KR101210889B1 - Severe plastic deformation system and method for working wire rod using the same - Google Patents

Abstract

PURPOSE: A severe plastic deformation apparatus and a wire rod processing method using the same are provided to improve productivity by processing a machine element with a head through a continuous process of a multi-stage press. CONSTITUTION: A severe plastic deformation method comprises the steps of: shearing a wire rod(10) with an ECAP(Equal Channel Angular Pressing) unit(200) to obtain a first preform(S20), extruding the first preform using an extrusion unit(300) to obtain a second preform with a head(S30), upsetting the second preform using an upsetting unit(400) to obtain a third preform with a head(S40), and heading the third preform using a first heading unit(500) first to obtain a machine element with a head(S50). [Reference numerals] (S10) Cutting; (S30) Extrusion; (S40) Upsetting; (S50) First heading; (S60) Second heading

Description

Rigid plastic processing equipment and wire processing method using the same {SEVERE PLASTIC DEFORMATION SYSTEM AND METHOD FOR WORKING WIRE ROD USING THE SAME}

The present invention relates to a rigid plastic working apparatus and a method for processing a wire rod using the same, and more particularly, to a rigid plastic working apparatus for processing a mechanical element having a head such as a head stud and a method for processing a wire rod using the same.

Plastic processing of metal materials is performed in various ways such as forging, rolling, extrusion, drawing, and form rolling. Wire rods are made of various mechanical elements with heads by extrusion, upsetting, heading, etc., for example studs, bolts, pins, rivets. (Rivet), a key (Key), a shaft (Shaft), etc. are manufactured.

Meanwhile, grain refinement of wire rods is characterized by having excellent mechanical properties such as improved strength, toughness and formability, low thermal conductivity, superplasticity, and weight reduction. Severe plastic deformation is a method of producing ultra-fine grain metal materials by applying large plastic deformation to wire rods. Rigid-fiber processing for producing wire rods into ultrafine or nanocrystalline microstructures is divided into equal channel angular pressing (ECAP) and equal channel angular drawing (ECAD). ECAP is processed by shearing wires while passing them through channels of dies that are bent at an angle. Therefore, the grains of the wire rod can be refined and manufactured.

However, as described above, the ECAP is limited to supply and discharge of wire rods, and thus, the ECAP has not been adopted for the production of headed mechanical elements such as headed studs.

The present invention has been made to solve the above problems, an object of the present invention, a rigid plastic processing apparatus that can manufacture a machine element having a head by a multi-step including ECAP and a wire rod processing method using the same In providing.

Another object of the present invention is to provide a rigid plastic working apparatus capable of improving the rigidity by miniaturizing the grains of the machine element by ECAP and a method of processing the wire rod using the same.

Still another object of the present invention is to provide a rigid plastic working apparatus which can be manufactured by a continuous process of a multi-stage molding machine and a method for processing wire rods using the same.

A feature of the present invention for achieving the above object is the ECAP step of shearing the wire rod by the ECAP unit to process the first pre-processed product; Extruding the first prefabricated article by an extrusion unit to process the second prefabricated article having a head; Upsetting the second pre-processed article by the upsetting unit to process the third pre-processed article having a head; In the rigid plastic processing method comprising a first heading step of processing the third pre-processed product by the first heading unit to the first heading machine element having a head.

Another feature of the present invention, ECAP unit for processing the first pre-work by shearing the wire rod; An extrusion unit, disposed downstream of the ECAP unit, for extruding the first pre-processed product into a second pre-processed product having a head; An upsetting unit disposed downstream of the extrusion unit and configured to upset the second prefabricated product to process into a third prefabricated product having a head; It is disposed downstream of the upsetting unit, and comprises a primary heading machine for primary heading the third pre-processed part into a headed mechanical element.

The rigid plastic processing apparatus and the method of processing the wire rod using the same according to the present invention can manufacture a machine element having a head such as a head stud and a bolt by a multi-step including an ECAP, and by minimizing the grain size of the machine element by the ECAP Stiffness can be improved. Since it can manufacture by the continuous process of a multistage molding machine, there exists an effect which can improve productivity.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view showing for explaining a first embodiment of a rigid plastic working apparatus and a method for processing a wire rod using the same according to the present invention;
2 is a cross-sectional view for explaining the ECAP apparatus in the first embodiment of a rigid plastic working apparatus according to the present invention;
Figure 3 is a photograph showing the pre-processed products and the finished product of Example 1 and Comparative Example manufactured by the first embodiment of the rigid plastic processing method according to the present invention,
4a and 4b are photographs taken by transmission electron microscope of the microstructure of the wire rod and the first prefabricated product in the first embodiment of the rigid plastic working method according to the present invention,
5 is a photograph taken by a transmission electron microscope of the microstructure of the head, neck and torso in the finished product of Example 1 and Comparative Example manufactured by the first embodiment of the Jiangsu processing method according to the present invention,
6 is a true strain-true stress diagram for the finished product of Example 1 and Comparative Example manufactured by the first embodiment of the rigid plastic processing method according to the present invention.
7 is a view showing a second embodiment of a rigid plastic working apparatus according to the present invention and a wire rod processing method using the same;
8 is photographs showing the pre-processed products and the finished product of the pre-processed product of Example 2 according to the second embodiment of the rigid plastic processing method according to the present invention.

