Manufacturing process of connecting piece with ball head in middle and flat positions at two ends

Abstract

The invention discloses a manufacturing process of a connecting piece with a ball head in the middle and flat positions at the two ends, and relates to the technical field of connecting pieces, which comprises the following steps: straightening, shearing and multi-station cold heading deformation are carried out on a wire to manufacture a rod-shaped blank with a thick middle and two thin ends, and annealing, degreasing and deoiling, wear-resistant layer plating and lubricating layer plating are carried out on the rod-shaped blank in sequence; movable nanoscale steel balls are contained in the lubricating layer; slender rods at the two ends of the rod-shaped blank are punched and flattened, and convex points are punched; the two ends of the flat position are punched and trimmed to form chamfers, and meanwhile the flat position is punched and punched to form an inner hole; the middle thick rod part of the rod-shaped blank is cut to form a middle ball head through CNC, grooves in the two sides of the ball head are formed, then the ball head is subjected to roll finish, overall galvanization is conducted, and a connecting piece is obtained; the nanoscale steel balls can form rolling friction in the stamping process, so that the friction coefficient during stamping is reduced, and the nanoscale steel balls are embedded into the surface layer of the blank under the action of stamping pressure to form a dispersion strengthening structure, so that the surface hardness of the blank is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of connecting pieces, in particular to a manufacturing process of a connecting piece with a middle ball head and flat positions at both ends. BACKGROUND

[0002] The connecting piece with a middle ball head and flat positions at both ends is a key component with transmission and connection functions, which is widely used in the fields of automobile suspension systems, engineering machinery joints, precision mechanical transmission mechanisms, etc. Its special structure design (the middle ball head ensures flexibility, and the flat positions at both ends cooperate with the inner hole to realize stable assembly) requires the product to have precise size accuracy and meet the requirements of wear resistance and load resistance under complex working conditions, which is directly related to the operation stability and service life of the whole machine equipment. With the rapid development of the automobile industry and the engineering machinery industry, the demand for such connecting pieces is continuously increasing, and the requirements for production efficiency, cost control and mechanical properties are also increasingly stringent.

[0003] At present, the commonly used manufacturing process of the connecting piece with a middle ball head and flat positions at both ends is to cut the bar material through a CNC machining center. This process needs to use a complete bar material as raw material, and gradually removes the excess material through multiple cutting processes to finally form the ball head, groove, flat position, protrusion and inner hole and other structures. This processing method has obvious defects: on the one hand, the cutting process is complicated, the processing period is long, the processing efficiency is low, and it is difficult to match the market demand of mass production; on the other hand, the waste generated in the cutting process accounts for a high proportion, the material utilization rate is low, a large amount of raw materials is wasted, and the production cost is significantly increased; in addition, the overall cutting processing will damage the original metal flow line of the material, resulting in damage to the continuity of the internal organization of the connecting piece, insufficient mechanical strength, and difficulty in meeting the use requirements of high-end equipment under complex working conditions, which limits the further expansion of its application scenarios. SUMMARY

[0004] The present application aims to solve the problems of low material utilization rate of the existing manufacturing process of the connecting piece with a middle ball head and flat positions at both ends and low mechanical strength of the connecting piece manufactured.

[0005] To solve the above problems, the present application provides a manufacturing process of a connecting piece with a middle ball head and flat positions at both ends, which comprises the following steps: Step 1, a rod-shaped blank with a middle thick and both ends thin is made by straightening, shearing and multi-station cold upsetting deformation of a wire rod; Step 2, the rod-shaped blank is sequentially subjected to annealing, degreasing and deoiling, plating of a wear-resistant layer and plating of a lubricating layer; wherein the lubricating layer contains movable nanoscale steel balls; Step 3, the thin rods at both ends of the rod-shaped blank are punched and flattened by a stamping die, and protrusions are punched out; Step 4, the two ends of the flat position are punched and cut to form a chamfer, and a punch hole is punched on the flat position to form an inner hole; Step 5, the middle ball head of the rod-shaped blank is cut by CNC to form grooves on both sides of the ball head, and a connecting piece is obtained. Step 6, the ball head of the connecting piece is polished, and then the whole is galvanized to obtain the connecting piece.

