Six-station cold extrusion manufacturing method for towing fixing nuts for automobile trailers

Abstract

The present invention provides a six-station cold extrusion manufacturing method for a towing fixing nut for a car trailer. The towing fixing nut for a car trailer is directly manufactured by cold extrusion of six dies. The method of the present invention can improve the utilization rate and quality of raw materials and improve production efficiency. In addition, the appearance quality is high and the product strength is high.

Description

Technical Field

[0001] The invention relates to the technical field of multi-station cold heading, in particular to a method for manufacturing a traction fixing nut for an automobile trailer. Background Art

[0002] The towing fixing nut for automobile trailers is an important fastener in the automobile towing structure. The external structure of the towing fixing nut for automobile trailers includes two cylindrical rods, and a flat cylindrical protrusion is provided at the front end of the two cylindrical rods. The diameter of the rear cylindrical rod of the two cylindrical rods is smaller than the diameter of the front cylindrical rod and is close to the diameter of the front cylindrical rod, which is 90-95% of the diameter of the front cylindrical rod. The diameter of the flat cylindrical protrusion is 115-125% of the diameter of the front cylindrical rod; the length of the rear cylindrical rod is 25-35% of the total length of the towing fixing nut for automobile trailers, and the height of the flat cylindrical protrusion is 4-8% of the total length of the towing fixing nut for automobile trailers; the towing fixing nut for automobile trailers is provided with a central through hole, the main body diameter of the central through hole is 55-65% of the diameter of the front cylindrical rod, and the rear end of the central through hole is provided with a constriction end, and the inner diameter of the constriction end is 65-85% of the main body diameter of the central through hole.

[0003] In the past, the towing fixing nuts for automobile trailers were mainly machined, which was slow, costly, and resulted in a lot of material waste. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for manufacturing a towing fixing nut for a car trailer, which can directly produce the towing fixing nut for a car trailer through a multi-station cold extrusion method, thereby improving the utilization rate and quality of raw materials and enhancing production efficiency. To this end, the present invention adopts the following technical solutions:

[0005] A six-station cold extrusion manufacturing method for a towing fixing nut for a car trailer is characterized in that the outer structure of the towing fixing nut for a car trailer includes two cylindrical rods, and a flat cylindrical protrusion is provided at the front end of the two cylindrical rods. The diameter of the rear cylindrical rod of the two cylindrical rods is smaller than the diameter of the front cylindrical rod and is close to the diameter of the front cylindrical rod, which is 90-95% of the diameter of the front cylindrical rod. The diameter of the flat cylindrical protrusion is 115-125% of the diameter of the front cylindrical rod; the length of the rear cylindrical rod is 25-35% of the total length of the towing fixing nut for a car trailer, and the height of the flat cylindrical protrusion is 4-8% of the total length of the towing fixing nut for a car trailer; the towing fixing nut for a car trailer is provided with a central through hole, the main body diameter of the central through hole is 55-65% of the diameter of the front cylindrical rod, and the rear end of the central through hole is provided with a constriction end, and the inner diameter of the constriction end is 65-85% of the main body diameter of the central through hole;

[0006] The manufacturing method comprises the following steps:

[0007] (1) Feeding the round disc into a cold heading machine and automatically shearing it into individual traction fixing nuts for automobile trailers, wherein the diameter of the round disc is close to the diameter of the front cylindrical rod, and the length of the raw material is shorter than the length of the two cylindrical rods;

[0008] (2) The raw material is transferred to the No. 1 mold mouth of the cold heading forming machine, and is cold headed in the No. 1 mold so that the diameter of the No. 1 molded product is consistent with the diameter of the front cylindrical rod, the rear end is forged with a rounded corner and a rear end positioning hole, and the front end is forged with the front shape of the flat cylindrical convex head, the diameter of the front shape is consistent with the flat cylindrical convex head, and the height is slightly shorter;

[0009] (3) The molded product No. 1 is translated to the mouth of the mold No. 2, and is cold-forged in the mold No. 2, so that the molded product No. 2 has a front end positioning hole on the end face of the flat cylindrical convex head front shape of the molded product No. 1, and the amount of metal transferred by forging the front end positioning hole is used to increase the height of the front shape; the diameter of the cylindrical rod outside the flat cylindrical convex head front shape of the molded product No. 2 with increased height is consistent with the diameter of the front cylindrical rod;