Other objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description and preferred embodiments with reference to the accompanying drawings.

Hereinafter, preferred embodiments of a rigid plastic working apparatus according to the present invention and a method for processing a wire rod using the same will be described in detail with reference to the accompanying drawings.

First, referring to Figure 1, the first embodiment of the rigid plastic processing method according to the present invention is cutting (Sutting), SCAP, ECAP (S20), Extrusion (S30), Upsetting (Upsetting) of the wire rod 10 S40), through the steps of the first heading (Heading, S50) and the second heading (S60) to produce a finished product (60).

The cutting unit 100 of the rigid plastic processing apparatus according to the present invention cuts the wire rod 10 to a predetermined length. The wire rod 10 cut by the cutting unit 100 is a so-called blank workpiece. The extrusion unit 300 has a die 302 and a punch 304, and extrudes the first pre-processed product 20 manufactured by the ECAP unit 200 into the second pre-processed product (30). The head 32 is formed in one end of the second preprocessed product 30. The upsetting unit 400 has a die 402 and a punch 404, and compresses the second preliminary workpiece 30 in the axial direction to shorten the length thereof to produce a third preprocessed article 40. . A head 42 is formed at one end of the third preprocessed product 40.

The first heading unit 500 has a die 502 and a punch 504, and heads the head 42 of the third pre-processed product 40 to produce the head 52 of the mechanical element 50. The second heading unit 600 is composed of a die 602 and a punch 604, the head 52 of the fifth pre-processing 50, the head 62 and the flange (Flange) of the finished product 60 64). In the present embodiment, the molding of the flange 64 by the secondary heading S60 may be eliminated. In this case, the mechanical element 50 with the head 52 is a finished product.

Cutting unit 100, ECAP unit 200, extrusion unit 300, upsetting unit 400, the first heading unit 500 and the second heading unit 600 of the rigid plastic processing apparatus according to the present invention It is installed in a multi-stage former or a multi-process press machine to process the wire rod 10 into a finished product 60. Multi-stage molding machine is a transfer type automatic forging machine for cutting and multi-stage molding of long material.

Referring to FIGS. 2A to 2D, the ECAP apparatus 200 for shear deformation of the wire rod 10 may include a housing 210, a sliding die 220, and an upper die 230. ), Spring 240 and kick-out pin (250). The housing 210 has a bore 214 in which the inlet 212 is formed. The sliding die 220 is mounted to slide in the bore 214. A bore 222 for inserting the wire rod 10 is formed at the center of the sliding die 220. The first channel 224 for shear deformation of the wire rod 10 is formed on the upper surface of the sliding die 220 from the bore 222. On the lower surface of the upper die 230, a second channel 232 is formed to mate with the first channel 224 for shear deformation of the wire rod 10. The upper die 230 is mounted on a ram or the like of the multi-stage molding machine and lifts with respect to the sliding die 220. The spring 240 is mounted to the bore 212 of the housing 210 to bias the sliding die 220 toward the inlet 214 by elastic resilience. The spring 240 is composed of a compression coil spring. Kickout pin 250 is fitted to bore 222.

As shown in FIG. 2A, the upper surface of the sliding die 220 is aligned with the inlet 214 in the die opening state of the sliding die 220 and the upper die 230. The upper end of the kickout pin 250 is aligned with the upper surface of the sliding die 220. The wire rod 10 is caught by a transfer feeder and a gripping unit and aligned with the top of the kickout pin 250. As shown in Fig. 1, the wire rod 10 is a so-called blank workpiece cut into a predetermined length by a cutter.

As shown in FIG. 2B, the upper die 230 is lowered to allow the first die 224 and the second die 232 to mate with the sliding die 220 and the die of the upper die 230. In the closing state, the wire rod 10 is inserted into the bore 222 while being pressed by the upper die 230. The kickout pin 250 is retracted by the insertion of the wire rod 10 by the driving of a pin actuator, for example, an air cylinder.

