Dieless Drawing Research Articles

Effects of oxidation and surface roughening on drawing limit in dieless drawing process of SUS304 stainless steel microtubes

In this study, we investigate the effects of surface roughening and oxidation, which are dependent on the heating temperature, on the drawing limit in the dieless drawing process of SUS304 stainless steel microtubes. The microtubes have an outer diameter of 0.5mm and a thickness of 0.13mm. Dieless drawing apparatus with a chamber filled with argon gas to prevent oxidation is used in the experiments. It was found that the limiting reduction in area increases to a maximum value and then decreases with increasing heating temperature in both argon gas and air. An appropriate heating temperature range from 950 to 1100°C with the maximum drawing limit is obtained from the dieless drawing experiment. In addition, the drawing limit in air is lower than that in argon gas at low temperatures of below 950°C owing to oxidization. In contrast, the drawing limit in air at high temperatures of over 1100°C is higher than that in argon gas, because the oxidation inhibits free surface roughening due to grain growth. Consequently, the drawing limit in dieless drawing strongly depends on the heating temperature. The roles of oxidation and surface roughening, which affect the drawing limit in the dieless drawing of microtubes, also vary widely depending on the heating temperature.

Experiment Study on Section Shape Variations During Tapered Square Pipe Dieless Drawing

Experiment Study on Section Shape Variations During Tapered Square Pipe Dieless Drawing

10512 レーザマルチパスダイレス引抜きにおけるステンレス微細管の表面平滑化の効果

10512 レーザマルチパスダイレス引抜きにおけるステンレス微細管の表面平滑化の効果

Formability Discussion in Dieless Drawing of Stainless Steel Tubes

Stainless steel tubes are widely used in various fields, such as electrode tubes, probe tubes, electronic parts, painless injection needles, and micro-nozzles etc. In this study, a self-developed prototype dieless drawing machine is used to explore the formability of the dieless drawing process of SUS304 stainless steel tubes. The critical process parameters of the forming temperature, drawing velocity, the drawing accelerations and area reduction are investigated. A commercial finite element code of DEFORM 3D is used to simulate the temperature, stress, strain distributions and drawing velocity limit in the dieless drawing process of the stainless steel tubes. The maximum area reduction obtained can reach 50% and the better forming temperatures are between 1000°C and 1100 °C.

Development of Rotary Laser Dieless Drawing Apparatus for Metal Microtubes

We develop new drawing technologies of rotary laser dieless drawing for the fabrication of micro-tubes without the need for tools such as dies, plugs and mandrels. A rotary laser dieless drawing apparatus with local heating using a laser irradiated from one direction as the heating source has been focused on for the fabrication of micro-tubes. In this study, a dieless drawing with a semiconductor laser setup with power of 30W is designed and developed. A workpieces was rotated about a tensile axis by rotary stage with chucks for circumferential uniform temperature distribution. A tube of stainless steel SUS304, with an outer diameter of 0.5mm and thickness of 0.13mm is used in the experiments. In this experiment, we verify the effectiveness of the developed rotary laser dieless drawing apparatus.

Mechanical, microstructural and thermal properties of a 50:50 at.% nickel–titanium alloy subjected to a dieless drawing process

It is widely recognized that hot working, grain structure, degree of deformation and crystal orientation can have a significant effect on the thermomechanical properties of Nitinol, the shape memory alloy of nickel and titanium, widely used in the biomedical device industry. In the current work, a novel hot-working process was applied to Nitinol rods with subsequent material hardness testing, electron backscatter diffraction (EBSD) and differential scanning calorimetry (DSC) analysis performed to determine the mechanical properties, grain texture and transformation temperatures of the processed Nitinol. The properties of the processed alloy, as ascertained by the aforementioned techniques, were compared to the as-received material. It was established that processing the material had the beneficial effect of softening the material from the as-received condition, making the material suitable for subsequent forming operations, such as cold drawing. EBSD results showed a strong preference towards a 〈101〉 texture in the processed material with some preference also towards a 〈111〉 texture. The results of the DSC analysis, which measured the transformation temperatures of the processed Nitinol material, showed a significant reduction in the austenite finish transformation temperature of the processed material compared to that of the as-received material. Tensile tests carried out to determine changes in the superelastic behaviour of the material due to the dieless drawing process corroborated and emphasized the results of the hardness tests, EBSD and DSC analyses. The process has resulted in a material with lower transformation temperatures, higher ductility and reduced tensile flow stress. The upper loading plateau begins at a lower strain and is present over a longer strain range.