[0010] (4) The molded product No. 2 is translated to the mouth of the mold No. 3, and is cold-forged in the mold No. 3 so that the molded product No. 3 is formed with a first center blind hole on the basis of the front end positioning hole of the molded product No. 2. The depth of the first center blind hole is between 25-33% of the center through hole, and the flat cylindrical convex head is formed. At the same time, the length of the cylindrical rod outside the flat cylindrical convex head of the molded product No. 3 is extended. The diameter of the cylindrical rod of the molded product No. 3 is consistent with the diameter of the front cylindrical rod; the diameter of the first center blind hole is consistent with the main body diameter of the center through hole;

[0011] (5) The finished product of the No. 3 mold is turned over and transferred to the mouth of the No. 4 mold, and is cold-forged in the No. 4 mold so that the finished product of the No. 4 mold is forged with a deeper second center blind hole on the basis of the first center blind hole of the finished product of the No. 3 mold. The depth difference between the second center blind hole and the first center blind hole is less than the depth of the first center blind hole. The diameter of the second center blind hole is consistent with the diameter of the center through hole. At the same time, the rear end of the finished product of the No. 3 mold is bundled. The metal amount of the bundled rod part is equivalent to the metal amount of the rear cylindrical rod. The diameter of the bundled rod section after the bundled rod is consistent with the diameter of the rear cylindrical rod; the diameter of the cylindrical rod between the bundled rod section and the flat cylindrical protrusion is consistent with the diameter of the front cylindrical rod, and its length is extended when the No. 4 mold is cold-extruded and punched;

[0012] (6) The finished product of the No. 4 mold is translated to the mouth of the No. 5 mold, and the mold surface line of the No. 5 mold is on the rear end surface of the flat cylindrical protrusion; after cold heading in the No. 5 mold, the depth of the second center blind hole is extended to the depth of the center through hole, and the thickness of the hole bottom matches the thickness of the iron core that can be punched. At the same time, the beam section of the No. 4 molded product is extended to the cylindrical rod between the flat cylindrical protrusion and the length of the beam section to form the rear cylindrical rod and the front cylindrical rod;

[0013] (7) The finished product of mold No. 5 is moved horizontally to the mouth of mold No. 6, and the iron core of the finished product of mold No. 5 is punched to form a bundle end to make a traction fixing nut for a car trailer.

[0014] Through a rational workstation arrangement, this invention enables continuous cold extrusion of trailer traction nuts using a six-station cold extrusion process. Subsequent tapping of the internal threads is sufficient, improving product mechanical properties and ensuring product quality. Compared to conventional processes, this invention eliminates a significant amount of lathe processing, saving materials and reducing costs. It also offers dimensional stability and improved production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the process flow of the manufacturing method of the present invention. DETAILED DESCRIPTION

[0016] Refer to the accompanying drawings. The outer structure of the towing fixing nut 100 for a car trailer manufactured by the present invention includes two cylindrical rods, and a flat cylindrical protrusion 63 is provided at the front end of the two cylindrical rods. The diameter of the rear cylindrical rod 61 of the two cylindrical rods is smaller than the diameter of the front cylindrical rod 62 and is close to the diameter of the front cylindrical rod 62, which is 90-95% of the diameter of the front cylindrical rod 62. The diameter of the flat cylindrical protrusion 63 is 115-125% of the diameter of the front cylindrical rod; the length of the rear cylindrical rod 61 is the length of the car trailer. The height of the flat cylindrical protrusion 63 is 25-35% of the total length of the traction fixing nut 100 for the automobile trailer, and the height of the flat cylindrical protrusion 63 is 4-8% of the total length of the traction fixing nut 100 for the automobile trailer; the traction fixing nut 100 for the automobile trailer is provided with a central through hole 64, and the main body diameter of the central through hole 64 is 55-65% of the diameter of the front cylindrical rod 62, and the rear end of the central through hole 64 is provided with a constriction end 65, and the inner diameter of the constriction end 65 is 65-85% of the main body diameter of the central through hole 64.

[0017] The six-station cold extrusion manufacturing method uses a coiled material that is first heat-treated and spheroidized, with the diameter of the selected coiled material being substantially consistent with the diameter of the front cylindrical rod 62; then undergoes a phosphate surface treatment, a fine drawing and sizing treatment, and then performs the following steps of cold extrusion manufacturing:

[0018] (1) The disc is fed into a cold heading machine and automatically cut into individual car trailer traction fixing nut raw material pieces 101, wherein the length of the raw material piece 101 is shorter than the length of the two cylindrical rods.