[0006] The manufacturing process of the connecting piece with the intermediate ball head and the flat position at both ends provided by the present application has the following beneficial effects, but is not limited to: In the manufacturing process of the present application, the rod-shaped blank with a middle thick and both ends thin is directly manufactured by a multi-station cold heading, the approximate shape of the finished product is preset in advance, and only the middle ball head and the groove need to be cut during the subsequent CNC, which greatly reduces the processing amount of CNC cutting, shortens the processing time compared with full CNC cutting, significantly improves the material utilization rate, reduces the waste of raw materials, and saves production costs; The movable nano steel balls are introduced into the lubricating layer in step 2. On the one hand, the nano steel balls can form rolling friction during the stamping process, replacing the sliding friction of the traditional saponification layer, reducing the friction coefficient during stamping, avoiding the situation that the blank is pulled and cracked due to excessive friction, and improving the stamping qualification; On the other hand, under the action of the stamping pressure, the nano steel balls will be embedded into the surface layer of the blank to form a dispersion strengthening structure, so that the surface hardness of the blank is improved, and the wear resistance is significantly enhanced during subsequent use. Moreover, the two-end flat position, the convex point and the inner hole are formed by stamping and cutting in steps, which is easier to ensure the size consistency of the flat position compared with full CNC cutting; The subsequent CNC is only for the middle ball head and the groove, which can accurately control the roundness of the ball head and the parallelism of the groove; The final ball head polishing and overall galvanizing not only improve the smoothness of the ball head surface, but also achieve excellent corrosion resistance through the galvanizing layer, meeting the complex working condition requirements of automobile parts.

[0007] Further, in step 1, the wire rod is a low-carbon steel wire rod.

[0008] Specifically, the carbon mass fraction of the low-carbon steel is ≤0.25%, which has excellent plasticity at room temperature and can smoothly withstand large deformation processes such as cold heading deformation and stamping and flattening, without cracks and fractures due to insufficient plasticity; At the same time, the smelting cost of low-carbon steel is lower than that of medium and high-carbon steel, which can reduce the raw material procurement cost; Moreover, the annealing process of low-carbon steel is easier to control, without high temperature and long time holding, which can be softened at 680-720℃, and the energy consumption can be reduced.

[0009] Preferably, the low-carbon steel wire rod is 10# steel or Q235 steel.

[0010] Further, in step 1, the total deformation of the cold upsetting deformation is ≤80%, the cold upsetting pressure is 800-1200 MPa, and the pressure holding time is 1-3 s.

[0011] Specifically, the total deformation is controlled within 80%, which can prevent the low-carbon steel from generating internal cracks or surface wrinkles due to deformation exceeding the plastic limit, ensure the integrity of the internal organization of the blank, and prevent defective blanks from causing waste products during subsequent stamping and CNC processing; if the deformation is >80%, the thin rod parts at both ends of the blank are prone to necking and breaking during stamping and flattening; the cold upsetting pressure of 800-1200 MPa can ensure that the wire fully fills the multi-station die cavity to form a pre-set shape with a thick middle and thin ends, avoiding insufficient pressure that causes local deformation of the blank; the pressure holding time of 1-3 s can make the material deformation stable and reduce the amount of springback.

[0012] Further, in step 2, the annealing process is as follows: the rod-shaped blank is heated to 680-720℃ at a heating rate of 5-10℃ / min, held for 3-5h, and then cooled with the furnace.

[0013] Specifically, internal stress is generated in the material during cold upsetting, and if the heating rate is too fast, the internal temperature difference of the blank will cause the internal stress to accumulate, which may cause cracking; slow heating at a rate of 5-10℃ / min can make the internal and external temperatures of the blank uniform, and 3-5h of holding can make the internal stress elimination rate reach more than 90%, so that the blank does not warp due to stress release during subsequent stamping; 680-720℃ is the temperature range for incomplete annealing of low-carbon steel, which can moderately reduce the hardness of the blank, ensuring that the blank is easily deformed during subsequent stamping, and preventing the blank from being damaged due to low hardness during handling and positioning; if the temperature is <680℃, the hardness is not reduced enough, and the pressure needs to be increased during stamping, which can easily damage the die; if the temperature is >720℃, it will cause the grains to become coarse, and the mechanical properties will decrease after subsequent quenching and tempering; 3-5h of holding time can make the internal organization of the blank fully uniform, avoiding large differences in local deformation resistance during subsequent stamping due to uneven organization, and preventing the thickness deviation of the flat part from exceeding the standard.