Deformation Profile in Rotary Laser Dieless Drawing Process for Metal Microtubes

A novel rotary laser dieless drawing process for metal microtube with local heating using a laser irradiated from one direction is proposed. A metal microtube is rotated about a tensile axis by rotary stage with chucks for circumferential uniform temperature distribution. A tube of stainless steel SUS304 with an outer diameter of 0.5mm and thickness of 0.13mm is used in the experiments. The rotating effects on outer diameter variation and outer radius error are evaluated in laser dieless drawing. As a result, the outer diameter variation under a condition of non-rotation is higher than that under condition of rotation. Thus, the limit of stable drawing condition can be enhanced by rotating effect in laser dieless drawing. In addition, in case of laser heating irradiated from one direction under non-rotating, the deformation amount of irradiated side is larger than that of non-irradiated side in laser dieless drawing. Meanwhile, the microtube is drawn subequally under condition of rotation due to circumferential uniform temperature distribution. Thus, the distorted radial deformation can be restrained by rotating effect. From these results, the effectiveness of the proposed rotary laser dieless drawing for fabricating metal microtubes can be demonstrated experimentally.

A New Forming Method of Tapered Wire-Pole with Square Cross-Section

It is difficult to give shapes for tapered wire-pole with square cross-section in conventional plastic working process. A new dieless drawing method for making wire-pole has been developed. Through the dieless drawing theoretical study and experimental analysis of the wire-pole, a new wire-pole dieless drawing process is developed. The methods to ascertain key technique parameter are given out and the drawing velocity model is established. The experimental study shows that the dieless drawing technique is reasonable novel, the equipment is simple and one dieless drawing production procedure can replaces complete forming procedure in the general for tapered wire-pole dieless forming, which completes the deformation heat treatment, enhances the product’s overall performance simultaneously and has the practical value.

Study on Mathematical Model of Dieless Drawing Speed Control for Variable Section Pipes

Dieless drawing, as a flexible metal forming method, could form pipes with arbitrary variable section. In order to control the shape and dimensions accurately, based on the analysis of deformation mechanism of arbitrary variable section pipes via dieless drawing process, the calculation method of dieless drawing speed during pipe forming is proposed theoretically,Furthermore, mathematical model of dieless drawing speed control is established by using piecewise polynomial to approach continuous speed curve. The study provide the basis for the dieless drawing speed microcomputer control system. The results of experimental investigation showed that the mathematical model indicates variation of dieless drawing speed quite well, and it is available to schedule the speeds for arbitrary variable section pipes dieless drawing.

Fabrication of noncircular multicore microtubes by superplastic dieless drawing process

A superplastic dieless drawing process that requires no dies or tools is applied to the drawing of a Zn–22Al superplastic alloy for noncircular microtubes such as square, rectangular and noncircular multi core tubes having square inner and rectangular outer cross-sections. In this study, the effects of heating condition, such as heating length and the use or nonuse of cooling device, on deformation behavior are investigated. As a result, a square microtube with 0.58mm side and a rectangular microtube of 0.75mm×1.3mm were fabricated after 3-pass superplastic dieless drawing. In addition, the fundamental deformation behavior of noncircular tubes combined with square and rectangular tubes during the dieless drawing process has been clarified experimentally. The cross-sectional shape of the noncircular tubes after the superplastic dieless drawing process tends to be maintained on the basis of the similarity law in case of a wide heating length compared with a narrow heating length. Furthermore, a noncircular microtube, which has inner square tubes with a 335μm side, and an outer rectangular tube of 533μm×923μm were fabricated successfully after a 4-pass superplastic dieless drawing process. Consequently, it was found that the superplastic dieless drawing is effective for the fabrication of noncircular multicore microtubes.

