The company has followed the continuous growth of customers step by step, and now it has begun to take shape, Vanroad has nearly 45 presses of various types ranging from 25t to 1250t (sets), the maximum stamping speed can reach 1000spm. With the strong support of auxiliary leveling machines and other equipment as well as our die processing equipment, we can meet various requirements for stamping products. The stamping materials include all kinds of copper alloy, aluminum alloy, steel, iron and all kinds of composite materials, with a thickness from 0.08mm to 6.0mm.

400T (continuous die production line), 500T (transfer die production line) punch

        Automotive stamping parts are an important part of the automotive industry. The improvement of stamping process is conducive to improve the quality of the overall automotive industry. The improvement of automobile stamping process has an important impact on the whole machining process. Wanrong auto parts has been committed to customized processing of automotive stamping parts for more than ten years and has accumulated rich experience.

        Vanroad strives to create a high level of stamping technology management. Vanroad conducts professional analysis, research, optimization and continuous improvement in all aspects, including on-site environment, tool and oil selection, as well as fool proof, wrong placement, online monitoring and automatic transformation, so as to ensure that the company has always maintained high advantages and competitiveness in the same industry.

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       Stretching, also known as drawing, deep drawing, calendering, etc., is one of the stamping processes. It refers to a stamping process in which a certain shape flat blank obtained after blanking is stamped into various open hollow parts by using a die, or the open hollow blank is reduced in diameter and increased in height. Thin wall parts with cylindrical, stepped, conical, spherical, box and other irregular shapes can be manufactured by drawing process. With flanging, bulging, expanding, necking and other stamping processes, it can also manufacture parts with extremely complex shapes. This process has a wide range of applications and plays a certain role in some automobile covers, covers, shells of electrical instruments and many daily necessities. Therefore, the drawing process plays a very important role in the production process of automobile, aircraft, communication, electrical appliances, instruments, electronics and other industrial departments.

       However, the drawing process is quite different from other stamping processes. The drawing process has a great impact on the experience and skills of die designers and die fitters, the analysis of product structure, the calculation of process parameters, the arrangement of drawing process, the accuracy of die making, the performance analysis of raw materials, the debugging of die, the selection of stamping machine The selection of lubricating oil has high technical and experience requirements. It is precisely because of this that the companies that can do all-round stretching products in the same industry are rare and few compared with other ordinary stamping companies.

        In the process of focusing on the field of auto parts, Wanrong company has accumulated more comprehensive experience in the development and production of various types of tensile parts, and the existing core technical team has rich experience in the development of tensile parts, At present, the developed stretch products have covered a variety of production modes (including single process die, continuous die and transfer die), a variety of materials (stainless steel, iron, aluminum alloy, copper, etc.) and applied in a variety of fields (such as automotive damping system, control unit, automotive electronics, etc.) based on the company's existing experience and the analysis of the above application fields of tensile parts, Wanrong company has always vigorously developed and promoted tensile parts products as a main business of the company.

     When evaluating the drawing process, VANROAD company comprehensively combines the actual situation of the company's equipment and personnel, and comprehensively considers the quality requirements of parts, production efficiency, production cost, labor intensity, environmental protection and production safety, and selects and designs a process scheme with advanced technology, reasonable economy and safe and reliable use, On the basis of ensuring that the production meets the technical requirements put forward in the design drawings, reduce the process cost and ensure safe production as much as possible, so as to provide customers with more reliable and cost-effective tensile parts solutions.

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1、 Types of metal drawing process

(1) Cylinder stretching: stretching of the cylinder with flange. The flange and the bottom are straight faces, the cylinder is axisymmetric, the deformation is uniform on the same circumference, and the blank on the flange produces deep drawing deformation.

(2) Elliptical stretching: the blank on the flange is stretched and deformed, but the deformation amount and deformation ratio change accordingly along the contour shape. The greater the curvature, the greater the deformation of the blank; the smaller the curvature, the smaller the deformation of the blank.

(3) Rectangular stretching: a low rectangular part formed by one-time stretching. During stretching, the tensile resistance at the fillet of the flange deformation area is greater than that at the straight edge, and the deformation degree at the fillet is greater than that at the straight edge.

(4) Mountain drawing: the side wall is suspended in the stamping process, and the die is not pasted until the end of forming. The deformation characteristics of different parts of the side wall are not exactly the same during forming.

(5) Hill shaped stretching: the blank deformation of hill shaped cover plate in the forming process is not a simple tensile deformation, but a composite forming in which tensile deformation and bulging deformation exist at the same time.

(6) Hemispherical drawing with flange: during the drawing of spherical parts, the blank is in partial contact with the spherical top of punch, and most of the rest are suspended.

