion integral casting process of claim 1 wherein, The upper traction body portion of the traction pin mold is provided with several anti-crack ribs at intervals corresponding to the bottom rounded corner.
9. The integral casting process for the traction pin according to claim 1, characterized in that, During medium-sized preparation, the sprue tube placed in the medium sand box is a two-section type.
10. The trunnion integral casting process of claim 1 wherein, The core box includes an upper movable block, a middle movable block, and a lower movable block that are interconnected by positioning pins.