Dieless drawing of stainless steel tubes

This study develops a dieless drawing prototype machine for tube or wire drawing processes. The proposed dieless drawing machine is composed of three main parts: a supporting frame, a heating device, and a transmission system. A high-frequency heating apparatus serves as the heating source, and an infrared thermocouple is used to monitor the heating temperature. A servomotor moves the heating coils in the opposite direction to the drawing clamp table to control the relative speed and area reduction of the stainless steel tube workpiece. A series of experiments were conducted to test the effects of different relative speeds between the heating source and drawing clamp table. The maximal area reduction achieved was approximately 40 % of the initial cross-sectional area at a drawing speed of 0.8 mm/s. Finite element simulations were also conducted to analyze the formable regions at different relative speed ratios, drawing speeds, and heating temperatures. The study verifies the validity of the numerical model by comparing the area reductions and shape similarity of the drawn tubes to numerically predicted and experimentally measured values.

Research on Dieless Drawing Process of Stainless Steel Tapered Tube

The traditional forming technologies of stainless steel tapered tube have some disadvantages, such as its complicated processes, few product specification, low production efficiency and high production cost. Dieless drawing is a new kind of near net-shaping process for fabricating tapered metallic tubes with large deformation per pass, high yield ratio of material and flexible production. Dieless drawing of stainless steel tapered tube was studied systematically in order to establish both temperature field model with respect to the changes of boundary condition and metal flow velocity during deformation, and a drawing speed controlling model with respect to the volume change of deformation zone. The models were verified by experiments in the present investigation. Finally, a continuous pickling process with variable-speed was proposed for tapered metallic tube, which was successfully applied to surface oxidation film removal of the stainless steel tapered tube.

Rectifying control of wire diameter during dieless drawing by a deformation measuring method of interframe displacement

A deformation measurement method of interframe displacement was proposed in this paper. By online monitoring the shape dimensions of both the deformation zone and its adjacent zone by machine vision, the initial and terminative positions of deformation were dynamically identified during dieless drawing, and the global monitoring and online closed-loop control of the deformation zone were achieved. The dieless drawing process was systematically carried out on NiTi shape memory alloy wires. It is shown that the deformation measurement method of interframe displacement can track the axial displacement of the wires, but this cannot be achieved by traditional machine vision. The initial and terminative positions of deformation can be accurately identified by this method. The proposed rectifying control technology can effectively decrease the wire diameter fluctuation during dieless drawing, that is, the standard deviation of the wire diameter fluctuation could be decreased from 0.30 to 0.08 mm after three passes of dieless drawing, indicating that the control system has a good rectifying ability.

Primary Study of Dieless Drawing Process for Bimetal Tube

At present, bimetal tube has been used wildly in industry and there are many methods for preparation these kinds of tubes. In consideration of deficiencies of available methods, a new technique of bimetal tube preparation was presented in this paper. With appropriate design and manufacture of facility and design of experiment, copper clad steel tube was prepared. Feasibility and practicability of this process was verified by conclusion of research. At last, the following study was discussed.

Experimental study on dieless drawing of Nickel–Titanium alloy

The effect of a dieless drawing process on commercial grade Nickel–Titanium rods, of 5 mm diameter, was investigated by varying the established critical process parameters of temperature, cooling rate, drawing velocity, and heating/cooling velocity. The rods were successfully dieless drawn with a maximum steady state reduction in cross-sectional area of 54%. The thermal and mechanical loading profiles of the rod during processing, and the resulting changes in microstructure and hardness, have been investigated. Uniform levels of stress and strain resulted in uniform reduction of the rod cross-sectional area. The grain structure was highly deformed in the drawing direction and increased porosity was observed as a result of the process. The longitudinal section hardness of the rod was significantly reduced as a result of the dieless drawing process. Any failures that arose were due to discontinuities within the material microstructure caused by a high necking rate, shorter exposure time to the process temperature and low heating and cooling rates. A uniform oxidation layer was observed on the surface of the processed rods as a result of processing in atmospheric conditions. This oxidation layer has the potential to aid in the lubrication of subsequent cold working operations of the dieless drawn rods. Coupling the thermomechanical effects of the dieless drawing process with a cold drawing processing step has the potential to produce a NiTi wire in fewer passes, and therefore at a reduced cost.