[0019] (2) The raw material 101 is transferred to the No. 1 mold mouth of the cold heading forming machine, and is cold headed in the No. 1 mold so that the diameter of the No. 1 molded product 1 is consistent with the diameter of the front cylindrical rod 62, and the rear end is upset with a rounded corner 11 and a rear end positioning hole 12, and the front end is upset with a front shape 13 of the flat cylindrical protrusion 63. The diameter of the front shape 13 is consistent with that of the flat cylindrical protrusion 63, and the height is slightly shorter;

[0020] (3) The molded product No. 1 is translated to the mouth of the mold No. 2, and is cold-forged in the mold No. 2 so that the molded product No. 2 has a front end positioning hole 21 formed on the end face of the front shape 13 of the flat cylindrical protrusion. The amount of metal transferred by forging the front end positioning hole 21 is used to increase the height of the front shape 13; the diameter of the cylindrical rod 22 of the molded product No. 2 is consistent with the diameter of the front cylindrical rod 62.

[0021] (4) The molded product 2 is translated to the mold mouth of the mold No. 3, and is cold-forged in the mold No. 3, so that the molded product 3 of the mold No. 3 is formed with a first center blind hole 31 on the basis of the front end positioning hole 21 of the molded product No. 2. The depth of the first center blind hole 31 is between 25% and 33% of the length of the center through hole, and the flat cylindrical protrusion 63 is formed. In this way, although the diameter of the flat cylindrical protrusion 63 is much different from the diameter of the front cylindrical rod, the metal transfer distance when the flat cylindrical protrusion 63 is cold-extruded is small. After multiple steps of cold extrusion, the structural performance is better and the appearance is better.

[0022] When the No. 3 mold is upset to form the first center blind hole 31, the length of the cylindrical rod 32 outside the front shape of the flat cylindrical protrusion of the No. 3 molded product is also extended at the same time. The diameter of the cylindrical rod 32 of the No. 3 molded product is consistent with the diameter of the front cylindrical rod 62; the diameter of the first center blind hole 31 is consistent with the main body diameter of the center through hole 64, and the hole depth of the first center blind hole has exceeded the flat cylindrical protrusion 63.

[0023] (5) The molded product 3 is translated to the mold opening of the mold No. 4, and is cold-forged in the mold No. 4, so that the molded product 4 is formed with a deeper second center blind hole 41 on the basis of the first center blind hole 31 of the molded product No. 3. The depth difference between the second center blind hole 41 and the first center blind hole 31 is less than the depth of the first center blind hole 31. The diameter of the second center blind hole 41 is consistent with the diameter of the center through hole 64. At the same time, the rear end of the molded product 3 is tied with a rod. The amount of metal in the tied rod part is equivalent to the amount of metal in the rear cylindrical rod 61. The diameter of the tied rod section 42 after the tied rod is consistent with the diameter of the rear cylindrical rod 61. The diameter of the cylindrical rod 43 between the tied rod section 42 and the flat cylindrical protrusion 63 is consistent with the diameter of the front cylindrical rod 62. Its length is extended when the mold No. 4 is cold-extruded and punched. Thus, the amount and distance of metal transferred during punching can be reduced, so that the appearance molding is better.

[0024] (6) The finished product 4 of the No. 4 mold is translated to the mouth of the No. 5 mold, and is manufactured by cold heading in the No. 5 mold. The mold surface line of the No. 5 mold is at the rear end face 631 of the flat cylindrical protrusion 63, thereby being able to better upset the deep hole and having a better shape retention effect on the flat cylindrical protrusion 63; after cold heading in the No. 5 mold, the depth of the second center blind hole 41 is extended to the depth of the center through hole 64, and the thickness of the hole bottom matches the thickness of the iron core that can be punched. At the same time, the length of the cylindrical rod 43 between the beam section 42 of the No. 4 molded product 4 and the flat cylindrical protrusion 63 and the beam section 42 are extended to form the rear cylindrical rod 61 and the front cylindrical rod 62.

[0025] (7) The molded product 5 is moved horizontally to the mold opening of the sixth mold, and the iron core 200 is punched into the molded product 5 to form a bundle end 65 to make a traction fixing nut 100 for a car trailer.

[0026] The above description is only a specific embodiment of the present invention, but the structural features of the present invention are not limited thereto. Any changes or modifications made by any technician in this field within the field of the present invention are included in the protection scope of the present invention.