(7) Flange stretching: stretch the part of the stretched flange lightly. Its stress-strain condition is similar to that of compression flanging.

(8) Edge stretching: carry out angular re stretching on the flange part, and the material is required to have good deformation.

(9) Deep stretching: it can only be completed after more than two times of stretching. For the wide flange stretching part, it will be stretched to the required flange diameter at the first stretching, and the flange diameter will remain unchanged during subsequent stretching.

(10) Conical stretching: due to the large degree of deep deformation, the deep conical part is very easy to cause local excessive thinning and even fracture of the blank, which needs to be gradually formed after many transitions.

(11) Rectangular re stretching: the deformation of high rectangular parts formed by multiple stretching is not only different from that of deep cylindrical parts, but also very different from that of low box parts.

(12) Surface forming: surface stretch forming, which reduces the outer flange part of the metal plate blank and elongates the inner flange part to form a non straight wall and non flat bottom surface shape.

(13) Step stretching: the initial stretching is re stretched to form a step shaped bottom. The deep part deforms at the early stage of stretching, and the shallow part deforms at the later stage of stretching.

(14) Reverse stretching: the reverse stretching of the workpiece stretched in the previous process is a kind of re stretching. The reverse stretching method can increase the radial tensile stress and achieve good results in preventing wrinkling. It is also possible to improve the stretching coefficient of re stretching.

(15) Thinning stretching: different from ordinary stretching, thinning stretching mainly changes the thickness of the cylinder wall of the stretched part during the stretching process.

(16) Panel stretching: the surface shape of the panel is complex. In the stretching process, the blank deformation is complex, and its forming property is not a simple stretching forming, but a composite forming with both deep drawing and bulging.

2、 Scheme of metal drawing process

(1) Design review: our engineers will review the part design in detail to ensure that it is suitable for deep stamping. This includes in-depth analysis of part size, material, drawing ratio and required tolerance. According to the workpiece drawing, analyze the shape characteristics, size, accuracy requirements, raw material size specifications and mechanical properties of the workpiece, combined with the available equipment specifications and production Production batch and other factors. Good drawing technology should ensure less material consumption, fewer processes, less equipment occupation, simple die structure, high service life, stable quality and simple operation.

(2) DFM analysis: the main process parameter calculation is based on the stamping process analysis to find out the process characteristics and difficulties, and put forward various possible drawing process schemes according to the actual situation, including process nature, process number, process sequence and combination mode, etc. sometimes there may be multiple feasible process schemes for the same workpiece, and usually each scheme has its own advantages and disadvantages The best scheme suitable for the existing production conditions shall be determined by comprehensive analysis and comparison from the aspects of product quality, production efficiency, equipment occupation, difficulty and service life of mold manufacturing, production cost, convenient operation and safety.

(3) Calculation of process parameters: process parameters refer to the data on which the process scheme is based, such as various forming coefficients (drawing coefficient, bulging coefficient, etc.), part expansion size and various stresses. There are two cases of calculation. The first is that the process parameters can be calculated accurately, such as material utilization of part layout, workpiece area, etc; The second is that the process parameters can only be approximately calculated, such as general bending or deep drawing forming force, blank expansion size of complex parts, etc. the determination of such process parameters is generally roughly calculated according to empirical formulas or charts, and some need to be adjusted through tests.

(4) CAE simulation analysis: use CAE simulation analysis software to create the prototype of parts. Before the production process begins, run the prototype through a large number of operation simulations to find any design problems.

Schematic diagram of blank unfolding simulation analysis of drawing and deep drawing parts

      (5) Equipment selection: select the stretching equipment, reasonably select the equipment type and tonnage according to the nature of the process to be completed and the force and energy characteristics of various equipment, consider the required deformation force, size and other main factors, and combined with the situation of existing equipment.

3、 Selection method of stretch oil

(1) Because silicon steel plate is a material that is easy to stretch, low viscosity stamping oil will be selected on the premise of preventing scratches in order to make the finished workpiece easy to clean.

(2) When selecting drawing oil for carbon steel plate, the first thing to pay attention to is the viscosity of drawing oil. The better viscosity is determined according to the process difficulty and degreasing conditions.

(3) Because of the chemical reaction with chlorine additives, when selecting drawing oil for galvanized steel plate, attention should be paid to the possibility of white rust in chlorine type stamping oil, and the use of sulfur type drawing oil can avoid rust.

(4) Stainless steel is a material easy to harden. It is required to use drawing oil with high oil film strength and good sintering resistance. Generally, drawing oil containing sulfur and chlorine composite additives is used to ensure extreme pressure performance and avoid burrs, cracks and other problems of workpieces.

        These are the common types of metal drawing process. With the rapid development of precision drawing technology, machinery manufacturing, automobile R & D, aerospace and other fields will benefit more.