922 金属マイクロチューブのダイレス引抜き過程における変形挙動に及ぼす表面性状の影響

Microtube is commonly used and required. Dieless drawing is fabrication process of microtube. However, in the dieless drawing process, oxidation occurs on tube surface because of local heating and it reduces reduction in area. In this study, methods of fabrication process of non-oxide tubes and the effect of surface quality on deformation behavior in dieless drawing process for metal microtubes was investigated. Materials used are stainless SUS304 tubes and copper alloy C1220 tubes. SUS304 tubes with outer diameter of 500μm and thickness of 130μm and 100μm. C1220 tubes with outer diameter of 500μm and thickness of 130μm. As a result, argon gas atmosphere reduced oxide film on the tube surface in dieless drawing process. In case of low temperature, oxide film decreases the limiting reduction in area. On the contrary, in case of high temperature, oxide film enhances the limiting reduction in area, because surface roughness with oxide film is lower than that of non-oxide film under condition of argon gas atmosphere.

Real-Time Process Control System of Dieless Tube Drawing with an Image Processing Approach

Dieless tube drawing is one of the advanced material forming technologies to reduce cross section area of a tube with the absence of dies, mandrel and lubricant. However, this promising technique has technological challenges to improve dimensional stability and accuracy. Machine vision based on image processing technique was selected to monitor deformation behavior on dieless drawing process. The present paper describes real-time monitoring using image processing approach in order to achieve real-time process control of dimensional profile and temperature distribution during dieless drawing process. The results show that machine vision is effective and efficient to monitor dieless drawing process.

Deformation and Heat Transfer Analysis for High Speed Dieless Drawing of AZ31 Magnesium Alloy Tubes

The effect of drawing speed and heating length on deformation behavior was investigated by numerical approach for AZ31 magnesium alloy tubes to realize high speed dieless drawing process. The length of deformation zone expands with increasing the feeding speed. The increase in heating length leads to expanding length of deformation zone. The mean strain rate increases with increasing the feeding speed firstly, and then rate of increase in the strain rate becomes gradual under condition of any length of heating band. Based on these results, a limiting reduction in area of 52.5% under higher speed and larger heating length conditions can be realized experimentally.

Processing limit maps for the stable deformation of dieless drawing

Tin bronze wires were produced by dieless drawing. The effects of heating power, the distance between cooler and heater as well as feeding speed on the diameter, the temperature field, and the deformation region profile of the wires were investigated. The results indicated that each processing parameter exhibited both lower and upper limits of stable deformation based on the criterion of stable deformation with the diameter fluctuation of ±0.05 mm. Both the temperature and its gradient of the deformation region increased with increasing heating power under stable deformation, but decreased with an increase in feeding speed. As the distance between cooler and heater increased, the temperature of the deformation region increased and the slope of the deformation region profile decreased. The processing limit map of stable deformation exhibited a closed curve and the unstable deformation consisted of wire breakage and diameter fluctuations.

Development of Precision Profile Control System with Fuzzy Model and Correction Function for Tube Dieless Drawing

Dieless drawing offers several advantages not only lack of the expensive dies and lubricant but also the ability to draw difficult material since the process is carried out at elevated temperature. However dimensional stability and accuracy is still unsolved issue. A finite element method (FEM) is utilized to examine a valid deformation behavior. As the result, a correction function is formulated from deformation sequence of dieless drawing to predict elongation of desired profile. A new approach to control desired profile of dieless drawing parts using a fuzzy model and correction function is presented in this paper. The result shows that by applying fuzzy control and correction function model, dimensional accuracy of drawn tube profile increases significantly.