Novel double-hole pull rod head production process

Abstract

The invention relates to the technical field of equipment manufacturing, and discloses a novel double-hole pull rod head production process which comprises the following steps: cutting and blanking: directly cutting an outline of a pull rod head from a Q235A steel plate with the thickness of 14 mm by adopting laser cutting; cold forging of the tail: carrying out cold forging and forming on the tail of the cut blank to achieve the shape required by the drawing; character pressing, wherein marks are pressed on the parts; and drilling and assembly welding are conducted, specifically, drilling is conducted, welding with other parts is conducted, and assembly is completed. According to the method, only four working procedures of cutting and blanking, cold forging of the tail, character pressing and drilling and assembly welding are needed, the technological process is greatly reduced, subsequent grinding is not needed, the problem that the thickness of the freely-forged double-hole pull rod head is not uniform is solved, control over the assembly welding size of parts in the subsequent working procedure is facilitated, selection and matching of pull riveting pins are effectively avoided, and the assembly quality and efficiency are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of production process, in particular to a novel double-hole drawbar head production process. BACKGROUND

[0002] In the existing manufacturing process of the C70E type general open car double-hole drawbar head, the free end forming mode is generally adopted, although the die anvil tooling is used for auxiliary forming in the forging process, but it still belongs to the production mode mainly relying on the operation of technical personnel, and repeated trimming is needed to realize the shape requirements. The key thickness size of the product is 14mm, in order to ensure that the tolerance is controlled within ±1mm, continuous measurement and adjustment must be carried out during forging, which leads to poor size consistency, and the product quality stability is difficult to effectively guarantee.

[0003] In addition, the current production process flow covers sawing, heating, forging, tail cutting, cold forging tail, grinding, shot blasting, character pressing, drilling and assembly welding, and many other links, the overall process is long and complex, not only restricts the production rhythm, but also causes the production efficiency to be significantly low, which has been difficult to adapt to and meet the large-scale production demand of the whole vehicle assembly progress. SUMMARY

[0004] The present application aims to provide a novel double-hole drawbar head production process to solve the problems of low production efficiency, poor size consistency and long process of the existing double-hole drawbar head, which affects the whole vehicle production progress.

[0005] To achieve the above purpose, the present application adopts the following technical scheme: a novel double-hole drawbar head production process, comprising the following steps, (1) cutting blank: cutting the shape contour of the drawbar head directly from the 14mm thick Q235A steel plate by laser cutting; (2) cold forging tail: cold forging the tail of the cut blank to form the shape required by the drawing; (3) character pressing: pressing the mark on the part; (4) drilling and assembly welding: drilling and welding with other components to complete the assembly.

[0006] The principle and advantages of the present application are: The existing production process is a relatively long hot working process, which has many links and relies on the operation of technicians. It is difficult to accurately control the thickness of 14 mm, and repeated measurement and trimming are required, resulting in low production efficiency and unstable quality. The reason why C70E open wagon double-hole drawbar head must go through a long forging process is that the underlying logic comes from a fundamental technical requirement: improving the internal organization of the material through thermal deformation to ensure its mechanical properties, especially tensile strength and toughness, to meet the safety requirements of vehicles under heavy load, impact and other complex working conditions. Heating, forging and subsequent trimming and polishing are considered necessary processes to achieve this technical goal, forming a seemingly non-compact process chain.

[0007] The key breakthrough comes from a quantitative finding that is easily overlooked: after analysis and comparison, it is found that when using Q235A material for double-hole drawbar head and adopting 14 mm thick plate directly, the raw material acceptance standard is "Carbon Structural Steel" (GB / T 700), with a tensile strength of 370-500 MPa in the mechanical property requirements; while using forging forming, according to the industry enterprise technical standard "General Technical Conditions for Forgings" (Q / QC35-102-2019), the grade and chemical composition of carbon steel for forgings comply with GB / T 700, and the mechanical properties of forgings comply with the requirements in Q / QC35-102, with a tensile strength of ≥325 MPa, Brinell hardness ≤183 HBW, and no requirements for yield strength and elongation after breaking after forging.