Claims

1. Six-station cold extrusion manufacturing method for traction fixing nuts for automobile trailers, characterized in that The outer structure of the towing fixing nut for automobile trailers includes two cylindrical rods, with flat cylindrical protrusions provided at the front ends of the two cylindrical rods. The diameter of the rear cylindrical rod of the two cylindrical rods is smaller than the diameter of the front cylindrical rod and is close to the diameter of the front cylindrical rod, which is 90-95% of the diameter of the front cylindrical rod. The diameter of the flat cylindrical protrusion is 115-125% of the diameter of the front cylindrical rod. The length of the rear cylindrical rod is 25-35% of the total length of the towing fixing nut for automobile trailers, and the height of the flat cylindrical protrusion is 4-8% of the total length of the towing fixing nut for automobile trailers. The towing fixing nut for automobile trailers is provided with a central through hole, the main body diameter of the central through hole is 55-65% of the diameter of the front cylindrical rod, and the rear end of the central through hole is provided with a constriction end, the inner diameter of the constriction end is 65-85% of the main body diameter of the central through hole. The manufacturing method comprises the following steps: (1) Feeding the round disc into a cold heading machine and automatically shearing it into individual car trailer traction fixing nut raw material parts, wherein the diameter of the round disc is close to the diameter of the front cylindrical rod, and the length of the raw material part is shorter than the length of the two cylindrical rods; (2) The raw material is transferred to the No. 1 mold mouth of the cold heading forming machine, and is cold headed in the No. 1 mold so that the diameter of the No. 1 molded product is consistent with the diameter of the front cylindrical rod, the rear end is forged with a rounded corner and a rear end positioning hole, and the front end is forged with the front shape of the flat cylindrical convex head, the diameter of the front shape is consistent with the flat cylindrical convex head, and the height is slightly shorter; (3) The molded product No. 1 is translated to the mouth of the mold No. 2, and is cold-forged in the mold No. 2, so that the molded product No. 2 has a front end positioning hole on the end face of the flat cylindrical convex head front shape of the molded product No. 1, and the amount of metal transferred by forging the front end positioning hole is used to increase the height of the front shape; the diameter of the cylindrical rod outside the flat cylindrical convex head front shape of the molded product No. 2 with increased height is consistent with the diameter of the front cylindrical rod; (4) The molded product No. 2 is translated to the mouth of the mold No. 3, and is cold-forged in the mold No. 3 so that the molded product No. 3 is formed with a first center blind hole on the basis of the front end positioning hole of the molded product No.

2. The depth of the first center blind hole is between 25-33% of the center through hole, and the flat cylindrical convex head is formed. At the same time, the length of the cylindrical rod outside the flat cylindrical convex head of the molded product No. 3 is extended. The diameter of the cylindrical rod of the molded product No. 3 is consistent with the diameter of the front cylindrical rod; the diameter of the first center blind hole is consistent with the main body diameter of the center through hole; (5) The finished product of the No. 3 mold is turned over and transferred to the mouth of the No. 4 mold, and is cold-forged in the No. 4 mold so that the finished product of the No. 4 mold is forged with a deeper second center blind hole on the basis of the first center blind hole of the finished product of the No. 3 mold. The depth difference between the second center blind hole and the first center blind hole is less than the depth of the first center blind hole. The diameter of the second center blind hole is consistent with the diameter of the center through hole. At the same time, the rear end of the finished product of the No. 3 mold is bundled. The metal amount of the bundled rod part is equivalent to the metal amount of the rear cylindrical rod. The diameter of the bundled rod section after the bundled rod is consistent with the diameter of the rear cylindrical rod; the diameter of the cylindrical rod between the bundled rod section and the flat cylindrical protrusion is consistent with the diameter of the front cylindrical rod, and its length is extended when the No. 4 mold is cold-extruded and punched; (6) The finished product of the No. 4 mold is translated to the mouth of the No. 5 mold, and the mold surface line of the No. 5 mold is on the rear end surface of the flat cylindrical protrusion; after cold heading in the No. 5 mold, the depth of the second center blind hole is extended to the depth of the center through hole, and the thickness of the hole bottom matches the thickness of the iron core that can be punched. At the same time, the beam section of the No. 4 molded product is extended to the cylindrical rod between the flat cylindrical protrusion and the length of the beam section to form the rear cylindrical rod and the front cylindrical rod; (7) The finished product of mold No. 5 is moved horizontally to the mouth of mold No. 6, and the iron core of the finished product of mold No. 5 is punched to form a bundle end to make a traction fixing nut for a car trailer.

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