As illustrated in FIG. 2C, the upper die 230 is lowered to press the sliding die 220 while entering the bore 212 of the housing 210. The sliding die 220 compresses the spring 240 while descending along the bore 212. The wire rod 10 is sheared while being transferred to the first channel 224 and the second channel 232 by the lowering of the sliding die 220 and is processed into the first pre-processed product 20.

As shown in (d) of FIG. 2, when the upper die 230 is raised to be in the die opening state, the sliding die 220 is raised by the elastic restoring force of the spring 240. The kickout pin 250 is advanced by driving the pin actuator to eject the first pre-processed product 20 from the first channel 224.

Figure 3 shows a picture of the wire rod obtained by cutting, ECAP, extrusion, upsetting, primary heading and secondary heading, the first to fifth pre-processed products and the finished product of the first embodiment of the rigid processing method according to the present invention. In FIG. 3, the comparative example is a photograph of wires, pre-processed products and finished products obtained by cutting, extruding, upsetting, primary heading and secondary heading. Processing of the finished product in Example 1 and Comparative Example was carried out by a multi-stage molding machine (product name: HBPF-530SS, manufacturer Korea Hyodong Machinery Co., Ltd. and Japan Sakamura (HyoDong & Sakamura)). The production speed of the multi-stage molding machine was set to 30 rpm, and cold forging lubricating oil (product name: Renoform 356H, manufacturer: Fuchs Lubricant Co., Ltd.) was used to prevent seizure of material and die due to friction during the process. . The wire rod was used after drawing aluminum alloy AA6061-T6 and calibrating it to a diameter of 10.0 mm.

4A and 4B show photographs taken by transmission electron microscope of the microstructure of the wire rod and the first prefabricated product in the first embodiment of the rigid plastic working method according to the present invention. Referring to FIGS. 4A and 4B, it is difficult to find the occurrence of dislocations in the grains, and it can be seen that precipitates are evenly distributed in the grains. In the case of the first prefabricated product that has undergone the ECAP, point 3 shows a microstructure similar to the wire rod without undergoing the shear deformation of the ECAP, but it can be seen that the dislocation is somewhat generated inside the grains. In the microstructures of points 1 and 2 of the prefabricated product that passed through the shear deformation region of the ECAP, a large amount of dislocations were observed in the shear deformation zone structure composed of the sub-crystalline grains stretched in the shear direction and in the grain boundary, and the width of the shear deformation zone was 1 μm. It can be seen that the micronized below.

5 shows photographs taken by transmission electron microscopy of the microstructure of the head, neck and torso in the finished product of Example 1 and the finished product of Comparative Example manufactured by the first embodiment of the rigid plastic processing method according to the present invention. 5, it can be seen that the deformation applied to the material is less in the head of the finished product of Example 1 and Comparative Example. In addition, it can be seen that the development of hard grain boundary grains was not observed through the selected area electron diffraction of the transmission electron microscope.

In the neck and torso of the finished product, it can be seen that the development of crystal grains is greatly different. In the case of extrusion, the deformation zone due to shear deformation is not observed, but the grains are stretched in a certain direction. In the finished product of Example 1, the shear strain band structure was observed in both the neck and the body by the shear strain, and the width of the strain band was narrowed further by the extrusion after ECAP, so that it was about 500 nm or less. In particular, when the extrusion after the ECAP sufficient shear deformation is maintained up to the neck of the finished product of Example 1, the crystal grains are finer than the finished product of the Comparative Example, the interval between the crystal grains is narrowed it can be seen that the strength of the finished product of Example 1 further improved . Through the limited field electron diffraction, a ring pattern appears in the neck and torso of the finished product of Example 1, and it can be seen that the finished pattern of Example 1 has developed a ring pattern than the finished product of the comparative example.

6 is a diagram showing the relationship between true strain and true stress (MPa) for the finished product of Example 1 and the finished product of Comparative Example. Referring to the true strain-true stress diagram of FIG. 6, the elongation of the wire rod is about 10.4%, which shows a lower elongation than that of a low carbon steel for general cold forging. In Example 1 and Comparative Example, it can be seen that the elongation is reduced compared to the wire rod. The elongation of Example 1 is 7.5%, which is somewhat higher than the elongation of 7.2% of the comparative example. Although the maximum tensile strength of the wire rod is about 388 MPa, it can be seen that Example 1 is increased to about 460 MPa after ECAP and extrusion to increase about 19%. This value is 27 MPa higher than 433 MPa of the comparative example.