[0008] This data comparison reveals a fact that is hidden by traditional processes: the original strength performance of qualified Q235A steel plate has fully met or even exceeded the final acceptance standard of forgings since its inception. The forging process does not create new properties that the plate itself does not have, but due to its hand forming characteristics, it introduces a series of problems such as poor dimensional consistency and the need for repeated trimming.

[0009] Therefore, theoretically, a double-hole drawbar head made of Q235A steel plate directly cut by numerical control and then cold forged can fully meet the acceptance standard of Q / QC35-102-2019.

[0010] Therefore, this scheme only needs to cut and downsize, cold forge the tail, press the character and drill and weld 4 processes, greatly reducing the process flow, and there is no need for subsequent polishing, avoiding the problem of uneven thickness of the double-hole drawbar head of free forging, which is beneficial to the control of the size of the parts welded in the subsequent process, effectively avoiding the selection of pull rivet pins, improving the assembly quality and efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 Flowchart of a new double-hole drawbar head production process of the present application; Figure 2 Surface quality comparison chart of double-hole pull rod head manufactured by using existing process and the present scheme; Figure 3 Appearance comparison chart of double-hole pull rod head manufactured by using existing process and the present scheme. DETAILED DESCRIPTION

[0012] The following is further described in detail through specific embodiments: The new double-hole pull rod head production process in the present embodiment directly simplifies the process into 4 steps, greatly reduces the process flow, and can ensure product performance, improve product quality, ensure the consistency of product size, improve production efficiency, and reduce production cost.

[0013] In the present embodiment, a new double-hole pull rod head production process is provided, as shown in the accompanying drawings, which includes the following steps, Figure 1 (1) Cutting and blanking: the laser cutting is directly used to cut the outer profile of the pull rod head from the 14mm thick Q235A steel plate.

[0014] In the present embodiment, a re-inspection process is further included before cutting. When it is internal blanking, i.e. the blanking is performed by the company itself, the raw material has completed pretreatment and factory re-inspection before cutting. The raw material does not need to be treated by shot blasting after pretreatment.

[0015] When it is external blanking, i.e. the raw material is provided by an external cooperation unit, the external cooperation unit may not have a pretreatment production line and the ability to re-inspect the steel plate in the factory. Therefore, after the blanking is returned to the factory, random sampling inspection and re-inspection are performed first, and then subsequent operations are performed.

[0016] When cutting, according to the two-dimensional profile drawing of the double-hole pull rod head, the CAD / CAM software is used for numerical control programming, and the steel plate is optimized for layout to improve material utilization. In the present embodiment, a high-power laser cutting machine is preferred because it has high cutting precision, small heat-affected zone, and good cutting quality.

[0017] The steel plate is fixed on the cutting workbench, and the equipment is started to automatically complete the profile cutting of all parts, with a cutting precision of within ±0.1mm to ensure the consistency of the profile size. After cutting, the parts are taken off the steel plate.

[0018] In the present embodiment, during laser cutting, the laser power and cutting speed are adjusted according to the cutting quality.

[0019] The cutting quality is monitored in real time by machine vision, and the laser power and cutting speed are automatically adjusted to ensure the quality consistency of each blank.

[0020] ​In this embodiment, one or more high-performance industrial CCD or CMOS cameras are installed near the laser cutting head, along with dedicated light sources such as coaxial light or backlighting, to ensure clear capture of the cutting seam image. Image capture is performed during the cutting process or at the instant a contour is cut. The captured image is compared with a stored basic shape image, and the laser power and cutting speed are adjusted based on the comparison results.

[0021] If severe slag buildup is detected during cutting, it is determined that the cutting power is too low or the speed is too high. In this case, the power will be increased or the speed will be decreased appropriately. If excessively wide cuts or excessive ablation are detected, it is determined that the cutting power is too high or the speed is too slow. In this case, the power will be decreased or the speed will be increased appropriately. If a rough cross-section is detected, it is determined that the cutting gas pressure is unsuitable or the speed is unstable. In this case, the gas pressure will be optimized or the speed will be fine-tuned to improve laser cutting accuracy and increase cutting efficiency.