[0014] Further, in step 2, the degreasing and oil removal process is as follows: the annealed rod-shaped blank is placed in an alkaline degreasing agent and ultrasonically cleaned at 60-70℃ for 10-15min, and then rinsed with clean water several times.

[0015] Specifically, the surface of the cold upsetting and annealed blank will be left with oil stains (cold upsetting lubricant), scale and dust. If not cleaned thoroughly, the coating will fall off when plating a wear-resistant layer. Alkaline degreaser can decompose oil stains through saponification reaction, and in combination with 20-40 kHz ultrasonic waves, it can penetrate into the small gaps on the surface of the blank and remove contaminants. A temperature of 60-70°C can accelerate the reaction rate of the degreaser, and the cleaning process can be completed in 10-15 min, which can improve the cleaning efficiency compared to cleaning at room temperature. If the temperature is >70°C, the degreaser will excessively corrode the surface of the blank, forming over-etching spots. If the time is <10 min, the oil stains will not be completely removed.

[0016] Preferably, the alkaline degreaser contains 50-80 g / L of sodium hydroxide, 30-50 g / L of sodium carbonate, 20-40 g / L of trisodium phosphate, and 5-10 g / L of sodium dodecylbenzenesulfonate.

[0017] Further, in step 2, the process of plating a wear-resistant layer is as follows: the degreased and oiled rod-shaped blank is placed in a phosphating solution, treated at 50-60°C for 8-12 min, and then taken out and dried to form a wear-resistant layer.

[0018] Specifically, the phosphating solution forms a wear-resistant layer on the surface of the blank, which improves the hardness. During stamping, the wear-resistant layer can isolate the blank from the die to prevent scratches on the surface of the blank caused by direct friction, and reduce the wear of the die. A temperature of 50-60°C and a time of 8-12 min can control the wear-resistant layer to form small pores to adsorb the subsequent saponification solution containing nano steel balls.

[0019] Preferably, the phosphating solution contains 80-120 g / L of zinc dihydrogen phosphate, 10-20 g / L of nickel nitrate, 30-50 g / L of zinc nitrate, and 5-10 g / L of sodium fluoride.

[0020] Further, in step 2, the process of plating a wear-resistant layer is as follows: the degreased and oiled rod-shaped blank is placed in a phosphating solution, treated at 50-60°C for 8-12 min, and then taken out and dried to form a wear-resistant layer.

[0021] Specifically, the saponification solution itself has lubricity, and the introduction of nano steel balls can convert sliding friction into rolling friction, and reduce the friction coefficient; the temperature of 70-80℃ can make the saponification solution keep good fluidity, and the time of 5-8min can ensure that the saponification solution fully adheres and wraps the nano steel balls, so that the friction between the blank and the mold is greatly reduced during stamping, and the tearing rate of the flat position at both ends is obviously reduced; the temperature of 70-80℃ can avoid the saponification solution from solidifying due to too low temperature, and avoid affecting the dispersion of steel balls, or too high temperature from causing volatilization to cause the lubricating layer to be too thin; the processing time of 5-8min can control the thickness of the lubricating layer within a certain range, and ensure that the nano steel balls are uniformly distributed without aggregation; natural draining until no liquid drops fall can ensure that the lubricating layer is formed but not completely dried, ensure the mobility of the steel balls, ensure the feasibility of rolling friction, and meet the stability requirements of batch stamping production.

[0022] Preferably, the saponification solution contains sodium stearate 30-50g / L, sodium hydroxide 5-10g / L, and additives 2-5g / L, and the additives are a mixture of calcium oxide and talc powder in a mass ratio of 1:1.