As such, it can be seen that in Example 1, the strength of the finished product can be increased without decreasing the elongation as compared with the comparative example. In addition, since the ECAP can be repeated ECAP without reducing the wire cross-section, when increasing the number of processes of the ECAP it can further improve the tensile strength of the finished product. On the other hand, it can be understood that the strength improvement of Example 1 is due to the finer grains and the precipitation hardening through the fine precipitates evenly distributed in the tissue during the measurement of the microstructure through the transmission electron microscope.

7 shows a second embodiment of a rigid plastic working method according to the present invention. Referring to Figure 7, the second embodiment of the rigid steel processing method according to the present invention is cut (S10), primary ECAP (S22), secondary ECAP (S24), extrusion (S30), upsetting of the wire rod 10 (S40), through the steps of the first heading (S50) and the second heading (S60) to produce a finished product (60). The cutting (S10), extrusion (S30), upsetting (S40), the first heading (S50), the second heading (S60) of the rigid plastic working method of the first and second embodiments. The primary and secondary ECAPs (S22, S24) of the rigid plastic working method of the second embodiment are to repeatedly perform the ECAP (S20) of the rigid plastic working method of the first embodiment twice. The second embodiment of the rigid plastic processing apparatus has the first and second ECAP units 200a and 200b, and the configuration and operation of the first and second ECAP units 200a and 200b are the same as those of the ECAP unit 200 described above. Do.

In the prefabricated product having passed through the primary ECAP (S22), fillets are formed near both ends with respect to the longitudinal direction. Such fillets may be left unattended during the molding process of the finished product and may cause unfilling. That is, when the end of the cut wire has a cylindrical shape, filling may occur in the vicinity of the head of the final head stud or bolt.

In the second embodiment of the rigid plastic processing method according to the present invention by performing the primary and secondary ECAP (S22, 24), the end of the pre-processed product after the secondary ECAP is formed in a cylindrical shape as shown in FIG. You can check it. Therefore, it is possible to prevent the unfilledness near the head of the finished product.

8 is a photograph of wire rods, pre-processed products and finished products obtained by cutting, primary ECAP, secondary ECAP, extrusion, upsetting, primary heading and secondary heading in a second embodiment of a rigid plastic working method according to the present invention. Indicated. Looking at the photograph of FIG. 8, it can be confirmed that the finished product of Example 2 is free of unfilled and flange defects near the head.

The embodiments described above are merely illustrative of the preferred embodiments of the present invention, the scope of the present invention is not limited to the described embodiments, those skilled in the art within the spirit and claims of the present invention It will be understood that various changes, modifications, or substitutions may be made thereto, and such embodiments are to be understood as being within the scope of the present invention.

10: wire rod 50: heading machine element
100: cutting unit 200: ECAP unit
200a: first ECAP unit 200b: second ECAP unit
210: housing 220: sliding die
230: upper die 240: spring
250: kickout pin 300: extrusion unit
400: upsetting unit 500: first heading unit
600: second heading unit

Claims (6)

An ECAP step of shearing the wire rod by the ECAP unit to process the first pre-processed product;
An extrusion step of extruding the first preprocessed product by an extrusion unit into a second preprocessed product having a head;
Upsetting the second pre-processed article by an upsetting unit to process the third pre-processed article with a head;
And a first heading step of processing the third pre-processed product first by means of a first heading unit into a mechanical element having a head. 2. The wire rod of claim 1, wherein the wire is cut by a cutting unit and supplied to the ECAP unit, and after the first heading step, the machine element is secondly headed by a second heading unit to flange the head of the machine element. Rigidity processing method further comprising a secondary heading step to form a. 3. The rigid steel processing method according to claim 1 or 2, further comprising a second ECAP step of shearing the first pre-processed article by a second ECAP unit after the ECAP step. An ECAP unit for shearing the wire rod and processing it into a first pre-processed product;
An extrusion unit, disposed downstream of the ECAP unit, for extruding the first pre-processed product into a second pre-processed product having a head;
An upsetting unit disposed downstream of the extrusion unit and configured to upset the second preprocessed product to a third preprocessed product having a head;
And a primary heading machine disposed downstream of the upsetting unit, the primary heading machine for primary heading the third pre-processed product into a machined element having a head. 5. The apparatus of claim 4, further comprising a cutting unit for cutting the wire rod and a secondary heading unit disposed downstream of the primary heading machine and secondary heading the machine element to form a flange to the head of the machine element. Jiangsu processing equipment, including. 6. The rigid steel processing apparatus according to claim 4 or 5, further comprising a second ECAP unit disposed between the ECAP unit and the extrusion unit and shearing the first pre-processed product.

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