[0022] (2) Cold forging tail: The tail of the cut billet is cold forged to achieve the shape required by the drawing.

[0023] In this embodiment, a cold forging die specifically designed for the head and tail shapes of a double-hole tie rod is used. The die must have high hardness and high surface finish. The CNC-cut billet is placed into the cold forging die, and the cold extrusion press is started. The upper die moves downward, and a certain pressure is applied to the tail of the billet at room temperature, such as applying a pressure of 1.1-3.1 KJ, to cause plastic deformation and form the tail shape.

[0024] After molding, the upper mold returns, and the ejection mechanism ejects the part from the mold.

[0025] In this embodiment, when the material is unloaded externally, the parts also need to be shot blasted to remove surface oxide scale and burrs.

[0026] At this point, the cold-forged parts are loaded into a shot blasting machine. The machine propels steel shot or iron shot at high speed to impact the surface of the parts, thereby removing tiny burrs and oxide scale that may be generated during cutting and turnover, and strengthening the surface. In this embodiment, the shot blasting time is 0.3~0.5h, the shot blasting force is 0.2~0.5mmA, and the shot diameter is 1~2mm to ensure the shot blasting effect and accuracy.

[0027] After cleaning, remove the parts and ensure they have a uniform matte surface that meets the surface quality requirements of Q / QC35-102-2019.

[0028] (3) Embossing: Embossing markings on parts.

[0029] Position the part on the embossing die, and use a press or special equipment to emboss the required mark, model or production batch number at the designated position on the part.

[0030] (4) Drilling and assembly: drilling and welding with other components to complete assembly.

[0031] In this embodiment, a numerical control drilling machine or machining center is used to drill two mounting holes at specific positions of the pull rod head according to the requirements of the drawing to meet the processing needs. The hole diameter, hole distance, and hole wall quality are checked to see if they meet the requirements. The pull rod head with drilled holes is assembled with other vehicle body parts through welding.

[0032] In this embodiment, before the cold forging process, laser shock peening or ultrasonic rolling can also be used for surface strengthening. Not only can it be formed, but it can also introduce compressive stress at key locations (such as the stress concentration at the tail corner), significantly improving fatigue life.

[0033] In this embodiment, compared to forging, the laser cutting size is controlled by the numerical control program, and the appearance quality and its consistency can be well controlled. The results are shown in the attached Figure 2 As can be seen from the figure, the surface of the laser cutting is smoother and more even. As can also be seen from the attached Figure 3 , the surface quality of the double-hole pull rod head directly formed from the steel plate (right side) is good, the thickness is uniform, there are no burrs, and it meets the surface quality requirements of Q / QC35-102-2019, without the need for polishing. Even if there are laser cutting marks on the side, they are not obvious and do not affect the performance. The forged double-hole pull rod head (left side) has uneven thickness and is prone to indentation, and the lower part also has burrs that need to be polished to eliminate, increasing the process flow and cost.

[0034] Laser cutting directly uses a 14mm thick steel plate to cut the outer shape, and then cold forging forms the tail, which can avoid the problem of uneven thickness of the double-hole pull rod head in free forging, is beneficial to the size control of the assembly welding of the parts in the later process, effectively avoids the selection of pull rivet pins, facilitates the procurement of pull rivet pins of the same specification, and thus improves the assembly quality and efficiency.

[0035] Using the new production process, the process flow only needs four processes of numerical control cutting of steel plate, cold forging, letter pressing, drilling and assembly welding, and the process flow is significantly reduced. The yield of laser cutting blanks per day can reach 2000 (outsourced), and the cold forging speed of the tail of these 2000 pieces can reach 5s / piece. The surface quality of the laser cutting parts is good, and there is no need for subsequent polishing, reducing the polishing process. According to the new production process, the production efficiency is much higher than that of the current forging production process, which can ensure the production progress of the company's whole vehicle.