[0023] Further, the size of the nano steel balls is 10-100nm.

[0024] Specifically, the size of 10-100nm can make the steel balls uniformly dispersed in the saponification solution through Brownian motion, and will not aggregate due to too small size, nor settle due to too large size; at the same time, the steel balls of this size can smoothly embed into the surface layer of the blank under the stamping pressure, if the steel balls are <10nm, they are easy to be wrapped by the matrix after embedding, and the strengthening effect is not obvious; if the steel balls are >100nm, they cannot completely embed into the surface of the blank, and are easy to fall off after stamping, resulting in invalidation of the lubricating layer, and even damage to the tool during subsequent CNC cutting; moreover, the steel balls of 10-100nm will not significantly increase the viscosity of the saponification solution, and the saponification solution can still keep good fluidity, facilitating uniform adhesion on the surface of the blank by immersion.

[0025] Further, the mass fraction of the nano steel balls in the saponification solution is 5-20%.

[0026] Specifically, if the mass fraction of the nano steel balls in the saponification solution is less than 5%, the number of steel balls in the saponification solution is too small, the rolling friction points are insufficient during stamping, the friction coefficient cannot be effectively reduced, and the number of steel balls embedded into the blank is small, so the strengthening effect is not obvious; if it is higher than 20%, the number of steel balls is too large, which can cause the steel balls to easily aggregate to form particle clusters, and scratch the surface of the blank during stamping.

[0027] Further, the nano steel balls are derived from turning waste generated in the CNC process.

[0028] Specifically, low-carbon steel turning waste is generated in the CNC cutting of the intermediate ball head and the groove, the traditional treatment method is waste recycling smelting, which has low utilization rate and high energy consumption; but the waste is processed into nanoscale steel balls, which can improve the resource utilization rate of waste, reduce industrial solid waste emissions, is more environmentally friendly, and can save costs; moreover, the turning waste and the connecting piece blank have the same material, which can avoid component differences and ensure that the steel ball and the base are tightly combined. BRIEF DESCRIPTION OF DRAWINGS

[0029] The application will be further described below with reference to the drawings.

[0030] Figure 1 is a structural schematic diagram of the intermediate rough, two-end-thin rod-shaped blank in step 1 of the embodiment 1 of the application; Figure 2 is a structural schematic diagram of the flat position and the convex point in step 3 of the embodiment 1 of the application; Figure 3 is a structural schematic diagram of the inner hole in step 4 of the embodiment 1 of the application; Figure 4 is a structural schematic diagram of the connecting piece embryo in step 5 of the embodiment 1 of the application. DETAILED DESCRIPTION

[0031] The specific embodiments of the application will be described in detail below, but it should be understood that the protection scope of the application is not limited by the specific embodiments.

[0032] The terms used in the embodiments of the application are merely for the purpose of describing specific embodiments, and are not intended to limit the application. The singular forms "a", "said" and "the" used in the embodiments of the application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0033] It should be understood that in various embodiments of the application, the size of the serial number of each process does not mean the order of execution, and part or all of the steps can be executed in parallel or in sequence, and the execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the application.

[0034] It should be understood that the weight of the related components mentioned in the embodiments of the application not only refers to the specific content of each component, but also represents the weight ratio relationship between each component, therefore, as long as the content of the related components in the embodiments of the application is enlarged or reduced in proportion, it is within the scope disclosed in the embodiments of the application. Specifically, the mass mentioned in the embodiments of the application can be μg, mg, g, kg and other mass units commonly known in the chemical field.

[0035] Unless otherwise defined, all terms used in the description herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. The description herein uses professional and technical terms merely for the purpose of describing specific embodiments and does not intend to limit the scope of protection of the present application.

[0036] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or prepared by existing methods; for example, the specific sources of some raw materials in the following examples and comparative examples are as follows: Alkaline degreasing agent: self-made, containing sodium hydroxide 50-80 g / L, sodium carbonate 30-50 g / L, trisodium phosphate 20-40 g / L, sodium dodecylbenzenesulfonate 5-10 g / L; Phosphating solution: self-made, containing zinc dihydrogen phosphate 80-120 g / L, nickel nitrate 10-20 g / L, zinc nitrate 30-50 g / L, sodium fluoride 5-10 g / L; Saponification solution: self-made, containing sodium stearate 30-50 g / L, sodium hydroxide 5-10 g / L, additives 2-5 g / L, the additives are a mixture of calcium oxide and talcum powder with a mass ratio of 1:1, and the size of the nanoscale steel beads is 10-100 nm, and the mass fraction is controlled at 5-20%, and the nanoscale steel beads are waste materials generated in the CNC process of the manufacturing process of the connecting piece in the last batch.

[0037] Example 1 The present embodiment discloses a manufacturing process of a connecting piece with a middle ball head and flat ends, which comprises the following steps: Step 1, the 10# steel wire rod is straightened, cut, and deformed by multi-station cold heading, and the total deformation is kept ≤80%, the cold heading pressure is 1000 MPa, and the pressure holding time is 2 s; a rod-shaped blank with a middle thick and two ends thin is prepared as shown in Figure 1 The diameter of the thick rod part is 20 mm, and the diameter of the thin rod part is 10 mm.

[0038] Step 2, the rod-shaped blank is heated to 700℃ at a heating rate of 8℃ / min, and then cooled in the furnace for 4h; then it is placed in an alkaline degreasing agent and ultrasonically cleaned at 65℃ for 12 min, and then rinsed with clean water for 3 times; the degreased and deoiled rod-shaped blank is placed in a phosphating solution and treated at 55℃ for 10 min, and then dried after standing; finally, the rod-shaped blank after plating the wear-resistant layer is placed in a saponification solution added with nanoscale steel beads (the size of the nanoscale steel beads is 50 nm, and the mass fraction is 10%), and treated at 75℃ for 6.5 min, and then naturally drained until no liquid drops fall, to form a wear-resistant layer.

[0039] Step 3, the thin rods at both ends of the rod-shaped blank are punched and flattened by a stamping die, and a protrusion is punched out, and the specific structure is as shown inFigure 2 As shown in FIG. 4; wherein the flat position thickness is 4mm, the flat position width is 12mm, the convex point height is 2mm, and the convex point diameter is 3mm.

[0040] Step 4, stamping and cutting the edges of the flat position to form a chamfer, and stamping a punch hole on the flat position to form an inner hole, the specific structure is as shown in Figure 3 As shown in FIG. 5; wherein the inner hole diameter is 8mm.

[0041] Step 5, cutting the middle ball head of the rod-shaped blank by CNC to form grooves on both sides of the ball head, to obtain a connection piece embryo as shown in Figure 4 As shown in FIG. 6. Step 6, polishing the ball head of the connection piece embryo until the roughness Ra≤0.8μm, and then adopting an acidic zinc plating process to plating the whole connection piece (the thickness of the zinc plating layer is 10um), to obtain the connection piece.

[0042] Example 2 Compared with Example 1, the only difference is that the size of the nanoscale steel ball in Step 2 is replaced by 10nm, and the other steps and conditions remain the same, and finally the connection piece is prepared.

[0043] Example 3 Compared with Example 1, the only difference is that the size of the nanoscale steel ball in Step 2 is replaced by 100nm, and the other steps and conditions remain the same, and finally the connection piece is prepared.

[0044] Example 4 Compared with Example 1, the only difference is that the mass fraction of the nanoscale steel ball in Step 2 is replaced by 5%, and the other steps and conditions remain the same, and finally the connection piece is prepared.

[0045] Example 5 Compared with Example 1, the only difference is that the mass fraction of the nanoscale steel ball in Step 2 is replaced by 20%, and the other steps and conditions remain the same, and finally the connection piece is prepared.

[0046] Comparative Example 1 Compared with Example 1, the only difference is that the nanoscale steel ball in Step 2 is cancelled, and the other steps and conditions remain the same, and finally the connection piece is prepared.

[0047] Comparative Example 2 The 10# steel wire is processed into a connection piece as shown in FIG. 4 by CNC.