[0036] In this embodiment, in order to verify the effect of the double-hole pull rod head formed by numerical control cutting and cold forging, the double-hole pull rod head formed by numerical control cutting is physically detected according to the requirements of the "General Technical Conditions for Forgings" (Q / QC35-102-2019). The detection items include chemical composition analysis, hardness detection, and mechanical property test, and the detection results are as follows: Chemical composition analysis:

[0037] Hardness detection:

[0038] Mechanical property test:

[0039] Through the chemical composition analysis, hardness detection and mechanical property test of the actual object, the results show that the double-hole pull rod head formed by the numerical control blanking of the steel plate has the chemical composition and mechanical properties meeting the requirements of GB / T700, and the tensile strength and hardness meet the requirements of Q / QC35-102-2019. It can be seen that after the double-hole pull rod head is changed from forging forming to steel plate numerical control blanking and then cold pressing forming, the product quality and production efficiency are obviously improved, and the product size and performance meet the requirements of the drawing and the related requirements.

[0040] The above is only an embodiment of the present application, and the specific technical solutions and / or common knowledge of characteristics in the scheme are not described in detail. It should be noted that for those skilled in the art, without departing from the technical solutions of the present application, a number of modifications and improvements can be made, which should also be considered as the protection scope of the present application, and these will not affect the effect and practicality of the present application. The protection scope of the present application should be subject to the content of its claims, and the specific implementation mode and the like recorded in the specification can be used to explain the content of the claims.

Claims

1. A novel process for production of double hole pull head characterized in that, The method comprises the following steps: (1) cutting blanking: cutting the outline profile of the pull rod head directly from a 14mm thick Q235A steel plate by laser cutting; (2) cold forging tail: cold forging the tail of the cut blank to form the shape required by the drawing; (3) letter pressing: pressing the identification on the part; (4) drilling and assembly welding: drilling and welding with other components to complete the assembly.

2. A process for producing a new double-hole drawbar head, according to claim 1, characterized by: Before cutting, the reinspection process is also included. When it is internal blanking, the raw material is pre-treated and re-inspected before cutting. When it is external blanking, random sampling inspection is carried out before subsequent operation.

3. A process for producing a new double-hole drawbar head, according to claim 1, characterized in that: In step (1), the steel plate is fixed on the cutting workbench, and the equipment is started to automatically complete the profile cutting of all parts, with a cutting accuracy of ±0.1mm.

4. A process for producing a new dual-hole pull rod head according to claim 1, characterized in that: In step (2), the numerically controlled cut blank is placed in the cold forging die, and a pressure of 1.1-3.1KJ is applied to the tail of the blank at room temperature to cause plastic deformation and form the tail shape.

5. A novel process for production of double hole pull stud head as claimed in claim 2, wherein: When it is external blanking, it also includes shot blasting after step (2) to perform shot blasting on the part to remove surface oxidation and burrs.

6. A process for producing a new dual-hole pull rod head according to claim 5, characterized in that: The shot blasting time is 0.3~0.5h, the shot blasting force is 0.2~0.5mmA, and the shot diameter is 1~2mm.

7. A new process for production of double hole pull stud head as claimed in claim 1, wherein: In step (3), the part is positioned on the letter pressing die, and the required identification, model or production batch number is pressed on the specified position of the part.

8. A new process for production of double hole pull stud head as claimed in claim 1, wherein: It also includes surface strengthening by laser shock peening or ultrasonic rolling before the cold forging process.

9. A new process for production of double hole pull stud head as claimed in claim 1, wherein: During laser cutting, the laser power and cutting speed are adjusted according to the quality of the cut.

10. A process for producing a new dual-hole pull rod head as claimed in claim 9, characterized in that: Image capture is performed during cutting or at the moment when one profile cutting is completed, the captured image is compared with the basic shape image, and the laser power and cutting speed are adjusted based on the comparison result.

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