[0048] The connection pieces prepared in Examples 1-5 and Comparative Examples 1-2 are tested for mechanical strength, including tensile strength and yield strength, and the test method is as follows: Tensile strength: GB / T 228.1-2021; Tensile strength: GB / T 228.1-2021.

[0049] The test results are listed in Table 1, which is as follows: Table 1 From the data in Table 1, it can be seen that, compared with Comparative Example 1-2, the connecting piece of Example 1-5 has significantly higher tensile strength and yield strength, which shows that the manufacturing process of the application can improve the mechanical strength of the connecting piece.

[0050] The above describes in detail the plurality of embodiments of the application, but the content described is only the preferred embodiments of the application and cannot be considered to limit the implementation scope of the application. Any equivalent changes and improvements made in the scope of the application should still belong to the patent coverage of the application.

Claims

1. A manufacturing process for a connector with flat ends at both ends of a central ball head, characterized in that, Includes the following steps: Step 1: The wire is straightened, sheared, and cold-forged in multiple stations to form a rod-shaped blank that is thick in the middle and thin at both ends; Step 2: Anneal the rod-shaped billet in sequence, degrease and deoil it, apply a wear-resistant layer, and apply a lubricating layer; wherein the lubricating layer contains movable nano-sized steel balls; Step 3: Flatten the thin rods at both ends of the rod-shaped blank and punch out protrusions using a stamping die; Step 4: Punch and cut the two ends of the flat part to form a chamfer, and at the same time punch holes in the flat part to form an inner hole; Step 5: Using CNC machining, the middle thick rod part of the rod-shaped blank is cut to form a middle ball head and grooves on both sides of the ball head to obtain the prototype of the connector; Step 6: Burnish the ball head of the connector prototype, and then galvanize the whole piece to obtain the connector.

2. The manufacturing process of the connector with flat ends at both ends of the intermediate ball head according to claim 1, characterized in that, In step 1, the wire is a low-carbon steel wire.

3. The manufacturing process of the connector with flat ends at both ends of the intermediate ball head according to claim 1, characterized in that, In step 1, the total deformation of the cold heading is ≤80%, the cold heading pressure is 800-1200MPa, and the holding time is 1-3s.

4. The manufacturing process of the connector with flat ends at both ends of the intermediate ball head according to claim 1, characterized in that, In step 2, the annealing process is as follows: the rod-shaped billet is heated to 680-720℃ at a heating rate of 5-10℃ / min, held at that temperature for 3-5 hours, and then cooled in the furnace.

5. The manufacturing process of the connector with flat ends at both ends of the intermediate ball head according to claim 1, characterized in that, In step 2, the degreasing and deoiling process is as follows: the annealed rod-shaped blank is placed in an alkaline degreasing agent and ultrasonically cleaned at 60-70℃ for 10-15 minutes, and then rinsed several times with clean water.

6. The manufacturing process of the connector with flat ends at both ends of the intermediate ball head according to claim 1, characterized in that, In step 2, the process of coating the wear-resistant layer is as follows: the degreased and deoiled rod-shaped blank is placed in a phosphating solution and treated at 50-60℃ for 8-12 minutes. After being removed, it is left to stand and dry to form a wear-resistant layer.

7. The manufacturing process of the connector with flat ends at both ends of the intermediate ball head according to claim 1, characterized in that, In step 2, the process of plating the lubricating layer is as follows: the rod-shaped blank after the wear-resistant layer is plated is placed in a saponification solution containing nano-sized steel balls, treated at 70-80℃ for 5-8 minutes, and then naturally drained until no liquid droplets drip off, thus forming the lubricating layer.

8. The manufacturing process of the connector with flat ends at both ends of the intermediate ball head according to claim 7, characterized in that, The size of the nanoscale steel balls is 10-100 nm.

9. The manufacturing process of the connector with flat ends at both ends of the intermediate ball head according to claim 7, characterized in that, The mass fraction of the nano-sized steel balls in the saponification solution is 5-20%.

10. The manufacturing process of the connector with flat ends at both ends of the intermediate ball head according to claim 7, characterized in that, The nanoscale steel balls are derived from machining waste generated during the CNC process.

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